Fig. 9. Comparison of the photocatalytic degradation and TOC removal efficiency using the as-synthesized Bi12O17Cl2/β-Bi2O3 (sample S4) with an initial PTBP concentration of 60 mg L−1 and a catalyst concentration of 1 g L−1 under visible light irradiation.Figure optionsDownload full-size imageDownload as PowerPoint slide
Fig. 10. (A) Mott–Schottky plots for the as-synthesized β-Bi2O3 (S1) and Bi12O17Cl2 (S7). (B) Schematic illustration of electron-hole TTNPB (Arotinoid Acid) and transport at the Bi12O17Cl2/β-Bi2O3 heterojunction interface. (C) Photocurrent transient responses for β-Bi2O3 (S1), Bi12O17Cl2/β-Bi2O3 (S4), and Bi12O17Cl2 (S7).Figure optionsDownload full-size imageDownload as PowerPoint slide
To further confirm and gain insight regarding the higher separation efficiency of photo-induced charges in the Bi12O17Cl2/β-Bi2O3 hybrid materials, the photocurrents were also measured for the β-Bi2O3 (sample S1), Bi12O17Cl2/β-Bi2O3 (sample S4), and Bi12O17Cl2 (sample S7) electrodes, as shown in Fig. 10C. It can be seen that fast photocurrent responses via on–off cycles appeared in these electrodes under visible light irradiation, which could be directly related with the separation efficiency of the photogenerated carriers. The photocurrent of the Bi12O17Cl2/β-Bi2O3 heterojunction electrodes is significantly higher than that of the single Bi12O17Cl2 or β-Bi2O3, indicating that the heterojunction is more effective to separate the electron-hole pairs . Therefore, the construction of Bi12O17Cl2/β-Bi2O3 heterojunctions largely reduced the recombination rate of the photogenerated electrons and holes, resulting in higher photodegradation activity.