Relationships Between Crystal, Internal Microstructures, and

Sep 25, 2018 - State Key Laboratory of Fine Chemicals, Key Laboratory of Industrial Ecology and ... Dalian University of Technology , Dalian 116024 , ...
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Relationships Between Crystal, Internal Microstructures and Physicochemical Properties of Copper-ZincIron Multinary Spinel Hierarchical Nano-Microspheres Shiying Fan, Xinyong Li, Libin Zeng, Mingmei Zhang, Zhifan Yin, Tingting Lian, and Aicheng Chen ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b11382 • Publication Date (Web): 25 Sep 2018 Downloaded from http://pubs.acs.org on September 29, 2018

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Relationships Between Crystal, Internal Microstructures and Physicochemical Properties of Copper-Zinc-Iron Multinary Spinel Hierarchical Nano-Microspheres Shiying Fan†, Xinyong Li*†, Libin Zeng †, Mingmei Zhang †, Zhifan Yin †, Tingting Lian †

and Aicheng Chen*‡

†State Key Laboratory of Fine Chemicals, Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China; ‡

Department

of

Chemistry, University

of

Guelph,

50

Stone

Rd

E, Guelph, Ontario N1G 2W1, Canada

*Corresponding author: Professor X. Li, E-mail: [email protected] Professor A. Chen, E-mail: [email protected]

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ABSTRACT Rational design and fabrication of high quality complex multicomponent spinel ferrite with specific microstructures and solar light harvestings towards CO2 reduction and antibiotic degradation to future energetic and catalytic applications are highly desirable. In this study, novel Copper-Zinc-Iron multinary spinel hierarchical nanomicrospheres (MSHMs) with different internal structures (solid nano-microspheres, yolkshell hollow nano-microspheres, and double-shelled hollow nano-microspheres) have been successfully developed by a facile self-templated solvothermal strategy. The morphology and structure, optical, as well as photo-induced redox reactions including interfacial charge carrier behaviors and the intrinsic relationship of structure-property between intrinsic nano-microstructures and physicochemical performance of CopperZinc-Iron ferrite MSHMs composites were systematically investigated with the assistance of various on- and/or off- line physic-chemical means and deeply elucidated in terms of the research outcomes. It is demonstrated that the modification of the interior microstructures can be applied to tune the catalytic properties of multinary spinel by tailoring the temperature programming to fine control the two opposite forces of contraction (Fc) and adhesion (Fa). Among various internal microstructures, the obtained double-shelled Copper-Zinc-Iron MSHMs exhibited the superior catalytic performance towards 8.8 and 38 μmol for H2 and CO productions as well as 80.4 % removal of Sulfamethoxazole (SMX) antibiotics. As evidenced from primary characterizations e.g., combined steady-state PL, ns-TAS, and Mössbauer and sequential investigations, the remarkable improvements in the catalytic activity can be primarily attributed to several crucial factors, e.g., the more effective e--h+ spatial separations and interfacial transfers, 2 ACS Paragon Plus Environment

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multiple internal light scattering, higher photonic energy harvesting and effective Reactive Oxygen Species (ROS) generation with long radical lifetimes. The current research provides new insights into the molecular design of novel Copper-Zinc-Iron multinary spinels and the intrinsic relationship of structure-property between interior structures

(e.g.

different

crystal

texture,

morphologies

structures)

and

the

physicochemical performance of the afore-mentioned multinary spinels. Keywords: Copper-Zinc-Iron multinary spinel; Hierarchical microstructures; Solar light harvestings; Physicochemical Properties; Structure activity relationship

1. Introduction Spinel structured materials BA2X4 ( B = Cu2+, Mg2+, Zn2+, A= Fe3+, Mn3+, Al3+, Co3+, X= O2-, S2-, CN-) have demonstrated intrinsic optical1, 2, electric3-5, intrinsic magnetic6, 7, adsorptive8, 9, catalytic10, 11 as well as bio-detection properties12, 13 , which currently received enormous scientific attentions due to their manifold compositions, electron configurations, and valence states. Specifically, the benefits of spinel compounds such as their controllable composition, structure, valence, and morphology have made them suitable as catalysts in various reactions including facilitating NOx reduction14, CO oxidation15, CO2 reduction16, hydrogen evolution reaction (HER)17, Oxygen Reduction Reaction (ORR)18, Zn ion batteries5 and environmental purifications19, 20. Spinel could usually be distinguished into three different structures, e.g., normal spinel, inverse spinel and complex spinel as derived from different cation distributions, which means that the A-site and B-site cations distributed in different ratios within the tetrahedral and octahedral interstices, respectively. To distinguish these spinels, a more 3 ACS Paragon Plus Environment

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accurate format of B1-χAχ (BχA2-χ)X4 has now been accordingly proposed and described in more details subsequentially. The ions before the parentheses are located in the tetrahedral sites, whereas the ions in the parentheses are located in the octahedral sites. When χ = 0, it is regarded as “normal” spinel (Figure 1a), while when χ = 1, the “inverse” spinel can therefore be formed (Figure 1b), and 0 Fc), almost all of the homogeneous heat could accordingly transfer from the surface to the core, in conjunction with the minimization of the surface energy due to the combustion of glycerate, would thus led to the final contraction of the materials into SMs. With the further increase of Fc, a dense layer of Copper-Zinc-Iron multinary spinel formed at the near-surface region of the CuZnFe-glycerate precursors, and the YSHMs then occurred due to high temperature gradients (ΔT). The increase of diffraction peak intensity implies the growth of crystalline Cu0.5Zn0.5Fe2O4 (Figure S4). Additionally, the inner core (CuZnFe-glycerate) contracted significantly as a consequence of glycerate oxidation, and the shell continued to protect the outer Copper-Zinc-Iron multinary spinel. As a consequence, the diameters of the inner yolk structures gradually contracted, whereas the outer shell thickness became much thicker, as confirmed by TEM image (Figure 2). Importantly, when the heating rate was high enough to obtain another dense shell, albeit not too quickly, DSHMs were finally generated (R = 20 ºC min-1 in this work). Therefore, to constructive DSHMs, the deliberate selection of the ramping rate was imperative to

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ensure that the Copper-Zinc-Iron multinary spinel shell was robust enough, while simultaneously the inner core gradually contracted to obtain another dense shell.

Scheme 1. Schematic diagram of the synthesis of Copper-Zinc-Iron multinary spinel hierarchical nanomicrospheres.

2.2 Physicochemical characterization

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Figure 4. (a) XRD Rietveld refined results of Copper-Zinc-Iron multinary spinel DSHMs. Experimental data, calculated profiles, and difference curve are marked with black dots, red line, vertical bars, and cyan lines, respectively. (b-c) XPS spectra, O 1s XPS spectra. (d) ESR spectra of Copper-Zinc-Iron multinary spinel hierarchical nano-microspheres. (e) Room temperature Mössbauer spectra Copper-Zinc-Iron multinary spinel DSHMs nanocomposites.

