The Effect of the 3D Nanoarchitecture and Ni-Promotion on the Hydrogen Evolution Reaction in MoS /Reduced GO Aerogel Hybrid Microspheres Produced by a Simple One-Pot Electrospraying Procedure.

The transition toward renewable energy sources requires low-cost, efficient, and durable electrocatalysts for green H production. Herein, an easy and highly scalable method to prepare MoS nanoparticles embedded in 3D partially reduced (pr) graphene oxide (GO) aerogel microspheres (MoS /prGOAMs) with controlled morphology and composition is described. Given their peculiar center-diverging mesoporous structure, which allows easy access to the active sites and optimal mass transport, and their efficient electron transfer facilitated by the intimate contact between the MoS and the 3D connected highly conductive pr-GO sheets, these materials exhibit a remarkable electrocatalytic activity in the hydrogen evolution reaction (HER). Ni atoms, either as single Ni atoms or NiO aggregates are then introduced in the MoS /prGOAMs hybrids, to facilitate water dissociation, which is the slowest step in alkaline HER, producing a bifunctional catalyst. After optimization, Ni-promoted MoS /prGOAMs obtained at 500 °C reach a remarkable η (overpotential at 10 mA cm ) of 160 mV in 1 m KOH and 174 mV in 0.5 m H SO . Moreover, after chronopotentiometry tests (15 h) at a current density of 10 mA cm , the η value improves to 147 mV in alkaline conditions, indicating an exceptional stability.