Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
Two-Dimensional Zeolitic Imidazolate Framework-L-Derived Iron− Cobalt Oxide Nanoparticle-Composed Nanosheet Array for Water Oxidation Yinge Li,† Wenxin Zhu,† Xue Fu,† Yi Zhang,† Ziyi Wei,† Yiyue Ma,† Tianli Yue,† Jing Sun,‡ and Jianlong Wang*,† Inorg. Chem. Downloaded from pubs.acs.org by UNIV OF LOUISIANA AT LAFAYETTE on 04/23/19. For personal use only.
†
College of Food Science and Engineering, Northwest A&F University, 22 Xinong Road, Yangling 712100, Shaanxi, China Qinghai Key Laboratory of Qinghai-Tibet Plateau Biological Resources, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Road, Xining 810008, Qinghai, China
‡
S Supporting Information *
ABSTRACT: Rational design of various functional nanomaterials using MOFs as a template provides an effective strategy to synthesize electrocatalysts for water splitting. In this work, we reported that an iron−cobalt oxide with 2D well-aligned nanoflakes assembling on carbon cloth (Fe-Co3O4 NS/CC), fabricated by an anion-exchange reaction followed by an annealing process, could serve as a high-performance oxygenevolving catalyst. Specifically, the zeolitic imidazolate framework-L-Co nanosheet array (ZIF-L-Co NS/CC) was synthesized through a facile ambient liquid-phase deposition reaction, and then reacted with [Fe(CN)6]3− ions as precursors during the anion-exchange reaction at room temperature. Finally, the Fe-Co3O4 NS/CC was obtained via annealing treatment. On account of the compositional and structural superiority, this 3D monolithic anode exhibited outstanding electrocatalytic performance with a low overpotential of 290 mV to obtain a geometrical current density of 10 mA cm−2 and good durability for water oxidation in base.
■
materials in water electrolysis systems.20,21 Hence, exploring alternative non-precious-metal-based stable and efficient OER catalysts becomes urgent. Particularly, we noticed that cobalt oxides/(oxy)hydroxides have been widely proven to be good alternative OER catalysts,22−27 though their intrinsic catalytic activities still could not be comparable to those of the Ru/Ir-based ones. To this end, some means such as structural/compositional/defect engineering have been recently developed for improving their OER performances. For structural engineering, the welldesigned 2D thin nanosheets,28−31 3D self-supported nanoarrays,27,32,33 and 0D hollow nanostructures34−36 of cobalt oxides/(oxy)hydroxides could enlarge the effective surface area and thereby expose more active sites. For compositional engineering, doping with heteroatoms,24−26,37−41 fabricating cobalt−cobalt oxides/bimetallic oxides/cobalt oxides@ C,32,42,43 and hybridizing with Au/CNTs/graphene44−46 could alter the local electronic structures or improve electron-transfer kinetics. For defect engineering, both oxygen and cobalt vacancies could modulate the electronic structures, facilitate water dissociation, or create more active sites.47−49
INTRODUCTION The increasing energy demands and environment issues resulting from fossil fuel combustion have aroused considerable interest in hunting for renewable and clean energy sources and storage devices.1−4 Among abundant alternative fuels, the carbon-free, renewable, and clean hydrogen has been well-identified as the ideal energy carrier with high gravimetric energy density.5−7 Electrochemical water splitting is a valid approach to produce the H2 fuel, due to its environmentally friendly nature, its low energy consumption, and the high purity of the product.8,9 There are two half reactions [hydrogen evolution reaction (HER) at cathode and the oxygen evolution reaction (OER) at anode] in a typical watersplitting system.10,11 However, the overall efficiency of water splitting is severely constrained by the OER, which is actually a four-electron-transfer process involving O−H bond breaking and O−O bond formation and will inevitably lead to a large overpotential requirement and intrinsic sluggish kinetics.12−14 In light of this, intensive efforts have been made to develop highly efficient electrocatalysts for OER.15−18 Conventionally, noble-metal (Ru/Ir)-based catalysts are still state-of-the-art OER catalysts with high intrinsic activities.19 Nevertheless, the low natural abundance, poor durability, and inherent high price hinder the large-scale application of these noble-metal-based © XXXX American Chemical Society
Received: February 16, 2019
A
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry In these above strategies, simultaneous compositional and structural engineering of cobalt oxides/(oxy)hydroxides to enhance their OER performances has aroused particular attention in recent years. Zhu et al. synthesized an ultrathin iron−cobalt oxide nanosheet with large specific surface area and abundant oxygen vacancies by a facile solution reduction method using NaBH4 as a reductant, which shows a high mass activity for OER.37 Meanwhile, Sun’s group reported that in situ electrochemical surface derivation of an amorphous Co−Bi layer on the Co3O4 nanowire array and Fe−Co−Bi layer on the Fe-Co3O4 nanowire array could significantly improve their alkaline or near-neutral OER performance.50,51 Subsequently, Li et al. developed an Fe-substituted CoOOH porous nanosheet array on a carbon fiber cloth by a facile electrochemical anodic oxidation process and proved its superior OER performance.40 Also, recently, Lou’s group reported that a hollow Co3O4@Co-Fe oxide double-shelled nanobox structure formed by a facile MOF-hybrid-assisted strategy presents high OER activity.34 All these results demonstrate that the structural and compositional engineering strategy could bring improved OER activities to cobalt-based oxides/(oxy)hydroxides. With inspiration from the above advances, and with the consideration that annealing MOF-based nanoarrays in special atmospheres has been well-recognized as a general approach to synthesize transition-metal oxides or oxide-carbon nanoarrays with good OER activities and no use of insulated binders,32,33,52 an iron−cobalt oxide ultra-small-particle-composed nanosheet array on carbon fiber cloth (Fe-Co3O4 NS/CC) by conversion of the zeolitic imidazolate framework-L-Co nanosheet array was fabricated here. The key synthetic procedure involves an ambient anion-etching reaction followed by a hotair annealing process. By virtue of the exposed abundant catalytic active sites and free diffusion of gas and electrolyte on the catalyst surface enabled by the rough nanoparticle-coated nanosheet array structure, as well as the facilitated electrontransfer kinetics and improved intrinsic catalytic activity enabled by the introduced Fe, this Fe-Co3O4 NS/CC exhibits a superb catalytic activity for alkaline OER, achieving a current density of 10 mA cm−2 at a low overpotential of 290 mV for at least 25 h.
