Phosphorous-doped molybdenum disulfide anchored on silicon as an efficient catalyst for photoelectrochemical hydrogen generation

Herein, molybdenum disulfide (MoS₂) integrated on Si pyramids was used as a co-catalyst to improve charge separation efficiency. Various quantities of phosphorus (P) heteroatoms were doped into MoS₂ materials to boost catalytic performance. Raman and extended X-ray absorption fine structure spectra showed that the introduction of P dopants increased the number of exposed edges and sulfur vacancies that acted as hydrogen evolution reaction (HER) active sites on MoS₂ and enhanced photoelectrochemical activity. Density functional theory calculations revealed that the HER inert basal plane of MoS₂ became catalytically active after P atoms doping. MoS_1.75P_0.25/Si pyramids presented the optimal onset potential of +0.29 V (vs. RHE) and current density −23.8 mA cm⁻². A titanium dioxide (TiO₂) layer was prepared through atomic layer deposition and served as a passivation layer that improved photocathode stability. The photocurrent retention of MoS_1.75P_0.25/10 nm TiO₂/Si pyramids was 84.0% after 2 h of chronoamperometric measurement.