Photocatalytic Reduction of Carbon Dioxide: Designing the Active Sites and Tracking the Pathways

Photocatalytic reduction of carbon dioxide (CO₂) realizes the recycling of carbon emissions and storage of solar energy into the bonding of organics at the same time, and thus attract great interest in the field of energy and environment. However, the current photocatalytic performance of CO₂ reduction cannot match the industrial application. The design of highly efficient photocatalysts with precise selectivity and reliable long-term stability is still a big challenge, partially because the mechanism of photocatalytic CO₂ reduction to guide the design and fabrication, is not completely clear yet. The reduction can involve at most eight electrons for each CO₂ molecule, during which several pathways might be opened up at the active sites to consume photocarriers to influence the selectivity and stability. The reduction pathways are dependent on the electronic structure and property of active sites, and the photocatalytic performance can be optimized if those pathways are thermodynamically or kinetically compatible for the target production. This review will summarize the strategy for designing the active sites on the surface of photocatalysts and the investigation on the relation between the active sites and pathways for photocatalytic CO₂ reduction, looking ahead at the future development of the photocatalysts and devices for CO₂ reduction.