In Situ Hydrothermal Synthesis MoS2/Guar Gum Carbon Nanoflowers as Advanced Electrocatalysts for Electrocatalytic Hydrogen Evolution

Herein, we report a simple in situ hydrothermal synthetic method for the preparation of novel three-dimensional (3D) nanoflowers forming with few-layered and expanded interlayer spacing MoS2 nanoflakes via restricting the polymerization of guar gum and the growth of MoS2. In this process, hexaammonium molybdate ((NH4)6Mo7O24·4H2O) and thiourea (CH4N2S) acted as the precursor of molybdenum and sulfur respectively, while guar gum functioned as both the template of chemical reaction and carbon source. The obtained MoS2/guar gum carbon hybrid nanoflowers (MoS2/CF) in a well-assembled 3D nanoflowers architecture provides copious active sites and thus prevents inherent stacking among MoS2 layers. Because of all these advantages, the electrochemical evaluation demonstrates that MoS2/CF-750 shows extraordinary hydrogen evolution reaction electrocatalytic performances, possessing extremely low onset potential of approximately 20 mV, low overpotential of ∼125 mV at 10 mA cm–2 and an extraordinary small Tafel slope of 34 mV dec–1, which is nearly identical to that of bulk platinum (Pt), "the gold benchmark" for hydrogen production. Moreover, the strong interactions between MoS2 nanoflakes and guar gum enable MoS2/CF-750 long-term stability and microstructural integrity, presenting nearly 100% activity retention after 2000 cycles and ∼95% after 16 h of chronoamperometry assessment (0.15 V). The preparation strategy is simple, inexpensive, and readily scalable, and could be extended to diverse 3D non-noble metal electrocatalysts.