The study revealed the mechanism of lattice oxygen-mediated-oxygen vacancy reaction

Recently, the team of Wu Zhongshuai, a researcher at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the team of researcher Xiao Jianping have made new progress in the design and mechanism analysis of electrocatalytic water oxidation catalysts. The collaborative team developed a new synergistic strategy for Rh doping and RuO2 surface oxygen vacancies to achieve efficient and stable catalytic conversion of acid water oxidation process, and revealed the lattice oxygen-mediated-oxygen vacancy reaction mechanism. The results were published in Nature Communications.

As a key semi-reaction in the water splitting process, electrocatalytic oxygen evolution plays an important role in the hydrogen production technology of proton exchange membrane water electrolysis. At present, the challenges faced by acid water oxidation are the balance of catalytic activity and stability of catalysts (RuO2, IrO2), as well as the theoretical thermodynamic activity limitation of the catalytic mechanism adsorption evolution mechanism and the lattice oxygen-mediated mechanism of excessive oxidation of active center metals resulting in low solubility resistance.

Schematic diagram of the reaction mechanism. Photo courtesy of Dalian Chemical Properties

In this work, the research team proposed a synergistic strategy between Rh doping and RuO2 surface oxygen vacancies to construct Ru-O-Rh active sites using RuO2 catalysts as the research object. At the same time, it optimizes the intrinsic activity and stability, and achieves an overpotential of 161 mV at a current density of 10 mA cm-2, and can still maintain 99.2% of its electrochemical activity after 700 h operation at 50 mA cm-2 current density. In addition, the research team further demonstrated the cycling process of reversible oxygen species through quasi-in situ/in situ characterization to achieve enhanced activity and stability. Based on the Rh-RuO2 catalytic model, the optimal reaction path of LOM-OVSM induced by oxygen-rich Ru-Rh-Rh sites was revealed to break the thermodynamic energy barrier limitation of traditional AEM.

This work reveals the lattice oxygen-mediated oxygen vacancies of electrochemical acid water oxidation, which provides new ideas for the design of high-performance acid OER catalysts and in-depth mechanism analysis, and provides a reference for the practical application of hydrogen production by electrolysis of water by proton exchange membrane. (Source: Sun Danning, China Science News)

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