Structural Evolution and Compositional Modulation of ZIF-8-Derived

2 days ago - Synopsis. Here we report an approach using an MOF (polyhedral ZIF-8) as a precursor to synthesize ZIF-8-derived hybrids with different ...
0 downloads 0 Views 7MB Size
Download PDF
Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX

pubs.acs.org/IC

Structural Evolution and Compositional Modulation of ZIF-8Derived Hybrids Comprised of Metallic Ni Nanoparticles and Silica as Interlayer Wenling He,†,⊥ Xiaohui Guo,†,⊥ Jing Zheng,† Jingli Xu,† Tasawar Hayat,‡,§ Njud S. Alharbi,∥ and Min Zhang*,†

Downloaded via UNIV OF ROCHESTER on May 16, 2019 at 15:15:49 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

†

College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, People’s Republic of China ‡ Department of Mathematics, Quaid-I-Azam University, Islamabad 44000, Pakistan § NAAM Research Group, King Abdulaziz University, Jeddah, Saudi Arabia ∥ Biotechnology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia S Supporting Information *

ABSTRACT: Great efforts on metal−organic framework (MOF) derived nanostructures have been devoted to modulating the compositional and structural complexities to enhance performance in various applications. However, a facile method that can simultaneously manipulate the structures of the MOF-derived material and the chemical component remains a considerable challenge. Here we report a facile strategy to use the polyhedral ZIF-8 as a precursor for synthesizing ZIF-8-derived hybrids with different components and morphologies. The synthesis involves the preparation of ZIF-8 MOF templates and sequential covering of the ZIF-8 with a interlayer of silica and then polydopamine-Ni2+ (PDA-Ni2+) and carbonizing at different high temperatures under a nitrogen atmosphere, finally leading to ZIF-8-derived hybrids with different components and structures. In the whole process, the preliminary ZIF-8 precursor play a crucial role in the morphology and structure of the final carbonized products, which can be considered as templates for silica coating and precursors of N-doped carbon layer and Zn species. We also found that the SiO2 interlayer coating is a crucial procedure for the formation of yolk−shell structured ZIF-8@SiO2@PDANi2+ composites. Owing to the uniformly distributed Ni NPs and unique structures of the composites, the as-prepared Ni-based composites show high performance in the catalysis of 4-nitrophenol as well as enrichment of histidine-rich proteins. In addition, this proposed strategy for the controllable design and synthesis of ZIF-8-derived nanocomposites paves a new way in developing superior active materials in energy storage conversion etc.

■

INTRODUCTION Recently, nano-/microcrystals with specific morphologies have aroused great interest for their wide applications in the areas of energy storage conversion, sensing, catalysis, and biomedicine.1−4 As a kind of promising architecture, hollow or yolk− shell nanostructures with a low density, high surface area, good chemical and mechanical stability, and high permeability for charge and molecule transport have attracted special attention. Especially, when they are used as catalysts, yolk−shell or hollow structured composites with metals/metal oxides as the © XXXX American Chemical Society

functional cores possess distinctive advantages over other structured composites, which were attributed to the stabilization of the active cores with a covering outer shell layer as well as improvement of catalytic efficiency by confinement effects, thus leading to high catalytic performance. Nevertheless, in previous works, the resultant products have been confined to a single composition and commonly a spherical shape, which Received: January 30, 2019

A

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

in the synthesis of yolk−shell ZIF-8-based material. Following carbonization at 500, 700, and 900 °C under a nitrogen atmosphere, yolk−shell structured ZnO@SiO2@C/Ni and Zn@SiO2@C/Ni and hollow structured C@SiO2@C/Ni were obtained, respectively. On evaluation as catalysts and adsorbents, the as-synthesized nickel-based composites with different components and structures have a multiple facet feature and more active sites, which make them attractive in the reduction of 4-nitrophenol as well as for excellent protein adsorption capability. Also, it is expected that this proposed strategy will afford a convenient way to synthesize a series of multifunctional composites with different components and structures, which will be advantageous for various applications. The established strategy can be extended to other multifaceted metal frameworks.

greatly limit its further application. Thus, it still remains a challenge to obtain hollow or yolk−shell structures with multiple compositions as well as complex configurations, which are highly needed for optimal functionalities in some applications.5 Currently, the synthetic strategy of a hard template has been widely employed to obtain hollow or yolk−shell architectures, which can effectively achieve high control of these nanostructures.6,7 Tremendous efforts have been devoted to the development of hard-template-assisted strategies using MOFs,8−13 polystyrene nanospheres,14,15 and cuprous oxide (Cu2O)16 as templates for synthesizing hollow or yolk−shell structured nanocomposites with tailored composition. Particularly, the low-cost MOFs (ZIF-8) can be easily synthesized with adjustable size control and used to obtain well-defined ZIF-8-based composites, which make ZIF-8 a good candidate to prepare yolk−shell and hollow nonspherical nanostructures with merits of porous characteristics, high thermal and chemical stability, and multiple facets. Thus, these nanostructures are expected to have novel physicochemical properties such as enhancement in catalytic activity, electrochemical lithium storage, and adsorption.17−22 Recently Chen et al. synthesized ZnS hollow polyhedra with ZIF-8 as a sacrifical template.23 Li et al. synthesized hollow Zn/Co-based ZIF rhombic dodecahedra by employing the mild phase transformation of ZIF-67 under hydrothermal treatment, integrated with the diffusion of Co2+ ions in methanol.24 Yang et al. used a facile strategy of chelation competition induced polymerization (CCIP) to prepare polydopamine capsules entrapped with gold nanorods or Fe3O4 NPs using ZIF-8 as a sacrificial template.25−27 In addition, the ZIF-8 templates can be applied to prepare ZIF-derived carbon capsules while the morphology of the parent ZIF-8 template is retained.28 In comparison with carbonaceous materials synthesized with other MOFs, ZIF-8derived carbons have multiple advantages of facile synthesis while endowing diversity, providing good control over complex architectures and specific surface areas. Furthermore, nitrogen atoms in the aromatic ring of the 2-methylimidazole ligand can be well preserved and doped into the resultant carbon materials.29,30 These special properties of ZIF-8-derived carbon materials make them highly attractive for various applications. Meanwhile, our recent works on metallic Ni carbon based composites have revealed that the formed N-doped carbon layer from polydopamine (PDA) can effectively improve the stability and dispersity of nickel species for application in catalysis and his-rich protein adsorption.31,32 In addition, the introduction of Ni2+ can greatly accelerate the graphitization degree of the carbon layer in the progress of carbonization and thus accelerate the electron mobility of metal-based composites.33 On the basis of the above works, for the first time, herein, we report a facile strategy to directly transform yolk−shell structured ZIF-8 rhombic dodecahedral composites into yolk−shell or hollow nickel based architectures by a twostep Stöber method and subsequent carbonization treatment process. To prove this strategy, a ZIF-8 dodecahedron was utilized as the template to obtain ZIF-8@SiO2 with a core− shell structure. After ZIF-8@SiO2 was coveried with a layer of polydopamine-Ni2+(PDA-Ni2+), the yolk−shell structured ZIF8@SiO2@PDA-Ni2+ was obtained. During the coating process, the ZIF-8 dodecahedra are partly etched, which is caused by the synergistic interaction between Zn2+ and PDA. The released Zn2+ ions from the etched ZIF-8 continuously diffuse out and coordinate with the PDA polymers, thereby resulting

