A Sn doped, strained CuAg film for electrochemical CO2 reduction

Abstract

The electrochemical CO₂ reduction reaction (CO₂RR) using renewably generated electricity under mild conditions is a promising and sustainable approach to convert CO₂ to value-added chemicals. Cu and Cu alloys are considered to be potential catalysts for CO₂ reduction among numerous catalysts. Unfortunately, the product selectivity and conversion efficiency during the CO₂RR are severely limited by the unavoidable competitive hydrogen evolution reaction (HER). Here, we developed a facile deposition method based on magnetron co-sputtering to optimize the alloy composition of Cu. As a result, we found that CuAg electrode of Sn addition can effectively inhibit the HER during the CO₂RR and improve the selectivity of CO, and the FE of CO can reach 93% at −0.85 V. The large lattice distortions and strain effect after Sn addition affect the electronic structure and further result in the downshift of the d-band center, which causes the Gibbs free energy of the formation of *H on the CuAgSn surface to increase dramatically. Although the formation energy barrier of *COOH doesn't decrease after Sn addition, the selectivity of CO is enhanced, owing to the selective suppression of the HER. This work provides an effective way to improve the CO₂ reduction performance of binary alloys by adding a small amount of a third metallic element.