Enhanced photocatalytic activity of BiVO4/Pt/PtOx photocatalyst: the role of Pt oxidation state

Abstract

Monoclinic bismuth vanadate (BVO) has gained attention as a low-cost and promising visible light photocatalyst but suffers from fast charge carrier recombination. The present study reports the controlled photoreduction deposition of different Pt-based co-catalysts on the surface of BVO to address this drawback and brings a detailed discussion on the role of the oxidation state of Pt in determining the photoactivity of the photocatalysts. Results evidenced the presence of both metallic Pt and Pt oxides on the surface of BVO, with proportions that depended on the photoreduction time. The photocatalytic activity towards degradation of three model dyes revealed that platinum oxides (PtOx, x = 1 or 2) or a mixture of Pt0/PtOx species act out as better cocatalysts than Pt0, with an almost 4-fold higher apparent quantum yield for the optimized sample. The enhanced photoactivity of BVO/Pt/PtOx photocatalysts was attributed to their improved visible light absorption and enhanced charge carrier separation than pristine BVO or BVO/Pt. This study provides important insight into and a better understanding of the general photodeposition strategy employed to prepare semiconductor/metal (photo)catalysts on one hand and highlights the role of the oxidation state of deposited metal in determining the properties of composite (photo)catalysts on the other.