Ultrafast charge separation in a WC@C/CdS heterojunction enables efficient visible-light-driven hydrogen generation

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Cadmium sulfide (CdS) photocatalysis is hindered by rapid carrier recombination and photocorrosion.
• Cocatalyst loading is a key strategy to improve photocatalytic efficiency.
• Developing noble-metal-free cocatalysts is crucial for cost-effective applications.

Purpose of the Study:

• To synthesize and evaluate a tungsten carbide@carbon (WC@C) composite as a noble-metal-free cocatalyst.
• To enhance the photocatalytic hydrogen evolution performance of CdS nanorods.
• To investigate the underlying mechanisms for improved photocatalysis.

Main Methods:

• A novel molten salt method was employed to prepare the WC@C cocatalyst.
• WC@C was loaded onto CdS nanorods to form a composite photocatalyst.
• Photocatalytic hydrogen evolution rates and apparent quantum efficiency (AQY) were measured under visible light irradiation.

Main Results:

• The WC@C/CdS composite with 7 wt% WC@C exhibited a hydrogen evolution rate of 8.84 mmol g^-1 h^-1, significantly outperforming CdS and Pt/CdS.
• A high AQY of 55.28% was achieved at 420 nm.
• The composite demonstrated excellent stability over 12 cycles (42 h) of photocatalytic testing.

Conclusions:

• WC@C serves as an effective noble-metal-free cocatalyst for CdS nanorods.
• The enhanced performance is attributed to accelerated carrier separation and efficient hydrogen evolution sites.
• The formation of a Schottky junction between WC@C and CdS plays a vital role in the improved photocatalytic activity.