Boosting MIL-101(V) as a Vanadium-Based Metal–Organic Framework via MoS ₂ /Graphene Quantum Dot Nanocomposite in Electrochemical Hydrogen Storage

Hydrogen is a promising source of noncarbon-based energy that is steadily replacing fossil fuels. As an alternative fuel, hydrogen production, its separation, and storage are critical components of advancing a global green energy economy. In this study, the syntheses and hydrogen sorption characteristics of three vanadium-based MOFs [MIL-47(V), MIL-88B(V), and MIL-101(V)] are presented. Additionally, graphene quantum dots (GQDs) having distinctive physiochemical properties were synthesized using a rapid, straightforward, and cost-effective technique and subsequently incorporated with MoS2 nanoparticles at varying molar ratios. The GQDs(0.4)/MoS2 electrode showed outstanding electrochemical hydrogen storage performance, achieving a maximum value of 9100 mAh g–1 after 20 cycles under a steady current of 1 mA, which represents a growth of more than 1.4 times in comparison with the pure MoS2 electrode. In addition, GQDs(0.4)/MoS2/MIL-101(V) nanocomposites are prepared and optimized via an environmentally friendly method at room temperature. The GQDs(0.4)/MoS2/MIL-101(V)-2 nanocomposites demonstrate superior electrochemical hydrogen storage efficiency, delivering a capacity of 10500 mAh g–1, nearly 1.2 times greater than the that for GQDs(0.4)/MoS2 nanoparticles and approximately 4.6 times higher than that of the MIL-101(V) framework.