Sulfur Substitution and Defect Engineering in an Unfavored MnMoO₄ Catalyst for Efficient Hydrogen Evolution under...

Area of Science:

• Materials Science
• Catalysis
• Renewable Energy

Background:

• Manganese molybdate (MnMoO4) is a semiconductor with a wide band gap, limiting its application in photocatalytic hydrogen evolution.
• Developing efficient and stable catalysts is crucial for renewable hydrogen production.

Purpose of the Study:

• To synthesize a novel Mn-Mo oxysulfide catalyst for efficient photocatalytic hydrogen evolution reaction (PHER).
• To investigate the effect of sulfur substitution on the electronic structure and catalytic performance of MnMoO4.

Main Methods:

• Synthesis of a nonstoichiometric Mn1-xMo(S,O)4-y oxysulfide catalyst.
• Characterization of the catalyst's structure, electronic properties, and oxygen vacancies.
• Evaluation of photocatalytic hydrogen evolution performance under visible light irradiation.

Main Results:

• The synthesized Mn-Mo oxysulfide exhibited a narrow band gap and suitable band positions for PHER.
• The catalyst achieved a high PHER rate of 415.8 μmol/h, an apparent quantum efficiency (AQE) of 4.31%, and a solar-to-hydrogen (STH) efficiency of 1.28%.
• Oxygen vacancies and altered Mn/Mo valence states were identified as key factors for enhanced catalytic activity.

Conclusions:

• Sulfur substitution in MnMoO4 is an effective strategy to design advanced oxysulfide catalysts for efficient PHER.
• The presence of oxygen vacancies and modified electronic structure significantly improves water adsorption and activation.
• This work demonstrates a promising material design approach for renewable hydrogen generation.