Bi/BiVO4 tailoring molecular oxygen activation for SPR-promoted photocatalytic contaminant removal

In recent years, photocatalytic technology has been gained widespread attention in contaminants removal due to its green, low-carbon, sustainable properties. Bismuth vanadate (BiVO4) with decahedral shapes has emerged as a promising photocatalyst with unique photoinduced charges directional transfer. In this study, a simple wet chemical reduction method was used to load stable Bi0 nanoparticles in situ on the surface of decahedral BiVO4 to enhance the charges movement for molecular oxygen activation and tetracycline photodegradation. The formed Bi0 nanoparticles induced abundant oxygen vacancy defect states and surface plasmon resonance effects on BiVO4 nanoparticles surface. In aid of the special function of a surface heterojunction, decahedral BiVO4 can be photoexcited to produce more photogenerated carriers, and its separation efficiency is greatly improved, thus enhancing both the oxidative activity and photocatalytic activity. In the photocatalytic degradation process, superoxide radicals (∙O2−) showed the most significant contribution, and singlet oxygen (1O2) played junior role in tetracycline hydrochloride (TC) removal. 1O2 is obtained by ∙O2− and hole energy conversion, and some of it is produced by tetracycline photodecomposition under alkaline conditions. The BBV0.4 photocatalytic system has the best catalytic activity under weakly alkaline conditions, and the synergistic effect of photocatalysis and photodecomposition greatly improves the mineralization rate of TC. The large numbers of ∙O2− and 1O2 reactive oxygen species produced by BBV0.4 activation of oxygen play a crucial role in the photodegradation of TC via demethylation, deoxidation, deamination, ring-opening, and carbonylation to complete mineralization. This work studies in depth the change in the decahedral BiVO4 photocatalytic mechanism caused by the in situ introduce of bismuth metal, providing an efficient and environmentally friendly reference method for the rapid removal of tetracycline hydrochloride under alkaline conditions.