Various physio-chemical techniques including XRPD Rietveld, XPS, FTIR, EPR, and Mossbauer spectra have been used to identify the physicochemical properties of the assynthesized materials, as shown in Figure 4 and S4-S8. X-ray powder diffraction (XRPD) to systematically investigate their crystallographic structure. As shown in Figure S4, several weak diffraction peaks in the corresponding XRD pattern can be indexed to the crystal planes of Cu0.5Zn0.5Fe2O4 at R = 1. With the increasing of the calcination temperatures rate, the prepared samples exhibit sharp diffraction peaks of 2θ = 30.1°, 35.5°, 42.9°, 53.4°, 57.0°, 63.0° can be indexed to the (220), (311), (400), (422), (511) and (440) crystallographic face-centered cubic planes of spinel Cu0.5Zn0.5Fe2O4 (JCPDS 15 ACS Paragon Plus Environment

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51-0386), which indicated that the products were successfully converted to Cu0.5Zn0.5Fe2O4 with good crystallinity. It is observed that elevated calcination temperatures rate produced samples with higher crystallinities, which may because the different kinetics of the amorphous relaxation process caused by the vastly different heating rates affect the crystallization behavior, and the increase in crystal size with increased heating rate. This would consequently endow them with different photocatalytic performances. The synthesized Copper-Zinc-Iron MSHMs were subjected to characterization by the structure of the double-shelled hollow nano-microspheres (DSHMs) (R = 20 ºC min-1) was determined by the Rietveld method, confirming the formation of spinel phases and cations position of the spinel structure. All the reflection peaks are marked and shown at the bottom of the plot. In Figure 4a the solid line curve in red represents the computed patterns in the same field and the lower field in green exhibits the distinction between the experimental and estimated intensities of each fitting. The DSHMs was simulated successfully with a normal spinel lattice with O atoms in cubic close-packed array, Zn and Cu atoms on tetrahedral sites, and Fe atoms on octahedral sites. Refinement is stable and provides low R-factors (Table 1).

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Table 1. Lattice parameter, crystallite size, and fit parameter values of Copper-Zinc-Iron multinary spinel DSHMs

Sample

Space group

Lattice Parameter s (Å)

Rwp (%)

Refinem ents Rp (%)

χ2

DSMHs

Fd-3m

8.429

9.53

6.60

1.21

The Cu/Zn atomic rate was approximately 1.0 as measured by ion coupled plasma atomic emission spectrometry (ICP-AES) and XPS in Table S1 and Table S2, which was coincidental with the atomic ratio of the Cu0.5Zn0.5Fe2O4 phase. The Fourier transform infrared (FTIR) spectrum of the ferrite describes the vibration mode of ions and the deformation of spinel structure. In order to know the nature of the chemical bonds formed in the prepared samples, the FTIR spectra of copper-zinc-iron Multinary Spinel DSHMs are shown in Figure S5. The spectra indicate the presence of absorption bands in the range of 440–600 cm-1 which is a common feature of the spinel ferrite, which could be assigned to the characteristic metal oxide bands in tetrahedral and octahedral positions. Absorption bands around of 3400 cm-1 is the hydrogen bonded O–H stretching vibration arising from surface bound hydroxyl groups on the nanoparticles, respectively53, 54. From Figure S5(b), the frequency absorption bands (ν1) at 500–600 cm-1 were accordingly attributed to the intrinsic vibrations of the tetrahedral groups, while the lower frequency absorption bands (ν2) at 400–490 cm-1 were related to the octahedral groups. These

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confirm the formation of the spinel phase, which was in good agreement with the XRPD spectra55. Figures 4b depict the wide XPS survey region spectra of Copper-Zinc-Iron MSHMs, zinc, iron, copper, oxygen and carbon were detected. The carbon element at binding energy 288.5 eV is from the referencing spectra56. Figure 4c, and S6 illustrated the O1s and Zn 2p, Cu 2p, Fe 2p high-resolution XPS spectra of SMs, YSHMs and DSHMs, respectively. All these are similar, in the Zn 2p spectra, two strong peaks at binding energies 1044.15-1044.32 eV and 1021.05-1021.25 eV for Zn 2p1/2 and Zn 2p3/2, respectively, which indicated the oxidation state of Zn2+ in Copper-Zinc-Iron multinary spinel composites. In the Cu 2p spectra revealed that two strong peaks at 932.75 eV for Cu 2p3/2 and 952.45-952.55 eV for Cu 2p1/2, and two shakeup satellites (indicated as “Sat.”). Two major peaks at 710.85-711.05 and 724.85 eV and two shakeup satellites, which were ascribed to Fe 2p3/2 and Fe 2p1/2 of Fe3+, respectively. As shown in Figure 4c, the each asymmetric O 1s high-resolution XPS spectra XPS spectrum of the as prepared composites could be deconvoluted into two Gaussian components. The Olatt component of O 1s spectra centered at 529.72-529.93 eV is attributed to the lattice oxygen in the Cu0.5Zn0.5Fe2O4 phase, the OV component at the medium binding energy (531.25-531.75 eV) is associated with O2‑ ions in oxygen-deficient regions within the matrix of Cu0.5Zn0.5Fe2O4 (oxygen vacancies)42, 57-59. Compared with SMs, YSHMs and DSHMs, the binding energy of Olatt of O 1s changed from DSHMs composites exhibits a negative shift ∼0.13 eV to YSHMs and ∼0.21 eV to SMs. And the binding energy of OV of O 1s of changed from DSHMs composites exhibits a negative shift ∼0.27 eV to YSHMs and ∼0.5 eV to SMs (Figure 4c). All the shifts for binding energies in the Cu 2p, Zn 2p, Fe 2p

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and O 1s spectra indicate that the chemical environment of Cu, Zn, Fe, and O elementals have been changed (Figure S6). Besides, the shifts in binding energies might be attributed to the variation of charge redistribution due to the crystal size, lattice strain and the final state relaxation effects, as well as electron/hole wave function distributions across the varies intrinsic microstructure among the MSHMs and, which are very essential for the efficient surface interface migration of photo-induced carriers and the marvelous enhancement of catalytic activity57, 60. EPR spectroscopy is a very sensitive technique for determining the paramagnetic species, role of magnetic dipolar interactions, anisotropy and superparamagnetic behavior during nanocrystalline ferrites formation61. The broad signal with g ∼2.00 belongs to high spin Fe3+ ions in an octahedral environment62-64. The appearance of this signal reveals the superparamagnetic behavior of Cu0.5Zn0.5Fe2O4 hierarchical nanomicrospheres. The intensity of the signal varies: DSHMs > YSHMs >SMs. It is supposed that some thermally excited electrons accumulated on the surface of DSHMs with a prolonged lifetime before recombination with the holes, hence, were observable by EPR spectroscopy65. Therefore, the fact of the highest EPR signal intensity with DSHMs obviously revealed that the double-shelled microstructure could significantly boost the efficiency of the photo-induced spatial charge carrier separation. Room temperature Mössbauer spectra and the parameters of hyperfine interactions of the investigated Copper-Zinc-Iron multinary spinel DSHMs are presented in Figure 4e. Isomer shifts (IS) were employed to identify the ionic state of Fe ions in the system, which was governed by s-electron density at the Fe nucleus. The IS values for iron were found to be ~0.33 mm/s with regard to Fe-metal, which suggested the presence of Fe3+

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ions in the system66. The QS value indicated a potent electric field gradient around the 57

Fe nuclei, which might be attributed to the large surface to volume ratio of

nanoparticles, though the bulk material had a cubic symmetry67. The room temperature Mössbauer spectra showed a doublet pattern that corresponded to paramagnetic behavior, where all of the Fe3+ ions were located at the B sites of unit cells, while Cu2+ and Zn2+ ions strongly preferred the A site positions. The results of the Mössbauer spectra and EPR measurements were in good agreement predict the mixed magnetic states. The determination of Cu2+ as an alternative to Zn2+ ions at A sites, and composites presented a normal spinel structure, which provided the theoretical basis for a model construction of the following DFT theory68,

69

. The Mössbauer parameters showed no significant

difference in the magnetic structure of ZnFe2O4, as reported in the literature70, which may have been attributed to the dependence of the magnetic properties on the preparation method and the microstructures. 2.3 Optical properties The optical properties and density of states of the as-prepared Copper-Zinc-Iron multinary spinel DSHMs were characterized through UV-vis light absorption spectra, Valence-band XPS, and first principle calculations. As shown in Figure. 5(a), the estimated band gap of Copper-Zinc-Iron multinary spinel MSHMs are similarly due to the similar crystalline sizes of nanoparticles the in the nano-microspheres which can be estimated to be 1.66, 1.69, 1.65, 1.65, 1.58, and 1.65 eV for R = 1, 2, 5, 10, 20, 50, respectively. Specially, compared with SMs (R = 1) and YSHMs (R = 5), DSHMs (R = 20) appeared the narrowest band gap measured by the Tauc equation, the stronger light absorption and suitable band gap would lead to more efficient utilization of visible light

