Nitrogen-Doped Sponge Ni Fibers as Highly Effcient Electrocatalysts for Oxygen Evolution Reaction

摘要

Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction(OER) is a particularly significant and challenging target.Herein,we report a 3D porous sponge-like Ni material,prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers,as an integrated binder-free OER electrocatalyst.To further enhance the electrocatalytic performance,an N-doping strategy is applied to obtain N-doped sponge Ni(N-SN) for the first time,via NH3 annealing.Due to the combination of the unique conductive sponge structure and N doping,the as-obtainedN-SN material shows improved conductivity and a higher number of active sites,resulting in enhanced OER performance and excellent stability.Remarkably,N-SN exhibits a low overpotential of 365 mV at 100 mA cm-2 and an extremely small Tafel slope of 33 mV dec-1,as well as superior long-term stability,outperforming unmodified sponge Ni.Importantly,the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER.Therefore,the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.