Clarifying the controversial catalytic active sites of Co<sub>3</sub>O<sub>4</sub> for the oxygen evolution reaction

Xu, Yong; Zhang, Fengchu; Sheng, Tian; Ye, Tao; Ding, Yi; Yang, Yijun; Liu, Shoujie; Wu, Xi; Yao, Jiannian

doi:10.1039/c9ta08379k

Cited by 124 publications

(92 citation statements)

References 48 publications

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“…When Co 3 O 4 is added to the heterostructure, a similar phenomenon of decreasing the overpotential is reported. [39] Hydrous NiMoO 4 helps in strengthening the electrochemical performances due to its high concentrations of active surface sites, and defective or "cracked" morphology, while cobalt decreases the overpotential due to the increase of the electrical conductivity (lower R ct ), which will be confirmed by the valence band measurement later. As a result, the overall performance improvement is associated with the synergistic effect of both hydrous NiMoO 4 and Co 3 O 4 electrocatalysts.…”

Section: Electrochemical Characterizationsmentioning

confidence: 70%

NiMoO₄@Co₃O₄ Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

Solomon

Landström

Mazzaro

et al. 2021

Advanced Energy Materials

111

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The sluggish kinetics of the oxygen evolution reaction (OER) is the bottleneck for the practical exploitation of water splitting. Here, the potential of a core–shell structure of hydrous NiMoO4 microrods conformally covered by Co3O4 nanoparticles via atomic layer depositions is demonstrated. In situ Raman and synchrotron‐based photoemission spectroscopy analysis confirms the leaching out of Mo facilitates the catalyst reconstruction, and it is one of the centers of active sites responsible for higher catalytic activity. Post OER characterization indicates that the leaching of Mo from the crystal structure, induces the surface of the catalyst to become porous and rougher, hence facilitating the penetration of the electrolyte. The presence of Co3O4 improves the onset potential of the hydrated catalyst due to its higher conductivity, confirmed by the shift in the Fermi level of the heterostructure. In particular NiMoO4@Co3O4 shows a record low overpotential of 120 mV at a current density of 10 mA cm−2, sustaining a remarkable performance operating at a constant current density of 10, 50, and 100 mA cm−2 with negligible decay. Presented outcomes can significantly contribute to the practical use of the water‐splitting process, by offering a clear and in‐depth understanding of the preparation of a robust and efficient catalyst for water‐splitting.

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Section: Electrochemical Characterizationsmentioning

confidence: 70%

NiMoO₄@Co₃O₄ Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

Solomon

Landström

Mazzaro

et al. 2021

Advanced Energy Materials

111

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“…Very recently, the Yao group revisited Co 3 O 4 to identify its real catalytic active sites by comparing Co 3 O 4 exhibiting the same morphology but with various ratios of Co 2+ Td and Co 3+ Oh sites via a combination of experimental and DFT calculations. [ 87 ] Specifically, the calculated overpotential was 290 mV for Co 3 O 4 hexagonal platelets with the (110)‐B plane containing only Co 3+ Oh on the surface that was significantly smaller than that of the (111) plane exposed with only Co 2+ Td (790 mV); this result demonstrated that Co 3+ Oh might act as the active site in Co 3 O 4 for water oxidation.…”

Section: High‐valence Metal Sitesmentioning

confidence: 99%

Designing High‐Valence Metal Sites for Electrochemical Water Splitting

Sun

Song

et al. 2021

Adv Funct Materials

213

162

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Electrochemical water splitting is a critical energy conversion process for producing clean and sustainable hydrogen; this process relies on low‐cost, highly active, and durable oxygen evolution reaction/hydrogen evolution reaction electrocatalysts. Metal cations (including transition metal and noble metal cations), particularly high‐valence metal cations that show high catalytic activity and can serve as the main active sites in electrochemical processes, have received special attention for developing advanced electrocatalysts. In this review, heterogenous electrocatalyst design strategies based on high‐valence metal sites are presented, and associated materials designed for water splitting are summarized. In the discussion, emphasis is given to high‐valence metal sites combined with the modulation of the phase/electronic/defect structure and strategies of performance improvement. Specifically, the importance of using advanced in situ and operando techniques to track the real high‐valence metal‐based active sites during the electrochemical process is highlighted. Remaining challenges and future research directions are also proposed. It is expected that this comprehensive discussion of electrocatalysts containing high‐valence metal sites can be instructive to further explore advanced electrocatalysts for water splitting and other energy‐related reactions.

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“…The OER intermediates, OH, O and OOH, were placed atop the two most catalytically active adsorption sites -Co oct and Co tet (Fig. 2) on both terminating planes (Xu et al, 2019).…”

Section: Resultsmentioning

confidence: 99%

Oxygen Evolution Reaction on a N-Doped Co_0.5-Terminated Co₃o₄ (001) Surface

Kaptagay

Sandibaeva

Inerbaev

et al. 2020

Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences.

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Recent experimental findings suggest that the catalytic activity of Co3O4 for oxygen evolution reaction (OER) could be improved by nitrogen doping. We present preliminary OER modelling on a N-doped Co3O4 surface, with varying concentration of the dopant and its spatial distribution around Cooct and Cotet adsorption sites. The overpotential was calculated for two adsorption sites on seven types of N-doped Co3O4 surface. The largest calculated overpotential value for a N-doped surface was ~1V.

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Clarifying the controversial catalytic active sites of Co₃O₄ for the oxygen evolution reaction

Abstract: Controversial results still exist about the activities of tetrahedral (Co2+) and octahedral (Co3+) sites in Co3O4 toward the OER. Theoretical and experimental data confirm that octahedral sites are responsible for the OER, using model catalysts.

Cited by 124 publications

References 48 publications

NiMoO₄@Co₃O₄ Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

NiMoO₄@Co₃O₄ Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

Designing High‐Valence Metal Sites for Electrochemical Water Splitting

Oxygen Evolution Reaction on a N-Doped Co_0.5-Terminated Co₃o₄ (001) Surface

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Clarifying the controversial catalytic active sites of Co3O4 for the oxygen evolution reaction

Abstract: Controversial results still exist about the activities of tetrahedral (Co2+) and octahedral (Co3+) sites in Co3O4 toward the OER. Theoretical and experimental data confirm that octahedral sites are responsible for the OER, using model catalysts.

Cited by 124 publications

References 48 publications

NiMoO4@Co3O4 Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

NiMoO4@Co3O4 Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

Designing High‐Valence Metal Sites for Electrochemical Water Splitting

Oxygen Evolution Reaction on a N-Doped Co0.5-Terminated Co3o4 (001) Surface

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Clarifying the controversial catalytic active sites of Co₃O₄ for the oxygen evolution reaction

NiMoO₄@Co₃O₄ Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

NiMoO₄@Co₃O₄ Core–Shell Nanorods: In Situ Catalyst Reconstruction toward High Efficiency Oxygen Evolution Reaction

Oxygen Evolution Reaction on a N-Doped Co_0.5-Terminated Co₃o₄ (001) Surface