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energy. The enhanced light absorption of DSHMs might be due to the multiple scattering of light within the hollow porous structure, which enhances the utilization of light tremendously71. As the band edge positions play a crucial role in determining the transfer of the photoinduced charge carries, and in order to further verify the mechanism of the enhancement photoactivity, the relative band positions of the MSHMs were accordingly investigated. As depicted in Figure 5(b), the valence band XPS of the prepared samples are determined by linear extrapolation method and found the edge of the maximum energy at about 1.21, 0.25 and 0.00 eV for SMs, YSHMs and DSHMs, respectively. For the DSHMs, the valence band maximum energy blue-shifts toward the vacuum level at approximately –0.25 eV to YSHMs and -1.21eV to SMs. Combined with the results from optical measurements , the positions of the conduction band minimum (CBM) could be determined using the formula: ECB = Eg − EVB. Consequently, the ECB of SMs, YSHMs and DSHMs is -0.45, -1.4, -1.58 eV, respectively. On the basis of the above analysis, the ECB of DSHMs is more negative than that of SMs and YSHMs which indicating a more

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efficient reduction performance and supposed to a promoting CO2 reduction activity72.

Figure 5. (a, b) Energy gap and XPS-VB spectra of Copper-Zinc-Iron multinary hierarchical nanomicrospheres. (c) Calculated band structures and (d) density of states of Copper-Zinc-Iron multinary spinel structures.

To understand the origin electronic and optical properties, the electronic structure and density of states of Copper-Zinc-Iron multinary spinel DSHMs were further investigated by DFT calculations. According to Y. Zhang’s report, Zn2+ ions occupy the tetrahedral sites and share faces with octahedral 16c vacancy sites, which provide a possible pathway for Zn2+ ion displacement and Fe3+ ion occupation of the octahedral sites73. With the Mossbauer results in this study, the model of Copper-Zinc-Iron multinary spinel was obtained by replacing Zn2+ ions using Cu2+ ions with automatic 22 ACS Paragon Plus Environment

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0.5:0.5 rates (Figure S7). The electronic structure and density of states of an optimized Copper-Zinc-Iron multinary spinel crystal are shown in Figures 5c and 5d. Obviously, the calculated value of the band gap was ~0.80 eV, which was smaller than the experimental value (~1.53 eV). Such an underestimation could be explained by the functional limitations of DFT, whilst the discontinuity in the exchange correlation potential was taken into account74. In addition, the total density of states (TDOS) and the partial DOS of zinc, copper, iron, and oxygen elements were calculated. It could be seen that the CBM and VBM primarily consisted of hybrid orbitals of Cu 3d , Fe 3d, and O 2p, while Zn 3d, Zn 3s, and Zn 3p contributed to the deeper VBM.

Figure 6. Electronic charge density (a) and the electronic density difference contour plots (b) of the spinel Copper-Zinc-Iron multinary spinel structures (Red region corresponds to high charge density and the blue region corresponds to low charge density.

In order to understand the distribution of the total electronic charge density, we calculated the electronic charge density and charge density differences of Copper-Zinc-Iron multinary spinel (Figure 6). From Figure 6a, chemical bonds are formed between Zn, Cu atoms and O atom. Moreover, charge density of the Zn, Cu atoms and O atom is much higher than that of the Fe–O interface75. We can therefore conclude that the Zn-O, Cu-O and Fe-O make the covalent bonding due to sharing of charge between Cu, Zn, Fe and O 23 ACS Paragon Plus Environment

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atoms. Red region corresponds to high charge density and the blue region corresponds to low charge density76. As clear from the color charge density scale that the red color (+8.5000) corresponds to the maximum charge accumulating site, and accordingly the Cu and Zn atoms have the greater charge density than the other atoms77. The electronic density difference contour plot (Figure 6b) also shows explicitly that there are strong interactions between Fe and O atoms, Cu and O atoms, and Zn and O atoms in the normal Copper-Zinc-Iron multinary spinel. From Figure 6b, it can be seen that the electron density difference contour of Fe atom is petal-shaped, which is the typical characteristic of d state, and while the electron density difference contour of O atom is triangular-shaped. This indicates that there is an effective overlap between Fe 3d state and O 2p state. The electron density difference contour of Zn and Cu atoms presentation a triangular shape, which is the typical characteristic of sp3 hybrid states 73, 78, 79

.

2.4 Catalytic performance and possible mechanisms The catalytic activity of the synthesized Copper-Zinc-Iron multinary spinel MSHMs was evaluated by CO2 reduction reactions and SMX degradation with simulated solar light and visible light irradiation under mild reaction conditions, respectively. As illustrated in Figure 7a, the SMX degradation rate using DSHMs attained its highest levels (80.4% under simulated solar light irradiation). The effect of various hierarchical nano-microstructures as obtained by the afore-mentioned strategy under variable conditions, e.g., different calcination ramping rate on the catalytic performance of the Cu0.5Zn0.5Fe2O4 material have been systematically investigated and elucidated in terms of the experimental outcomes. As presented in Fig. 7b, the sample of R = 20 (DSHMs)

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exhibited a stronger activity (yield rate of 38 µmol of CO, and 8.3 µmol of H2). This CO2 reduction rate is comparable to that of many other CO2 conversion systems (Table S4). This finding might illustrate that the double shelled nanostructure possess the features of the effective interfacial transportations of photoinduced electrons as well as effective solar light harvestings. Specifically, our investigations revealed that intrinsic nanomicrostructure of the Cu0.5Zn0.5Fe2O4 material play a crucial role for governing the catalytic activity, and the featured hollow and multishell intrinsic structure endowed the material with the highest catalytic function. The generations of CO and H2 from the Cu0.5Zn0.5Fe2O4 DSHMs promoted CO2 photoreduction system as a function of irradiation time were depicted and presented in Figure 7c. The reaction system first exhibited high reaction rates for CO and H2 generations then the reaction rates were decreased gradually, which can be attributed to the photobleaching of the Ru(bpy)32+ photosensitizer after limited catalytic runs1, 80.

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Figure 7. (a) The concentration vs. time plotted for photoelectrocatalytic degradation of SMX by CopperZinc-Iron multinary spinel under simulated sun light irradiation (I0 = 33 mW cm−2, 0.6 V 𝜈𝑠. SCE, C0 = 20 mg L-1). (b) The concentration vs. time plotted for photoelectrocatalytic degradation of CO/H2 by CopperZinc-Iron multinary spinel hierarchical nano-microspheres under visible light irradiation. (c) Yields CO/H2 produced by DSHMs as a function of reaction time. (d) DMPO spin-trapping ESR spectra of -O2•- radicals under UV-vis light illumination. (e) Room-temperature PL spectra. (f) TAS Characteristic kinetic curves at 360 nm of Copper-Zinc-Iron multinary spinel structures.

