Promoting body carriers migration of CdS nanocatalyst by N-doping for improved hydrogen production under simulated sunlight irradiation

Abstract

Cadmium sulfide (CdS) has been extensively employed to achieve highly efficient H2 production under visible-light irradiation due to its features of narrow bandgap and appropriate conduction band position. However, fast carriers recombination and severe photocorrosion inevitably result in low carriers utilization, leading to undesirable photocatalytic performance and poor durability. To address the issues, N heteroatoms were introduced into the lattice of hexagonal CdS NPs to prepare the N-doped CdS (N-CdS) nanocatalyst via a wet chemical precipitation coupled with a hydrothermal process. Due to the synergetic promotion of heteroatom-semiconductor coordination (HSC) interaction to body carriers migration of CdS, their recombination behavior was effectively hampered, resulting obviously increased photocurrent density (~2 times) and significantly improved photoexcited carriers utilization. Thereby, high apparent quantum yield (AQY = 32.41%, λ = 500 nm) was achieved by the optimized N0.2-CdS nanocatalyst. Under simulated sunlight (SSL) irradiation, about 3983.4 μmol·h−1·g−1 of HER rate with excellent photostability was achieved at absence of cocatalyst, which raises to about 9-fold greater than that of bare CdS NPs. Moreover, density functional theory (DFT) calculations proved that the energy barrier of water splitting on Cd sites and |ΔGH*| of H2 generation on S sites were reduced obviously due to the synergetic HSC interaction, which thermodynamically accelerated the H2 generation. This study provides a simple and green strategy for gaining highly stable CdS photocatalyst with improved HER photoactivity.