Recent Advances in Heterogeneous Photocatalytic CO₂ Conversion to Solar Fuels

TLDR

Photocatalytic CO₂ conversion to C1/C2 solar fuels offers a dual solution to global warming and energy demand by harnessing solar energy and atmospheric CO₂, yet challenges in activity and selectivity persist. This review surveys fundamental aspects and recent advances in heterogeneous photocatalytic CO₂ conversion over the past three years, categorizes catalysts into one‑step excitation, photosensitized, and two‑step hybrid systems, and proposes strategies to confirm CO₂ as the carbon source and outlines future research directions. The authors examine various heterogeneous photocatalytic CO₂ conversion systems—including one‑step excitation semiconductor, photosensitized semiconductor, and two‑step hybrid heterojunction and Z‑scheme configurations—to highlight their mechanisms and recent progress.

Abstract

As a promising approach to achieving two objectives with one strategy, photocatalytic CO2 conversion for C1/C2 "solar fuels" production can provide a package solution to the current global warming and growing energy demand by using inexhaustible solar energy and increasing atmospheric CO2. Although numerous efforts have been made to enhance the CO2 conversion efficiency through developing photocatalysts and CO2 reduction systems in recent years, some challenges still remain in improving the activity and selectivity of the CO2 photoreduction reactions. This review gives an overview of fundamental aspects and recent research advances of heterogeneous photocatalytic CO2 conversion systems in the last 3 years, and the catalysts are categorized as one-step excitation semiconductor systems, one-step excitation photosensitized semiconductor systems, and two-step excitation hybrid systems such as semiconductor heterojunction and Z-scheme systems. Also, some suggestions are given for further confirming that the carbon-containing "solar fuels" are derived from CO2 rather than from the possible carbonaceous impurities in the photocatalytic system, because most of the papers cited in this review have not demonstrated that CO2 is the actual carbon source for photoreduction through 13CO2 labeling or other techniques. Lastly, a short perspective on the challenges and new directions in this field is proposed, which would be of great interest for the further improvements of activity and selectivity of the CO2 reduction reactions.