It has been well recognized from previously studies that the specific surface area and pore sizes were of importance in enhancing catalytic performance, since they are directly associated with the active sites and adsorption capacities of catalysts81. Herein, the surface areas of Copper-Zinc-Iron multinary spinel with different internal structures were accordingly investigated using nitrogen adsorption-desorption isotherms. As shown in Figure S8 and Table 2, both of the as prepared catalysts were typical IV isotherms with long and narrow hysteresis loops at relative pressure. The pore size distributions were revealed to be in the range of from 4.5-12.2 nm, indicating that the mesoporous structure

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could be successfully fabricated by a facile solvothermal method. Furthermore, the Brunauer-Emmett-Teller specific surface areas of the Copper-Zinc-Iron multinary spinel obtained from different ramping rates declined gradually with the ramping rate, from 145.32 m2 g-1 for R = 1 ℃/min, to 114.82, 82.22, 75.87, and 70.90 m2 g-1 for R = 2, 5, 10, and 50 ℃/min, respectively (Table 2). This was in good agreement with the results of the SEM, with an enhancement of the ramping rate, the surface of as-synthesized microspheres transitioned from villiform processes to nanoparticles, which were used to deduce the surface areas. Even though the surface areas for R = 20 is 84.651 m2/g, which was smaller than that of R = 1, 5, and 10 ℃/min, DSHMs obtained at this ramping rate had the greatest SMX degradation efficiency and CO2 reduction. Hence, it may be initially suggested that BET was not the primary factor in governing of the catalytic efficiency.

Table 2. Physicochemical properties of Copper-Zinc-Iron multinary spinel hierarchical nano-microspheres

Type of Material

Diameter (nm)

Pore Diameter (nm)

BET

SMX Degradation Rate%

CO/μmol

H2/μmol

R=1

≈ 500

4.50

145.32

66.67

25

7.2

R=2

≈ 500

6.74

114.82

67.9

26

7.5

R=5

≈ 480

7.86

82.22

72.97

30

8.1

R = 10

≈ 450

12.22

75.86

78.52

32

8.3

R = 20

≈ 400

9.72

84.65

80.38

38

8.8

R = 50

≈ 380

7.86

70.89

79.27

36

8.6

To reveal the catalytic kinetics and detail mechanisms, the generated active species (•OH and O2•-) in the catalytic reaction under simulated solar light irradiation were 27 ACS Paragon Plus Environment

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investigated using in situ EPR DMPO-capture techniques. Following illumination, there were no distinct EPR peaks of the DMPO– •OH, while the characteristic signals of the DMPO -O2•- (Figure 7d) were successfully detected, which indicated that O2•- was generated after the light irradiation and was the main active species in the reaction. It can be seen that the intensities of DMPO -O2•- adduct for DSHMs nanocomposite were much stronger than that for YSHMs and SMs implying that the microstructure of DSHMs nanocomposite is very beneficial for the effective spatial generation and interfacial transfer of the photoelectrons which can be captured by molecular oxygen (e.g., molecular oxygen uptaking) and lattice oxygen to form O2•- radical. Additionally, the PL spectra of the as-prepared samples are displayed in Figure 7e. Two obvious peaks can be observed in all samples at λ = 325 and 435 nm, respectively. The former was attributed to the near band-edge (NBE) emission of spinel ferrite, whereas the latter was possibly due to the presence of neutral or singularly charged oxygen species (thermally activated holes) in the structure, as trap sites for electrons or oxygen vacancies65, 82. The PL intensities of the Copper-Zinc-Iron multinary spinel DSHMs were much weaker than that of the solid spheres and YSMs, which basically revealed that Copper-Zinc-Iron multinary spinel DSHMs possessed the features of higher charge separation efficiency, and this would be pretty helpful for further enhancing the photocatalytic activity accordingly. Furthermore, the TAS technology has also been employed to demonstrate the effect of spatial charge separation and further investigate the intrinsic correlations between hollow structures with different internal architectures and the photocatalytic performance. Specifically, the TAS investigations have been conducted over Cu-Zn-Fe oxide dispersions in C2H5OH under 266 nm wavelength laser excitations. The transient kinetics of Zn0.5Cu0.5Fe2O4 with

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different internal structures (SMs, YSHMs, DSHMs) acquired at 350 nm (Figure 7f), could be fitted using a multi-exponential function to obtain the time constants (τx), and associated fractional contributions (ax %)83. The derived lifetime parameters by curve fitting are summarized in Table 3. The significantly longer microsecond-scale lifetimes (τ1 and τ2) can be attributed to the separation of excited electrons and holes upon irradiation65. The average lifetime (τ) of the recombination time over Zn0.5Cu0.5Fe2O4 DSHMs (R = 20 ℃/min) were estimated to be 16.61 μs, while that for Copper-Zinc-Iron multinary spinel solid spheres and YSSs were only 0.28 and 11.97 μs, respectively. These results indicated that a lower recombination rate of photo-induced charges attaining microseconds with a longer lifetime were successfully generated over Copper-Zinc-Iron multinary spinel DSHMs (R = 20 ℃/min.), along with a more efficient e--h+ spatial separation rate

84

. The resulting interactions enhanced the rate of exciton dissociation,

thereby reducing exciton recombination which further confirmed the sequential highest catalytic efficiency of the afore-mentioned Copper-Zinc-Iron multinary spinel DSHMs. From the XPS and ICP results (Table S1 and Table S2), it can be deduced that the copper and zinc atomic ratio was nearly 1:1, and the BET becomes much smaller with the increasing of the ramping rate. Interestingly, the obtained double-shelled structures (e.g. Copper-Zinc-Iron multinary spinel DSHMs ) demonstrated the ability of possessing of the best CO2 reduction and SMX degradation efficiencies. In combinations with all of the experimental outcomes, it can be initially suggested that the specific surface area might not constitute the primary controlling factor in the specific catalytic reactions, and the characteristic features including more effective e--h+ spatial separations and interfacial transfers, multiple-improved light scattering, higher photonic energy absorption and long

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radical lifetimes jointly works and were the core elements for the highly efficient catalytic eliminations of environmental toxic antibiotics.

Table 3. Exponential decay components of fractional emission amplitudes of CopperZinc-Iron multinary spinel hierarchical nano-microspheres Sample

τ1(μs)

a1 (%)

τ2(μs)

a2 (%)

τ(μs)

SMs

0.067

47.76

0.5

52.24

0.28

YSHMs

0.11

5.14

12.62

94.36

11.97

DSHMs

0.053

3.99

12.09

96.01

16.61

3. Conclusion In summary, novel Copper-Zinc-Iron multinary spinel hierarchical nanomicrospheres (MSHMs) with different internal structures (solid nano-microspheres, yolkshell hollow nano-microspheres, and double-shelled hollow nano-microspheres) possessing superior catalytic performance towards photo-induced catalytic reduction of CO2 and eliminations of SMX antibiotics have been first successfully developed by a facile self-templated solvothermal strategy. The interiors of the as-prepared Copper-ZincIron MSHMs could be precisely controlled by varying the reaction factors including temperature-programmed calcinations rate for facial tuning the two principle inverse forces (e.g., contraction (Fc) from oxidation of the organic species and adhesion (Fa) from the dense shell) and avoiding of the sequential inward contraction. Mössbauer spectra and DFT analysis confirmed that the synthesized multinary spinels are normal 30 ACS Paragon Plus Environment

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spinel and, there appears effective overlap between Fe 3d state and O 2p state and Zn and Cu atoms presentation a sp3 hybrid states in the multinary spinel structure possessing of superparamagnetic characteristics. Specifically, the novel dedicate hierarchical and diverse nano-microspheres with different intrinsic structures composites show pretty much more enhanced photo-induced catalytic efficiency up to a dedicate 8.8 and 38 μmol for H2 and CO production and 80.4 % under simulated solar light irradiation for the degradation of SMX of double-shell hollow nano-microspheres (DSHMs) compared to 7.2, 25 μmol and 66.7 % for solid nano-microspheres (SMs), 8.1, 30 μmol and 73 % for yolk-shell hollow nano-microspheres (YSHMs), which can be attributed to the primary factors including featured MSHMs and long-lived photo-induced charges with average lifetime exceeding 16.61 μs generated among Cu0.5Zn0.5Fe2O4 DSHMs than that of 0.28 μs for SMs and 11.94 μs for YSHMs etc. as revealed by TEM/HRTEM/mapping, in situ Spin-trap ESR and TAS investigations. Additionally, ESR detection analyses confirmed that more •O2− active species can be generated over Cu0.5Zn0.5Fe2O4 DSHMs nanocomposites, which have provided powerful evidence for deep understanding the intrinsic mechanisms of photo-induced catalytic reactions. This current contribution has definitely provided brand new deep insight into the rational design of multiple spinels with different micro-morphology possessing remarkable visible-light harvesting and utilization characteristics, which would offer a prospective strategy to design highly efficient and easily recyclable photocatalytic materials for environmental remediation and energy conversions, respectively.

