Spontaneously Sn-Doped Bi/BiO_<i>x</i> Core–Shell Nanowires Toward High-Performance CO₂ Electroreduction to Liquid Fuel

Abstract

Electrochemical CO2 reduction provides a promising strategy to product value-added fuels and chemical feedstocks. However, it remains a grand challenge to further reduce the overpotentials and increase current density for large-scale applications. Here, spontaneously Sn doped Bi/BiOx nanowires (denoted as Bi/Bi(Sn)Ox NWs) with a core–shell structure were synthesized by an electrochemical dealloying strategy. The Bi/Bi(Sn)Ox NWs exhibit impressive formate selectivity over 92% from −0.5 to −0.9 V versus reversible hydrogen electrode (RHE) and achieve a current density of 301.4 mA cm–2 at −1.0 V vs RHE. In-situ Raman spectroscopy and theoretical calculations reveal that the introduction of Sn atoms into BiOx species can promote the stabilization of the *OCHO intermediate on the Bi(Sn)Ox surface and suppress the competitive H2/CO production. This work provides effective in situ construction of the metal/metal oxide hybrid composites with heteroatom doping and new insights in promoting electrochemical CO2 conversion into formate for practical applications.