Efficient Solar-Driven Water Splitting Enabled by CoMoWS Catalysts on Silicon Photocathodes.

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Multicomponent amorphous metal sulfides are promising for enhanced Hydrogen Evolution Reaction (HER) catalysis.
• Developing efficient and stable photoelectrocatalysts is crucial for scalable solar hydrogen production.

Purpose of the Study:

• To synthesize and evaluate an amorphous CoMoWS catalyst for photoelectrocatalytic water splitting.
• To investigate the electronic structure and charge transfer properties of the catalyst.
• To assess the solar-to-hydrogen efficiency and stability of a tandem device.

Main Methods:

• Ultrasonic spray pyrolysis for catalyst synthesis.
• X-ray Photoelectron Spectroscopy (XPS) for electronic structure analysis.
• Electrochemical Impedance Spectroscopy (EIS) and time-resolved carrier dynamics for charge transfer studies.
• Fabrication of a tandem photoelectrode integrated with a silicon solar cell.

Main Results:

• The CoMoWS-Si photoelectrode achieved a photocurrent density of 30.1 mA cm^-2 and an Applied Bias Photon-to-Current Efficiency (ABPE) of 7.26%.
• The catalyst demonstrated excellent operational stability (>500 h).
• XPS revealed strong Co/Mo/W electronic coupling, enhancing catalytic performance.
• Accelerated interfacial charge transfer and extended carrier lifetimes were observed, suppressing recombination.
• The tandem device achieved 5.17% solar-to-hydrogen efficiency for unbiased water splitting with over 100 h of stable operation.

Conclusions:

• Amorphous multimetallic sulfide systems are effective photoelectrocatalysts for efficient and durable solar hydrogen production.
• The CoMoWS catalyst exhibits superior performance due to enhanced electronic structure and charge dynamics.
• This work highlights a viable pathway for scalable solar fuel generation.