ASSOCIATED CONTENT

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Supporting Information Supporting Information is available free of charge on the ACS Publications website at DOI:10.1021/acs.chemmater.XXXXXXX. Detailed Copper-Zinc-Iron multinary spinel MSHMs synthesis, material characterization method, computational method, photocatalytic evaluation, Schematic diagram of the solvothermal approach used for the synthesis of the Copper-Zinc-Iron multinary spinel hierarchical nanomicrospheres, SEM & EDS of the as-prepared Copper-Zinc-Iron glycerate precursors, TEM images of the as-prepared Copper-Zinc-Iron multinary spinel hierarchical nanomicrospheres calcined at different ramping rate, Thermogravimetry

49

curves of the

Copper-Zinc-Iron glycerate precursors, XRD pattern of Copper-Zinc-Iron multinary spinel MSHMs calcined at different ramping rate, FTIR spectra of the as-synthesized Copper-Zinc-Iron range from 400 to 4000 (a) and (b) the amplification map of x= 400-800, XPS spectra of the as-synthesized Copper-Zinc-Iron multinary spinel hierarchical nano-microspheres, theoretical model of Cu0.5Zn0.5Fe2O4, N2 adsorption– desorption isotherms and pore-size distribution of Copper-Zinc-Iron multinary spinel MSHMs at different ramping rate, all of the percent of atoms in the synthesized samples from the results of XPS and ICP characterizations, comparison of the catalysis performance of Cu0.5Zn0.5Fe2O4with the State-of-art catalysts.

AUTHOR INFORMATION Corresponding Author *Professor Xinyong Li, E-mail: [email protected]; *Professor Aicheng. Chen, E-mail: [email protected]

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Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was financially supported by the National Natural Science Foundation of China (No. 21577012), the Major Program of the National Natural Science Foundation of China (No. 21590813), the Key Project of the National Ministry of Science and Technology (No. 2016YFC0204204), the Program of Introducing Talents of Discipline to Universities (B13012), and the Key Laboratory of Industrial Ecology and Environmental Engineering, China Ministry of Education.

References (1) Wang, S.; Hou, Y.; Wang, X., Development of a Stable Mnco2o4 Cocatalyst for Photocatalytic Co2 Reduction with Visible Light. ACS applied materials & interfaces 2015, 7 (7), 4327-4335. (2) Liu, Q.; Wu, D.; Zhou, Y.; Su, H.; Wang, R.; Zhang, C.; Yan, S.; Xiao, M.; Zou, Z., Single-Crystalline, Ultrathin Znga2o4 Nanosheet Scaffolds to Promote Photocatalytic Activity in Co2 Reduction into Methane. ACS Appl. Mater. Interfaces. 2014, 6 (4), 2356-2361. (3) Park, M. S.; Kim, J.; Kim, K. J.; Lee, J. W.; Kim, J. H.; Yamauchi, Y., Porous Nanoarchitectures of Spinel-Type Transition Metal Oxides for Electrochemical Energy Storage Systems. Phys. Chem. Chem. Phys. 2015, 17 (46), 30963-30977. (4) Tong, Y.; Chen, P.; Zhang, M.; Zhou, T.; Zhang, L.; Chu, W.; Wu, C.; Xie, Y., Oxygen Vacancies Confined in Nickel Molybdenum Oxide Porous Nanosheets for Promoted Electrocatalytic Urea Oxidation. ACS Catalysis 2017, 1-7. (5) Pan, C.; Nuzzo, R. G.; Gewirth, A. A., Znalxco1-Xo4 Spinels as Cathode Materials for Non-Aqueous Zn Batteries with an Open Circuit Voltage up to 2 V. Chemistry of Materials 2017, 29(21): 9351-9359.. (6) Singh, A. V.; Khodadadi, B.; Mohammadi, J. B.; Keshavarz, S.; Mewes, T.; Negi, D. S.; Datta, R.; Galazka, Z.; Uecker, R.; Gupta, A., Bulk Single Crystal-Like Structural and Magnetic Characteristics of Epitaxial Spinel Ferrite Thin Films with Elimination of Antiphase Boundaries. Adv. Mater. 2017, 29(21): 1605336. (7) Zeng, X.; Zhang, J.; Zhu, S.; Deng, X.; Ma, H.; Zhang, J.; Zhang, Q.; Li, P.; Xue, D.; Mellors, N. J.; Zhang, X.; Peng, Y., Direct Observation of Cation Distributions of Ideal Inverse Spinel Cofe2o4 Nanofibres and Correlated Magnetic Properties. Nanoscale 2017, 9 (22), 7493-7500. (8) Zou, S.; Liao, Y.; Xiong, S.; Huang, N.; Geng, Y.; Yang, S., H2s-Modified Fe-Ti Spinel: A Recyclable Magnetic Sorbent for Recovering Gaseous Elemental

33 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 34 of 40

Mercury from Flue Gas as a Co-Benefit of Wet Electrostatic Precipitators. Environ. Sci. Technol. 2017, 51 (6), 3426-3434. (9) La, D. D.; Nguyen, T. A.; Jones, L. A.; Bhosale, S. V., GrapheneSupported Spinel Cufe2o4 Composites: Novel Adsorbents for Arsenic Removal in Aqueous Media. Sensors 2016, 17 (1): 6 (10) Li, C.; Han, X.; Cheng, F.; Hu, Y.; Chen, C.; Chen, J., Phase and Composition Controllable Synthesis of Cobalt Manganese Spinel Nanoparticles Towards Efficient Oxygen Electrocatalysis. Nat. Commun. 2015, 6, 7345. (11) Arun, P. S.; Ranjith, B. P.; Shibli, S. M., Control of Carbon Monoxide (Co) from Automobile Exhaust by a Dealuminated Zeolite Supported Regenerative Mnco2o4 Catalyst. Environmental science & technology 2013, 47 (6), 2746-2753. (12) Zhou, Z.; Zheng, W.; Kong, J.; Liu, Y.; Huang, P.; Zhou, S.; Chen, Z.; Shi, J.; Chen, X., Rechargeable and Led-Activated Znga2o4 : Cr3+ near-Infrared Persistent Luminescence Nanoprobes for Background-Free Biodetection. Nanoscale 2017, 9 (20), 6846-6853. (13) Chen, H.; Li, G.-D.; Fan, M.; Gao, Q.; Hu, J.; Ao, S.; Wei, C.; Zou, X., Electrospinning Preparation of Mesoporous Spinel Gallate (Mga2o4 ; M Ni, Cu, Co) Nanofibers and Their M(Ii) Ions-Dependent Gas Sensing Properties. Sensor. Actuat. B: Chem. 2017, 240, 689-696. (14) Kaczmarczyk, J.; Zasada, F.; Janas, J.; Indyka, P.; Piskorz, W.; Kotarba, A.; Sojka, Z., Thermodynamic Stability, Redox Properties, and Reactivity of Mn3o4, Fe3o4, and Co3o4 Model Catalysts for N2o Decomposition: Resolving the Origins of Steady Turnover. ACS Catal. 2016, 6 (2), 1235-1246. (15) Mo, S.; Li, S.; Ren, Q.; Zhang, M.; Sun, Y.; Wang, B.; Feng, Z.; Zhang, Q.; Chen, Y.; Ye, D., Vertically-Aligned Co3o4 Arrays on Ni Foam as Monolithic Structured Catalysts for Co Oxidation: Effects of Morphological Transformation. Nanoscale 2018, 10 (16), 7746-7758. (16) Wang, S.; Guan, B. Y.; Lou, X. W. D., Construction of Znin2s4-In2o3 Hierarchical Tubular Heterostructures for Efficient Co2 Photoreduction. Journal of the American Chemical Society 2018, 140(15): 5037-5040. (17) Murakami, N.; Miyake, H.; Tajima, T.; Nishikawa, K.; Hirayama, R.; Takaguchi, Y., Enhanced Photosensitized Hydrogen Production by Encapsulation of Ferrocenyl Dyes into Single-Walled Carbon Nanotubes. Journal of the American Chemical Society 2018, 140 (11), 3821-3824. (18) Liang, Y.; Li, Y.; Wang, H.; Zhou, J.; Wang, J.; Regier, T.; Dai, H., Co3o4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction. Nat. Mater. 2011, 10 (10), 780-786. (19) Zhang, T.; Zhu, H.; Croue, J. P., Production of Sulfate Radical from Peroxymonosulfate Induced by a Magnetically Separable Cufe2o4 Spinel in Water: Efficiency, Stability, and Mechanism. Environ. Sci. Technol. 2013, 47 (6), 2784-2791. (20) Zhang, T.; Chen, Y.; Leiknes, T., Oxidation of Refractory Benzothiazoles with Pms/Cufe2o4: Kinetics and Transformation Intermediates. Environ. Sci. Technol. 2016, 50 (11), 5864-5873. (21) Zhao, Q.; Yan, Z.; Chen, C.; Chen, J., Spinels: Controlled Preparation, Oxygen Reduction/Evolution Reaction Application, and Beyond. Chem. Rev. 2017, 117(15): 10121-10211. 34 ACS Paragon Plus Environment

