In Situ Growth of Nickel-Based Sulfide Nanoneedles on Nickel Foam as a Highly Efficient Bifunctional Electrocatalyst for Oxygen and Hydrogen Evolution Reaction

초록

Water electrolysis, consisting of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), has attracted increasing attention because of the potential to provide future sustainable and clean energy source. However, the thermodynamically sluggish process of gas evolution reaction at each electrode have hindered the practical applications in the industrial fields. To overcome this issue, nickel-based sulfide materials are regarded as an effective electrocatalyst for OER owing to their abundance, durability, good redox properties, and superior electrocatalytic activities. Herein, iron/nickel-based sulfide nanoneedles were directly grown on nickel foam by two step hydrothermal method and was applied as a bifunctional electrocatalyst for OER and HER. The iron/nickel sulfide nanoneedles only require the low overpotentials of 269 and 314?mV for OER and HER, respectively, to deliver current density of 100?mA?cm?2 in alkaline media. Assembled as an overall water electrolyzer, iron/nickel sulfide nanoneedles on Ni foam electrocatalyst also exhibits unexpected low onset potential of only 1.39 V and reach a current density of 10 mA cm?2 at a very low cell voltage of 1.58 V. The superior electrocatalytic activity of iron/nickel sulfide on nickel foam is mainly originated from the synergistic effect of Fe and Ni, which lead to increase of the electric conductivity, active surface area, and intrinsic catalytic activity. The successful fabrication procedure of these iron/nickel sulfide materials can be widely applied to efficient bifunctional electrocatalysts for overall water electrolysis