Nanoporous Ag-Sn derived from codeposited AgCl-SnO2 for the electrocatalytic reduction of CO2 with high formate selectivity

Abstract

Nanoporous Ag-Sn was prepared by direct electroreduction of a codeposited AgCl-SnO2 mixture in 0.1 M HCl, and evaluated as an electrode catalyst for the reduction of CO2 in 0.5 M KHCO3. A volcano-type correlation between selectivity for the formate product and the atomic ratio of Ag to Sn in the nanoporous catalysts was revealed. It was found that the bimetallic catalyst with a Ag:Sn ratio of 3:2, mainly composed of the Ag4Sn alloy, showed excellent catalytic performance for the conversion of CO2 to formate. This catalyst delivered a current of about 10 mA cm−2 with a high formate faradaic efficiency of about 85% at −0.8 V vs. the reversible hydrogen electrode. Moreover, the catalytic activity remained reasonably stable during a 13.5-hour electrolysis. Keywords: Ag-Sn bimetals, Solid electroreduction, Electrocatalysis, Carbon dioxide, Format