Photocatalytic activity evaluation of polyvinylpyrrolidone K30 assisted synthesis of 1D oxygen-vacancy-rich Bi5O7BrxI1-x nanorod solid solution

Abstract

The unique layered structure of bismuth halide oxide has led to an extensive application in the degradation of refractory antibiotics from water environments. With the aid of regulating the energy band structure of photocatalytic materials and equilibrating the response towards visible light and redox ability, a novel oxygen-vacancy-rich Bi₅O₇Br_xI_1-x nanorod solid solution was synthesized by polyvinylpyrrolidone K30 assisted solvothermal method, and its photocatalytic behavior was investigated for the degradation of antibiotic levofloxacin under visible light. The degradation rate of the optimal Bi₅O₇Br_0.5I_0.5 to levofloxacin can reach 82.7% within 30 min, which is 9.22 and 4.74 times higher than those of the monomers Bi₅O₇Br and Bi₅O₇I. The catalyst of Bi₅O₇Br_0.5I_0.5 shows 99.88% antibacterial activity against Escherichia coli. The efficient photocatalytic ability of the Bi₅O₇Br_0.5I_0.5 is resulted from the alteration of energy band structure and suppression of charge recombination due to benign changes in the electronic and crystal structures. Furthermore, both various characterizations and Density Functional Theory calculations reveal that a multitude of oxygen vacancies exist in the Bi₅O₇Br_0.5I_0.5. The photocatalytic degradation pathways were explored and the toxicity of the intermediates was also appraised. The present work provides a mild and feasible construction of solid solutions and introduction of oxygen vacancies to eliminate environmentally refractory organic pollutants with photocatalytic technology.

Keywords: Antibacterium; Density functional theory; Levofloxacin; Oxygen vacancies; Photo degradation.