Enhanced photocatalytic performance of BiOBr/CQDs hierarchical nanostructures mixed with SiO2 nanospheres

Reinforcing light harvesting is an effective means to improve photocatalytic efficiency of semiconductors. In this study, carbon-quantum-dot-modified BiOBr mixed with SiO 2 nanospheres (BiOBr/CQDs + SiO 2 ) were prepared via stepwise chemical precipitation route. The characterizations of X-ray diffraction, field-emission scanning electron microscopy and energy-dispersive X-ray apparatus demonstrated that the as-prepared BiOBr/CQDs + SiO 2 displayed nanosheets-building spherelike hierarchical nanostructures mixing with dispersive SiO 2 nanospheres. Control photocatalytic degradation of orange II under natural sunlight illumination indicated that the presence of SiO 2 nanospheres could further promote the photocatalytic behaviors of BiOBr/CQDs apart from CQDs. Diffuse reflection spectrum demonstrated that SiO 2 nanospheres were capable of reflecting UV − Vis light near to 100%. The possible mechanism for the enhanced light-absorption surface of suspending hierarchical photocatalyst in presence of SiO 2 nanospheres was proposed via light propagation over suspending SiO 2 nanospheres under vertical light illumination. Our method for enhancing photocatalytic efficiency provided a general method to enhance light harvesting of every suspending two- or three-dimensional photocatalysts.