Figure 1. Low- and high-magnification SEM images of (a, d) CoMOF NS/CC, (b, e) Fe@Co-MOF NS/CC, and (c, f) Fe-Co3O4 NS/CC. (g) TEM image, (h) HRTEM image, and (i) SAED pattern of the scratched Fe-Co3O4 nanosheets.
MOF to thinner Co3O4 nanosheets (Figure 1b and Figure S4). Meanwhile, the height of these nanosheets on CC decreased from 4.8 μm (Fe@Co-MOF) to 3.85 μm (Fe-Co3O4) (Figure S3c,d). In addition, note that the surface of the Fe-Co3O4 nanosheets is much rougher than that of the Co3O4 nanosheets (Figure 1f and Figures S3b and S4b). Also, the recorded corresponding energy-dispersive X-ray (EDX) spectrum and elemental mappings of Fe-Co3O4 NS/CC indicate the Co, Fe, and O elements coexist and are distributed homogeneously on this material, and the ratio of Co, Fe, and O elements is about 1:0.25:2.5 (Figure S5). The transmission electron microscope (TEM) images (Figure 1g and Figure S6) also indicate that both the Fe-Co3O4 and Fe@Co-MOF have a plate-like structure. From the high-resolution TEM (HRTEM) image, distinct lattice fringes can be clearly observed, in which lattice spacings of 0.28 and 0.23 nm belong to the (220) and (222) planes of cubic Co3O4 (Figure 1h), respectively. Meanwhile, obvious diffraction rings in the selected area diffraction (SAED) pattern for the Fe-Co3O4 nanosheets are also wellindexed to the (220), (311), (400), (511), and (440) planes of Co3O4 (Figure 1i). Corresponding elemental mappings confirm the uniform distribution of elements on the surface of the Fe-Co3O4 nanosheet (Figure S7). In addition, as determined by N2 sorption measurements, the Fe-Co3O4 nanosheets possess a relatively high Brunauer−Emmett−Teller (BET) specifc surface area of 50.76 m2 g−1 and an average pore size of 18 nm (Figure S8). The crystalline information on these materials was surveyed by X-ray diffraction (XRD) analysis, as shown in Figure 2a. The peaks existing at 25.6° and 43.5° in each material could be assigned to CC substrate.53 In the XRD pattern of Co-MOF NS/CC, in addition to the two typical peaks assigned to the CC, all other peaks belong well to the diffraction pattern of the leaf-like ZIF-L-Co phase.11 The XRD pattern of Fe@Co-MOF NS/CC only shows the diffraction peaks ascribed to the CC, indicating that, after hybriding with [Fe(CN)6]3− ions, the initial crystal structure of ZIF-L-Co was destroyed and the Fe@Co-MOF has a low crystallinity. After air annealing, both the products converted from the Co-MOF NS/CC and Fe@ Co-MOF NS/CC show the characteristic peaks indexed to cubic Co3O4 (JCPDS 42-1467), which is consistent with the HRTEM-SAED results.54 Also, note that there is no peak of
■
RESULTS AND DISCUSSION The synthetic process of the Fe-Co3O4 NS/CC was depicted as follows. First, the Co-MOF was synthesized by the reaction of Co2+ and C4H6N2 at room temperature. Then, the Co-MOF NS/CC was converted into Fe@Co-MOF NS/CC through an anion-exchange process with [Fe(CN)6]3− ions, after which the Fe@Co-MOF NS/CC was annealed at 350 °C in air to convert into Fe-Co3O4 NS/CC. An apparent color change from bluish violet to brown to black could be observed in the synthesis process (Figure S1). The morphology change of these samples was further investigated through the fieldemission scanning electron microscope (FE-SEM). Figure S2 shows the low-magnification FESEM images of these samples. At the very beginning, Co-MOF with an orderly and smoothfaced nanosheet array was vertically grown on the carbon cloth (Figure 1a,b). After the anion-exchange reaction with [Fe(CN)6]3− ions, the surface of the nanosheets became rough with generated ultrasmall nanoparticles (Figure 1c,d and Figure S3a). After annealing in air, the rough Fe-Co3O4 nanosheets became thinner to be about 0.155 μm (Figure 1e,f and Figure S3b), which is similar to the transition of CoB
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
Figure 2. (a) XRD patterns of the bare CC, Co-MOF NS/CC, Fe@ Co-MOF NS/CC, Co3O4 NS/CC, and Fe-Co3O4 NS/CC. (b) XPS survey spectrum and high-resolution XPS spectra of (c) Co 2p and (d) Fe 2p of the Fe-Co3O4 NS/CC.
