Delocalized Electron Accumulation at Nanorod Tips: Origin of Efficient H₂ Generation

Photocatalytic hydrogen (H₂) evolution requires efficient electron transfer to catalytically active sites in competition with charge recombination. Thus, controlling charge-carrier dynamics in the photocatalytic H₂ evolution process is essential for optimized photocatalyst nanostructures. Here, the efficient delocalization of electrons is demonstrated in a heterostructure consisting of optimized MoS₂ tips and CdS nanorods (M-t-CdS Nrs) synthesized by amine-assisted oriented attachment. The heterostructure achieves photocatalytic H₂ activity of 8.44 mmol h⁻¹ g⁻¹ with excellent long-term durability (>23 h) without additional passivation under simulated solar light (AM 1.5, 100 mW cm⁻²). This activity is nearly two orders of magnitude higher than that of pure CdS Nrs. The impressive photocatalytic H₂ activity of M-t-CdS Nrs reflects favorable charge-carrier dynamics, as determined by steady-state PL and time-correlated single photon counting correlation analysis at low temperature. The MoS₂ cocatalysts precisely located at the end of the CdS Nrs exhibit ultrafast charge transfer and slow charge recombination via spatially localized deeper energy states, resulting in a highly efficient H₂ evolution reaction in lactic acid containing an electrolyte.