Synergistic Multiple Charge Carrier Transfer Pathways for High-Efficiency Visible-Light-Driven Hydrogen Evolution

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Step-scheme (S-scheme) heterojunctions improve visible-light photocatalysis by enhancing charge transfer.
• Ternary semiconductor integration with strategic cocatalyst loading is key for efficient photocatalytic hydrogen evolution.
• Understanding charge transfer pathways is crucial for designing advanced photocatalytic materials.

Purpose of the Study:

• To synthesize and investigate In2O3/CdS/NiSe2 and In2O3/NiSe2/CdS heterostructures.
• To elucidate the S-scheme charge transfer mechanisms and identify the role of cocatalyst loading order.
• To evaluate the photocatalytic hydrogen evolution efficiency of the synthesized materials under visible light.

Main Methods:

• Sequential deposition of CdS and NiSe2 onto In2O3 nanosheets.
• In situ irradiated X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) for charge transfer analysis.
• Charge density difference analysis, photoelectrochemical measurements, and Gibbs free energy calculations.

Main Results:

• Confirmed S-scheme charge transfer in both In2O3/CdS and In2O3/NiSe2/CdS systems.
• In2O3/CdS/NiSe2 exhibited three charge transfer pathways, enhancing electron migration compared to In2O3/NiSe2/CdS (one pathway).
• In2O3/CdS/NiSe2 achieved a hydrogen evolution rate of 16,797.1 µmol g⁻¹, nearly four times higher than In2O3/NiSe2/CdS (3,902.4 µmol g⁻¹).

Conclusions:

• The loading order of cocatalysts significantly impacts charge transfer pathways and photocatalytic efficiency.
• Multiple charge transfer pathways in In2O3/CdS/NiSe2, coupled with optimal Ni adsorption properties, enhance hydrogen evolution.
• This study provides a framework for designing efficient ternary heterojunctions for visible-light-driven photocatalysis.