iron or iron oxide observed, and the intensity of the peaks of Fe-Co3O4 NS/CC is weaker than that of Co3O4 NS/CC. Meanwhile, the large iron content suggests that the existing form of the Fe species in the catalyst is not likely to be a dopant. On the basis of the above results, we think that an amorphous or low-crystallinity Co−Fe oxide phase was likely formed on the surface of the nanosheets.34 The surface chemical state of the Fe-Co3O4 NS/CC was revealed by X-ray photoelectron spectroscopy (XPS) analysis. The survey XPS spectrum also proves the coexistence of Fe, Co, and O elements in this sample, as depicted by Figure 2b. The high-revolution XPS spectrum of Co 2p could be fitted for two spin−orbit doublets. The bingding energies (BEs) at 780.1 and 795.3 eV are assigned to Co 2p3/2 and Co 2p1/2 for Co3+, respectively. Also, BEs at 781.3 and 796.9 eV are assigned to Co 2p3/2 and Co 2p1/2 for Co2+, respectively (Figure 2c).12,53 Figure 2d shows the high-resolution XPS spectrum of Fe 2p. The peaks at 713.4 and 724.6 eV could be assigned to the binding energies of Fe 2p3/2 and Fe 2p1/2, respectively, with a shakeup satellite peak located at 718.2 eV. In addition, the peak located at 711.0 eV suggests the existence of Fe3+.55−58 Here, the two mixed-valence Co2+/Co3+ and Fe2+/Fe3+ pairs with rich reversible redox behaviors might be conducive to the high OER activity of this catalyst. Considering its compositional and structural advantages, the Fe-Co3O4 NS/CC was thereby expected to exhibit excellent electrocatalytic OER activity. In detail, its OER performance was investigated by linear sweep voltammetry (LSV) at 2 mV s−1 in a homemade three-electrode device in 1.0 M KOH. For comparison, the OER performances of RuO2 particles with the same loading on CC (RuO2/CC), bare CC, and Co3O4 NS/ CC were also evaluated in the same condition. Figure 3a shows the OER LSV curves of the Fe-Co3O4 NS/CC and control samples. It is noteworthy that, due to the influence of ohmic resistance, the as-tested initial reaction currents were all iR corrected to reflect directly the intrinsic behavior of catalysts.59,60 The characteristic oxidation peak belonging to Co2+/Co3+ before OER catalysis could be observed in a lowcurrent-density region (Figure S9), which is in accordance with
Figure 3. (a) OER polarization curves of Fe-Co3O4 NS/CC, Co3O4 NS/CC, bare CC, and RuO2/CC at a scan rate of 2 mV s−1 in 1.0 M KOH. (b) Corresponding Tafel plots. (c) Capacitive current densities (Δj) of Fe-Co3O4 NS/CC, Co3O4 NS/CC, and bare CC at 0.35 V as a function of the scan rates in the range 0.3−0.4 V vs MOE. (d) Nyquist plots measured in 1.0 M KOH. (e) Multistep chronopotentiometric curve for the Fe-Co3O4 NS/CC recorded in 1.0 M KOH (without iR correction). (f) Long-term chronopotentiometric curves at 10, 50, and 100 mA cm−2 for the Fe-Co3O4 NS/CC in 1.0 M KOH (without iR correction).
a previous report.31,61 Obviously, the Fe-Co3O4 NS/CC just requires a low overpotential of 290 mV to obtain a current density of 10 mA cm−2, which is much lower than those for bare CC (435 mV) and Co3O4 NS/CC (360 mV), and only a bit larger than that for RuO2/CC (270 mV). Notably, though the OER performance of RuO2/CC is superior to that for FeCo3O4 NS/CC at low overpotentials, the rise of OER current density for Fe-Co3O4 NS/CC is faster than that for RuO2/CC, which could be due to the easier diffusion of electrolyte and generated O2 enabled by the open-shelled rough nanosheets array structure.59 This OER performance of Fe-Co3O4 NS/CC is also superior/comparable to many recently reported state-ofthe-art OER electrocatalysts (Table S1). The recorded massnormalized OER performances of Fe-Co3O4 NS/CC, Co3O4 NS/CC, and RuO2/CC (Figure S10) illustrate that the intrinsic OER activity of Co3O4 NS/CC is greatly improved after the incorporation of Fe. In addition, the influence of the concentration of [Fe(CN)6]3− ions during the anion-exchange reaction on the OER activity of the derived Fe-Co3O4 NS/CC was also investigated. LSV curves in Figure S11 show almost the same catalytic activity of the obtained samples with different concentrations of [Fe(CN)6]3− ions, suggesting that the concentration of [Fe(CN)6]3− may have little effect on the OER performance in a certain range. Figure 3b shows the Tafel plots of these samples. The Tafel slope of Fe-Co3O4 NS/CC is 67.9 mV dec−1, much lower than those for RuO2/CC, Co3O4 C
