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Nanostructured amalgams with tuneable silver–mercury bonding sites for selective electroreduction of carbon dioxide into formate and carbon monoxide

Yang, Wanfeng, Chen, Sheng, Ren, Wenhao, Zhao, Yong, Chen, Xianjue, Jia, Chen, Liu, Junnan, Zhao, Chuan
Journal of materials chemistry A 2019 v.7 no.26 pp. 15907-15912
alloys, carbon dioxide, carbon monoxide, catalysts, chemical bonding, commercialization, cost effectiveness, electrochemistry, formates, mercury, nanopores, silver
Realizing highly efficient and selective electrochemical CO₂ reduction by using cost-effective catalysts is a key to the large-scale commercialization of this technology. In this work, a nanoporous amalgam catalyst with a tuneable amount of Ag–Hg bonding sites has been developed for selective CO₂ electroreduction to formate or CO via a one-step wet-chemistry method. This catalyst is composed of a Ag(Hg) solid solution phase and a Ag–Hg intermetallic compound, exhibiting a loosened nanorod-channel network morphology. The Ag₇₀Hg₃₀ alloy drives efficient formate generation with a high faradaic efficiency of 85% at a moderate overpotential of 790 mV while the Ag₉₁Hg₉ alloy promotes CO₂ reduction to CO with a faradaic efficiency of 58% at a low overpotential of 590 mV. The switchable product selectivity has been correlated with preferable formation of HCOO* or *COOH intermediates at Ag–Hg and Ag–Ag bonding sites. This work highlights amalgams as novel electrocatalysts for CO₂ reduction to valuable products on demand.