MoS2/graphene cocatalyst for efficient photocatalytic H2 evolution under visible light irradiation

Area of Science:

• Materials Science
• Photocatalysis
• Renewable Energy

Background:

• Developing efficient noble-metal-free cocatalysts is crucial for solar-driven photocatalytic water splitting.
• Molybdenum disulfide (MoS2) and graphene (G) are promising materials for enhancing photocatalytic activity.

Purpose of the Study:

• To develop and characterize a novel MoS2/graphene-CdS (MoS2/G-CdS) composite as a high-performance, noble-metal-free photocatalyst for hydrogen (H2) evolution.
• To optimize the composition of the MoS2/G-CdS composite for maximum H2 production efficiency.

Main Methods:

• Synthesis of a composite material with CdS nanocrystals grown on a nanosized MoS2/graphene hybrid support.
• Optimization of MoS2/graphene cocatalyst content (2.0 wt %) and MoS2 to graphene molar ratio (1:2).
• Testing and comparison of photocatalytic H2 evolution rates in Na2S-Na2SO3 and lactic acid solutions, including apparent quantum efficiency (AQE) measurements.

Main Results:

• The optimized MoS2/G-CdS composite exhibited the highest photocatalytic H2 production activity.
• A H2 evolution rate of 1.8 mmol/h was achieved in lactic acid solution, with an AQE of 28.1% at 420 nm.
• The performance in lactic acid solution surpassed that in Na2S-Na2SO3 solution (1.2 mmol/h) and was significantly higher than Pt/CdS.

Conclusions:

• The MoS2/G-CdS composite is a highly efficient and cost-effective noble-metal-free photocatalyst for H2 evolution.
• The optimized material shows great potential for practical applications in solar energy conversion and hydrogen production.
• Further investigation into the reaction mechanism is warranted.