Coupled plasma reduction-sputtering synthesis of multisite electrocatalyst for neutral hydrogen evolution reaction

Rigid hydrogen-bonding network and sluggish water dissociation kinetics severely hinder the performance of hydrogen evolution reaction (HER) in neutral electrolyte. Herein, a multisite electrocatalyst (Ni/LDH/CrN) with Ni and CrN nanoparticles (NPs) anchored on nickel–iron layered double hydroxide (LDH) nanosheets (NSs) is constructed through a combined plasma synthetic strategy–plasma reduction and subsequent plasma sputtering processes. In Ni/LDH/CrN, the amorphous CrN NPs efficiently break the rigid hydrogen-bonding network and the Ni NPs can accelerate the kinetics of water dissociation, while the LDH NSs serve as hydrogen evolution site. In addition, both Ni and CrN NPs facilitate the formation of a locally acidic microenvironment, providing more reactant (H3O+) for HER. As expected, the Ni/LDH/CrN exhibits enhanced HER activity with a low overpotential of 22 and 235 mV at 10 and 500 mA cm–2, respectively, in 1 M phosphate buffered solution (PBS). A remarkable long-term catalysis up to 650 h at the industrial current density of 1000 mA cm–2 is also demonstrated by Ni/LDH/CrN. This work highlights an intriguing coupled plasma synthetic approach to obtain advanced multisite electrocatalysts.