■

EXPERIMENTAL SECTION

Preparation of Dodecahedral ZIF-8 Nanocrystals. ZIF-8 nanocrystals were synthesized as stated in previous literature.34 In a typical synthesis, 0.84 g of Zn(NO3)2·6H2O was dissolved in 20 mL of methanol (MeOH) to give a homogeneous solution. A 2 g portion of 2-methylimidazole in 30 mL of MeOH was mixed into the above Zn2+ solution, followed by vigorous stirring for 30 min. The mixed binary solution was then aged without stirring for 24 h; the product was washed several times with MeOH by centrifugation and finally dried overnight. Preparation of ZIF-8@SiO2 Nanoparticles. A 100 mg portion of the above ZIF-8 dodecahedral precursor was dispersed into 44 mL of an ethanol−water system (VE/VW 10/1), and the mixture was continuously stirred for 20 min. Then 0.1 mL of diethylamine and 0.3 mL of TEOS were added separately. The mixture was allowed to reacted for 24 h. The resultant product was washed three times with 95% ethanol by centrifugation and finally dried overnight. Preparation of ZIF-8@SiO2@PDA-Ni2+ Yolk−Shell Polyhedron. Typically, 100 mg of ZIF-8@SiO2 was dispersed in a mixed solvent of 25 mL of ethanol and 15 mL of deionized water, and then 200 mg of tris dissolved in 5 mL of water was dropped into the above solution, subsequently followed by adding dopamine hydrochloride (30 mg) and NiCl2·6H2O (75.2 mg). After that, the mixed solution was gently stirred for 15 h. Finally, the ZIF-8@SiO2@PDA-Ni2+ composites with yolk−shell polyhedral structure were obtained, washed three times with distilled water and pure ethanol, respectively, and dried in an oven. For comparison, a layer of PDA-Ni2+ was directly coated onto ZIF-8 via the same procedures to obtain ZIF-8@ PDA-Ni2+. Synthesis of ZnO@SiO2@C/Ni, Zn@SiO2@C/Ni, and C@SiO2@ C/Ni Nanocomposites. The as-prepared ZIF-8@SiO2@PDA-Ni2+ composites were placed in the middle of a quartz crucible. After calcination at 500 °C for 2 h at a heating rate of 2 °C min−1 under a N2 atmosphere, a black powder of ZnO@SiO2@C/Ni composites was acquired, which was named ZnO@SiO2@C/Ni. The synthesis procedure used for Zn@SiO2@C/Ni and C@SiO2@C/Ni was the same as the experimental procedure used for preparing ZnO@SiO2@ C/Ni, and the only difference is that calcination temperatures were changed to 700 and 900 °C during the heating step, respectively. Characterization. Fourier transform infrared (FT-IR) spectra were recorded on a VECTOR-22 FT-IR spectrophotometer (KBr disk). X-ray photoelectron spectroscopy (XPS) was performed on a VGES-CALAB MKII X-ray photoelectron spectrometer using 200 W monochromated Al Kα radiation. Thermogravimetric analysis (TGA) was carried out on a Shimadzu 50 thermoanalyzer at a heating rate of 10 °C min−1 from 50 to 700 °C under an nitrogen atmosphere with a flow rate of 20 mL min−1. Scanning electron microscopy (SEM) images were obtained on a JEOL JSM-6700 M scanning electron microscope. Transmission electron microscopy (TEM) was tested on a JEM-2100F instrument at an accelerating voltage of 200 kV. Powder X-ray diffraction (XRD) patterns were taken on an Shimadzu (Japan) D/Max-2500 diffractometer using Cu Kα radiation. Raman spectra B

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Scheme 1. Schematic Diagram of the Construction of Nickel-Based Carbonaceous Composites by a Two-Step Stöber Method and Carbonization Treatment Process

Figure 1. TEM images of ZIF-8 nanocrystals (A, B) smf ZIF-8@SiO2 core−shell nanoparticles (C, D), X-ray diffraction patterns of ZIF-8 (E(a)) and ZIF-8@SiO2 (E(b)), TEM images of the ZIF-8@SiO2@PDA-Ni2+ yolk−shell polyhedron (F, G) and ZnO@SiO2@C/Ni (H, I), and the corresponding X-ray diffraction patterns of ZIF-8@SiO2@PDA-Ni2+ (J(a)) and ZnO@SiO2@C/Ni (J(b)). C

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

shell layer of PDA-Ni2+ on the surface of the ZIF-8@SiO2. TEM images of ZIF-8@SiO2@PDA-Ni2+ particles clearly show that the size is slightly increased by about 10 nm, while the yolk−shell structured composites were observed in which the polyhedron of ZIF-8 was etched to spheres with less diameter. Because of the noncrystallinity of amorphous SiO2 and PDANi2+, the contrast of the dual layer cannot be clearly found from TEM images (Figure 1F,G). However, from the EDS mapping images in Figure S3, the elements of Ni, Si, Zn, C, N are well established in ZIF-8@SiO2@PDA-Ni2+, further demonstrating the successful formation of ZIF-8@SiO2@ PDA-Ni2+ yolk−shell structures. On the basis of the above observation, an SiO2 interlayer and PDA-Ni2+ outer layer were uniformly coated on the surface of ZIF-8, while the morphology wa changed from solid to yolk−shell structures. Furthermore, strong interactions between ZIF-8 and PDA have been verified in the coating process of ZIF-8@SiO2, during which the PDA-Ni2+ layer was the capturing layer via simultaneously chelating the Zn2+ ion. Since PDA has a strong capturing ability to transition-metal cations such as Fe3+, Ni2+, Zn2+, and Cu2+, the phenomenon in which the ZIF-8 core is partly etched reveals that PDA has a superior coordination ability with Zn2+ than does 2-methylimidazole, which is also confirmed by Yang’s work.25−27 Therefore, it can be inferred that that the etching of ZIF-8 NPs for ZIF-8@SiO2 in the coating process of the PDA-Ni2+ layer is due to the fact that the Zn2+−2-methylimidazole coordination bond was broken up, while the released Zn2+ ions were simultaneously chelated by the unsaturated catechol groups of the PDA-Ni2+ layer. Previous work has demonstrated a preferential coordination interaction of the ligand (1,4-benzenedicarboxylic acid) to Zn2+ over Ni2+.40 As a result, the PDA-Ni2+ layer further acts as a Zn2+ collector that captures the free Zn2+. Such capturing of the released Zn2+ surrounding the ZIF-8 core drives the equilibrium toward the dissolution of the MOF. As a comparison, we also coated PDA-Ni2+ directly on the ZIF-8 polyhedral surface, and no yolk−shell or hollow structure was obtained, which is totally different from previous work. This is probably due to the existence of Ni2+ in the coating of PDA. As shown in Figure S4A,B, ZIF-8@PDA-Ni2+ with a rougher surface was obtained and no obvious gap was found in the ZIF8@PDA-Ni2+. Without the interlayer of silica, the carbonized product of ZIF-8@PDA-Ni2+ at 500 °C (ZnO@C/Ni) seriously aggregated (Figure S4C,D), greatly limiting further application. This fully indicates that the silica coating plays a crucial role in the synthesis of yolk−shell structured ZIF-8@ PDA-Ni2+. Following thermal treatment under a nitrogen atmosphere, the silica interlayer is thermally stable enough to suppress aggregation in the carbonization process. The ZIF-8@SiO2@ PDA-Ni2+ composites were then carbonized at a temperature of 500 °C under a nitrogen atmosphere. During the thermal treatment, the Zn ions of the ZIF-8 were converted to ZnO, accompanied by the carbonization of the organic ligand, while the Ni2+ embedded in the PDA layer was reduced to metallic Ni NPs by the carbon from PDA and ZIF. Figure S2C,D and Figure 1H,I give panoramic FESEM and TEM images of the carbonized product, indicating that they replicated the polyhedral shape of the ZIF-8 template, clearly displaying many black dots on its surface. The present of a large void in ZnO@SiO2@C/Ni composites is clearly confirmed by the sharp contrast between the edge and the central region. Meanwhile, the XRD pattern of ZIF-8@SiO2@PDA-Ni2+

were obtained with a confocal microprobe Raman system (HR 800). The specific surface area was measured by the Brunauer− Emmett− Teller (BET) method, and the pore size distribution was calculated from the adsorption branch of the isotherm. The magnetic performance of the samples was analyzed by vibration sample magnetometry (VSM, MicroSense EV7) at room temperature. ICP was detected by using a Thermo Scientific ICP6300 instrument. UV− vis absorption spectra were obtained on a UV-1601PC spectrophotometer.