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry NS/CC, and bare CC, indicative of a more favorable OER kinetics of this Fe-Co3O4 NS/CC.8 To explore the reasons for performance improvement, both the electrochemical surface area (ECSA) and electrochemical impedance spectroscopy data (EIS) were measured. Generally, the ECSA is proportional to the electrochemical double-layer capacitance (Cdl).62 Hence, the Cdl was calculated to evaluate the ECSA through measuring the cyclic voltammetric (CV) curves in a typical potential range without the redox process; that is, in a chosen 0.1 V potential window, all the measured currents are assumed to be associated with double-layer charging.20,63 Figure S12 shows the CV curves of Fe-Co3O4 NS/CC, Co3O4 NS/CC, and CC at different scan rates in the range 0.3−0.4 V vs mercuric oxide electrode (MOE) in 1.0 M KOH. Figure 3c indicates the Fe-Co3O4 NS/CC has a larger Cdl value (37.11 mF cm−2) than the Co3O4 NS/CC (30.59 mF cm−2) and bare CC (2.48 mF cm−2), implying the Fe-Co3O4 NS/CC exposes more catalytic active sites.64 One reason for the improvement of Cdl might be the generated defects during the ionic exchange reaction process.65 An EIS test was conducted to further evaluate the electron-transfer kinetics of the Fe-Co3O4 NS/CC and Co3O4 NS/CC. From the Nyquist plots depicted in Figure 3d, we could find that the Fe-Co3O4 NS/CC displays a much lower electron-transfer resistance compared with that of Co3O4 NS/CC. The largely reduced impedance and thus accelerated electron-transfer kinetics become another factor for the enhanced OER performance. Here, the excellent OER activity of Fe-Co3O4 NS/CC could be explained as follows: (i) increased catalytic active sites endowed by anion etching; (ii) improved electron-transfer kinetics endowed by the introduction of Fe into Co3O4 phase; (iii) enlarged electrolyte/electrode contact area for the electrochemical reaction and O2 diffusion endowed by the open-shelled rough nanosheet array structure. Stability is another essential parameter for evaluation of the OER performance of catalytic anodes. Both the multistep and long-term chronopotentiometric curves without iR correction were recorded to investigate the catalytic stability of the FeCo3O4 NS/CC in base. The current densities in the multistep chronopotentiometric test were set to be from 10 to 100 mA cm−2 (10 mA cm−2 per 500 s). The fast response for each current density, well-maintained current density for each remaining 500 s, and the almost overlapping polarization curves before and after the test of this Fe-Co3O4 NS/CC (Figure 3e) suggest its good mass transport property and working stability for OER.66 Moreover, this Fe-Co3O4 NS/CC was operated to catalyze OER at the fixed current densities of 10, 50, and 100 mA cm−2 for long-term chronopotentiometric measurements. As expected, this electrode displayed outstanding electrochemical robustness with its current density being maintained at 10 mA cm−2 for at least 25 h without evident voltage change (Figure 3f). In addition, it should be noted that the voltages at 50 and 100 mA cm−2 increased a little bit faster than that at 10 mA cm−2, which could be explained by the O2 produced on the surface of electrode possibly occupying the active sites on the electrode surface and impeding the ionic transportation during the OER catalysis, especially for catalysts operating under a relative high current density.67 To study the structural and compositional stability of this Fe-Co3O4 NS/CC during OER catalysis, SEM, XRD, and XPS analyses of this catalyst after over 20 h electrolysis at 10, 50, and 100 mA cm−2 were employed. SEM images in Figure 4a−c show that the particle-composed nanosheet array
Figure 4. (a−c) SEM images, (d) XRD pattern, and (e) XPS survey spectrum. High-resolution XPS spectra of (f) Co 2p and (g) Fe 2p for the Fe-Co3O4 NS/CC after long-term chronopotentiometric measurements at 10, 50, and 100 mA cm−2 for over 20 h.
structure of the Fe-Co3O4 NS/CC was well-maintained after long-term chronopotentiometric measurements at 10, 50, and 100 mA cm−2, respectively. XRD and XPS analyses were then conducted to characterize the evolution of the Fe-Co3O4 NS/ CC in the OER process. It is found that the peaks in the XRD pattern after the OER test are consistent with those before the OER test (Figure 4d), and the surface composition and chemical states after OER have no evident change (Figure 4e− g), revealing the good chemical stability of the Fe-Co3O4 NS/ CC.
■
CONCLUSION In summary, we successfully fabricated the well-aligned iron− cobalt oxide nanosheets array on carbon fiber cloth through an anion-exchange reaction with [Fe(CN)6]3− ions and followed annealing strategy in air using the ZIF-L-Co nanosheets array as a template. Both the incorporation of Fe and nanoparticlesconsisted open-shelled nanosheets array structure endow the Fe-Co3O4 NS/CC with some expectant virtues like enlarged active surface area, improved electron-transfer kinetics, and facilitated electrolyte penetration and O2 diffusion. By virtue of these aspects, the Fe-Co3O4 NS/CC presents excellent electrocatalytic OER activity with low overpotential and good stability. We believe that the facile approach proposed here could inspire further extension on constructing heteroatoms-incorporated nanostructures utilizing MOFs as templates for more energy-related applications.
