Microwave‐assisted reflux synthesis of Tungsten‐doped BiVO₄ for improved photocatalytic activity

Abstract

Given its favorable physical and chemical properties, Bismuth vanadate (BiVO4) is a commonly studied metal oxide semiconductor for photocatalytic applications. However, BiVO4 shows a high recombination rate of photogenerated charges and limited charge transport capacity, which can be addressed by doping it with tungsten. To develop a highly efficient tungsten‐doped BiVO4‐based (W‐BiVO4) photocatalyst, it is necessary to control the dopant content, crystal structure, and morphology. These properties are, in turn, governed by the synthesis conditions. This work describes a pioneering method of microwave‐assisted reflux synthesis of W‐BiVO4, using ethanol as solvent and polyvinyl pyrrolidone (PVP) as a capping agent. Thus, it is possible to perform the synthesis procedure in only 30 min at 78°C, obtaining extremely regular monoclinic W‐BiVO4 nanosquares. Furthermore, the experiments showed that the most efficient photocatalyst contains 3% tungsten as the dopant. Moreover, the direct oxidation of rhodamine B by the photogenerated holes plays a crucial role in the degradation mechanism. Finally, we observed that although the addition of PVP promotes control of the morphology, it results in a poorly efficient material. This low efficiency may be related to the formation of a polymeric coating on the surface of the catalyst or to a high amount of oxygen defects. Finally, we show that the unique interaction of microwaves with the species present in the reaction media influences nanoparticle growth.