■

RESULTS AND DISCUSSION The procedure for preparing ZIF-8-derived Ni-based composites is shown in Scheme 1. The morphology of products at each stage is observed by SEM and TEM, as shown in Figures S1 and S2 and Figure 1. The ZIF-8 polyhedron was synthesized through a simple solution method. Rhombic dodecahedral-shaped ZIF-8 crystals with a size of around 220 nm are shown in TEM and SEM images of Figure 1A,B and Figure S1A,B. To prevent aggregation in the following carbonization progress, a facile strategy of “silica protected thermal treatment” was employed, in which a silica layer was covered on the ZIF-8 polyhedron with a sol−gel method. Experimentally, the silica coating is easily fulfilled by adding TEOS precursor to an ethanol/H2O mixed solution using diethylamine as the base catalyst. We have previously developed a facile method to cover a layer of SiO2 on the surface of Co3[Co(CN)6]2 cores, in which NH3·H2O was used as the base catalyst.35,36 However, in this study, ZIF-8 templates were easily etched in ammonium hydroxide solution, while Co3[Co(CN)6]2 was not easily dissolved due to the superior CN− coordination ability in comparison to that of NH3. To address this issue, diethylamine was selected as a suitable catalyst, since it does not coordinate with ZIF-8, which is greatly beneficial for retaining the morphology of the ZIF-8 during silica coating.37,38 Figure 1C,D and Figure S1C,D show the resulting core−shell structured ZIF-8@SiO2. As can be seen, there is no perceivable boundary between the SiO2 layer and ZIF-8, but the diameter of ZIF-8@SiO2 is increased to 280 nm in comparison to ZIF-8. The XRD pattern of Figure 1E(a) shows intense diffraction peaks of the ZIF-8 polyhedron, indicating that the polyhedron is highly crystalline. After it is coated with SiO2, ZIF-8@SiO2 exhibits a diffraction spectrum similar to that for the pure ZIF-8, with all sharp peaks attributed to the structure of crystalline ZIF-8 (Figure 1E(b)). Notably, the intensity of all peaks for ZIF-8 is greatly lessened, further indicating that the silica coating has been successfully achieved while the morphology and structure of ZIF-8 have not been destroyed. Also, no obvious peak of a SiO2 phase was found, owing to its thin layer as well as amorphous phase. Additionally, the thickness of the SiO2 shell layer could be tailored by regulating and optimizing the synthesis conditions, such as the concentration of diethylamine or TEOS. As a control, ammonia was also used for silica coating on ZIF-8. However, the ammonia solution can fully dissolve the ZIF-8 polyhedra to form a clear solution, which further confirms that diethylamine as a base catalyst plays a vital role in the synthesis of ZIF-8@SiO2. As is well-known, transition metal ion assisted dopamine polymerization can be achieved in a basic solution such as tris buffer (pH 8.5)39 or ammonia solution.24 Considering the instability of the ZIF-8 in ammonia solution, tris buffer (pH 8.5) was chosen as the solution for covering PDA-Ni2+ on ZIF-8@SiO2. Surprisingly, the yolk−shell structured ZIF-8@SiO2@PDA-Ni2+ was obtained. Figure 1F,G and Figure S2A,B confirm the successful coating of a D

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry composites (Figure 1J(a)) further proves that ZIF-8 cores still exist in the ZIF-8@SiO2@PDA-Ni2+ composites except for the lower diffraction intensity in comparison to that for ZIF-8 and ZIF-8@SiO2. However, after carbonization, the peaks of ZIF-8 were not observed in Figure 1J(b). Although no distinct peaks of ZnO were found in Figure 1J(b), Zn ions in ZIF-8 should be changed to ZnO after thermal treatment at 500 °C, as stated previously and verified by the following XPS results. No distinct peaks of the Ni crystal phase are observed, owing to the ultrasmall dimensions of the Ni NPs with diameters of about 4−6 nm. However, on the basis of the SEM, TEM, and following XPS analysis, the metallic Ni does indeed exist, which was considered as face-centered-cubic (fcc) Ni (JCPDS Card no. 04-0850). At the same time, a broad and weak characteristic peak centered at around 28.7° of 2θ originated from an amorphous silica phase. In order to assess the effect of the pyrolysis temperature on the component and structure of configuration composites, ZIF8@SiO2@PDA-Ni2+ was annealed at 700 and 900 °C separately to obtain the carbonized products of Zn@SiO2@ C/Ni and C@SiO2@C/Ni (Figure 2). From Figure 2A,B, we can see that, when the carbonization temperature was raised to 700 °C, reduction of ZnO by carbon derived from PDA and ZIF-8 leads to the generation of Zn metal and carbon oxides, which was in accordance with previous work.34 Then, the emerging Zn clusters are entrapped by a uniform SiO2 shell layer with a thickness of probably 46 nm, and the outer Ni NPs are increased to 10−12 nm in diameter, indicating a serious sintering effect and formation of larger Ni NPs along with an increase in the thermal temperature. On further increase in the thermal temperature to 900 °C, the coverage of Ni NPs is greatly reduced and the metallic Zn evaporates and leaves the composites to give the final C@ SiO2@C/Ni composites (Figure 2C,D). From the XRD pattern of Zn@SiO2@C/Ni in Figure 2E(a), the corresponding Zn peaks were not observed, although the ZnO phase was reduced to amorphous metallic Zn by carbon, and three obvious diffraction peaks were indexed at 2θ = 43.6, 54.0, and 76.3° assigned to the reflections of the (111), (200), and (220) planes, respectively, implying the growth of metallic nickel NPs (JCPDS No. 65-3107). Moreover, the diffraction peak of Ni NPs of C@SiO2@C/Ni grew more sharp, as shown in Figure 2E(b). On the basis of the aforementioned experiments, it is revealed that both the ZIF-8 core and the SiO2 interlayer play an essential role in producing the yolk−shell or hollow structure silica−carbon capsules. Samples of every stage were characterized by FT-IR to verify their components and structural features, and these are shown in Figure 3A. A broad peak at 3410 cm−1 was observed in curves a−c that could be attributed to the water of free hydrogen bonds and an O−H stretching mode. The typical absorption bands at 2913 cm−1 corresponded to the stretching vibration C−H of 2-methylimidazole. As shown in the spectra of a−c, the obvious peaks at around 1613, 1452, and 761 cm−1 are derived from the stretching and bending of the CC bond of imidazole rings, respectively. In comparison with ZIF-8, the stretching vibration of Si−O−Si groups at 1086 cm−1 and the symmetric stretching of Si−O−Si at 792 cm−1 are found in the spectra of ZIF-8@SiO 2 , showing that the SiO 2 shell successfully covered the surface of ZIF-8. After coating with PDA-Ni2+, no obvious change before and after coating was observed, since the bands for O−H and N−H stretching from PDA are difficult to distinguish. After carbonization, the series

