Photocatalytic Reduction of CO2 by Metal‐Free‐Based Materials: Recent Advances and Future Perspective

Photocatalytic CO 2 reduction to produce valuable chemicals and fuels using solar energy provides an appealing route to alleviate global energy and environmental problems. Searching for photocatalysts with high activity and selectivity for CO 2 conversion is the key to achieving this goal. Among the various proposed photocatalysts, metal‐free materials, such as graphene, nitrides, carbides, and conjugated organic polymers, have gained extensive research interest for photocatalytic CO 2 reduction, due to their earth abundance, cost‐effectiveness, good electrical conductivity, and environmental friendliness. They exhibit prominent catalytic activity, impressive selectivity, and long durability for the conversion of CO 2 to solar fuels. Herein, the recent progress on metal‐free photocatalysis of CO 2 reduction is systematically reviewed. Opportunities and challenges on modification of nonmetallic catalysts to enhance CO 2 transformation are presented. Theoretical calculations on possible reduction mechanisms and pathways as well as the potential in situ and operando techniques for mechanistic understanding are also summarized and discussed. Based on the aforementioned discussions, suitable future research directions and perspectives for the design and development of potential nonmetallic photocatalysts for efficient CO 2 reduction are provided.