Cost-effective synthesis of highly-dispersed WS2 nanosheets assembled on tourmaline for improved photocatalytic activity

Tungsten disulfide (WS2) has attracted much attention in photocatalysis due to the excellent visible light harvesting and charge transfer kinetics, yet practical applications have been severely limited by the restacking property. In this work, a novel WS2/tourmaline composite was fabricated by coupling hydrothermal and calcination methods. The highly dispersed WS2 nanosheets homogeneously deposited on the tourmaline surface were revealed by electron microscopy, with sufficient exposure of the photocatalytic sites to enhance the migration efficiency of interfacial electrons. The armadillo-like WS2/tourmaline composite exhibited excellent photocatalytic activity for rhodamine B (RhB), with a degradation efficiency of 89.4 % after 150 min irradiation, while only 30.4 % was achieved by the pure WS2 microspheres. Electron paramagnetic resonance and density functional theory (DFT) calculations showed that the WS2/tourmaline composites with more sulfur vacancies preferred to produce sufficient reactive species for photocatalytic RhB degradation. In addition, photogenerated holes (h+) play a more important role in the degradation process of RhB than superoxide radicals (·O2–) and hydroxyl radicals (·OH), as confirmed by radical quenching experiments. This work presents a new option for the low-cost preparation of high-performance 2D materials via mineral assembly.