Molecular tuning for electrochemical CO₂ reduction

Electrochemical carbon dioxide reduction reaction (CO₂RR) offers unprecedented opportunities to alleviate the greenhouse effect and produce valuable chemicals/fuels simultaneously. Recently, molecular tuning has emerged as a powerful method to modify catalyst's surface and has been verified effective in improving CO₂RR performance. However, a comprehensive and insightful review of this topic is still missing. Herein, we first summarize the reaction pathways of CO₂RR to produce C₁ and C₂ products, followed by discussion of the merits of molecular decoration. Next, density functional theory (DFT) calculation toward different products is elaborated. Relative experiments using various molecular tuning strategies are then demonstrated, including regulating electronic structure of catalysts, stabilizing important intermediates, creating confinement effect, protecting active sites, and serving as active sites or linkers to promote tandem catalysis. The relationship between molecular structure and CO₂RR performance is thoroughly recapped. Finally, several issues regarding the future development of molecular tuning are raised, and the corresponding solutions are provided. © 2023 Elsevier Inc.