■
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.9b00463. D
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
■
(12) Wang, X.; Li, F.; Li, W.; Gao, W.; Tang, Y.; Li, R. Hollow Bimetallic Cobalt-based Selenide Polyhedrons Derived from MetalOrganic Framework: An Efficient Bifunctional Electrocatalyst for Overall Water Splitting. J. Mater. Chem. A 2017, 5, 17982−17989. (13) Yu, L.; Yang, J. F.; Guan, B. Y.; Lu, Y.; Lou, X. W. Hierarchical Hollow Nanoprisms Based on Ultrathin Ni-Fe Layered Double Hydroxide Nanosheets with Enhanced Electrocatalytic Activity towards Oxygen Evolution. Angew. Chem., Int. Ed. 2018, 57, 172−176. (14) Li, S.; Peng, S.; Huang, L.; Cui, X.; Al-Enizi, A. M.; Zheng, G. Carbon-Coated Co3+-Rich Cobalt Selenide Derived from ZIF-67 for Efficient Electrochemical Water Oxidation. ACS Appl. Mater. Interfaces 2016, 8, 20534−20539. (15) Tang, T.; Jiang, W.-J.; Niu, S.; Liu, N.; Luo, H.; Chen, Y.-Y.; Jin, S.-F.; Gao, F.; Wan, L.-J.; Hu, J.-S. Electronic and Morphological Dual Modulation of Cobalt Carbonate Hydroxides by Mn Doping toward Highly Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting. J. Am. Chem. Soc. 2017, 139, 8320−8328. (16) Han, L.; Yu, X.-Y.; Lou, X. W. Formation of Prussian-BlueAnalog Nanocages via a Direct Etching Method and their Conversion into Ni-Co-Mixed Oxide for Enhanced Oxygen Evolution. Adv. Mater. 2016, 28, 4601−4605. (17) Zhu, X.; Shi, X.; Asiri, A. M.; Luo, Y.; Sun, X. Efficient Oxygen Evolution Electrocatalyzed by a Cu Nanoparticle-Embedded NDoped Carbon Nanowire Array. Inorg. Chem. Front. 2018, 5, 1188− 1192. (18) Li, P.; Zhao, R.; Chen, H.; Wang, H.; Wei, P.; Huang, H.; Liu, Q.; Li, T.; Shi, X.; Zhang, Y.; Liu, M.; Sun, X. Recent Advances in the Development of Water Oxidation Electrocatalysts at Mild pH. Small 2019, 15, 1805103. (19) Reier, T.; Oezaslan, M.; Strasser, P. Electrocatalytic Oxygen Evolution Reaction (OER) on Ru, Ir, and Pt Catalysts: A Comparative Study of Nanoparticles and Bulk Materials. ACS Catal. 2012, 2, 1765−1772. (20) Yan, L.; Dai, P.; Wang, Y.; Gu, X.; Li, L.; Cao, L.; Zhao, X. In Situ Synthesis Strategy for Hierarchically Porous Ni2P Polyhedrons from MOFs Templates with Enhanced Electrochemical Properties for Hydrogen Evolution. ACS Appl. Mater. Interfaces 2017, 9, 11642− 11650. (21) Liu, Q.; Xie, L.; Shi, X.; Du, G.; Asiri, A. M.; Luo, Y.; Sun, X. High-Performance Water Oxidation Electrocatalysis Enabled by a NiMOF Nanosheet Array. Inorg. Chem. Front. 2018, 5, 1570−1574. (22) Hutchings, G. S.; Zhang, Y.; Li, J.; Yonemoto, B. T.; Zhou, X.; Zhu, K.; Jiao, F. In Situ Formation of Cobalt Oxide Nanocubanes as Efficient Oxygen Evolution Catalysts. J. Am. Chem. Soc. 2015, 137, 4223−4229. (23) Bajdich, M.; García-Mota, M.; Vojvodic, A.; Nørskov, J. K.; Bell, A. T. Theoretical Investigation of the Activity of Cobalt Oxides for the Electrochemical Oxidation of Water. J. Am. Chem. Soc. 2013, 135, 13521−13530. (24) Wang, J.; Liu, J.; Zhang, B.; Cheng, F.; Ruan, Y.; Ji, X.; Xu, K.; Chen, C.; Miao, L.; Jiang, J. Stabilizing the Oxygen Vacancies and Promoting Water-Oxidation Kinetics in Cobalt Oxides by Lower Valence-State Doping. Nano Energy 2018, 53, 144−151. (25) Chen, P.; Zhou, T.; Wang, S.; Zhang, N.; Tong, Y.; Ju, H.; Chu, W.; Wu, C.; Xie, Y. Dynamic Migration of Surface Fluorine-Anions on Cobalt-based Materials Realizing Enhanced Oxygen Evolution Catalysis. Angew. Chem., Int. Ed. 2018, 57, 15471−15475. (26) Han, X.; Yu, C.; Zhou, S.; Zhao, C.; Huang, H.; Yang, J.; Liu, Z.; Zhao, J.; Qiu, J. Ultrasensitive Iron-Triggered Nanosized FeCoOOH Integrated with Graphene for Highly Efficient Oxygen Evolution. Adv. Energy Mater. 2017, 7, 1602148. (27) Wu, D.; Wei, Y.; Ren, X.; Ji, X.; Liu, Y.; Guo, X.; Liu, Z.; Asiri, A. M.; Wei, Q.; Sun, X. Co(OH)2 Nanoparticle-Encapsulating Conductive Nanowires Array: Room-Temperature Electrochemical Preparation for High-Performance Water Oxidation Electrocatalysis. Adv. Mater. 2018, 30, 1705366. (28) Sun, Y.; Gao, S.; Lei, F.; Liu, J.; Liang, L.; Xie, Yi. AtomicallyThin Non-Layered Cobalt Oxide Porous Sheets for Highly Efficient Oxygen-Evolving Electrocatalysts. Chem. Sci. 2014, 5, 3976−3982.
Supplementary method, optical photographs, SEM images, EDX spectrum, TEM image, TEM elemental mappings, BET data, electrochemical data, and Table S1 (PDF)
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Jianlong Wang: 0000-0002-2879-9489 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS The authors thank the National Natural Science Foundation of China (21675127), the Shaanxi Provincial Science Fund for Distinguished Young Scholars (2018JC-011), the Development Project of Qinghai Key Laboratory (2017-ZJ-Y10), and the Capacity Building Project of Engineering Research Center of Qinghai Province (2017-GX-G03).
