Modulation of the morphology of layered Bi5O7NO3 and analysis of its catalytic and antibacterial activity under visible light conditions

The development of efficient photocatalytic antimicrobial agents is considered to be an environmentally friendly low-cost treatment strategy for addressing microbial contamination in water bodies. In this paper, various morphologies of layered Bi5O7NO3 photocatalysts were obtained in the hydrothermal synthesis by altering the pH value of the starting solution, and the selective adsorption ability and photocatalytic degradation behavior of the samples against anionic dyes (methyl orange) and cationic dyes (rhodamine B) were investigated under visible light irradiation. In addition, the broad-spectrum photocatalytic antibacterial effect on Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) was investigated. Experimental results show that controlling morphological size, oxygen vacancy (OV) defect concentration, and relative content of multivalent bismuth in these Bi5O7NO3 photocatalysts by regulating the hydroxide concentration is the key to improving their photocatalytic activity. Abundant defect OVs and multivalent bismuth can operate as electron traps in small-sized materials, improving the separation efficiency of electron-hole pairs. Therefore, the B-p8 sample, prepared with an initial solution pH of 8, exhibited a small catalyst size, high OV concentration, and multivalent bismuth and achieved optimal visible light photocatalytic performance. Furthermore, the experimental exploration of the antibacterial mechanism revealed the degradation by reactive oxygen species, mainly ·OH and ·O2-, as the mechanism of Bi5O7NO3 photocatalysis. This research work provides a novel and efficient photocatalytic antibacterial nanomaterial and exhibits its prospective application in water purification.