Electrolyte‐Assisted Structure Reconstruction Optimization of Sn‐Zn Hybrid Oxide Boosts the Electrochemical CO2‐to‐HCOO− Conversion

Abstract Electrolyte plays crucial roles in electrochemical CO 2 reduction reaction (e‐CO 2 RR), yet how it affects the e‐CO 2 RR performance still being unclarified. In this work, it is reported that Sn‐Zn hybrid oxide enables excellent CO 2 ‐to‐HCOO − conversion in KHCO 3 with a HCOO − Faraday efficiency ≈89%, a yield rate ≈0.58 mmol cm −2 h −1 and a stability up to ≈60 h at −0.93 V, which are higher than those in NaHCO 3 and K 2 SO 4 . Systematical characterizations unveil that the surface reconstruction on Sn‐Zn greatly depends on the electrolyte using: the Sn‐SnO 2 /ZnO, the ZnO encapsulated Sn‐SnO 2 /ZnO and the Sn‐SnO 2 /Zn‐ZnO are reconstructed on the surface by KHCO 3 , NaHCO 3 and K 2 SO 4 , respectively. The improved CO 2 ‐to‐HCOO − performance in KHCO 3 is highly attributed to the reconstructed Sn‐SnO 2 /ZnO, which can enhance the charge transportation, promote the CO 2 adsorption and optimize the adsorption configuration, accumulate the protons by enhancing water adsorption/cleavage and limit the hydrogen evolution. The findings may provide insightful understanding on the relationship between electrolyte and surface reconstruction in e‐CO 2 RR and guide the design of novel electrocatalyst for effective CO 2 reduction.