Spontaneously Sn Doped Bi/BiOx Core–shell Nanowires Toward High-Performance CO2 Electroreduction to Formate

Abstract Electrochemical CO2 reduction to formate using renewable electricity provides a promising strategy to product value-added carbon-based fuels and feedstocks. However, it still remains a grand challenge to further reduce the cathodic potentials and increase current density for the large-scale practical applications of formate. Herein, we report that spontaneously Sn doped Bi/BiOx nanowires (denoted as Bi/Bi(Sn)Ox NWs) are prepared from electrochemical dealloying strategy. The Bi/Bi(Sn)Ox NWs exhibit impressive CO2 electroreduction activity to formate with a Faradaic efficiency (FE) > 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 under gas diffusion cell configuration. In-situ Raman spectroscopy and theory calculations reveal that the incorporation of Sn atoms into BiOx species modulates the electron states of Bi, allowing the *OCHO intermediate to favorably adsorb onto the reconstructed Bi(Sn)Ox surface while promotes formate generation by suppressing the competitive hydrogen evolution reaction. This work provides effective in-situ construction of the metal/metal oxide hybrid composites with heteroatom doping and offers insights in promoting practical CO2 conversion technology.