Structural Evolution and Catalytic Activity of Tin Telluride for the Electrochemical Carbon Dioxide Reduction

Abstract

Tin-based compounds, particularly SnO2-derived catalysts, are extensively studied for selective electrochemical reduction of carbon dioxide (eCO2RR) to formate. Compared with tin oxides, tin chalcogenides such as SnTe remain relatively unexplored for eCO2RR, in spite of having desired electronic properties, often combined with native surface oxide layers. In this work, we report the catalytic behavior of finely powdered polycrystalline SnTe showing high activity toward CO2 reduction as well as the hydrogen evolution reaction (HER). We show that SnTe exhibits selective eCO2RR toward formate in 0.5 M CsHCO3, with a partial current density of −35 mA cm–2 at −1.1 V vs RHE, similar to SnO2. Concurrently, SnTe exhibits high activity toward HER, in contrast to SnO2. Comprehensive potential-dependent structural characterizations and operando SEIRAS measurements suggest that the chemical transformation of SnTe and SnO2 to a Sn-rich active surface under high reductive potential may be the reason for their similar eCO2RR activity. On the other hand, control experiments on elemental Te and SnO2 as well as XPS and operando SEIRAS data point to a possible role of residual tellurium on the surface of the SnTe precatalyst to drive the HER. This work underscores the significance of understanding the in situ transformation of the precatalyst to the active species during the eCO2RR to rationalize its activity and product selectivity.