In-situ oxidation of Sn catalysts for long-term electrochemical CO2 reduction to formate

• Published in: Catalysis today Vol. 426; p. 114393
• Main Authors: Khiarak, Behnam Nourmohammadi, Fell, Adam, Anand, Nirmal, Sadaf, Sharif Md, Dinh, Cao-Thang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2024
• Subjects: CO2 electroreduction; Electrocatalysis; Formate production; In-situ regeneration; Tin-based catalysts; Tin-based catalysts; In-situ regeneration; CO2 electroreduction; Electrocatalysis; Formate production
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2023.114393

Electrochemical carbon dioxide (CO2) reduction (ECR) into valuable products such as formate is a compelling approach to managing excessive CO2 emissions. Tin (Sn)-based catalysts have been used for selective CO2 reduction to formate. However, they are often unstable for long-term ECR operation, especially at high reaction rates. In this work, we report highly selective Sn-based catalysts for CO2 reduction to formate at high current densities. The catalysts were prepared by depositing a layer of Sn nanoparticles on the surface of sputtered Ag on a polymer membrane. The catalysts exhibited over 90% Faradaic efficiency toward formate in the current density range of 50–300 mA/cm2 and were stable for over 20 h at a current density of 100 mA/cm2. Characterization of catalysts after ECR reaction reveals significant changes in catalyst morphology during ECR. To extend ECR operation time, we developed an in-situ catalyst regeneration strategy in which the catalysts are periodically oxidized during the reduction reaction. Using this approach, the operation time of Sn-catalysts was extended to more than 150 h with a selectivity over 90%, at the current density of 100 mA/cm2. [Display omitted] •Sn/Ag/PTFE electrodes are selective for CO2-to-formate conversion.•Sn particle morphology changes drastically during CO2 reduction reaction.•In-situ Sn oxidation extends lifetime of the catalysts.•150-hour stability at 100 mA/cm2 is achieved with in-situ catalyst regeneration.