Boosting Alkaline Hydrogen Evolution Activity with Ni-Doped MoS₂ /Reduced Graphene Oxide Hybrid Aerogel

Highly active, durable, and cost-effective non-precious-metal-based electrocatalysts are urgently needed to improve the sluggish hydrogen evolution reaction (HER) in an alkaline environment. Herein, a lyophilization/thermolysis method is successfully applied to prepare Ni-doped MoS₂ (Ni-MoS₂ )/reduced graphene oxide (RGO) hybrid aerogels. The MoS₂ aerogel possesses a higher density of exposed active sites than its corresponding bulk material. Inheriting from GO its abundant functional groups during pyrolysis, the RGO aerogel can uniformly disperse MoS₂ and simultaneously maintain excellent conductivity. The incorporation of Ni atoms can accelerate the cleavage of the HO-H bond and enhance the adsorption and desorption of intermediate OH^- . Owing to the synergistic effect of the compositional and structural advantages of aerogels, the Ni-MoS₂ /RGO hybrid aerogel delivers highly promoted HER kinetics in alkaline media. As a result, an optimal η₁₀ (overpotential at 10 mA cm^-2 ) of 168 mV in 1 m KOH is obtained, which is superior to the non-doped MoS₂ /RGO hybrid aerogel (225 mV) and MoS₂ aerogel (263 mV), letting alone bulk MoS₂ (448 mV). Moreover, the η₆₀ (overpotential at 60 mA cm^-2 ) is maintained at 262 mV after chronopotentiometry tests at a constant current density of 10 mA cm^-2 for 24 h, indicating an exceptionally stability of the HER catalyst.