Electrolyte-Assisted Structure Reconstruction Optimization of Sn-Zn Hybrid Oxide Boosts the Electrochemical CO₂-to-HCOO^- Conversion.

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.