TiO₂/CdS/PDA Ternary Heterojunction Photoanode for Enhancing Photoelectrochemical Water Splitting

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting is crucial for sustainable solar-to-fuel conversion.
• Developing efficient and stable photoanodes is key to advancing PEC technology.
• Titanium dioxide (TiO2) based materials are widely explored for PEC applications.

Purpose of the Study:

• To engineer a novel TiO2/CdS/PDA ternary heterojunction photoanode.
• To enhance light absorption, charge transfer, and stability for PEC water splitting.
• To investigate the role of polydopamine (PDA) in improving photoanode performance.

Main Methods:

• Fabrication of the TiO2/CdS/PDA heterojunction using chemical bath deposition and oxidative self-polymerization.
• Characterization of the photoanode's structure, optical, and electronic properties.
• Performance evaluation through photocurrent density measurements and stability testing under PEC conditions.

Main Results:

• The PDA component significantly enhanced light absorption and provided efficient charge transfer pathways.
• A type-II band alignment was formed, accelerating interfacial charge transfer and carrier lifetime.
• The PDA layer acted as an effective antiphotocorrosion barrier, protecting the CdS component.
• The optimized TiO2/CdS/PDA-60 photoanode achieved a photocurrent density of 4.57 mA/cm² at 1.23 V vs RHE, a 3.5-fold increase over pristine TiO2.
• Excellent stability was demonstrated for the fabricated photoanode.

Conclusions:

• The TiO2/CdS/PDA ternary heterojunction is a highly effective photoanode for PEC water splitting.
• PDA incorporation is a promising strategy to improve light harvesting, charge dynamics, and durability.
• This work offers a new approach for designing advanced photoanodes for efficient solar fuel production.