Co-Doped Ni₃N Nanosheets with Electron Redistribution as Bifunctional Electrocatalysts for Efficient Water Splitting

Abstract

Preparation of high-activity and earth-abundant bifunctional catalysts for efficient electrochemical water splitting are crucial and challenging. Herein, Co-doped Ni 3 N nanosheets loaded on nickel foam (Co−Ni 3 N) were synthesized. The as-prepared Co−Ni 3 N exhibits excellent catalytic activity toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline media. Density functional theory (DFT) calculation reveals that Co−Ni 3 N with redistribution of electrons not only can facilitate the HER kinetics but also can regulate intermediates adsorption energies for OER. Specifically, the Co−Ni 3 N exhibits high efficiency and stable catalytic activity, with an overpotential of only 30 and 270 mV at a current density of 10 mA cm −2 for the HER and OER in 1 M KOH, respectively. This work provides strong evidence to the merit of Co doping to improve the innate electrochemical performance in bifunctional catalysts, which might have a common impact in many similar metal− metal nitride electrocatalysts.

Oxygen Vacancies and Interface Engineering on Amorphous/Crystalline CrOx‐Ni3N Heterostructures toward High‐Durability and Kinetically Accelerated Water Splitting

“…Among these electrocatalysts, metal nitrides have demonstrated remarkable catalytic performance due to their high electrical conductivity originating from the metallic property, favorable electronic structure, and high anti‐corrosion. [ 9 ] Particularly, Ni 3 N exhibits a favorable HER activity due to a small hydrogen adsorption energy (ΔG H ) value based on the Ni−N co‐effect, [ 10 ] and also a relatively high OER activity originated from the introduction of negatively charged nitrogen as a proton acceptor, which facilitates the adsorption of oxygen intermediates and desorption of oxygen. [ 11 ] Nevertheless, the Ni 3 N delivers large overpotentials in alkaline water splitting, mainly ascribing to the high dissociation energy of water for HER [ 12 ] and sluggish OER kinetics based on the multi‐electron transfer process.…”

Metal nitride-based nanostructures for electrochemical and photocatalytic hydrogen production

“…Another material that has proved to be a potential HER cathode is Ti nitride. Various TiN nanostructures with oxynitrides [ 229 ], other metals [ 208 ], metal sulfide [ 230 ], metal oxide [ 231 ], bimetallic [ 232 ], and porous [ 233 ] have been explored. For example, Wu and co-workers studied the performance of copper nitride/3D porous titanium oxynitride as an HER catalyst in alkaline, acidic, and neutral media [ 229 ].…”

Theoretical Insights into the Hydrogen Evolution Reaction on the Ni3N Electrocatalyst

“…These results suggest that efforts need to be made to engineer the surface properties of the Ni3N electrocatalyst in order to achieve improved HER activity. Recent experimental efforts have shown that substitutional doping of Ni with other transition metals could vastly improve HER activity by providing alternative hydrogen adsorption sites to the (001) surface [49][50][51]. The formation of heterostructures by coupling Ni3N with other materials, such as transition metal oxides [52,53] or nitrides [54,55], have also shown great At the Ni 3 N(110) surface, a low ∆G H * value was calculated at an Ni bridge site (−0.26 eV).…”