Hierarchically plasmonic photocatalysts of Ag/AgCl nanocrystals coupled with single-crystalline WO3 nanoplates

Abstract

The hierarchical photocatalysts of Ag/AgCl@plate-WO₃ have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO₃ nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag⁺-WO₃ suspensions with a Cl⁻ solution added drop-wise was developed to synthesize AgCl@WO₃ composites, which were then photoreduced to form Ag/AgCl@WO₃ nanostructures in situ. WO₃ nanocrystals with various shapes (i.e., nanoplates, nanorods, and nanoparticles) were used as the substrates to synthesize Ag/AgCl@WO₃ photocatalysts, and the effects of the WO₃ contents and photoreduction times on their visible-light-driven photocatalytic performance were investigated. The techniques of TEM, SEM, XPS, EDS, XRD, N₂ adsorption-desorption and UV-vis DR spectra were used to characterize the compositions, phases and microstructures of the samples. The RhB aqueous solutions were used as the model system to estimate the photocatalytic performance of the as-obtained Ag/AgCl@WO₃ nanostructures under visible light (λ ≥ 420 nm) and sunlight. The results indicated that the hierarchical Ag/AgCl@plate-WO₃ photocatalyst has a higher photodegradation rate than Ag/AgCl, AgCl, AgCl@WO₃ and TiO₂ (P25). The contents and morphologies of the WO₃ substrates in the Ag/AgCl@plate-WO₃ photocatalysts have important effects on their photocatalytic performance. The related mechanisms for the enhancement in visible-light-driven photodegradation of RhB molecules were analyzed.