Nitrogen-doped porous carbon encapsulated nickel iron alloy nanoparticles, one-step conversion synthesis for application as bifunctional catalyst for water electrolysis

Oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) constitute the water electrolysis toward clean and sustainable hydrogen fuel. Highly active and low cost bifunctional catalysts for both OER and HER are highly desired to fulfill the practical water electrolysis. Herein, we report a low-cost and efficient tactics for preparation of N doped carbon confined nickel iron alloy nanoparticles electrocatalysts via facile pyrolysis of ethylenediamine tetraacetic acid (EDTA) chelated Ni, Fe salts precursor. Benefited by the high electrochemical active surface area and the catalytic effect of the N doped carbon (NC) shell promoted by encapsulated alloy nanoparticles, the optimal Ni2Fe@NC composite with Ni:Fe ratio of 2:1 demonstrates low overpotential of 237 mV at 10 mA cm−2, low Tafel slope of 37 mV dec−1 and robust stability for OER, as well as overpotential of 198 mV at -10 mA cm−2 for HER in alkali electrolyte. Furthermore, the full water electrolysis cell using Ni2Fe@NC as both anodic and cathodic catalytic electrodes can operate with low input voltage (1.81 V, at 10 mA cm−2) and good durability. The current work shows the potential of Ni2Fe@NC composite as OER and HER bifunctional electrocatalyst for water splitting.