Interface-defect synergy in PCN/WS2-Vs heterostructures for enhanced photoelectrochemical hydrogen evolution

Photoelectrochemical (PEC) water splitting represents a promising strategy for sustainable hydrogen production. The development of highly efficient photoelectrocatalysts that facilitate charge transport and minimize overpotential is therefore of great significance. In this work, a synergistic approach was employed by constructing a PCN/WS 2 heterojunction through electrostatic self-assembly and introducing sulfur vacancies via HF etching. The as-prepared PCN/WS 2 -Vs composite demonstrated outstanding HER performance: under illumination, the overpotential at 10 mA·cm −2 decreased from 157 to 73 mV, and the Tafel slope was reduced from 223 to 114 mV·dec -1 . Moreover, the optimized photocathode delivered an applied bias photon-to-current efficiency (ABPE) of 1.33 % and achieved a photocurrent density of 7.65 mA·cm −2 at 0 V (vs. RHE). Remarkably, the photocathode enabled stable continuous operation for 150 h under simulated solar irradiation. Spectroscopic characterizations (XPS, UV–vis, and EPR) confirmed band structure modulation, including a narrowed bandgap and a downward-shifted valence band, which collectively promoted efficient charge separation and transfer. These results highlight the synergistic contributions of p-n heterojunction formation and sulfur-vacancy engineering toward enhanced PEC-HER, offering an effective strategy for designing efficient, durable, and noble-metal-free photoelectrocatalysts.