Photocatalytically recovering hydrogen energy from wastewater treatment using MoS2 @TiO2 with sulfur/oxygen dual-defect

Photocatalysis is a promising technology for energy and environment applications. Herein, a dual-defect heterojunction system of TiO2 hierarchical microspheres with oxygen vacancies modified with ultrathin MoS2−x nanosheets (MoS2−x @TiO2-OV) is designed for simultaneously degrading pollutants and evolving hydrogen. MoS2−x @TiO2-OV exhibits a dramatically enhanced photocatalytic activity with a H2 evolution rate of 2985.16 μmol g−1h−1. In treating the simulated pharmaceutical wastewater, MoS2−x @TiO2-OV is capable of purifying various refractory contaminants, with the highest H2 evolution rate of 41.59 μmol g−1h−1 during enrofloxacin degradation. While treating the simulated coking wastewater, the catalyst achieves a H2 evolution rate of 102.72 μmol g−1h−1 and a mineralization rate of 50%. Computational studies suggest that the dual-defect is superior for the adsorption of H* and producing·OH (‘dual-defect boosted dual-function’). Also, the dual-defect sites significantly boosted the charge-carrier separation and transfer efficiencies. This work highlights the crucial role of defect engineering to develop the energy-recovering wastewater treatment approaches.