Interface-Engineered Ni-Coated CdTe Heterojunction Photocathode for Enhanced Photoelectrochemical Hydrogen Evolution

[Image: see text] Photoelectrochemical (PEC) water splitting for hydrogen production using the CdTe photocathode has attracted much interest due to its excellent sunlight absorption property and energy band structure. This work presents a study of engineered interfacial energetics of CdTe photocathodes by deposition of CdS, TiO(2), and Ni layers. A heterostructure CdTe/CdS/TiO(2)/Ni photocathode was fabricated by depositing a 100-nm n-type CdS layer on a p-type CdTe surface, with 50 nm TiO(2) as a protective layer and a 10 nm Ni layer as a co-catalyst. The CdTe/CdS/TiO(2)/Ni photocathode exhibits a high photocurrent density (J(ph)) of 8.16 mA/cm(2) at 0 V versus reversible hydrogen electrode (V(RHE)) and a positive-shifted onset potential (E(onset)) of 0.70 V(RHE) for PEC hydrogen evolution under 100 mW/cm(2) AM1.5G illumination. We further demonstrate that the CdTe/CdS p–n junction promotes the separation of photogenerated carriers, the TiO(2) layer protects the electrode from corrosion, and the Ni catalyst improves the charge transfer across the electrode/electrolyte interface. This work provides new insights for designing noble metal-free photocathodes toward solar hydrogen development.