Improved photoactivities for CO₂ conversion and phenol degradation of α-Fe₂O₃ nanoparticles by co-coupling nano-sized BiPO₄ and CuO to modulate electrons

It's highly desired to design and fabricate effective α-Fe₂O₃-based photocatalysts by increasing the surface area, promoting the charge separation and providing catalytic function. Herein, specific surface area-enlarged α-Fe₂O₃ (SE-FO) nanoparticles have been successfully synthesized by a functional molecule-modulated phase-separated hydrothermal method, with high photocatalytic activities for CO₂ conversion and phenol degradation. The photocatalytic activities of SE-FO could be greatly improved by coupling nano-sized BiPO₄ via an in-situ introduction method. This is attributed to the coupled BiPO₄ as a high-energy platform to accept photogenerated electrons from α-Fe₂O₃ so as to enhance the charge separation mainly by means of surface photovoltage spectra and fluorescence spectra-related to the amount of produced •OH species. Moreover, the photocatalytic activities are further improved by introducing a proper amount of nanocrystalline CuO via a simple impregnation process. It is confirmed based on the temperature-programmed desorption and electrochemical reduction measurements that the improved photoactivity is attributed to the introduced CuO as the co-catalyst for promoting electron-induced reduction reactions. Remarkably, the optimized α-Fe₂O₃ nanocomposite exhibits about 3-time photoactivity improvement compared with the pristine α-Fe₂O₃. This work would provide a feasible route to fabricate high-activity α-Fe₂O₃-based photocatalysts for CO₂ conversion and phenol degradation.