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

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting is crucial for sustainable hydrogen production.
• Cadmium telluride (CdTe) photocathodes offer excellent light absorption for PEC water splitting.
• Improving the efficiency and stability of photocathodes is key for solar hydrogen development.

Purpose of the Study:

• To engineer the interfacial energetics of CdTe photocathodes by depositing CdS, TiO2, and Ni layers.
• To fabricate and characterize a novel CdTe/CdS/TiO2/Ni heterostructure photocathode.
• To investigate the role of each deposited layer in enhancing photoelectrochemical performance.

Main Methods:

• Fabrication of a CdTe/CdS/TiO2/Ni heterostructure photocathode.
• Deposition of n-type CdS (100 nm), TiO2 (50 nm) as a protective layer, and Ni (10 nm) as a co-catalyst onto a p-type CdTe surface.
• Measurement of photocurrent density (Jph) and onset potential (Eonset) under AM1.5G illumination.

Main Results:

• The CdTe/CdS/TiO2/Ni photocathode achieved a photocurrent density (Jph) of 8.16 mA/cm2 at 0 V versus reversible hydrogen electrode (V_RHE).
• A positive-shifted onset potential (Eonset) of 0.70 V_RHE was observed for PEC hydrogen evolution.
• The CdTe/CdS p-n junction enhanced carrier separation, TiO2 provided corrosion protection, and Ni improved charge transfer.

Conclusions:

• The engineered CdTe/CdS/TiO2/Ni photocathode demonstrates significantly improved performance for solar hydrogen production.
• The combination of CdS, TiO2, and Ni layers effectively enhances charge separation, stability, and catalytic activity.
• This work offers valuable insights for developing efficient, noble metal-free photocathodes for solar fuel applications.