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

Electrolyte plays crucial roles in electrochemical CO reduction reaction (e-CORR), yet how it affects the e-CORR performance still being unclarified. In this work, it is reported that Sn-Zn hybrid oxide enables excellent CO-to-HCOO conversion in KHCO with a HCOO Faraday efficiency ≈89%, a yield rate ≈0.58 mmol cm h and a stability up to ≈60 h at -0.93 V, which are higher than those in NaHCO and KSO. Systematical characterizations unveil that the surface reconstruction on Sn-Zn greatly depends on the electrolyte using: the Sn-SnO/ZnO, the ZnO encapsulated Sn-SnO/ZnO and the Sn-SnO/Zn-ZnO are reconstructed on the surface by KHCO, NaHCO and KSO, respectively. The improved CO-to-HCOO performance in KHCO is highly attributed to the reconstructed Sn-SnO/ZnO, which can enhance the charge transportation, promote the CO 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-CORR and guide the design of novel electrocatalyst for effective CO reduction.