CHEMICAL SCIENCE

Research on high-temperature carbon dioxide electrolysis has progressed


Recently, Academician Bao Xinhe, researcher Wang Guoxiong and Dr. Lv Houfu’s team from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences have made new progress in the electrolysis of high-temperature carbon dioxide (CO2). Through electrochemical in situ characterization studies, the team revealed the mechanism of dynamic cathode reconstruction and CO2 electrolysis reaction mechanism of solid oxide electrolyzer. The results were published in the National Science Review.

Solid oxide electrolyzers use renewable energy to efficiently reduce CO2 to carbon monoxide (CO) under high temperature conditions, which is a carbon-negative technology with great potential for industrial applications. However, during the CO2 electrolysis process, the in-situ dynamic reconstruction of the cathodic catalytic active site of the electrolyzer and the mechanism of CO2 adsorption activation are still insufficient.

Schematic diagram of the catalytic structure. Photo courtesy of Dalian Chemical Properties

In this work, the research team studied the dynamic electrochemical reconstruction characteristics and CO2 adsorption activation mechanism of Ir-doped Sr2Fe1.45Ir0.05Mo0.5O6-δ(SFIrM) perovskite catalyst with the help of high-temperature in-situ electrochemical X-ray diffraction, near-ambient pressure X-ray photoelectron spectroscopy and in-situ X-ray absorption spectroscopy.

It was found that SFIrM perovskite cathodes dissolved highly dispersed and high-density IrFe alloy nanoparticles during CO2 electrolysis during surface segregation. Moreover, the alloy nanoparticles exhibit the characteristics of forming and disappearing as voltage is applied and stopped. This study elucidates the mechanism by which voltage as the main driving force promotes the in-situ dissolution of IrFe alloy nanoparticles on the perovskite surface during CO2 electrolysis.

In addition, carbonate species were observed as intermediates in CO2 adsorption and activation reactions, and their intensity changed correspondingly with the formation and disappearance of the interface. Moreover, IrFe alloy nanoparticles can be redispersed by transient oxidation, which further improves the electrolytic stability of CO2 in solid oxide electrolyzers.

The surface reconstruction process and catalytic mechanism of SFIrM cathode are elucidated, which is helpful for in-depth study of the CO2 electrolysis process in solid oxide electrolyzer. (Source: Sun Danning, China Science News)

Related paper information:https://doi.org/10.1093/nsr/nwad078



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