Heterostructured WS₂-MoS₂ Ultrathin Nanosheets Integrated on CdS Nanorods to Promote Charge Separation and Migration and Improve Solar-Driven Photocatalytic Hydrogen Evolution

Solar-driven photocatalytic hydrogen evolution is important to bring solar-energy-to-fuel energy-conversion processes to reality. However, there is a lack of highly efficient, stable, and non-precious photocatalysts, and catalysts not designed completely with expensive noble metals have remained elusive, which hampers their large-scale industrial application. Herein, for the first time, a highly efficient and stable noble-metal-free CdS/WS₂-MoS₂ nanocomposite was designed through a facile hydrothermal approach. When assessed as a photocatalyst for water splitting, the CdS/WS₂-MoS₂ nanostructures exhibited remarkable photocatalytic hydrogen-evolution performance and impressive durability. An excellent hydrogen evolution rate of 209.79 mmol g⁻¹ h⁻¹ was achieved under simulated sunlight irradiation, which is higher than the values for CdS/MoS₂ (123.31 mmol g⁻¹ h⁻¹) and CdS/WS₂ nanostructures (169.82 mmol g⁻¹ h⁻¹) and the expensive CdS/Pt benchmark catalyst (34.98 mmol g⁻¹ h⁻¹). The apparent quantum yield reached 51.4 % at λ=425 nm in 5 h. Furthermore, the obtained hydrogen evolution rate was better than those of several noble-metal-free catalysts reported previously. The observed high rate of hydrogen evolution and remarkable stability may be a result of the ultrafast separation of photogenerated charge carriers and transport between the CdS nanorods and the WS₂-MoS₂ nanosheets, which thus increases the number of electrons involved in hydrogen production. The proposed designed strategy is believed to potentially open a door to the design of advanced noble-metal-free photocatalytic materials for efficient solar-driven hydrogen production.