Novel Ag/p-AgBr/n-BiVO4 Plasmonic Heterojunction Photocatalyst: Study on the Excellent Photocatalytic Performance and Photocatalytic Mechanism

A novel three-dimensional microspheres Ag/p-AgBr/n-BiVO4 plasmonic p–n heterojunction photocatalyst was successfully obtained for the first time; the photocatalytic performance of the as-prepared sample was systematically examined via the photocatalytic reduction of Cr6+ and oxidation of bisphenol S under visible-light irradiation. Among these samples, 3 mM-Ag/p-AgBr/n-BiVO4 exhibits the highest photocatalytic performances; the photocatalytic reduction and oxidation efficiency can be achieved at 76.9 and 98.8%, respectively. Enhancing photocatalytic performance is attributed to the increasing lifetime of the charge carrier confirmed by the results of time-resolved fluorescence spectra and photoelectrochemical measures. Moreover, based on the results of free radical scavenging activity test, and EPR experiments, we verify that h+ and •OH radicals are the main reactive species. Furthermore, the theoretical understanding of the underlying mechanism was also supported; we systematically calculated the energy band structure and Fermi level using the density functional theory approach. The results show that the matched positions of the CB and VB band edge between BiVO4 and AgBr are beneficial for efficiently separating electron–hole pairs. The strategy to form a three-dimensional microspheres plasmonic p–n heterojunction photocatalyst may offer a new strategy for applications in the field of solar energy conversion.