Cytomembrane-inspired engineering of oxygen transfer channel for modulating Ni/NiO heterostructure and boosting water oxidation

Abstract

Development of low-cost and efficient non-precious metal electrocatalysts for oxygen evolution reaction (OER) is of predominant importance for promoting the large-scale application of water splitting. Herein, we use ZIF-8 as a sacrifice template, and successfully prepare the freestanding N-doped carbon nanofibers that decorated with Ni/NiO nanoparticles (denoted as xNi/NiO-NCNFs) via a scalable electrospinning-pyrolysis strategy. Inspired by the cytomembrane, we tune the dosage of ZIF-8 (x) to optimize the amount of micropores on the carbon layer that encapsulating the Ni species, which could act as oxygen transfer channels and enable suitable amount of oxygen to input to modulate the oxidation state of Ni. Moreover, the porous structure could facilitate the mass transfer of the reactants and contact with the active sites, as well as provide more channels for oxygen to release during the OER process. Benefiting from the synergistic effect of the Ni/NiO active sites, porous structure of carbon shell, and the doped N atoms, the 0.075Ni/NiO-NCNFs presents an ultralow overpotential of 210 mV to achieve a current density of 20 mA cm−2 in 0.1 M KOH solution and a low Tafel slope of 29.6 mV dec-1. This work provides a simple and cost-effective pathway to develop porous free-standing non-noble metal-based catalyst with high OER efficiency for potential sustainable electrochemical energy conversion.