Facile synthesis of flower-like Bi12O17Cl2/β-Bi2O3 composites with enhanced visible light photocatalytic performance for the degradation of 4-tert-butylphenol

Novel three-dimensional flower-like Bi12O17Cl2/β-Bi2O3 composites are prepared using a facile solvothermal-calcining process and their photocatalytic performances for the degradation of 4-tert-butylphenol (PTBP, a representative alkylphenol) are evaluated under visible light irradiation. The formation of such composites is assumed to involve the reduction of Bi(III) to nano-metallic bismuth via a solvothermal process, followed by the reaction of bismuth with oxygen and bismuth oxide chloride hydroxide during the calcination in air. The XRD, XPS, EDS mapping, HRTEM, UV–vis DRS, and photocurrent measurement results indicate that heterojunctions are formed between Bi12O17Cl2 and β-Bi2O3 with broad contact interfaces. The as-synthesized Bi12O17Cl2/β-Bi2O3 hybrid materials possess favorable band structures, heterojunction structures, relatively high specific surface areas, and hierarchical micro/nano-structures, resulting in superior photocatalytic and mineralization efficiencies for the decomposition of PTBP under visible light irradiation. The optimum photocatalytic activity of a Bi12O17Cl2/β-Bi2O3 sample is approximately 3, 12, 51, and 107 times higher than the activities of single β-Bi2O3, Bi12O17Cl2, nitrogen-doped TiO2, and BiOCl, respectively. In addition, the photogenerated reactive species are identified based on free radicals trapping experiments and EPR analysis, which reveals that the photodegradation of PTPB over Bi12O17Cl2/β-Bi2O3 under visible light is dominated by direct hole and superoxide radical oxidation rather than oxidized by hydroxyl radical.