Page 35 of 40 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

(22) Wei, C.; Feng, Z.; Baisariyev, M.; Yu, L.; Zeng, L.; Wu, T.; Zhao, H.; Huang, Y.; Bedzyk, M. J.; Sritharan, T.; Xu, Z. J., Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite Xfe2o4 (X = Mn, Co, Ni, Fe). Chemistry of Materials 2016, 28 (12), 41294133. (23) Shi, X.; Bernasek, S. L.; Selloni, A., Oxygen Deficiency and Reactivity of Spinel Nico2o4 (001) Surfaces. The Journal of Physical Chemistry C 2017, 121 (7), 3929-3937. (24) Kim, J. H.; Jang, Y. J.; Kim, J. H.; Jang, J. W.; Choi, S. H.; Lee, J. S., Defective Znfe(2)O(4) Nanorods with Oxygen Vacancy for Photoelectrochemical Water Splitting. Nanoscale 2015, 7 (45), 19144-19151. (25) Song, X.-Z.; Meng, Y.-L.; Tan, Z.; Qiao, L.; Huang, T.; Wang, X.-F., Concave Znfe2o4 Hollow Octahedral Nanocages Derived from Fe-Doped Mof-5 for High-Performance Acetone Sensing at Low-Energy Consumption. Inorganic chemistry 2017, 56(22): 13646-13650. (26) Yue, Q.; Li, J.; Zhang, Y.; Cheng, X.; Chen, X.; Pan, P.; Su, J.; Elzatahry, A. A.; Alghamdi, A.; Deng, Y.; Zhao, D., Plasmolysis-Inspired Nanoengineering of Functional Yolk-Shell Microspheres with Magnetic Core and Mesoporous Silica Shell. J Am. Chem. Soc. 2017, 139 (43), 15486-15493. (27) Liu, Z.; Wang, L.; Cheng, Y. F.; Cheng, X.; Lin, B.; Yue, L.; Chen, S., Facile Synthesis of Nico2–Xfexo4 Nanotubes/Carbon Textiles Composites for HighPerformance Electrochemical Energy Storage Devices. ACS Applied Nano Materials 2018. (28) Zhang, Y. Z.; Wang, Y.; Xie, Y. L.; Cheng, T.; Lai, W. Y.; Pang, H.; Huang, W., Porous Hollow Co3o4 with Rhombic Dodecahedral Structures for HighPerformance Supercapacitors. Nanoscale 2014, 6 (23), 14354-14359. (29) Guo, J.; Yin, Z.; Zang, X.; Dai, Z.; Zhang, Y.; Huang, W.; Dong, X., Facile One-Pot Synthesis of Nico2o4 Hollow Spheres with Controllable Number of Shells for High-Performance Supercapacitors. Nano Research 2017, 10 (2), 405-414. (30) Hu, X.; Huang, L.; Zhang, J.; Li, H.; Zha, K.; Shi, L.; Zhang, D., Facile and Template-Free Fabrication of Mesoporous 3d Nanosphere-Like Mnxco3−Xo4 as Highly Effective Catalysts for Low Temperature Scr of Nox with Nh3. J.Mater. Chem. A 2018, 6 (7), 2952-2963. (31) Zha, K.; Cai, S.; Hu, H.; Li, H.; Yan, T.; Shi, L.; Zhang, D., In Situ Drifts Investigation of Promotional Effects of Tungsten on Mnox-Ceo2/Meso-Tio2 Catalysts for Nox Reduction. J. Phys. Chem. C 2017, 121 (45), 25243-25254. (32) Hu, F.; Chen, J.; Peng, Y.; Song, H.; Li, K.; Li, J., Novel Nanowire SelfAssembled Hierarchical Ceo2 Microspheres for Low Temperature Toluene Catalytic Combustion. Chem. Eng. J. 2018, 331, 425-434. (33) Zhang, D.; Qian, Y.; Shi, L.; Mai, H.; Gao, R.; Zhang, J.; Yu, W.; Cao, W., Cu-Doped Ceo2 Spheres: Synthesis, Characterization, and Catalytic Activity. Catal. Commun. 2012, 26, 164-168. (34) Chen, M.; Zhang, Y.; Xing, L.; Liao, Y.; Qiu, Y.; Yang, S.; Li, W., Morphology-Conserved Transformations of Metal-Based Precursors to Hierarchically Porous Micro-/Nanostructures for Electrochemical Energy Conversion and Storage. Adv. Mater. 2017, 29, 1607015. 35 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 36 of 40

