A study on the photocatalytic sterilization performance and mechanism of Fe-SnO2/g-C3N4 heterojunction materials

Abstract

A novel visible-light catalytic material, modified g-C₃N₄ with Fe-doped SnO₂ (Fe-SnO₂/g-C₃N₄), was prepared by a chemical precipitation-ball milling-baking method. This photocatalytic material showed sterilization performance for Escherichia coli and Staphylococcus aureus under the irradiation of a daylight lamp, natural sunlight, near ultraviolet light and simulated sunlight, among which the sterilization performance–enhancing effect was the most prominent under daylight lamp irradiation, suggesting practical application prospects. Scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy were used to analyze the structure of Fe-SnO₂/g-C₃N₄. It was found that Fe-SnO₂ was uniformly dispersed on g-C₃N₄, forming a new type of porous layered heterojunction, which increased the surface activity and specific surface area. Fe doping further regulates the energy band structure and promotes the Z-scheme electron conduction capability of the Fe-SnO₂/g-C₃N₄ heterojunction. The main free radicals that perform sterilization are ˙OH and ˙O₂. Based on the biochemical structure of bacteria, the charge Z-scheme conduction sterilization mechanism is proposed from the perspectives of free radical generation energy level, biochemical reaction energy and chemical bond energy.