Synergistic Photoelectrical–Photothermal Modulation of Heterostructured p-Si Photocathode by Cascaded Interfacial Engineering for Efficient and Stable Hydrogen Production

The efficiency of the p-Si photocathode for photoelectrochemical hydrogen production remains limited by the interfacial carrier losses and insufficient surface catalytic activity. Herein, a cascaded interfacial engineering strategy is presented to fabricate a p-Si photocathode with optimized interfacial charge transport and catalytic activity through synergistic photoelectrical–photothermal modulation. The p-Si/ZAO/NiMoS₃/Co (ZAO: Zn-doped Al₂O₃) photocathode achieves a high photovoltage (544 mV), exhibiting a positive onset potential of 0.17 V vs RHE, a high photocurrent density of 17.8 mA cm^–2 at 0 V vs RHE, and a high saturation photocurrent density of 32.5 mA cm^–2 for hydrogen evolution reaction (HER). It is revealed that the 4 nm ZAO layer enables efficient electron tunneling while suppressing interfacial charge recombination, the 150 nm NiMoS₃ layer assists in charge carrier migration and provides catalytic active sites for HER, and the 3 nm Co layer enhances catalytic activity via photothermal effect to reduce the activation energy for HER.