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

Abstract

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.