Boosting visible-light-driven photocatalytic H2 production by optimizing surface hydrogen desorption of NiS/CdS-P photocatalyst

Metal chalcogenides are regarded as favorable H2 2-evolution cocatalysts; however, they often exhibit unfavorable H desorption characteristics due to the strong affinity of nascent H and highly electronegative S sites, which significantly inhibit H2 2 generation. To address this issue, a general approach to electron-enriched control of sulfur-active sites is developed for weakening the strong interaction of S-H bonds. This is achieved through the formation of a nanostructured model composed of NiS/CdS-P, in which the surface phosphorus (P) atoms are incorporated in CdS NRs to create an imbalanced charge distribution and a localized built-in electric field in the crystal structure of CdS. In this situation, the built-in electric field not only separates the photogenerated electron hole pairs, but it also accelerates the photogenerated electrons from the CdS-P conduction band to the NiS surface for rapid hydrogen reduction rather than hydrogen adsorption. Photocatalytic tests show that the resultant NiS/CdS-P photocatalyst displays a significant H2 2-generation rate of 44.39 mmol g- 1 h- 1 and an apparent quantum efficiency of 41% at 420 nm. Valance band XPS analysis shows that CdS-P has a higher electron density than CdS, leading to the production of electron-rich S delta- active centers. This better photocatalytic hydrogen generation might be due to the synergistic impact of tailoring the intrinsic built-in electric field for the acceleration of photogenerated charges by P-doping and the fabrication of a NiS cocatalyst for hydrogen reduction rather than hydrogen adsorption. The concept of optimizing the electron densities of active sites by morphology tailoring, with an extra built-in electric field, gives a method for rationally constructing artificial photocatalysts for solar power conversion.