Copper–tin bimetallic aerogel alloy for the electroreduction of CO2 to formate†

The electrochemical reduction of CO₂ (CO₂RR) enables the conversion of CO₂ into various value-added hydrocarbons, with formate garnering significant interest due to its high energy density and efficient conversion potential. Although tin (Sn)-based catalysts generally exhibit high selectivity for formate and effectively suppress the hydrogen evolution reaction (HER), the simultaneous presence of low selectivity and current density limits further applications. In this work, a series of bimetallic Cu–Sn aerogel catalysts were synthesized; the Cu–Sn (1 : 1) aerogel catalyst demonstrated superior CO₂ reduction performance, with higher cathodic reaction activity (35.61 mA cm⁻²) and a formate faradaic efficiency (FE) exceeding 90%, while maintaining stable CO₂ selectivity over a period of 7 hours. The high efficiency in generating formate is attributed to the high surface area provided by the bimetallic aerogel, which facilitates CO₂ transport and product desorption. Additionally, the high-energy interfaces formed during alloying and electronic synergistic effects increase the charge density at active sites. The self-supporting structure further optimizes electron transfer performance. This study provides new insights into the development of bimetallic catalysts for efficiently reducing CO₂ to formate.