Converting greenhouse gas carbon dioxide (CO2) to value-added chemicals is an appealing approach to tackle CO2 emission challenges. The chemical transformation of CO2 requires suitable catalysts that can lower the activation energy barrier to minimize the energy penalty associated with the CO2 reduction reaction. First-row transition metals are potential candidates as catalysts for electrochemical CO2 reduction; however, their high oxygen affinity makes them easy to be oxidized, which could strongly affect the catalytic properties of metal-based catalysts. In this work, we propose a strategy to synthesize ultra-thin electrocatalysts using a core-shell nanostructure that contains a bimetallic core responsible for high electronic conductivity and an ultra-thin partially oxidized shell for catalytic CO2 conversion. This concept was demonstrated by a series of core-shell electrocatalysts with a Ag-Sn bimetallic core and a SnOx shell. At an optimal SnOx shell thickness of ~1.7 nm, the catalyst exhibited a high formate Faradaic efficiency of ~80% and a formate partial current density of ~16 mA cm-2 at -0.8 V vs. RHE, a remarkable performance in comparison to state-of-the-art formate-selective CO2 reduction catalysts.

Ag-Sn bimetallic catalyst with a core-shell structure for CO2 reduction

254th National Meeting (2017)

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