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Selective CO₂ electroreduction over an oxide-derived gallium catalyst

Yan, Chengcheng, Lin, Long, Gao, Dunfeng, Wang, Guoxiong, Bao, Xinhe
Journal of materials chemistry 2018 v.6 no.40 pp. 19743-19749
X-ray photoelectron spectroscopy, ammonia, carbon, carbon dioxide, catalysts, electrochemistry, electrodes, gallium, gels, global warming, hydrogen, nanoparticles, nitrates, potassium bicarbonate, renewable electricity
The electrochemical CO₂ reduction reaction (CO₂RR) powered by renewable electricity has emerged as a promising approach to alleviate global warming and energy depletion simultaneously. Notably, efficient catalysts containing Earth-abundant elements to achieve high CO₂RR performance are in great demand for future applications. Herein, carbon-supported gallia gel nanoparticles were synthesized by precipitating gallium nitrate on carbon black in an ethanolic ammonia solution. Nano-sized gallia nanoparticles uniformly dispersed on the carbon support achieved a maximum CO faradaic efficiency of 77.0% at −0.71 V vs. the reversible hydrogen electrode (RHE) in CO₂-saturated 0.1 M KHCO₃ solution, showing a dramatic improvement compared to a bulk Ga electrode with only 24.2% CO faradaic efficiency at −0.80 V vs. RHE. X-ray photoelectron spectroscopy measurements revealed that surface Ga³⁺ species were reduced to metallic Ga when subjected to a negative potential during the CO₂RR, indicative of the formation of oxide-derived active gallium sites. Control experiments further highlighted the necessity of close coalescence between the nano-sized gallia particles and the conductive carbon support. The present study underscores the feasibility of improving the CO₂RR performance of Ga-related materials through nanostructuring of oxide-derived gallium catalysts.