The nature of synergistic effects in transition metal oxides/in-situ intermediate-hydroxides for enhanced oxygen evolution reaction

Bo, Xin; Zan, Ling; Jia, Rouna; Dastafkan, Kamran; Zhao, Chuan

doi:10.1016/j.coelec.2022.100987

Cited by 8 publications

(6 citation statements)

References 78 publications

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“…Among typical OER catalyst transformations that need to be accounted for are (i) the possible oxidation of metals to higher oxidation states under reaction conditions, (ii) charge redistribution phenomena and the presence of metal complexes having an oxyl radical ligand at the surface (M n+ − O • ), 10,11 (iii) transformations of the initial (often amorphous) oxides into thermodynamically more favored spinel structures, 8,9,12,13 where the distribution of cations between tetrahedrally and octahedrally coordinated sites may vary from one material to another and change under reaction conditions, 12,14 and (iv) reversible surface-structure transformations of spinels into oxyhydroxide-like structures, where edge-sharing MO 6 octahedra are believed to be the active sites for the OER. 6,9,15 These considerations make X-ray absorption fine structure spectroscopy (XAFS) an invaluable tool for tracking the evolution of bimetallic oxide catalysts. Indeed, this elementspecific method enables probing the catalyst structure from the perspective of both metals, features high sensitivity to both, the oxidation state of the metals and the local atomistic structure, and can be applied to study materials with any degree of disorder.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deciphering the Structural and Chemical Transformations of Oxide Catalysts during Oxygen Evolution Reaction Using Quick X-ray Absorption Spectroscopy and Machine Learning

et al. 2023

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Bimetallic transition-metal oxides, such as spinel-like Co x Fe3–x O4 materials, are known as attractive catalysts for the oxygen evolution reaction (OER) in alkaline electrolytes. Nonetheless, unveiling the real active species and active states in these catalysts remains a challenge. The coexistence of metal ions in different chemical states and in different chemical environments, including disordered X-ray amorphous phases that all evolve under reaction conditions, hinders the application of common operando techniques. Here, we address this issue by relying on operando quick X-ray absorption fine structure spectroscopy, coupled with unsupervised and supervised machine learning methods. We use principal component analysis to understand the subtle changes in the X-ray absorption near-edge structure spectra and develop an artificial neural network to decipher the extended X-ray absorption fine structure spectra. This allows us to separately track the evolution of tetrahedrally and octahedrally coordinated species and to disentangle the chemical changes and several phase transitions taking place in Co x Fe3–x O4 catalysts and on their active surface, related to the conversion of disordered oxides into spinel-like structures, transformation of spinels into active oxyhydroxides, and changes in the degree of spinel inversion in the course of the activation treatment and under OER conditions. By correlating the revealed structural changes with the distinct catalytic activity for a series of Co x Fe3–x O4 samples, we elucidate the active species and OER mechanism.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deciphering the Structural and Chemical Transformations of Oxide Catalysts during Oxygen Evolution Reaction Using Quick X-ray Absorption Spectroscopy and Machine Learning

et al. 2023

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“…And, they suggest developing operando spectroscopic techniques to investigate the optimal M–O coordinative number and elaborating the regional effect on the active area. 98 Meanwhile, Sargent and his co-workers modified the Co–Co distance and intermediate coverage by doping Ba into Co 3 O 4 . The OPM pathway was transformed from the AEM after the doping of Ba, which increases the OER activity in acidic electrolytes.…”

Section: Fundamentals Of the Oer Mechanismsmentioning

confidence: 99%

Advances in the mechanism investigation for the oxygen evolution reaction: fundamental theory and monitoring techniques

Gong,

Zhang,

Meng

et al. 2024

Mater. Chem. Front.

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“…Additionally, these materials also have a large surface area and can provide abundant active sites for the OER. [ 101 ] Furthermore, hydroxides and oxides are easy to synthesize and relatively stable, making them the best candidates for electrocatalytic reactions. Iridium oxide (IrO 2 ), ruthenium oxide (RuO 2 ), and NiFe hydroxide (NiFeOH x ) are examples of commonly used oxide and hydroxide OER electrocatalysts.…”

Section: Fabrication Of Self‐supported Fe‐based Oer Electrocatalystsmentioning

confidence: 99%

Self‐Supported Fe‐Based Nanostructured Electrocatalysts for Water Splitting and Selective Oxidation Reactions: Past, Present, and Future

Gaikwad,

Burungale,

Malavekar

et al. 2024

Advanced Energy Materials

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Electrochemical water splitting plays a vital role in facilitating the transition towards a sustainable energy future by enabling renewable hydrogen (H2) production, energy storage, and emission‐free transportation. Developing earth‐abundant electrocatalysts with outstanding overall water‐splitting performance, excellent catalytic activity, and robust long‐term stability is highly important in the practical application of water electrolysis. Self‐supported electrocatalysts have emerged as the most appealing candidate for practical H2 production due to their increased active site loading, rapid mass and charge transfer, and strong interaction with the underneath conducting support. Additionally, these electrocatalysts also provide enhanced reaction kinetics and stability. Here, a comprehensive review of recent progress in developing self‐supported Fe‐based electrocatalysts for water splitting and selective oxidation reactions is presented with examples of oxyhydroxides, layered double hydroxides, oxides, chalcogenides, phosphides, nitrides, and other Fe‐containing electrocatalysts. A comprehensive historical development in the synthesis of self‐supported Fe‐based electrocatalysts is provided, with an emphasis on the various deposition methods and the choice of self‐supported conducting substrates considering large‐scale commercial applications. An overview of mechanistic understanding and approaches for enhanced H2 production are also presented. Finally, the challenges and opportunities associated with developing Fe‐based electrocatalysts for practical applications in water splitting and alternative oxidation reactions are discussed.

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The nature of synergistic effects in transition metal oxides/in-situ intermediate-hydroxides for enhanced oxygen evolution reaction

Cited by 8 publications

References 78 publications

Deciphering the Structural and Chemical Transformations of Oxide Catalysts during Oxygen Evolution Reaction Using Quick X-ray Absorption Spectroscopy and Machine Learning

Deciphering the Structural and Chemical Transformations of Oxide Catalysts during Oxygen Evolution Reaction Using Quick X-ray Absorption Spectroscopy and Machine Learning

Advances in the mechanism investigation for the oxygen evolution reaction: fundamental theory and monitoring techniques

Self‐Supported Fe‐Based Nanostructured Electrocatalysts for Water Splitting and Selective Oxidation Reactions: Past, Present, and Future

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