2D/2D heterojunctions of WO3 nanosheet/K+Ca2Nb3O10- ultrathin nanosheet with improved charge separation efficiency for significantly boosting photocatalysis

Harvesting solar energy using semiconductor photocatalysts for wastewater decontamination offers a greener solution to address serious environmental crises. Delamination of layer photocatalysts into ultrathin two-dimensional (2D) nanosheets has induced fascinating properties such as electronic/protonic-conductivity and photocatalytic and fluorescent properties. K+Ca2Nb3O10- is one prominent type of such materials, which is derived from the Dion-Jacobsen phase KCa2Nb3O10 by exfoliation. Here, a Z-scheme WO3/K+Ca2Nb3O10- binary 2D-2D heterojunction photocatalyst is successfully constructed through an easy hydrothermal coassembly method at room temperature. The as-synthesized WO3/K+Ca2Nb3O10- photocatalyst exhibited remarkable improvement in the photodegradation performance of tetracycline hydrochloride under simulated sunlight irradiation as compared to pristine WO3 and K+Ca2Nb3O10- nanosheets. Sample 20%-WO3/K+Ca2Nb3O10- exhibited optimum efficiency, which is about 5.1-fold and 2-fold higher than those of WO3 and K+Ca2Nb3O10-, respectively. Such an improvement is mainly related to its strongly coupled heterointerfaces, enlarged specific surface area and improved charge carrier separation and transfer. Radical capturing experiments and the spin-trapping ESR technique demonstrate that both O-center dot(2)- and h(+) are the important active species responsible for the tetracycline hydrochloride degradation process over the nanosheet heterojunctions.