In situ loading of ultra-small Cu2O particles on TiO2nanosheets to enhance the visible-light photoactivity

Abstract

In this work, ultra-small Cu₂O nanoparticles have been loaded on TiO₂ nanosheets with {001} facets exposed through a one-pot hydrothermal reaction. These Cu₂O nanoparticles are well-dispersed on TiO₂ nanosheets with narrow size distributions and controllable sizes from 1.5 to 3.0 nm. Through XRD, TEM, N₂ absorption–desorption isotherms and UV-vis diffuse reflectance spectra, the Cu₂O/TiO₂ nanosheets show similar phase structures, morphologies, pore structures as compared to pure TiO₂ nanosheets. Due to the loading of ultra-small Cu₂O nanoparticles, heterojunctions are formed between Cu₂O and TiO₂, which favors the efficient separation of photo-generated electrons and holes. Caused by the electron transfer from Cu₂O to TiO₂, Cu₂O/TiO₂ nanosheets show excellent visible-light activity, about 3 times that of N-doped TiO₂ nanosheets with {001} facets exposed. Furthermore, charge transfer rate across the interface of Cu₂O and TiO₂ shows great dependence on the size of Cu₂O particles. The charge transfer across the interface may be more efficient between TiO₂ nanosheets and smaller Cu₂O nanoparticles. Therefore, the Ti : Cu = 30 : 1(atomic ratio) sample shows the best activity due to its balance in light harvest and electron transfer rate in the degradation of phenol under visible light.