Figure 2. TEM images of Zn@SiO2@C/Ni (A, B) and C@SiO2@C/ Ni (C, D) and X-ray diffraction patterns of Zn@SiO2@C/Ni (E(a)) and C@SiO2@C/Ni (E(b)).

of characteristic organic peaks of PDA and 2-methylimidazole disappeared, which indicated that the inner ZIF-8 cores and PDA outer layer were successfully carbonized (spectrum d). The thermal stability of ZIF-8@SiO2@PDA-Ni2+ was also evaluated by means of thermogravimetric analyses as shown in Figure 3B. In the initial stage, the curve exhibited a weight decrease of 5% between 25 and 190 °C corresponding to the loss of water and residual organic solvent. After that, a further weight loss of 16.41% in the rang from 190 to 570 °C appeared, which corresponded to the total decomposition of ZIF-8 and the external PDA-Ni2+ layer. When the temperature range was 570−900 °C, the zinc component changed from ZnO to metallic Zn, after which the Zn vaporized and escaped from the material to give C@SiO2@C/Ni composites and the weight fractions of samples decreased to 59.69%. The Raman spectra of the ZnO@SiO2@C/Ni composites exhibit the characteristic D and G bands of carbon around 1342 and 1591 cm−1, which are closely related with disordered carbon and graphitic sp2-hydridized carbon, respectively (Figure S5). The E

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Figure 3. (A) FTIR spectra of ZIF-8 (a), ZIF-8@SiO2 (b), ZIF-8@SiO2@PDA-Ni2+ (c) ,and ZnO@SiO2@C/Ni (d). (B) TGA curve of ZIF-8@ SiO2@PDA-Ni2+. (C) Magnetic hysteresis curves of ZnO@SiO2@C/Ni (a), Zn@SiO2@C/Ni (b), and C@SiO2@C/Ni (c) measured at room temperature. The insets give a digital picture showing that ZnO@SiO2@C/Ni can be separated from the solution with a magnet (upper left) and the corresponding magnified hysteresis loops at low applied magnetic fields (lower right). (D) Nitrogen adsorption/desorption isotherm of ZnO@ SiO2@C/Ni. The inset gives the pore size distribution.

mesopores exist.41 Due to the porous and hollow structure, the Brunauer−Emmett−Teller specific surface area is as much as 70.54 m2 g−1 with a pore size distribution ranging from 3.5 to 60.7 nm with the majority of pores concentrated at 3.8 nm. As a comparison, the BET surface area and pore structure of Zn@ SiO2@C/Ni and C@SiO2@C/Ni were also measured by nitrogen adsorption/desorption isotherms, which is shown in Figure S6. The isotherms of Zn@SiO2@C/Ni (Figure S6A) and C@SiO2@C/Ni (Figure S6B) exhibit a type IV curve, which reveals the presence of mesopores and micropores. Notably, the existence of mesopores and micropores depends on the carbonization of the PDA and ZIF-8 and high evaporation of the metallic Zn, while the formation of macropores may be attributed to the creation of hollow cages. The BET specific surface area (SSA) and total pore volumes of Zn@SiO2@C/Ni and C@SiO2@C/Ni are 147.2 m2/g, 0.43 cm3/g and 153.1 m2/g, 0.48 cm3/g, respectively, which are obviously higher than those of ZnO@SiO2@C/Ni (70.54 m2/g, 0.29 cm3/g). This can be explained as follows: the evaporated Zn probably is vitally important in the creation of porous N-doped carbon as well as the porous SiO2 interlayer. During the progress of carbonization, reduction of ZnO by the carbonized PDA and ZIF-8 leads to the formation of Zn along with carbon oxides. The vaporization of Zn and the release of generated gases above 900 °C lead to the formation of the porous framework. Although the SSA of ZnO@SiO2@C/Ni is lower than those of other structured Nibased composites, the high coverage of Ni NPs with tiny diameter and this type of accessible yolk−shell structure of

low intensity of the D and G bands shows that low content of N-doped carbon in the ZnO@SiO2@C-Ni composites. After calculation and analysis, the value of ID/IG is 0.92 for ZnO@SiO2@C/Ni, demonstrating the enhanced graphitization degree of the carbon layer after carbonization treatment. To evaluate the recycle ability in the application, the magnetic properties of the obtained composites with different carbonization temperatures were also explored. As indicated in Figure 3C, the saturation magnetizations of ZnO@SiO2@C/Ni, Zn@ SiO2@C/Ni, and C@SiO2@C/Ni are approximately 0.14, 1.07, and 1.40 emu g−1 separately, showing their rapid magnetic response properties by an external magnet. Thus, the Zn@SiO2@C/Ni composites could be recycled and recovered in 12 s with a magnet (as shown in the upper left corner of Figure 3C). Furthermore, the corresponding magnification of hysteresis loops at low applied magnetic fields is shown in the lower right corner of Figure 3C; the coercivity (HC) values increase with an increase in the thermal temperature: the ZnO@SiO2@C/Ni showed no coercivity (HC) from the curve, which attests to its superparamagnetic behavior. However, the coercivities of Zn@SiO2@C/Ni and C@SiO2@C/Ni composites were 44.91 and 70.55 Oe, respectively, indicating ferromagnetic properties. The increase in HC is attributed to the constant growth of metallic nickel inside the samples with increasing temperature. The pore structures of the ZnO@SiO2@C/Ni were also tested by nitrogen adsorption/desorption isotherms, which was shown in Figure 3D. It is apparent from the ZnO@SiO2@C/Ni hysteresis loop from the pressure region of 0.5−1.0 that F

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Figure 4. (A) XPS spectra of the full survey scans of ZnO@SiO2@C/Ni (a) and C@SiO2@C/Ni (b) and (B) Zn 2p, (C) Ni 2p, and (D) N 1s regions corresponding to the spectra of the ZnO@SiO2@C/Ni (a) and C@SiO2@C/Ni (b).

Figure 5. (A) UV−vis absorption spectra of 4-AP and 4-NP before and after adding NaBH4. (B) Ct/C0 versus reaction time for the reduction of 4NP with and without a catalyst as the blank (red line). (C) ln(Ct/C0) versus reaction time for the reduction of 4-NPs over different catalysts. (D) Reusability of ZnO@SiO2@C/Ni as the catalyst for the reduction of 4-NP with NaBH4. G