■
REFERENCES
(1) 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. (2) Zhang, L. Y.; Gong, Y.; Wu, D.; Wu, G.; Xu, B.; Bi, L.; Yuan, W.; Cui, Z. Twisted Palladium-Copper Nanochains toward Efficient Electrocatalytic Oxidation of Formic Acid. J. Colloid Interface Sci. 2019, 537, 366−374. (3) Huang, Y.; Zhu, M.; Huang, Y.; Pei, Z.; Li, H.; Wang, Z.; Xue, Q.; Zhi, C. Multifunctional Energy Storage and Conversion Devices. Adv. Mater. 2016, 28, 1601928. (4) Wu, H. B.; Lou, X. W. Metal-Organic Frameworks and Their Derived Materials for Electrochemical Energy Storage and Conversion: Promises and Challenges. Sci. Adv. 2017, 3, eaap9252. (5) Popczun, E. J.; Read, C. G.; Roske, C. W.; Lewis, N. S.; Schaak, R. E. Highly Active Electrocatalysis of the Hydrogen Evolution Reaction by Cobalt Phosphide Nanoparticles. Angew. Chem., Int. Ed. 2014, 53, 5427−5430. (6) Zhang, L.; Mi, T.; Ziaee, M. A.; Liang, L.; Wang, R. Hollow POM@MOF Hybrid-Derived Porous Co3O4/CoMoO4 Nanocages for Enhanced Electrocatalytic Water Oxidation. J. Mater. Chem. A 2018, 6, 1639−1647. (7) Wang, Z.; Ren, X.; Wang, L.; Cui, G.; Wang, H.; Sun, X. A Hierarchical CoTe2-MnTe2 Hybrid Nanowire Array Enables High Activity for Oxygen Evolution Reactions. Chem. Commun. 2018, 54, 10993−10996. (8) Zhu, W.; Yue, Z.; Zhang, W.; Hu, N.; Luo, Z.; Ren, M.; Xu, Z.; Wei, Z.; Suo, Y.; Wang, J. Wet-Chemistry Topotactic Synthesis of Bimetallic Iron-Nickel Sulfide Nanoarrays: An Advanced and Versatile Catalyst for Energy Efficient Overall Water and Urea Electrolysis. J. Mater. Chem. A 2018, 6, 4346−4353. (9) Zhou, W.; Lu, X.-F.; Chen, J.-J.; Zhou, T.; Liao, P.-Q.; Wu, M.; Li, G.-R. Hierarchical Porous Prism Arrays Composed of Hybrid Ni/ NiO Carbon as Highly Efficient Electrocatalysts for Overall Water Splitting. ACS Appl. Mater. Interfaces 2018, 10, 38906−38914. (10) Zhang, P.; Li, L.; Nordlund, D.; Chen, H.; Fan, L.; Zhang, B.; Sheng, X.; Daniel, Q.; Sun, L. Dendritic Core-Shell Nickel-IronCopper Metal/Metal Oxide Electrode for Efficient Electrocatalytic Water Oxidation. Nat. Commun. 2018, 9, 381. (11) Zhu, W.; Zhang, W.; Li, Y.; Yue, Z.; Ren, M.; Zhang, Y.; Saleh, N. M.; Wang, J. Energy-Efficient 1.67 V Single- and 0.90 V DualElectrolyte based Overall Water-Electrolysis Devices Enabled by a ZIF-L Derived Acid-Base Bifunctional Cobalt Phosphide Nanoarray. J. Mater. Chem. A 2018, 6, 24277−24284. E
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
Bifunctional Electrocatalysts in Alkaline Media. Appl. Catal., B 2017, 203, 138−145. (46) Leng, M.; Huang, X.; Xiao, W.; Ding, J.; Liu, B.; Du, Y.; Xue, J. Enhanced Oxygen Evolution Reaction by Co-O-C Bonds in Rationally Designed Co3O4/Graphene Nanocomposites. Nano Energy 2017, 33, 445−452. (47) Xu, L.; Jiang, Q.; Xiao, Z.; Li, X.; Huo, J.; Wang, S.; Dai, L. Plasma-Engraved Co3O4 Nanosheets with Oxygen Vacancies and High Surface Area for the Oxygen Evolution Reaction. Angew. Chem., Int. Ed. 2016, 55, 5277−5281. (48) Zhang, R.; Zhang, Y.-C.; Pan, L.; Shen, G.-Q.; Mahmood, N.; Ma, Y.-H.; Shi, Y.; Jia, W.; Wang, L.; Zhang, X.; Xu, W.; Zou, J.-J. Engineering Cobalt Defects in Cobalt Oxide for Highly Efficient Electrocatalytic Oxygen Evolution. ACS Catal. 2018, 8, 3803−3811. (49) Ling, T.; Yan, D.-Y.; Jiao, Y.; Wang, H.; Zheng, Y.; Zheng, X.; Mao, J.; Du, X.-W.; Hu, Z.; Jaroniec, M.; Qiao, S.-Z. Engineering Surface Atomic Structure of Single-Crystal Cobalt (II) Oxide Nanorods for Superior Electrocatalysis. Nat. Commun. 2016, 7, 12876. (50) Zhou, D.; He, L.; Zhang, R.; Hao, S.; Hou, X.; Liu, Z.; Du, G.; Asiri, A. M.; Zheng, C.; Sun, X. Co3O4 Nanowire Arrays toward Superior Water Oxidation Electrocatalysis in Alkaline Media by Surface Amorphization. Chem. - Eur. J. 2017, 23, 15601−15606. (51) Zhu, G.; Ge, R.; Qu, F.; Du, G.; Asiri, A. M.; Yao, Y.; Sun, X. In Situ Surface Derivation of an Fe-Co-Bi Layer on an Fe-Doped Co3O4 Nanoarray for Efficient Water Oxidation Electrocatalysis under NearNeutral Conditions. J. Mater. Chem. A 2017, 5, 6388−6392. (52) Xu, H.; Shi, Z.