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

Journal of Materials Chemistry A Pub Date: 2019-06-05 DOI: 10.1039/C9TA03611C

Abstract

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.

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