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

relationships between ln(Ct/C0) and the reaction time using different catalysts are displayed in Figure 5C. It can be found that the apparent rate constant k of ZnO@SiO2@C/Ni is estimated to be 1.56 min−1, which is much larger than those of Zn@SiO2@C/Ni (0.235 min−1) and C@SiO2@C/Ni (0.159 min−1), which means that ZnO@SiO2@C/Ni had a higher catalytic performance in comparison to the products synthesized at a higher temperature. However, comparing the activity of catalysts depending on the apparent rate constant k is not appropriate due to their different nickel loadings. Therefore, the activity parameter κ was introduced, which is defined as the ratio of k (the apparent rate constant) to the loading amounts of catalysts. On the basis of ICP data (Table S1), the loading amount of Ni NPs for ZnO@SiO2@C/Ni is 28.43 μg mg−1, which is much lower than that for Zn@SiO2@ C/Ni (80.49 μg mg−1). Table S2 provides a comparison of ZnO@SiO2@C/Ni in our work and other catalysts that have been reported. By comparison, the activity parameter κ of ZnO@SiO2@C/Ni is markedly larger than most other noblemetal catalysts such as Au@meso-SiO2,45 Pd/MIL-100(Cr) NCs,46 and Au@Ag,47 but a lower cost. This could be attributed to the special synthetic approach, which led to the high-density distribution of active Ni NPs embedded into the N-doped carbon from PDA. An additional benefit of ZnO@ SiO2@C/Ni is the good catalytic stability and the more convenient recycling, because the catalyst with excellent magnetic properties can be quickly isolated by a magnet. Figure 5D shows the reusability of ZnO@SiO2@C/Ni composites for the reduction of 4-NP with NaBH4, which were still highly active with a stable conversion of 95% even after use for more than eight cycles, indicating high stability. The support of catalytic efficiency may be due to the protection from silica and carbon layers, which can be effective against the oxidation of nickel NPs when nickel is exposed to air for a long time. These results indicated that the yolk−shell ZnO@SiO2@C/Ni displayed not only high catalysis performance but also good stability and recyclability, which promoted the widespread application of the catalyst. The outstanding catalytic performance is ascribed to the rational design of the ZIF-8-based catalyst from the following two aspects: (i) the rattle-type structure, the formation of ZnO cores, and the improved dispersity of carbon supported tiny Ni NPs enhance the catalysis performance and stability; (ii) both the graphitized carbon layer and the metallic Ni greatly accelerate the mobility of electrons from the catalyst and thus improve the chemical kinetics. The research results here show that ZIF8-derived nanoreactors with modulation of the structures and compositions have potential applications in other catalysis applications. Adsorption and Separation of Histidine-Rich Proteins. We have used his-rich protein (BHb) and buffer solutions (PBS, pH 8.0) to give the desired concentrations (0.025, 0.05, 0.1, 0.2, 0.4 mg mL−1), and then ZnO@SiO2@C/ Ni was added to 6 mL of the above BHb solutions with different concentrations; the mixture was then shaken for 3 h. Then the supernatants were collected by centrifugation and analyzed through UV−vis spectrometry. The equilibrium adsorption capacity (Qe, mg g−1) was calculated according to the formula

ZnO@SiO2@C/Ni could efficiently promote the separation of charges, the mass transfer of small molecules, and the applications of the catalyst. X-ray photoelectron spectroscopy (XPS) was also used to identify the electronic state of Ni and the compositions of ZnO@SiO2@C/Ni and C@SiO2@C/Ni composites (Figure 4). The survey scan spectrum shown in Figure 4A reveals the presence of Si, C, N, Ni, and Zn in both composites, which demonstrates that the interlayer of SiO2 and outer C/Ni shell both existed. As observed in Figure 4B(a), the high-resolution spectrum of Zn 2p shows characteristic peaks at 1022.5 eV (Zn 2p3/2) and 1045.9 eV (Zn 2p1/2) corresponding to chemical element state Zn2+ (ZnO),42,43 indicating the existence of ZnO cores in ZnO@SiO2@C−Ni according to the peak distance (23.3 eV) between Zn 2p3/2 and Zn 2p1/2.44 As the carbonization temperature increased to 900 °C, the Zn signal nearly disappeared from the XPS spectra at this point due to metallic Zn vaporization and release from the material to give the C@SiO2@C/Ni composite (Figure 4B(b)). Two notable peaks of Ni 2p3/2 and Ni 2p1/2 appeared with binding energies at 853.0 and 874.9 eV, respectively, revealing the existence of metallic nickel of ZnO@SiO2@C-Ni (Figure 4C(a)) and C@SiO2@C-Ni (Figure 4C(b)). The N 1s spectrum in ZnO@SiO2@C-Ni (Figure 4D(a) and Figure S7) can be deconvoluted into three well-fitted peaks located at 398.3, 400.8, and 401.0 eV, which can be ascribed to pyridinic N, pyrrolic N, and graphitic N, respectively. In contrast, the N 1s spectrum peaks of C@SiO2@C/Ni almost vanished (Figure 4D(b)), which is mainly attributed to the transformation of doped N atoms from the carbon layer to nitrogen oxides at higher temperature. According to the XPS results, yolk−shell structured ZnO@SiO2@C-Ni and hollow structured C@ SiO2@C-Ni polyhedra were successfully synthesized. Catalytic Performance of As-Prepared Nanocatalysts. Owing to the high coverage of tiny Ni NPs, large surface area, and unique yolk−shell structure for the ZnO@SiO2@C/Ni composite, the as-prepared ZnO@SiO2@C/Ni composites are expected to exhibit high catalytic activity in a variety of reactions. Meanwhile, to have a better understanding that the special structures of ZnO@SiO2@C/Ni composites determine their special characters and utilities, and the catalytic liquidphase reduction of nitrophenols to aminophenol was considered as a typical reaction to evaluate the catalysis performance on metallic Ni NPs in the final products. This catalysis process can be monitored by ultraviolet spectra, and the aqueous solution of 4-NP demonstrates a characteristic absorption peak at 317 nm (Figure 5A). After addition of NaBH4, the characteristic peak red-shifts to 400 nm owing to the generation of 4-nitrophenolate. Then, with a trace amount of ZnO@SiO2@C/Ni (25 μL, 1 mg mL−1) added into the mixture, the intensity of the absorption peak at a value of 400 nm gradually decreased and the color changed from bright yellow to colorless, indicating that the reduction reaction started promptly (Figure 5A). Figure 5B shows the ratio of the concentration Ct at time t to its original value C0 (Ct/C0) versus reaction time for the reduction of 4-NP with and without catalysts at the maximum absorption wavelength of 400 nm. Obviously, when a small amount of ZnO@SiO2@C/ Ni was added, the intensity of the absorbance peak decreased quickly within just 150 s. In contrast, the absorbence of 4-NP at 400 nm almost showed no change without the presence of a catalyst. Owing to the excess NaBH4 added, the reduction reaction can be considered as a pseudo-first-order reaction to evaluate the catalytic rate on 4-NP alone. The linear

Qe = H

C0 − Ce V m

(1) DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry

Figure 6. Adsorption isotherms of BHb onto ZnO@SiO2@C/Ni (A) and the linear regression by fitting the equilibrium adsorption data on the basis of the Langmuir adsorption model (B).

where C0 is the initial BHb concentration (mg mL−1), Ce is the supernatant protein concentration (mg mL−1), V is the volume of the protein solution (mL), and m is the weight of asprepared adsorbents (g). The adsorption isotherms (Figure 6A) were fitted by the Langmuir model of conventional adsorption isotherms eqs 2 and 3 Ce C 1 = + e Qe Q mKL Qm

Qe =

the ZnO@SiO2@C/Ni were analyzed by a UV/vis spectrophotometer at absorption peaks of 280 and 406 nm for BSA and BHb, respectively. As shown in Figure S9A−C, the absorption spectra of BHb at 406 nm decreased sharply for BHb and diluted human blood among the three solution samples, but the decrease in the peak of 406 nm for the binary BHb/BSA was negligible. The reason for their difference comes from the interaction among different proteins possibly having a strong inhibition effect on the adsorption of BHb. The eluted adsorbents were collected by an external magnetic field and then reused for the adsorption of BHb, which remained highly active through the six cycles (Figure S9D). The superior adsorption performance and stability of the ZnO@SiO2@C/Ni hybrid can be attributed to its ingenious structure. Figure 7 shows sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the initial solution, supernatant solution, and desorption solution from as-prepared adsorbent for three solution samples. Protein bands with molecular weights of 14.4 and 66.2 kDa were found in lane 1, corresponding to hemoglobin and albumin, respectively. Followed by treatment with ZnO@SiO2@C/Ni

