Nickel complex engineered interface energetics for efficient photoelectrochemical hydrogen evolution over p-Si

Here we report a p-Si photocathode decorated with nickel complex Ni(TEOA)₂Cl₂ (Ni1) in acidic aqueous solution (pH = 0.3) for photoelectrochemical (PEC) H₂ generation. Compared to bare p-Si, p-Si/Ni1 electrode exhibits significantly enhanced PEC performance, with higher cathodic photocurrent and exceptional lower onset potential. A relatively high photocurrent density of 5.57 mA/cm² was obtained at 0.0 V vs. reversible hydrogen electrode (RHE) under simulated 1 Sun illumination, which is even comparable to that of p-Si/Pt. Furthermore, the highly active p-Si/Ni1 electrode shows a remarkable stability over 24 h. The possible catalysis mechanism of Ni1 for p-Si in the PEC H₂ evolution process was also proposed in detail. The excellent PEC performance should be attributed to the Ni1 engineered p-Si/electrolyte interface energetics and the Ni1 catalyzed water reduction reaction, leading to robust hydrogen generation and excellent PEC stability. The present study made a deep insight into the engineered interface charge transfer and catalyst-driven surface water reduction processes at the semiconductor/electrolyte interface, which could provide some referable guidelines for fabricating highly efficient PEC system for solar H₂ generation from the viewpoint of interface energetics engineering with metal complexes.