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

Abstract

Abstract Electrolyte plays crucial roles in electrochemical CO2 reduction reaction (e‐CO2RR), yet how it affects the e‐CO2RR performance still being unclarified. In this work, it is reported that Sn‐Zn hybrid oxide enables excellent CO2‐to‐HCOO− conversion in KHCO3 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 NaHCO3 and K2SO4. Systematical characterizations unveil that the surface reconstruction on Sn‐Zn greatly depends on the electrolyte using: the Sn‐SnO2/ZnO, the ZnO encapsulated Sn‐SnO2/ZnO and the Sn‐SnO2/Zn‐ZnO are reconstructed on the surface by KHCO3, NaHCO3 and K2SO4, respectively. The improved CO2‐to‐HCOO− performance in KHCO3 is highly attributed to the reconstructed Sn‐SnO2/ZnO, which can enhance the charge transportation, promote the CO2 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‐CO2RR and guide the design of novel electrocatalyst for effective CO2 reduction.

Keywords

• CO2 reduction
• electrolyte
• formate
• Sn‐Zn oxide
• surface reconstruction