Controlled synthesis of copper sulfide-based catalysts for electrochemical reduction of CO2 to formic acid and beyond: a review

Converting carbon dioxide (CO₂) into value-added chemicals is considered as a promising strategy to mitigate climate change. Among the various CO₂ reduction techniques, electrochemical CO₂ reduction (ECO₂R) using renewable energy sources holds significant potential. Consequently, the design and development of electrocatalysts capable of offering both high performance and cost-effectiveness hold the potential to expedite reaction kinetics and facilitate widespread industrial adoption. In recent years, abundant copper sulfide (Cu/S)-based nanomaterials among various metal–chalcogenides have attracted extensive research interest due to their semiconductivity and low toxicity, enabling them to be used in a wide range of applications in the ECO₂R field. This review highlights the progress in engineered Cu/S-based nanomaterials for ECO₂R reactions and elaborates on the correlations between engineering strategies, catalytic activity, and reaction pathways. This paper also summarises the controllable synthesis methods for fabricating various state-of-the-art Cu/S-based structures and outlines their possible implementation as electrocatalysts for CO₂ reduction. Finally, challenges and prospects are presented for the future development and practical applications of Cu/S-based catalysts for ECO₂R to value-added chemicals.