NiS modified CdS pyramids with stacking fault structures: Highly efficient and stable photocatalysts for hydrogen production from water

NiS modified three-dimensional pyramidic CdS with stacking fault structures were successfully synthesized by using the one-step method and an ammonia aqueous solvent as the hydrothermal solvent. Thus, CdS showed superior photocatalytic activities for hydrogen evolution from water under visible light irradiation (λ ≥ 420 nm), which could achieve a hydrogen evolution rate of 49.2 mmol g⁻¹ h⁻¹, with an extremely high apparent quantum yield (AQY = 74.6%) at 420 nm. To our knowledge, this value is the highest reported efficiency value for NiS_x modified CdS photocatalysts. CdS exhibited a three-dimensional pyramid structure with large specific surface areas, which may provide more active sites for the photocatalytic reaction. Stacking fault structures were observed in CdS by transmission electron microscopy (TEM). P-type NiS nanoparticles were highly dispersed on the surface of n-type CdS pyramids, forming p-n junctions at the interface. The stacking fault structures and junctions strengthened the separation of photo-carriers near the interface, which may greatly enhance the activity of photocatalytic hydrogen production for CdS. The catalyst also showed perfect stability, and the photoactivity showed no significant degradation during continuous hydrogen production over nearly 120 h, which has not been reported in the literature.