-X.; Tong, Y.-X.; Li, G.-R. Porous Microrod Arrays Constructed by Carbon-Confined NiCo@NiCoO2 Core@ Shell Nanoparticles as Efficient Electrocatalysts for Oxygen Evolution. Adv. Mater. 2018, 30, 1705442. (53) Zhu, W.; Ren, M.; Hu, N.; Zhang, W.; Luo, Z.; Wang, R.; Wang, J.; Huang, L.; Suo, Y.; Wang, J. Traditional NiCo2S4 Phase with Porous Nanosheets Array Topology on Carbon Cloth: a Flexible, Versatile and Fabulous Electrocatalyst for Overall Water and Urea Electrolysis. ACS Sustainable Chem. Eng. 2018, 6, 5011−5020. (54) Gupta, S.; Yadav, A.; Bhartiya, S.; Singh, M. K.; Miotello, A.; Sarkar, A.; Patel, N. Co Oxide Nanostructures for Electrocatalytic Water-Oxidation: Effect of Dimensionality and Related Properties. Nanoscale 2018, 10, 8806−8819. (55) Hu, E.; Ning, J.; Zhao, D.; Xu, C.; Lin, Y.; Zhong, Y.; Zhang, Z.; Wang, Y.; Hu, Y. A Room-Temperature Postsynthetic Ligand Exchange Strategy to Construct Mesoporous Fe-Doped CoP Hollow Triangle Plate Arrays for Efficient Electrocatalytic Water Splitting. Small 2018, 14, 1704233. (56) Lu, X.-F.; Gu, L.-F.; Wang, J.-W.; Wu, J.-X.; Liao, P.-Q.; Li, G.R. Bimetal-Organic Framework Derived CoFe2O4/C Porous Hybrid Nanorod Arrays as High-Performance Electrocatalysts for Oxygen Evolution Reaction. Adv. Mater. 2017, 29, 1604437. (57) Guan, B. Y.; Lu, Y.; Wang, Y.; Wu, M.; Lou, X. W. Porous IronCobalt Alloy/Nitrogen-Doped Carbon Cages Synthesized via Pyrolysis of Complex Metal-Organic Framework Hybrids for Oxygen Reduction. Adv. Funct. Mater. 2018, 28, 1706738. (58) Tang, C.; Zhang, R.; Lu, W.; He, L.; Jiang, X.; Asiri, A. M.; Sun, X. Fe-Doped CoP Nanoarray: A Monolithic Multifunctional Catalyst for Highly Efficient Hydrogen Generation. Adv. Mater. 2017, 29, 1602441. (59) Zhu, W.; Zhang, T.; Zhang, Y.; Yue, Z.; Li, Y.; Wang, R.; Ji, Y.; Sun, X.; Wang, J. A Practical-Oriented NiFe-based Water-Oxidation Catalyst Enabled by Ambient Redox and Hydrolysis Co-Precipitation Strategy. Appl. Catal., B 2019, 244, 844−852. (60) Zhang, X.; Liu, Q.; Shi, X.; Asiri, A. M.; Sun, X. An Fe-MOF Nanosheet Array with Superior Activity towards the Alkaline Oxygen Evolution Reaction. Inorg. Chem. Front. 2018, 5, 1405−1408. (61) Wei, R.; Fang, M.; Dong, G.; Lan, C.; Shu, L.; Zhang, H.; Bu, X.; Ho, J. C. High-Index Faceted Porous Co3O4 Nanosheets with Oxygen Vacancies for Highly Efficient Water Oxidation. ACS Appl. Mater. Interfaces 2018, 10, 7079−7086. (62) He, P.; Yu, X.-Y.; Lou, X. W. Carbon-Incorporated NickelCobalt Mixed Metal Phosphide Nanoboxes with Enhanced Electro-
(29) Huang, J.; Chen, J.; Yao, T.; He, J.; Jiang, S.; Sun, Z.; Liu, Q.; Cheng, W.; Hu, F.; Jiang, Y.; Pan, Z.; Wei, S. CoOOH Nanosheets with High Mass Activity for Water Oxidation. Angew. Chem., Int. Ed. 2015, 54, 8722−8727. (30) Bao, J.; Zhang, X.; Fan, B.; Zhang, J.; Zhou, M.; Yang, W.; Hu, X.; Wang, H.; Pan, B.; Xie, Y. Ultrathin Spinel-Structured Nanosheets Rich in Oxygen Deficiencies for Enhanced Electrocatalytic Water Oxidation. Angew. Chem. 2015, 127, 7507−7512. (31) Sidhureddy, B.; Dondapati, J. S.; Chen, A. Shape-Controlled Synthesis of Co3O4 for Enhanced Electrocatalysis of the Oxygen Evolution Reaction. Chem. Commun. 2019, 55, 3626−3629. (32) Ma, T. Y.; Dai, S.; Jaroniec, M.; Qiao, S. Z. Metal-Organic Framework Derived Hybrid Co3O4-Carbon Porous Nanowire Arrays as Reversible Oxygen Evolution Electrodes. J. Am. Chem. Soc. 2014, 136, 13925−13931. (33) Zhu, Y. P.; Ma, T. Y.; Jaroniec, M.; Qiao, S. Z. Self-Templating Synthesis of Hollow Co3O4 Microtube Arrays for Highly Efficient Water Electrolysis. Angew. Chem., Int. Ed. 2017, 56, 1324−1328. (34) Wang, X.; Yu, L.; Guan, B. Y.; Song, S.; Lou, X. W. MetalOrganic Framework Hybrid-Assisted Formation of Co3O4/Co-Fe Oxide Double-Shelled Nanoboxes for Enhanced Oxygen Evolution. Adv. Mater. 