Recent advances on visible-light-driven CO2 reduction: Strategies for boosting solar energy transformation

The massive emission of greenhouse gas carbon dioxide (CO2) has attracted great attention due to its impact on global warming. Researchers have been working on this project for a long time and found that photocatalytic CO2 reduction has shown great potential in developing cost-effective clean energy resources. However, the efficiency of CO2 photo-reduction is low because of limited light absorption efficiency, undesired charge recombination, and high CO2 activation barrier in thermodynamics and kinetics. In this Perspective, we concentrate on recent advanced strategies to improve CO2 photo-reduction and illustrate the mechanism of CO2 activation and we intend to find the most plausible strategy on solving the problems listed. The mainstream approaches for boosting CO2 photo-reduction efficiency lie in (1) tuning the bandgap of the photocatalysts by incorporating heteroatoms in a photosensitizer causing enhanced light absorption; (2) constructing heterojunctions resulting in effective charge separation; and (3) introducing surface defects, basic sites, and functional groups, as well as increasing the surface area of catalysts contributing to enhanced CO2 adsorption and activation. Moreover, this Perspective will conclude with brief perspectives and recommendations regarding the promising research of converting CO2 into valuable fuels.