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.

Silicon (Si) is a commercially available semiconductor for photoelectrochemical hydrogen production with advantages of its abundance, low environmental hazard, wide range of solar energy absorption spectrum, high current density and...