In-situ structural evolution of Bi2O3 nanoparticle catalysts for CO2 electroreduction

In recent years, the conversion and utilization of renewable energy have become particularly significant for making progress in environmental and energy sustainable development. However, the use of wind and solar energy with intermittent characteristics will lead to high electricity storage costs. Electrocatalytic CO₂ reduction reaction (CO₂RR) technology, which converts greenhouse gas CO₂ into high value-added products for carbon neutralization and energy storage, has received extensive attention. With the further progress of the CO₂RR research, researchers gradually realized that such metal compounds underwent dynamic structural evolution in the reduction process, which could lead to the uncertainty of active species. More importantly, the micromorphology and structure of the catalyst are greatly restricted by external environmental conditions (it is affected by external potential, electrolytes and other factors). There is an urgent need to employ the in-situ spectroscopic characterizations to track its real evolution process and assist in establishing a real active electronic structure model. The above is of great significance for the study of the structure–activity relationship and determining the reaction active sites in the CO₂RR system.

The research team, led by Professor Xiangheng Xiao from School of Physics and Technology, Wuhan University, China, have published the research article "In-situ structural evolution of Bi₂O₃ nanoparticle catalysts for CO₂ electroreduction" in International Journal of Extreme Manufacturing. The surface reconstruction process of Bi₂O₃ nanoparticle catalysts in CO₂ electroreduction monitored by in-situ Raman spectroscopy and internal reaction mechanism were systematically studied.

The surface reconstruction of the catalyst was firstly characterized by ex-situ methods and in-situ Raman spectroscopy in CO₂ electroreduction. The final results showed that the Bi₂O₃ nanoparticles were transformed into Bi/Bi₂O₃ two-dimensional thin-layer nanosheets (4-6 nm). It is considered to be the active phase in the electrocatalytic process. The Bi/Bi₂O₃ nanosheets showed good catalytic performance with a Faraday efficiency (FE) of 94.8% for formate and a current density of 26 mA cm^-2 at -1.01 V. While the catalyst maintained a 90% FE in a wide potential range (-0.91 V to -1.21 V) and long-term stability (24 h). Theoretical calculations support the theory that the excellent performance originates from the enhanced bonding state of surface Bi-Bi, which stabilized the adsorption of the key intermediate OCHO* and thus promoted the production of formate.

These scientists summarize the features and advantages:

“1. The evolution process of Bi₂O₃ nanoparticles to Bi/Bi₂O₃ nanosheets is successfully detected by in-situ Raman combined with ex-situ characterization methods; 2. It is verified that Bi/Bi₂O₃ nanosheets are the real active phase in CO₂ electroreduction and have high-efficiency formate production capacity; 3. Theoretical calculations indicate that the CO₂ electroreduction activity originates from the electron-rich state of surface-exposed Bi supplied by the Bi₂O₃ substrate.”

“This work explores the structural evolution of the catalyst under cathode conditions and constructs a model to understand the origin of the activity, which provides a reference for the rational design of the CO₂ reduction electrocatalyst and the future theoretical research of the activity mechanism.” the scientists forecast.

About IJEM:

International Journal of Extreme Manufacturing (IF: 10.036) is a new multidisciplinary, double-anonymous peer-reviewed and fully open access journal uniquely covering the areas related to extreme manufacturing. The journal is devoted to publishing original articles and reviews of the highest quality and impact in the areas related to extreme manufacturing, ranging from fundamentals to process, measurement and systems, as well as materials, structures and devices with extreme functionalities.

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