Developing hierarchical CdS/NiO hollow heterogeneous architectures for boosting photocatalytic hydrogen generation

The hierarchical binary CdS/NiO hollow heterogeneous architectures (HHAs) with p–n heterojunction are constructed by a facile microwave-assisted wet chemical process for high-efficient photocatalytic hydrogen evolution reaction (HER) from water. The as-designed CdS/NiO HHAs are composed of hexagonal n-type CdS nanoparticles with a size in the range of 20–40 nm attaching to cubic p-type NiO hollow microspheres (HMSs) which are aggregates of porous nanoplates with a thickness of about 20 nm. The photocatalytic water splitting over CdS/NiO HHAs is significantly increased under simulated solar irradiation, among which the most active sample of CdS/NiO-3 (the mass ratio of CdS to NiO is 1:3) exhibits the fastest photocatalytic HER rate of 1.77 mmol∙g⁻¹∙h⁻¹, being 16.2 times than that of pure CdS. The boosted photocatalytic HER could be attributed to the synergistic effect on the proportional p–n heterojunction with special hierarchical hollow and porous morphology, an enhancement of visible light absorption, and an improvement of photoinduced charge separation as well as the photo-stability given by the composite heterojunction. This work shows a viable strategy to design the heterojunction with special morphology for the efficient hydrogen generation by water splitting utilizing solar energy.