Direct Carbonate Reduction on Sn Oxide Surface

Direct reduction of carbonate (CO₃ ^2-) to value-added chemicals presents several advantages for integrating CO₂ capture from air with electrochemical conversion at near-unity efficiency. However, a critical challenge lies in effectively adsorbing CO₃ ^2- as a reactive intermediate for sequential reduction. Density functional theory calculations indicate that the presence of oxygen vacancies (V_O) on a SnO₂ surface significantly enhances its reactivity toward CO₃ ^2- adsorption, with the resulting adsorbed species (*CO₃) detectable by Raman spectroscopy. Operando electrochemical Raman spectra have confirmed the formation of *CO₃ on the partially reduced SnO₂-xV_O surface. Pulsed electrolysis has successfully converted CO₃ ^2- to CO at a constant flow rate in an electrolyzer featuring a gas diffusion electrode configuration. A reaction cycle, encompassing SnO₂ partial reduction, CO₃ ^2- adsorption and reduction, and SnO₂ regeneration, has been proposed as a viable approach for continuous direct CO₃ ^2- reduction.