(35) Hu, H.; Guan, B.; Xia, B.; Lou, X. W., Designed Formation of Co3o4/Nico2o4 Double-Shelled Nanocages with Enhanced Pseudocapacitive and Electrocatalytic Properties. Journal of the American Chemical Society 2015, 137 (16), 5590-5595. (36) Yang, Y.; Zhang, W.; Yang, F.; Zhou, B.; Zeng, D.; Zhang, N.; Zhao, G.; Hao, S.; Zhang, X., Ru Nanoparticles Dispersed on Magnetic Yolk-Shell Nanoarchitectures with Fe3o4 Core and Sulfoacid-Containing Periodic Mesoporous Organosilica Shell as Bifunctional Catalysts for Direct Conversion of Cellulose to Isosorbide. Nanoscale 2018, 10 (5), 2199-2206. (37) Lu, X. F.; Gu, L. F.; Wang, J. W.; Wu, J. X.; Liao, P. Q.; Li, G. R., Bimetal-Organic Framework Derived Cofe2 O4 /C Porous Hybrid Nanorod Arrays as High-Performance Electrocatalysts for Oxygen Evolution Reaction. Advanced materials 2017, 29 (3): 1604437 (38) Hu, E.; Feng, Y.; Nai, J.; Zhao, D.; Hu, Y.; Lou, X. W., Construction of Hierarchical Ni–Co–P Hollow Nanobricks with Oriented Nanosheets for Efficient Overall Water Splitting. Energy & Environmental Science 2018, 11(4): 872-880. (39) Zhang, G.; Lou, X. W. D., General Synthesis of Multi-Shelled Mixed Metal Oxide Hollow Spheres with Superior Lithium Storage Properties. Angew Chem Int Ed Engl 2014, 53 (34), 9041-9044. (40) Guan, B. Y.; Kushima, A.; Yu, L.; Li, S.; Li, J.; Lou, X. W., Coordination Polymers Derived General Synthesis of Multishelled Mixed Metal-Oxide Particles for Hybrid Supercapacitors. Adv. Mater. 2017, 1605902. (41) Zhao, X.; Yu, R.; Tang, H.; Mao, D.; Qi, J.; Wang, B.; Zhang, Y.; Zhao, H.; Hu, W.; Wang, D., Formation of Septuple-Shelled (Co2/3mn1/3 )(Co5/6mn1/6 )2o4 Hollow Spheres as Electrode Material for Alkaline Rechargeable Battery. Adv. Mater. 2017, 29 (34): 1700550. (42) Liu, B.; Li, X.; Zhao, Q.; hou, y.; Chen, G., Self-Templated Formation of Znfe2o4 Double-Shelled Hollow Microspheres for Photocatalytic Degradation of Gaseous O-Dichlorobenzene. J. Mater. Chem. A 2017, 5(19), 8909-8915. (43) Sun, X.; Zhang, H.; Zhou, L.; Huang, X.; Yu, C., Polypyrrole-Coated Zinc Ferrite Hollow Spheres with Improved Cycling Stability for Lithium-Ion Batteries. Small 2016, 12 (27), 3732-3737. (44) Zhang, Z.; Ji, Y.; Li, J.; Tan, Q.; Zhong, Z.; Su, F., Yolk Bishell Mn(X)Co(1-X)Fe2o4 Hollow Microspheres and Their Embedded Form in Carbon for Highly Reversible Lithium Storage. ACS Appl. Mater. Interfaces 2015, 7 (11), 6300-6309. (45) Hao, J.; Yang, W.; Zhang, Z.; Pan, S.; Lu, B.; Ke, X.; Zhang, B.; Tang, J., Hierarchical Flower-Like Co(3)-Xfexo(4) Ferrite Hollow Spheres: Facile Synthesis and Catalysis in the Degradation of Methylene Blue. Nanoscale 2013, 5 (7), 3078-3082. (46) Huang, Y.; Han, C.; Liu, Y.; Nadagouda, M.; Machala, L.; O’Shea, K. E.; Sharma, V. K.; Dionysiou, D. D., Degradation of Atrazine by Zn xcu1−Xfe2o4 Nanomaterial-Catalyzed Sulfite under Uv-Visible Light Irradiation: Green Strategy to Generate So4−. Appl. Catal., B 2018, 221: 380-392. (47) Singh, A.; Singh, S.; Joshi, B. D.; Shukla, A.; Yadav, B. C.; Tandon, P., Synthesis, Characterization, Magnetic Properties and Gas Sensing Applications of Znxcu1−Xfe2o4 (0.0≤X≤0.8) Nanocomposites. Mat. Sci. Semicon.Proc. 2014, 27, 934949. 36 ACS Paragon Plus Environment

Page 37 of 40 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(48) Jr, O. F. Z.; CARLYLE, D. W., Electrontransfer between Sulfur(Iv) and Chloroiron(Iii) and Chlorocopper(Ii) Ions in Aqueous Chloride Media. Formation of a Sulfur Dioxide Complex with Chlorocopper(I). Inorg. Chem. 1974, 13 (1), 34-38. (49) Etgar, L.; Moehl, T.; Gabriel, S.; Hickey, S. G.; Alexander Eychmu¨ ller, a.; tzel, M. G., Light Energy Conversion by Mesoscopic Pbs Quantum Dots/Tio2 Heterojunction Solar Cells. ACS nano 2012, 6, 3092–3099. (50) Liu, B.; Li, X.; Zhao, Q.; Liu, J.; Liu, S.; Wang, S.; Tadé, M., Insight into the Mechanism of Photocatalytic Degradation of Gaseous O-Dichlorobenzene over Flower-Type V2o5 Hollow Spheres. J. Mater. Chem. A 2015, 3 (29), 15163-15170. (51) Shen, L.; Yu, L.; Yu, X. Y.; Zhang, X.; Lou, X. W., Self-Templated Formation of Uniform Nico2o4 Hollow Spheres with Complex Interior Structures for Lithium-Ion Batteries and Supercapacitors. Angew. Chem., Int. Ed. 2015, 54 (6), 18681872. (52) Zhang, G.; Yu, L.; Wu, H. B.; Hoster, H. E.; Lou, X. W., Formation of Znmn2o4 Ball-in-Ball Hollow Microspheres as a High-Performance Anode for LithiumIon Batteries. Advanced materials 2012, 24 (34), 4609-4613. (53) Hou, X.; Wang, X.; Yao, L.; Hu, S.; Wu, Y.; Liu, X., Facile Synthesis of Znfe2o4 with Inflorescence Spicate Architecture as Anode Materials for Lithium-Ion Batteries with Outstanding Performance. New J. Chem. 2015, 39 (3), 1943-1952. (54) Ibrahim, I.; Ali, I. O.; Salama, T. M.; Bahgat, A. A.; Mohamed, M. M., Synthesis of Magnetically Recyclable Spinel Ferrite (Mfe2o4, M=Zn, Co, Mn) Nanocrystals Engineered by Sol Gel-Hydrothermal Technology: High Catalytic Performances for Nitroarenes Reduction. Appl. Catal., B 2016, 181, 389-402. (55) Daruka Prasad, B.; Nagabhushana, H.; Thyagarajan, K.; Nagabhushana, B. M.; Jnaneshwara, D. M.; Sharma, S. C.; Shivakumara, C.; Gopal, N. O.; Ke, S.-C.; Chakradhar, R. P. S., Temperature Dependent Magnetic Ordering and Electrical Transport Behavior of Nano Zinc Ferrite from 20 to 800k. J. Alloy. Compd. 2014, 590, 184-192. (56) Fan, S.; Li, X.; Tan, J.; Zeng, L.; Yin, Z.; Tadé, M. O.; Liu, S., Enhanced Photoeletrocatalytic Reduction Dechlorinations of Pcp by Ru-Pd Bqds Anchored Titania Naes Composites with Double Schottky Junctions: First-Principles Evidence and Experimental Verifications. Appl. Catal. B Environ. 2018, 227, 499-511. (57) Zhang, F.; Li, X.; Zhao, Q.; Zhang, D., Rational Design of Znfe2o4/In2o3 Nanoheterostructures: Efficient Photocatalyst for Gaseous 1,2-Dichlorobenzene Degradation and Mechanistic Insight. ACS Sustain. Chem. Eng. 2016, 4 (9), 4554-4562. (58) Sun, J.; Li, X.; Zhao, Q.; Tadé, M. O.; Liu, S., Construction of P-N Heterojunction Β-Bi2o3/Bivo4 Nanocomposite with Improved Photoinduced Charge Transfer Property and Enhanced Activity in Degradation of Ortho -Dichlorobenzene. Appl. Catal. B Environ. 2017, 219, 259-268. (59) Lu, Y.; Zhan, W.; He, Y.; Wang, Y.; Kong, X.; Kuang, Q.; Xie, Z.; Zheng, L., Mof-Templated Synthesis of Porous Co3o4 Concave Nanocubes with High Specific Surface Area and Their Gas Sensing Properties. ACS Appl. Mater. Interfaces 2014, 6 (6), 4186-4195. (60) Zhu, H.; Song, N.; Lv, H.; Hill, C. L.; Lian, T., Near Unity Quantum Yield of Light-Driven Redox Mediator Reduction and Efficient H2 Generation Using Colloidal

