FeWO4 nanosheets with enhanced exposed (001) facets for promoting photocatalytic Fenton degradation of organic pollutants

Abstract

Crystal faceted engineering has been widely used to improve the performance of photocatalysts, but there is still a lack of a general strategy for the wise design of nanocrystal morphology, and the fast recombination rate of photoinduced carriers seriously hinders the photocatalytic performance. Here, we report a new method to enhance the photocatalytic activity of FeWO₄ through crystal faceted engineering, and investigate the evolution of FeWO₄ morphology. The preparation of three different morphologies of FeWO₄ samples allowed us to carefully investigate the factors that contribute to the intrinsic reactivity of the sample, including H₂O₂ activation and band gap location. The results confirm that the selective exposure of the relatively active facets in the direction of the internal electric field gives the catalyst excellent photoactivity, and the decolorization efficiency of Rhodamine B (RhB) with the main (001) facets reaches 96.5 %, which is higher than that of the nanorods (010), and has excellent performance for the degradation of RhB dyes. Theoretical analysis and EPR trap experiments show that the cycling and photoinduced electron-hole separation efficiency of the coordination unsaturated iron ions is the main reason for the improvement of the photocatalytic activity of the FeWO₄ photofenton system, and the degradation intermediates and pathways of RhB dyes are studied. This work is expected to inform the development of a general approach for the morphology design of photocatalysts.