Hydrogen evolution from water using Ag(x)Cu(1-x)GaSe2 photocathodes under visible light

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Photoelectrochemical (PEC) water splitting is a promising technology for sustainable hydrogen fuel production.
• Copper gallium selenide (CuGaSe2) is a potential material for photocathodes, but its efficiency and stability need improvement.
• Modifying the composition of CuGaSe2 can tune its electronic properties and enhance its performance.

Purpose of the Study:

• To investigate the effect of partial substitution of copper (Cu) with silver (Ag) in CuGaSe2 thin films for PEC water splitting.
• To analyze the structural and electronic property changes in AgxCu1-xGaSe2 (ACGSe) thin films.
• To evaluate the PEC performance and stability of modified ACGSe photocathodes.

Main Methods:

• AgxCu1-xGaSe2 (ACGSe) thin films were synthesized using co-evaporation with molecular beam epitaxy (MBE).
• Thin films were deposited on Molybdenum-coated soda-lime glass substrates.
• A Pt and CdS co-catalyst modified ACGSe electrode was prepared and tested for PEC water splitting.

Main Results:

• Partial substitution of Cu with Ag in CuGaSe2 resulted in deeper valence band maximum (VBM) potential and increased grain size.
• A Pt/CdS/ACGSe electrode with approximately 5% Ag/(Cu + Ag) ratio achieved a cathodic photocurrent of 8.1 mA cm(-2) at 0 VRHE.
• The modified electrode exhibited an onset potential of 0.70 VRHE and demonstrated stable performance for over 55 hours.

Conclusions:

• Partial substitution of Cu with Ag in CuGaSe2 is an effective strategy to enhance photocathode performance for PEC water splitting.
• The improved VBM potential and grain structure contribute to higher photocurrent densities.
• The developed Pt/CdS/ACGSe photocathode shows excellent stability, indicating its potential for practical applications in solar hydrogen generation.