Photocatalytic single electron reduction of CO2 into carbon dioxide radical anion (CO2·−): Generation, detection and chemical utilization

The photocatalytic reduction of CO2 is a crucial area of research aimed at addressing the dual challenges of mitigating rising CO2 emissions and producing sustainable chemical feedstocks. While multielectron reduction pathways for CO2 are well explored, the single electron reduction to produce the highly reactive carbon dioxide radical anion (CO2·−) remains challenging yet promising for green organic transformations. This review contributes to the field by providing a comprehensive analysis of the mechanisms, materials, and reaction pathways involved in CO2·− generation, focusing on the use of visible-light-driven photocatalytic materials to circumvent the need for high-energy ultraviolet irradiation. Through a systematic examination of CO2·− production, detection methods, and chemical utilization in photocatalytic carboxylation reactions, this review advances understanding of the chemistry of CO2·− and its applications in sustainable chemical synthesis. In addition, it highlights existing key challenges, such as redox potential limitations, and proposes strategies for scaling up photocatalytic systems to enable practical application. By illuminating the pathway to effectively photocatalyze CO2·− generation and its transformative potential in sustainable chemical synthesis, this review equips scientists with critical insights and strategic approaches for overcoming current limitations, driving innovation in photocatalytic materials for solar-to-chemical energy conversion.