In situ synthesized α-Fe₂O₃/BCN heterojunction for promoting photocatalytic CO₂ reduction performance

The conversion of CO₂ into clean fuels by utilizing solar energy is still limited by a low photoconversion efficiency, and heterojunction photocatalysts are considered a very effective way to solve this problem. Herein, a heterojunction system consisting of hematite (α-Fe₂O₃) and boron carbonitride (BCN) was fabricated through a one-pot ionothermal method. α-Fe₂O₃ nanoparticles were grown in situ on the surface of BCN nanosheets, forming an α-Fe₂O₃/BCN heterojunction (FBCN) with tiny amounts of α-Fe₂O₃ (less than 2 wt%). The as-synthesized FBCN catalyst with 1.46 wt% α-Fe₂O₃ provides the highest CO₂ photoreduction activity (55.1 µmol g^-1 for CO) without any cocatalyst or sacrificial reagents, which is 3.9 times higher than that obtained for pure BCN. The enhanced CO₂ reduction activity can be attributed to the high surface area and effective interface-contacted heterostructure, which endows the catalyst with broadband visible light absorption, suppressed separation of photogenerated electron holes, and promoted charge transfer. Meanwhile, cycling experiments demonstrate that the FBCN photocatalyst shows good reusability and stability. This work can assist in the design and preparation of BCN-based heterojunctions with effective CO₂ reduction performance.