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Page 38 of 40

Nanorod Heterostructures. Journal of the American Chemical Society 2012, 134 (28), 11701-11708. (61) Klencsar, Z.; Kontos, Z., Epr Analysis of Fe(3+) and Mn(2+) Complexation Sites in Fulvic Acid Extracted from Lignite. The journal of physical chemistry. A 2018, 122(12): 3190-3203. (62) Kong, L.; Jiang, Z.; Xiao, T.; Lu, L.; Jones, M. O.; Edwards, P. P., Exceptional Visible-Light-Driven Photocatalytic Activity over Biobr-Znfe2o4 Heterojunctions. Chem. Commun. 2011, 47 (19), 5512-5514. (63) Bayrakdar, H.; Yalcin, O.; Cengiz, U.; Ozum, S.; Anigi, E.; Topel, O., Comparison Effects and Electron Spin Resonance Studies of Alpha-Fe2o4 Spinel Type Ferrite Nanoparticles. Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 2014, 132, 160-164. (64) Pathak, N.; Gupta, S. K.; Sanyal, K.; Kumar, M.; Kadam, R. M.; Natarajan, V., Photoluminescence and Epr Studies on Fe(3)(+) Doped Znal(2)O(4): An Evidence for Local Site Swapping of Fe(3)(+) and Formation of Inverse and Normal Phase. Dalton Trans 2014, 43 (24), 9313-9323. (65) Liao, F.; Lo, B. T.; Sexton, D.; Qu, J.; Ma, C.; Chan, R. C.-T.; Lu, Q.; Che, R.; Kwok, W.-M.; He, H.; Fairclough, S.; Tsang, S. C. E., A New Class of Tunable Heterojunction by Using Two Support Materials for the Synthesis of Supported Bimetallic Catalysts. ChemCatChem 2015, 7 (2), 230-235. (66) Modi, K. B.; Raval, P. Y.; Shah, S. J.; Kathad, C. R.; Dulera, S. V.; Popat, M. V.; Zankat, K. B.; Saija, K. G.; Pathak, T. K.; Vasoya, N. H.; Lakhani, V. K.; Chandra, U.; Jha, P. K., Raman and Mossbauer Spectroscopy and X-Ray Diffractometry Studies on Quenched Copper-Ferri-Aluminates. Inorg. Chem. 2015, 54 (4), 1543-1555. (67) Kurian, J.; John, S. P.; Jacob, M. M.; Reddy, V. R.; Abraham, K. E.; Prasad, V. S., Mössbauer Studies of Nanocrystalline Znfe2o4 Particles Prepared by Spray Pyrolysis Method. Mater. Sci. Engine. 2015, 73, 012032. (68) Mitra, S.; Mandal, K., Superparamagnetic Behavior in Noninteracting Nife2o4 Nanoparticles Grown in Sio2 Matrix. Mater. Manuf. Process 2007, 22 (4), 444449. (69) Koleva, K.; Velinov, N.; Tsoncheva, T.; Mitov, I., Mössbauer Study of Cu1−Xznxfe2o4 Catalytic Materials. Hyperfine. Interact. 2013, 226 (1-3), 89-97. (70) Wang, Y.; Zhao, X.; Cao, D.; Wang, Y.; Zhu, Y., Peroxymonosulfate Enhanced Visible Light Photocatalytic Degradation Bisphenol a by Single-Atom Dispersed Ag Mesoporous G-C3n4 Hybrid. Applied Catalysis B: Environmental 2017, 211, 79-88. (71) Zhou, Q.; Zhao, Q.; Xiong, W.; Li, X.; Li, J.; Zeng, L., Hollow Porous Zinc Cobaltate Nanocubes Photocatalyst Derived from Bimetallic Zeolitic Imidazolate Frameworks Towards Enhanced Gaseous Toluene Degradation. Journal of colloid and interface science 2018, 516, 76-85. (72) Chen;, X.; Liu;, L.; Yu;, P. Y.; Mao, S. S., Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals. Science 2011, 331 (6018), 746-750. (73) Zhang, Y.; Pelliccione, C. J.; Brady, A. B.; Guo, H.; Smith, P. F.; Liu, P.; Marschilok, A. C.; Takeuchi, K. J.; Takeuchi, E. S., Probing the Li Insertion Mechanism of Znfe2o4 in Li-Ion Batteries: A Combined X-Ray Diffraction, Extended X-Ray

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ACS Applied Materials & Interfaces

Absorption Fine Structure, and Density Functional Theory Study. Chem. Mater. 2017, 29 (10), 4282-4292. (74) Yao, J.; Li, X.; Li, Y.; Le, S., Density Functional Theory Investigations on the Structure and Electronic Properties of Normal Spinel Znfe2o4. Integ. Ferroelectr. 2013, 145 (1), 17-23. (75) Singh, G.; Gupta, S. L.; Prasad, R.; Auluck, S.; Gupta, R.; Sil, A., Suppression of Jahn–Teller Distortion by Chromium and Magnesium Doping in Spinel Limn2o4: A First-Principles Study Using Gga and Gga+U. Journal of Physics and Chemistry of Solids 2009, 70 (8), 1200-1206. (76) Yang, J.; Zhang, P.; Zhou, Y.; Guo, J.; Ren, X.; Yang, Y.; Yang, Q., FirstPrinciples Study on Ferrite/Tic Heterogeneous Nucleation Interface. J. Alloy. Compd. 2013, 556, 160-166. (77) N, B., Structural, Electronic and Magnetic Properties of Geometrically Frustrated Spinel Cdcr2o4 from First-Principles Based on Density Functional Theory. J. Material. Sci. Eng. 2016, 5 (4), 1-4. (78) Yao, J.; Li, Y.; Li, X.; Le, S., First-Principles Investigation on the Electronic Structure and Stability of in-Substituted Znfe2o4. Metall. Mater. Trans. A 2014, 45 (8), 3686-3693. (79) Paudel, T. R.; Zakutayev, A.; Lany, S.; d'Avezac, M.; Zunger, A., Doping Rules and Doping Prototypes in A2bo4 Spinel Oxides. Advanced Functional Materials 2011, 21 (23), 4493-4501. (80) Jiang, M.; Gao, Y.; Wang, Z.; Ding, Z., Photocatalytic Co 2 Reduction Promoted by a Cuco 2 O 4 Cocatalyst with Homogeneous and Heterogeneous Light Harvesters. Applied Catalysis B: Environmental 2016, 198, 180-188. (81) Wang, S.; Guan, B. Y.; Lou, X. W., Rationally Designed Hierarchical NDoped Carbon@Nico2o4 Double-Shelled Nanoboxes for Enhanced Visible Light Co2 Reduction. Energy Environmental Science 2018, 11 (2), 306-310. (82) Sripriya, R. C.; Ezhil, A.; Madhavan, J.; Victor, A. R., Synthesis and Characterization Studies of Znfe2o4 Nanoparticles. Mech. Mater. Sci. Engin. 2017, 9(1).. (83) Li, M. M.-J.; Zeng, Z.; Liao, F.; Hong, X.; Tsang, S. C. E., Enhanced Co2 Hydrogenation to Methanol over Cuzn Nanoalloy in Ga Modified Cu/Zno Catalysts. J. Catal. 2016, 343, 157-167. (84) Manser, J. S.; Kamat, P. V., Band Filling with Free Charge Carriers in Organometal Halide Perovskites. Nature Photon. 2014, 8 (9), 737-743.

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