(2)

Q mC0 Kd + C 0

(3)

−1

where Qm (mg g ) is the maximum adsorption capacity, KL (L mg−1) is described as the Langmuir constant, and Kd is the decomposition rate in the Langmuir model. By fitting the experimental data to the Langmuir equation (2), Qm is calculated to be 1667.224 mg g−1, which is greater than those in most previous reports. As shown in Figure 6B, Kd is calculated to be 0.465 and the adsorption kinetics is quite in accord with the Langmuir and pseudo-second-order model (R2 = 0.9986), which made it clear that the chemical interactions probably existed in the adsorption processes.48−53 Figure S8 shows the comparison of isothermal adsorption curves for Zn@SiO2@C/Ni (A, B) and ZnO@SiO2@C/Ni (C, D), which were calcined at different pyrolysis temperatures (700, 900 °C). The corresponding linear fitting analysis utilizing eq 2 indicated that the adsorption process for BHb is also completely in conformity with the Langmuir adsorption model. The Qm values estimated by the linear slopes were 1265.8 and 1085.78 mg g−1, respectively. The decomposition rates Kd calculated by eq 3 were 0.33 and 0.27, respectively. It is obvious that the adsorption properties of ZnO@SiO2@C/Ni were the best among the three as-prepared nanocomposites, which is ascribed to the large surface area and great numbers of adsorption sites for the products for the reduced nickel particles with a smaller size at the relatively lower calcination temperature. The result is also in accord with a previous catalytic conclusion. In order to estimate the selectivity of ZnO@SiO2@C/Ni on His-rich proteins and make further efforts to explore practical application values in biomedical science, a certain amount of BHb, a binary solution of BHb and BSA (BHb/BSA), and diluted human whole blood samples were chosen as target proteins. The initial solution, supernatant solution, and desorption solution (eluted with 0.2 g mL−1 imidazole) from

Figure 7. SDS-PAGE analysis of adsorption by ZnO@SiO2@C/Ni from solution: (lane 0) marker; (lane 1) 1 mg mL−1 of BHb and BSA binary solution; (lane 2) the supernatant BHb and BSA solution after treatment with ZnO@SiO2@C/Ni; (lane 3) the eluted BHb and BSA mixture using 0.2 g mL−1 imidazole solution; (lane 4) 100-fold diluted human whole blood; (lane 5) supernatant human whole blood solution after treatment with ZnO@SiO2@C/Ni; (lane 6) the eluted 100-fold diluted human whole blood using 0.2 g mL−1 imidazole solution. I

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry hybrids, the BHb band obviously faded while the BSA band faded slightly. The eluted solution from the adsorbents showed a deep band for BHb but a faint band of BSA, which represented the greater capture of BHb than of BSA by the ZnO@SiO2@C/Ni hybrids owing to the greater number of histidine groups of BHb (lane 3). The 600-fold diluted human blood showed multiple distributed bands in lane 4, which were attributable to HHb, HSA, and other proteins existing in human blood. After treatment with ZnO@SiO2@C/Ni, the HHb and HSA bands appeared as shadows in lane 5 but the other bands including HSA were almost reserved. In addition, the HHb and HSA bands reappeared and become more visible through the elution process of ZnO@SiO2@C/Ni-protein chelates, which further demonstrated the excellent selectivity on His-rich proteins.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail for M.Z.: [email protected]. ORCID

Min Zhang: 0000-0002-5242-0491 Author Contributions ⊥

W.H. and X.G. contributed equally to this work.

Notes

The authors declare no competing financial interest.

■

■

ACKNOWLEDGMENTS This research was supported by the National Natural Science Fund of China (grant numbers 21601121, 21305086), the Natural Science Foundation of Shanghai City (18ZR1416400), and the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning (grant number QD2016037).

CONCLUSIONS To sum up, a facile and efficient strategy for the design of nickel-based composites with yolk−shell or hollow structures have been developed. This strategy includes two steps a of sol−gel process to give a dual-layer coating (silica and PDANi2+) onto the ZIF-8 cores and subsequent carbonization treatment at various temperatures. The yolk−shell or hollow structured composites (ZnO@SiO2@C/Ni, Zn@SiO2@C/Ni, C@SiO2@C/Ni) inherited the morphology of ZIF-8 with multiple facets that have large surface area and more active sites. Such porous complex composites are expected to exhibit outstanding performance in the application of catalysis and histidine-rich protein adsorption. The superior performance of Ni-based composites prepared by the SiO2-protected interlayer mediated pyrolysis strategy should be cooperatively determined by following two aspects. First, the SiO2 interlayer not only entrapped more nitrogen and carbon species but also resolved the sintering effect during the pyrolysis process, resulting in a well-dispersed state for the final product. Second, owing to the existence of SiO2, the yolk−shell structured composite ZIF-8@SiO2@PDA-Ni2+ was observed due to the etching effect of PDA-Ni2+ coating, which afford high surface area and a great number of active sites. Overall, the SiO2protected shell mediated pyrolysis method affected both the component and structure of nickel-based catalyst or adsorbent with yolk−shell or hollow structures, thus leading to superior performance in the catalysis and protein adsorption. We anticipate that this proposed strategy will be extended to other yolk−shell or hollow multifaceted composites that can be widely applied in gas sensing, energy storage, drug delivery, and so on.

■

catalysts and adsorbents for His-rich protein capture, and the corresponding references (PDF)

■

REFERENCES

(1) Chen, Y.; Chen, H.-R.; Shi, J.-L. Construction of Homogenous/ Heterogeneous Hollow Mesoporous Silica Nanostructures by SilicaEtching Chemistry: Principles, Synthesis, and Applications. Acc. Chem. Res. 2014, 47, 125−137. (2) Lin, L.-S.; Song, J.; Yang, H.-H.; Chen, X. Yolk−Shell Nanostructures: Design, Synthesis, and Biomedical Applications. Adv. Mater. 2018, 30, 1704639. (3) Priebe, M.; Fromm, K. M. Nanorattles or Yolk−Shell NanoparticlesWhat Are They, How Are They Made, and What Are They Good For? Chem. - Eur. J. 2015, 21, 3854−3874. (4) Purbia, R.; Paria, S. Yolk/Shell Nanoparticles: Classifications, Synthesis, Properties, and Applications. Nanoscale 2015, 7, 19789− 19873. (5) Zhang, M.; Wang, C.; Liu, C.; Luo, R.; Li, J.; Sun, X.; Shen, J.; Han, W.; Wang, L. Metal−Organic Framework Derived Co3O4/C@ SiO2 Yolk−Shell Nanoreactors with Enhanced Catalytic Performance. J. Mater. Chem. A 2018, 6, 11226−11235. (6) Petkovich, N. D.; Stein, A. Controlling Macro- and Mesostructures with Hierarchical Porosity through Combined Hard and Soft Templating. Chem. Soc. Rev. 2013, 42, 3721−3739. (7) Liang, Y.; Wei, J.; Hu, Y. X.; Chen, X. F.; Zhang, J.; Zhang, X. Y.; Jiang, S. P.; Tao, S. W.; Wang, H. T. Metal-Polydopamine Frameworks and Their Transformation to Hollow Metal/N-Doped Carbon Particles. Nanoscale 2017, 9, 5323−5328. (8) Yang, J.; Yu, C.; Fan, X.; Liang, S.; Li, S.; Huang, H.; Ling, Z.; Hao, C.; Qiu, J. Electroactive Edge Site-Enriched Nickel−Cobalt Sulfide into Graphene Frameworks for High-Performance Asymmetric Supercapacitors. Energy Environ. Sci. 2016, 9, 1299−1307. (9) Zhang, H.; Nai, J.; Yu, L.; Lou, X. W. Metal-Organic-FrameworkBased Materials as Platforms for Renewable Energy and Environmental Applications. Joule 2017, 1, 77−107. (10) Zhang, P.; Guan, B. Y.; Yu, L.; Lou, X. W. Facile Synthesis of Multi-Shelled ZnS-CdS Cages with Enhanced Photoelectrochemical Performance for Solar Energy Conversion. Chem. 2018, 4, 162−173. (11) Zou, H.; He, B.; Kuang, P.; Yu, J.; Fan, K. Metal−Organic Framework-Derived Nickel−Cobalt Sulfide on Ultrathin Mxene Nanosheets for Electrocatalytic Oxygen Evolution. ACS Appl. Mater. Interfaces 2018, 10, 22311−22319. (12) Wu, R.; Wang, D. P.; Han, J.; Liu, H.; Zhou, K.; Huang, Y.; Xu, R.; Wei, J.; Chen, X.; Chen, Z. A General Approach Towards MultiFaceted Hollow Oxide Composites Using Zeolitic Imidazolate Frameworks. Nanoscale 2015, 7, 965−974.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.9b00288. SEM images of the precursor and products, XRD patterns and elemental mappings, N2 adsorption− desorption isotherms and pore size distribution curves of Zn@SiO2@C/Ni and C@SiO2@C/Ni, high-resolution N 1s XPS spectrum of ZnO@SiO2@C/Ni, adsorption isotherms of protein BHb and linear fitting of adsorption isotherm plots, UV−vis spectra, ICP data of three samples, a comparison of samples with other J

