Synthesis and Electrocatalytic Performance Study of Sulfur Quantum Dots Modified MoS₂

The electrolysis of water for hydrogen production is currently receiving significant attention due to its advantageous features such as non-toxicity, safety, and environmental friendliness. This is especially crucial considering the urgent need for clean energy. However, the current method of electrolyzing water to produce hydrogen largely relies on expensive metal catalysts, significantly increasing the costs associated with its development. Molybdenum disulfide (MoS2) is considered the most promising alternative to platinum for electrocatalyzing the hydrogen evolution reaction (HER) due to its outstanding catalytic efficiency and robust stability. However, the practical application of this material is hindered by its low conductivity and limited exposure of active sites. MoS2/SQDs composite materials were synthesized using a hydrothermal technique to deposit SQDs onto MoS2. These composite materials were subsequently employed as catalysts for the HER. Research findings indicate that incorporating SQDs can enhance electron transfer rates and increase the active surface area of MoS2, which is crucial for achieving outstanding catalytic performance in the HER. The MoS2/SQDs electrocatalyst exhibits outstanding performance in the HER when tested in a 0.5 M H2SO4 solution. It achieves a remarkably low overpotential of 204 mV and a Tafel slope of 65.82 mV dec−1 at a current density of 10 mA cm−2. Moreover, during continuous operation for 24 h, the initial current density experiences only a 17% reduction, indicating high stability. This study aims to develop an efficient and cost-effective electrocatalyst for water electrolysis. Additionally, it proposes a novel design strategy that uses SQDs as co-catalysts to enhance charge transfer in nanocomposites.