Advances in Sn-based oxide catalysts for the electroreduction of CO2 to formate

The excessive consumption of fossil fuels increases CO2 emissions, and the consequent greenhouse effect resulting from higher levels of this gas in the atmosphere has a significant impact on the environment and climate. This has necessitated the development of environmentally friendly and efficient methods for CO2 conversion. The carbon dioxide electroreduction reaction (CO2RR), which is driven by electricity generated by renewable energy sources (e.g., wind and solar) to convert CO2 into value-added fuels or chemicals, is regarded as a promising prospective path toward carbon cycling. Among the various products, formate, with its relatively simple preparation process, has broad application prospects, and can be used as fuel, hydrogen storage material, and raw material for downstream chemicals. Sn-based oxide electrocatalysts have the advantages of being inexpensive and nontoxic. In addition, these catalysts offer high product selectivity and are regarded as promising catalysts for the electrochemical reduction of CO2 to formate. In this review, we first clarify the reaction mechanisms and factors that influence the reduction of CO2 to formate, and then provide some examples of technologies that could be used to study the evolution of catalysts during the reaction. In particular, we focus on traditional Sn-based oxides (SnO2) and novel Sn-based perovskite oxides that have been developed for use in the field of CO2RR in recent years by considering their synthesis, catalytic performance, optimization strategies, and intrinsic principles. Finally, the current challenges and opportunities for Sn-based oxide electrocatalysts are discussed. The perspectives and latest trends presented in this review are expected to inspire researchers to contribute more efforts toward comprehensively optimizing the performance of the CO2RR to produce formate.