Rational Design of Bi Nanoparticles for Efficient Electrochemical CO2 Reduction: The Elucidation of Size and Surface Condition Effects

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• 作者：Zhiyong Zhang ; Miaofang Chi ; Gabriel M. Veith ; Pengfei Zhang ; Daniel A. Lutterman ; Joel Rosenthal ; Steven H. Overbury ; Sheng Dai ; Huiyuan Zhu
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：September 2, 2016
• 年：2016
• 卷：6
• 期：9
• 页码：6255-6264
• 全文大小：603K
• 年卷期：0
• ISSN：2155-5435

文摘

We report an efficient electrochemical conversion of CO₂ to CO on surface-activated bismuth nanoparticles (NPs) in acetonitrile (MeCN) under ambient conditions, with the assistance of 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][OTf]). Through the comparison between electrodeposited Bi films (Bi-ED) and different types of Bi NPs, we, for the first time, demonstrate the effects of catalyst’s size and surface condition on organic phase electrochemical CO₂ reduction. Our study reveals that the surface inhibiting layer (hydrophobic surfactants and Bi³⁺ species) formed during the synthesis and purification process hinders the CO₂ reduction, leading to a 20% drop in Faradaic efficiency for CO evolution (FE_CO). Bi particle size showed a significant effect on FE_CO when the surface of Bi was air-oxidized, but this effect of size on FE_CO became negligible on surface-activated Bi NPs. After the surface activation (hydrazine treatment) that effectively removed the native inhibiting layer, activated 36-nm Bi NPs exhibited an almost-quantitative conversion of CO₂ to CO (96.1% FE_CO), and a mass activity for CO evolution (MA_CO) of 15.6 mA mg^–1, which is three-fold higher than the conventional Bi-ED, at −2.0 V (vs Ag/AgCl). This work elucidates the importance of the surface activation for an efficient electrochemical CO₂ conversion on metal NPs and paves the way for understanding the CO₂ electrochemical reduction mechanism in nonaqueous media.