Ternary Earth-Abundant Catalyst Enabling Stable Silicon Photocathodes for Solar Hydrogen Generation.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Silicon photocathodes are promising for photoelectrochemical (PEC) hydrogen production but suffer from instability and slow kinetics.
• Developing efficient and stable non-precious metal catalysts is crucial for practical PEC applications.

Purpose of the Study:

• To develop a highly active and stable silicon-based photocathode for efficient PEC hydrogen evolution.
• To investigate the role of a ternary bimetallic CoMoS catalyst in enhancing hydrogen evolution reaction (HER) activity and interfacial properties.

Main Methods:

• Photoelectrodeposition of a CoMoS ternary bimetallic catalyst onto a TiO2-passivated Si substrate.
• Characterization of catalyst properties, including electronic interactions and charge distribution.
• Electrochemical measurements (IMVS, IMPS, EIS, OCP, transient photocurrent) to analyze carrier dynamics and interfacial resistance.
• Performance evaluation of the photocathode for PEC hydrogen evolution.

Main Results:

• The CoMoS catalyst exhibits strong electronic coupling and optimized electronic structure, enhancing HER activity by regulating hydrogen adsorption free energy.
• Optimized photocathode shows significantly reduced interfacial resistance, extended carrier lifetime, and faster charge transport.
• Achieved an onset potential of 0.69 V_RHE, photocurrent density of 31.2 mA cm^-2 at 0 V_RHE, and an applied bias photon-to-current efficiency (ABPE) of 7.04%.
• Demonstrated exceptional operational stability.

Conclusions:

• The CoMoS/TiO2/Si photocathode offers an efficient and durable solution for PEC hydrogen production.
• Ternary bimetallic catalysts and interface engineering are effective strategies for advancing silicon-based PEC devices.
• The findings support the viability of non-precious metal catalysts for scalable clean energy applications.