Visible Light-Responsive AlFeO₃@g-C₃N₄ Heterojunction for Efficient Degradation of Organic Wastewater

A Z-type AlFeO₃@g-C₃N₄ photocatalyst was successfully prepared via sol-gel and high-temperature polymerization. The morphology, structure, and composition of the catalysts were analyzed by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The photocatalytic performance was evaluated by nitrobenzene degradation experiments and electrochemical station, comparing with single g-C₃N₄ and AlFeO₃. Optimizing AlFeO₃ precursor content in the composite yielded 1.6 and 1.8-fold higher degradation rates than single g-C₃N₄ and AlFeO₃, respectively. Furthermore, in comparison to other ratios of AlFeO₃@g-C₃N₄ composites, AF-CN-100, which exhibited the best degrading performance, had the smallest impedance, the strongest transient photocurrent response strength, and the strongest redox capacity. The heterojunction produced between AlFeO₃ and g-C₃N₄ was a Z-type heterojunction, as revealed by investigations on energy band structure and mechanism. This heterojunction substantially improved the separation efficiency of photogenerated electrons and holes and increased the photocatalytic activity of the composites.