Integrating Z-scheme heterojunction of Co1-C3N4@α-Fe2O3 for efficient visible-light-driven photocatalytic CO2 reduction

Abstract

Photocatalytic CO₂ reduction coupled with water oxidation provides a fascinating approach to mitigating the issues of global warming and energy shortage. Herein, a direct Z-scheme heterojunction of Co₁-C₃N₄@α-Fe₂O₃ comprising a g-C₃N₄-supported single-atomic Co site catalyst (denoted as Co₁-C₃N₄) and α-Fe₂O₃ nanorod arrays is fabricated for efficient CO₂ reduction. A CO production rate of 14.9 μmol g⁻¹ h⁻¹ with a high CO selectivity (>99%) is achieved under visible-light irradiation without any sacrificial agents other than water. Time-resolved photoluminescence (TRPL) analysis reveals that both the Z-scheme mechanism and the single-atomic Co sites contribute to the prolonged lifetime of the photo-induced excitons. Moreover, the formation of the Z-scheme heterojunction would lead to an altered charge density of the single-atomic Co sites. In situ diffuse reflectance infrared Fourier-transform spectroscopy and anion adsorption measurements reveal that the key intermediate CO₂⁻ could be efficiently stabilized by the positively charged Co sites in Co₁-C₃N₄@α-Fe₂O₃, thus enhancing the CO₂ reduction performance. This work offers a new direction for the rational design of single-atomic site catalysts in artificial photosynthesis.