Advanced semiconductor catalyst designs for the photocatalytic reduction of CO2

Using clean solar energy to reduce CO₂ into value-added products not only consumes the over-emitted CO₂ that causes environmental problems, but also generates fuel chemicals to alleviate energy crises. The photocatalytic CO₂ reduction reaction (PCO₂RR) relies on the semiconductor photocatalysts that suffer from high recombination rate of the photo-generated carriers, low light harvesting capability, and low stability. This review explores the recent discoveries on the novel semiconductors for PCO₂RR, focusing on the rational catalyst design strategies (such as surface engineering, band engineering, hierarchical structure construction, single-atom catalysts, and biohybrid catalysts) that promote the catalytic performance of semiconductor catalysts on PCO₂RR. The advanced characterization techniques that contribute to understanding the intrinsic properties of the photocatalysts are also discussed. Lastly, the perspectives on future challenges and possible solutions for PCO₂RR are presented.