2018, 30, 1801211. (35) Jiang, Z.; Jiang, Z.-J.; Maiyalagan, T.; Manthiram, A. Cobalt Oxide-Coated N- and B-Doped Graphene Hollow Spheres as Bifunctional Electrocatalysts for Oxygen Reduction and Oxygen Evolution Reactions. J. Mater. Chem. A 2016, 4, 5877−5889. (36) Hu, H.; Guan, B.; Xia, B.; Lou, X. W. Designed Formation of Co3O4/NiCo2O4 Double-Shelled Nanocages with Enhanced Pseudocapacitive and Electrocatalytic Properties. J. Am. Chem. Soc. 2015, 137, 5590−5595. (37) Zhuang, L.; Ge, L.; Yang, Y.; Li, M.; Jia, Y.; Yao, X.; Zhu, Z. Ultrathin Iron-Cobalt Oxide Nanosheets with Abundant Oxygen Vacancies for the Oxygen Evolution Reaction. Adv. Mater. 2017, 29, 1606793. (38) Wang, Z.; Liu, H.; Ge, R.; Ren, X.; Ren, J.; Yang, D.; Zhang, L.; Sun, X. Phosphorus-Doped Co3O4 Nanowire Array: A Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting. ACS Catal. 2018, 8, 2236−2241. (39) Liu, X.; Xi, W.; Li, C.; Li, X.; Shi, J.; Shen, Y.; He, J.; Zhang, L.; Xie, L.; Sun, X.; Wang, P.; Luo, J.; Liu, L.-M.; Ding, Y. Nanoporous Zn-Doped Co3O4 Sheets with Single-Unit-Cell-Wide Lateral Surfaces for Efficient Oxygen Evolution and Water Splitting. Nano Energy 2018, 44, 371−377. (40) Ye, S.-H.; Shi, Z.-X.; Feng, J.-X.; Tong, Y.-X.; Li, G.-R. Activating CoOOH Porous Nanosheet Arrays by Partial Iron Substitution for Efficient Oxygen Evolution Reaction. Angew. Chem., Int. Ed. 2018, 57, 2672−2676. (41) Li, X.; Wei, J.; Li, Q.; Zheng, S.; Xu, Y.; Du, P.; Chen, C.; Zhao, J.; Xue, H.; Xu, Q.; Pang, H. Nitrogen-Doped Cobalt Oxide Nanostructures Derived from Cobalt-Alanine Complexes for HighPerformance Oxygen Evolution Reactions. Adv. Funct. Mater. 2018, 28, 1800886. (42) Ding, D.; Shen, K.; Chen, X.; Chen, H.; Chen, J.; Fan, T.; Wu, R.; Li, Y. Multi-Level Architecture Optimization of MOF-Templated Co-based Nanoparticles Embedded in Hollow N-Doped Carbon Polyhedra for Efficient OER and ORR. ACS Catal. 2018, 8, 7879− 7888. (43) Yu, Z.; Bai, Y.; Liu, Y.; Zhang, S.; Chen, D.; Zhang, N.; Sun, K. Metal-Organic-Framework-Derived Yolk-Shell-Structured Cobaltbased Bimetallic Oxide Polyhedron with High Activity for Electrocatalytic Oxygen Evolution. ACS Appl. Mater. Interfaces 2017, 9, 31777−31785. (44) Fester, J.; Makoveev, A.; Grumelli, D.; Gutzler, R.; Sun, Z.; Rodríguez-Fernández, J.; Kern, K.; Lauritsen, J. V. The Structure of the Cobalt Oxide/Au Catalyst Interface in Electrochemical Water Splitting. Angew. Chem., Int. Ed. 2018, 57, 11893−11897. (45) Zhao, S.; Rasimick, B.; Mustain, W.; Xu, H. Highly Durable and Active Co3O4 Nanocrystals Supported on Carbon Nanotubes as F
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry catalytic Activity for Oxygen Evolution. Angew. Chem. 2017, 129, 3955−3958. (63) 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. Adv. Sci. 2017, 4, 1700247. (64) Cai, P.; Huang, J.; Chen, J.; Wen, Z. Oxygen-Containing Amorphous Cobalt Sulfide Porous Nanocubes as High-Activity Electrocatalysts for the Oxygen Evolution Reaction in an Alkaline/ Neutral Medium. Angew. Chem., Int. Ed. 2017, 56, 4858−4861. (65) Liu, P. F.; Yang, S.; Zhang, B.; Yang, H. G. Defect-Rich Ultrathin Cobalt-Iron Layered Double Hydroxide for Electrochemical Overall Water Splitting. ACS Appl. Mater. Interfaces 2016, 8, 34474− 34481. (66) Gao, M. Y.; Yang, C.; Zhang, Q. B.; Zeng, J. R.; Li, X. T.; Hua, Y. X.; Xu, C. Y.; Dong, P. Facile Electrochemical Preparation of SelfSupported Porous Ni-Mo Alloy Microsphere Films as Efficient Bifunctional Electrocatalysts for Water Splitting. J. Mater. Chem. A 2017, 5, 5797−5805. (67) Lu, X.; Zhao, C. Electrodeposition of Hierarchically Structured Three-Dimensional Nickel-Iron Electrodes for Efficient Oxygen Evolution at High Current Densities. Nat. Commun. 2015, 6, 6616.
G
DOI: 10.1021/acs.inorgchem.9b00463 Inorg. Chem. XXXX, XXX, XXX−XXX
