Dual S-scheme graphitic carbon-doped α-Bi2O3/β-Bi2O3/Bi5O7I ternary heterojunction photocatalyst for the degradation of Bisphenol A

Graphitic carbon-doped α-Bi2O3/β-Bi2O3/Bi5O7I ternary heterojunction photocatalysts were synthesized by calcination of urea, malonic acid and BiOIO3 in a simple and low-cost way. The photocatalytic activity of the photocatalysts was evaluated by the degradation of Bisphenol A (BPA) under simulated sunlight irradiation. The reaction rate constants of graphitic carbon-doped α-Bi2O3/β-Bi2O3/Bi5O7I were 4.6, 4.2, 17.8, and 231 times higher than those of BIO-550 (Bi5O7I), MA-BIO (α-Bi2O3/Bi5O7I), MACN and CN-BIO (α-Bi2O3/β-Bi2O3), respectively. The enhanced photocatalytic activity is due to the high separation efficiency of heterogeneous photogenerated electron-hole pairs, which is caused by the synergistic effect of the heterojunction between the different components and the efficient electron transfer efficiency of graphitic carbon. In addition, a dual S-scheme heterojunction mechanism has been proposed to explain the excellent redox properties of the composites.