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry (13) Yang, H.; Kruger, P. E.; Telfer, S. G. Metal−Organic Framework Nanocrystals as Sacrificial Templates for Hollow and Exceptionally Porous Titania and Composite Materials. Inorg. Chem. 2015, 54, 9483−9490. (14) Ling, Y.; Zhang, M.; Li, X.; Zheng, J.; Xu, J. Formation of Uniform Mesoporous TiO2@C−Ni Hollow Hybrid Composites. Dalton Transactions 2018, 47, 10093−10101. (15) Ling, Y.; Zhang, M.; Zheng, J.; Xu, J.; Hayat, T.; Alharbi, N. S. Formation of Uniform Magnetic C@CoNi Alloy Hollow Hybrid Composites with Excellent Performance for Catalysis and Protein Adsorption. Dalton Transactions 2018, 47, 7839−7847. (16) Sun, S.; Yang, Z. Cu2O-Templated Strategy for Synthesis of Definable Hollow Architectures. Chem. Commun. 2014, 50, 7403− 7415. (17) Guan, B. Y.; Lu, Y.; Wang, Y.; Wu, M.; Lou, X. W. Porous Iron−Cobalt Alloy/Nitrogen-Doped Carbon Cages Synthesized Via Pyrolysis of Complex Metal−Organic Framework Hybrids for Oxygen Reduction. Adv. Funct. Mater. 2018, 28, 1706738. (18) Guan, B. Y.; Yu, L.; Lou, X. W. A Dual-Metal−OrganicFramework Derived Electrocatalyst for Oxygen Reduction. Energy Environ. Sci. 2016, 9, 3092−3096. (19) Guan, B. Y.; Yu, L.; Lou, X. W. Formation of Single-Holed Cobalt/N-Doped Carbon Hollow Particles with Enhanced Electrocatalytic Activity toward Oxygen Reduction Reaction in Alkaline Media. Advanced Science 2017, 4, 1700247. (20) Guan, B. Y.; Yu, X. Y.; Wu, H. B.; Lou, X. W. Complex Nanostructures from Materials Based on Metal−Organic Frameworks for Electrochemical Energy Storage and Conversion. Adv. Mater. 2017, 29, 1703614. (21) Wang, J.; Luo, X.; Young, C.; Kim, J.; Kaneti, Y. V.; You, J.; Kang, Y.-M.; Yamauchi, Y.; Wu, K. C. W. A Glucose-Assisted Hydrothermal Reaction for Directly Transforming Metal−Organic Frameworks into Hollow Carbonaceous Materials. Chem. Mater. 2018, 30, 4401−4408. (22) Wu, R.; Qian, X.; Zhou, K.; Wei, J.; Lou, J.; Ajayan, P. M. Porous Spinel ZnxCO3−XO4 Hollow Polyhedra Templated for HighRate Lithium-Ion Batteries. ACS Nano 2014, 8, 6297−6303. (23) Jiang, Z.; Sun, H.; Qin, Z.; Jiao, X.; Chen, D. Synthesis of Novel ZnS Nanocages Utilizing ZIF-8 Polyhedral Template. Chem. Commun. 2012, 48, 3620−3622. (24) Yang, J.; Zhang, F.; Lu, H.; Hong, X.; Jiang, H.; Wu, Y.; Li, Y. Hollow Zn/Co ZIF Particles Derived from Core−Shell ZIF-67@ZIF8 as Selective Catalyst for the Semi-Hydrogenation of Acetylene. Angew. Chem. 2015, 127, 11039−11043. (25) Xiang, S.; Qian, H.-J.; Chen, Y.; Zhang, K.; Shi, Y.; Liu, W.; Sun, H.; Sun, H.; Yang, B. Chelation Competition Induced Polymerization (CCIP): A Binding Energy Based Strategy for Nonspherical Polymer Nanocontainers’ Fabrication. Chem. Mater. 2017, 29, 6536−6543. (26) Xiang, S.; Shi, Y.; Zhang, K.; Chen, Y.; Ge, R.; Wu, C.; Sun, H.; Yang, B. Design and Synthesis of Dodecahedral Carbon Nanocages Incorporated with Fe3O4. RSC Adv. 2017, 7, 13257−13262. (27) Xiang, S.; Wang, D.; Zhang, K.; Liu, W.; Wu, C.; Meng, Q.; Sun, H.; Yang, B. Chelation Competition Induced Polymerization (CCIP): Construction of Integrated Hollow Polydopamine Nanocontainers with Tailorable Functionalities. Chem. Commun. 2016, 52, 10155−10158. (28) Salunkhe, R. R.; Kaneti, Y. V.; Kim, J.; Kim, J. H.; Yamauchi, Y. Nanoarchitectures for Metal−Organic Framework-Derived Nanoporous Carbons toward Supercapacitor Applications. Acc. Chem. Res. 2016, 49, 2796−2806. (29) Jiang, J.; Soo Lim, Y.; Park, S.; Kim, S.-H.; Yoon, S.; Piao, L. Hollow Porous Cu Particles from Silica-Encapsulated Cu2O Nanoparticle Aggregates Effectively Catalyze 4-Nitrophenol Reduction. Nanoscale 2017, 9, 3873−3880. (30) Zhang, J.; Yu, L.; Lou, X. W. D. Embedding CoS2 Nanoparticles in N-Doped Carbon Nanotube Hollow Frameworks for Enhanced Lithium Storage Properties. Nano Res. 2017, 10, 4298−4304.

