Redox‐Stabilized Sn/SnO2 Nanostructures for Efficient and Stable CO2 Electroreduction to Formate

• Published in: ChemElectroChem Vol. 10; no. 8
• Main Authors: Jiang, Haoyang, Fan, Ziqi, Zhang, Mingzhe, Guo, Shuyi, Li, Le, Yu, Xiaohan, Liu, Zhaoyang, Wang, Wei, Dong, Hao, Zhong, Miao
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 14-04-2023; Wiley-VCH
• Subjects: Adsorption; Carbon dioxide; Catalysts; Chemical bonds; Chemical etching; Chromatography; CO2 reduction; Conversion; Efficiency; electrocatalysts; Electrolytes; Electrowinning; Energy; Etching; Evaporation; Hydrogen evolution; intermediate binding optimization; nanostructures; redox stabilization; Scanning electron microscopy; Spectrum analysis; Tin dioxide; Transmission electron microscopy
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.202201164

Electroreduction of CO2 (CO2R) to formate enables the storage of renewable electricity in liquid chemical bonds in an efficient manner. However, hydrogen evolution competes with CO2R, decreasing Faradaic efficiency (FE) and energy efficiency (EE) for formate production, particularly under acidic and neutral conditions. The deterioration of the catalysts during CO2R further hinders long‐term and effective operation. To overcome these challenges, we fabricate nanostructured Sn/SnO2 through physical evaporation and wet‐chemical etching, improving the CO2‐to‐formate conversion with finely tuned *OCHO adsorption. The in‐situ formation of Sn/SnO2 surfaces during CO2R stabilizes the active sites for reliable formate production across a broad range of electrolyte pH from base to neutral. Our results show a 94 % CO2R‐to‐formate FE and a 58 % formate cathodic EE at 100 mA cm−2 in 1 M KOH over 70 hours of continuous operation. Under neutral conditions (pH=7), the CO2‐to‐formate conversion remains stable for 100 h with a selectivity of >90 %.
Large‐scale Sn/SnO2 nanoporous catalysts were fabricated via thermal evaporation and wet‐chemical etching. The finely tuned surface *OCHO adsorption enabled active and stable production of formate with a >90 % CO2R‐to‐formate Faradaic efficiency and a >50 % formate cathodic energy efficiency at a current density of 100 mA cm−2 over 100 hours under neutral conditions.