Activating the Hydrogen Evolution and Overall Water Splitting Performance of NiFe LDH by Cation Doping and Plasma Reduction

Abstract NiFe layered double hydroxides (LDH) have been intensively investigated as promising electrocatalysts for oxygen evolution reaction. However, their hydrogen evolution reaction (HER) and overall water splitting performance are not satisfactory. Herein, we report a facile cation doping combined with plasma reduction strategy to generate heterostructured Ni nanoparticles/V-doped NiFe LDH nanosheet array with multiple vacancies, exhibiting excellent HER performance with a small overpotential of 19 mV at 10 mA cm-2. Moreover, when evaluated as bi-functional electrocatalyst for overall water splitting, a small cell voltage (1.43 V at 10 mA cm-2) and ultralong stability (over 1000 h) are achieved. Density functional theory (DFT) calculations reveal that V-doping, oxygen vacancy (Ov), Ni vacancy (Niv), and Ni nanoparticles can effectively improve the conductivity and optimize the hydrogen adsorption, Ov, Niv, and Ni nanoparticles help to facilitate H2O adsorption and dissociation progress in HER, the V-doping and Ov can efficiently reduce the energy barrier of O* in OER, and Ni/NiFe LDH heterostructure ameliorates the electronic structure and tunes electron transfer route.