(31) Wen, Q.; Zhang, M.; Zheng, J.; Xu, J. Rationally Designed Hierarchical Nickel Nanoparticles-Based Magnetic Yolk-Like Nanospindles for Enhanced Catalysis and Protein Adsorption. CrystEngComm 2018, 20, 5377−5386. (32) Yang, X.; Zhang, M.; Zheng, J.; Li, W.; Gan, W.; Xu, J.; Hayat, T.; Alharbi, N. S.; Yang, F. Ni Nanoparticles Decorated onto Graphene Oxide with SiO2 as Interlayer for High Performance on Histidine-Rich Protein Separation. Appl. Surf. Sci. 2018, 439, 128− 138. (33) Chen, Y.; Li, X.; Zhou, X.; Yao, H.; Huang, H.; Mai, Y.-W.; Zhou, L. Hollow-Tunneled Graphitic Carbon Nanofibers through NiDiffusion-Induced Graphitization as High-Performance Anode Materials. Energy Environ. Sci. 2014, 7, 2689−2696. (34) Yang, H.; Bradley, S. J.; Chan, A.; Waterhouse, G. I. N.; Nann, T.; Kruger, P. E.; Telfer, S. G. Catalytically Active Bimetallic Nanoparticles Supported on Porous Carbon Capsules Derived from Metal−Organic Framework Composites. J. Am. Chem. Soc. 2016, 138, 11872−11881. (35) Guo, X.; Zhang, M.; Zheng, J.; Xu, J.; Hayat, T.; Alharbi, N. S.; Xi, B.; Xiong, S. Fabrication of Co@SiO2@C/Ni Submicrorattles as Highly Efficient Catalysts for 4-Nitrophenol Reduction. Dalton Transactions 2017, 46, 11598−11607. (36) Zhang, S.; Zhang, Y.; Liu, J.; Xu, Q.; Xiao, H.; Wang, X.; Xu, H.; Zhou, J. Thiol Modified Fe3O4@SiO2 as a Robust, High Effective, and Recycling Magnetic Sorbent for Mercury Removal. Chem. Eng. J. 2013, 226, 30−38. (37) Gao, C.; Lu, Z.; Yin, Y. Gram-Scale Synthesis of Silica Nanotubes with Controlled Aspect Ratios by Templating of NickelHydrazine Complex Nanorods. Langmuir 2011, 27, 12201−12208. (38) Yu, H.; Zhang, Q.; Joo, J. B.; Li, N.; Moon, G. D.; Tao, S.; Wang, L.; Yin, Y. Porous Tubular Carbon Nanorods with Excellent Electrochemical Properties. J. Mater. Chem. A 2013, 1, 12198−12205. (39) Fang, Q.; Zhang, J.; Bai, L.; Duan, J.; Xu, H.; Cham-Fai Leung, K.; Xuan, S. In Situ Redox-Oxidation Polymerization for Magnetic Core-Shell Nanostructure with Polydopamine-Encapsulated-Au Hybrid Shell. J. Hazard. Mater. 2019, 367, 15−25. (40) Zhang, Z.; Chen, Y.; He, S.; Zhang, J.; Xu, X.; Yang, Y.; Nosheen, F.; Saleem, F.; He, W.; Wang, X. Hierarchical Zn/Ni-MOF2 Nanosheet-Assembled Hollow Nanocubes for Multicomponent Catalytic Reactions. Angew. Chem. 2014, 126, 12725−12729. (41) Chen, K.; Sun, Z.; Fang, R.; Shi, Y.; Cheng, H.-M.; Li, F. Metal−Organic Frameworks (MOFs)-Derived Nitrogen-Doped Porous Carbon Anchored on Graphene with Multifunctional Effects for Lithium−Sulfur Batteries. Adv. Funct. Mater. 2018, 28, 1707592. (42) Lee, G.; Seo, Y. D.; Jang, J. ZnO Quantum Dot-Decorated Carbon Nanofibers Derived from Electrospun ZIF-8/PVA Nanofibers for High-Performance Energy Storage Electrodes. Chem. Commun. 2017, 53, 11441−11444. (43) Wang, T.; Shi, L.; Tang, J.; Malgras, V.; Asahina, S.; Liu, G.; Zhang, H.; Meng, X.; Chang, K.; He, J.; Terasaki, O.; Yamauchi, Y.; Ye, J. A Co3O4-Embedded Porous ZnO Rhombic Dodecahedron Prepared Using Zeolitic Imidazolate Frameworks as Precursors for CO2 Photoreduction. Nanoscale 2016, 8, 6712−6720. (44) Bai, F.; Xia, Y.; Chen, B.; Su, H.; Zhu, Y. Preparation and Carbon Dioxide Uptake Capacity of N-Doped Porous Carbon Materials Derived from Direct Carbonization of Zeolitic Imidazolate Framework. Carbon 2014, 79, 213−226. (45) Chen, J.; Xue, Z.; Feng, S.; Tu, B.; Zhao, D. Synthesis of Mesoporous Silica Hollow Nanospheres with Multiple Gold Cores and Catalytic Activity. J. Colloid Interface Sci. 2014, 429, 62−67. (46) Li, R.; Yang, Y.; Li, R.; Chen, Q. Experimental and Theoretical Studies on the Effects of Magnetic Fields on the Arrangement of Surface Spins and the Catalytic Activity of Pd Nanoparticles. ACS Appl. Mater. Interfaces 2015, 7, 6019−6024. (47) Zhang, X.; Su, Z. Polyelectrolyte-Multilayer-Supported Au@Ag Core-Shell Nanoparticles with High Catalytic Activity. Adv. Mater. 2012, 24, 4574−4577. (48) Gao, H.; Cao, R.; Xu, X.; Xue, J.; Zhang, S.; Hayat, T.; Alharbi, N. S.; Li, J. Surface Area- and Structure-Dependent Effects of Ldh for K

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX

Article

Inorganic Chemistry Highly Efficient Dye Removal. ACS Sustainable Chem. Eng. 2019, 7, 905−915. (49) Liu, X.; Sun, J.; Xu, X.; Alsaedi, A.; Hayat, T.; Li, J. Adsorption and Desorption of U(Vi) on Different-Size Graphene Oxide. Chem. Eng. J. 2019, 360, 941−950. (50) Wang, D.; Xu, Y.; Xiao, D.; Qiao, Q.; Yin, P.; Yang, Z.; Li, J.; Winchester, W.; Wang, Z.; Hayat, T. Ultra-Thin Iron Phosphate Nanosheets for High Efficient U(Vi) Adsorption. J. Hazard. Mater. 2019, 371, 83−93. (51) Zheng, J.; Lin, Z.; Lin, G.; Yang, H.; Zhang, L. Preparation of Magnetic Metal−Organic Framework Nanocomposites for Highly Specific Separation of Histidine-Rich Proteins. J. Mater. Chem. B 2015, 3, 2185−2191. (52) Zheng, J.; Lin, Z.; Liu, W.; Wang, L.; Zhao, S.; Yang, H.; Zhang, L. One-Pot Synthesis of CuFe2O4 Magnetic Nanocrystal Clusters for Highly Specific Separation of Histidine-Rich Proteins. J. Mater. Chem. B 2014, 2, 6207−6214. (53) Zheng, J.; Zhang, M.; Miao, T.; Yang, J.; Xu, J.; Alharbi, N. S.; Wakeel, M. Anchoring Nickel Nanoparticles on Three-Dimensionally Macro-/Mesoporous Titanium Dioxide with a Carbon Layer from Polydopamine Using Polymethylmethacrylate Microspheres as Sacrificial Templates. Materials Chemistry Frontiers 2019, 3, 224−232.

L

DOI: 10.1021/acs.inorgchem.9b00288 Inorg. Chem. XXXX, XXX, XXX−XXX