Synergy effects on Sn-Cu alloy catalyst for efficient CO2 electroreduction to formate with high mass activity

[Display omitted] To acquire the synergy effects between Sn and Cu for the jointly high Faradaic efficiency and current density, we develop a novel strategy to design the Sn-Cu alloy catalyst via a decorated co-electrodeposition method for CO2 electroreduction to formate. The Sn-Cu alloy shows high formate Faradaic efficiency of 82.3% ± 2.1% and total C1 products Faradaic efficiency of 90.0% ± 2.7% at −1.14 V vs. reversible hydrogen electrode (RHE). The current density and mass activity of formate reach as high as (79.0 ± 0.4) mA cm−2 and (1490.6 ± 7.5) mA mg−1 at −1.14 V vs. RHE. Theoretical calculations suggest that Sn-Cu alloy can obtain high Faradaic efficiency for CO2 electroreduction by suppressing the competitive hydrogen evolution reaction and that the formate formation follows the path of CO2 → HCOO* → HCOOH. The stepped (2 1 1) surface of Sn-Cu alloy is beneficial towards selective formate production.