Hierarchical Iron/Nickel-Based Sulfide Supported on Ni Foam as A Bifunctional Electrocatalyst for Efficient Overall Water Splitting

초록

Water splitting, consisting of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), has received great attention owing to the potential to provide future sustainable and renewing energy source. However, the kinetically sluggish process of OER at anode and HER at cathode requires highly active electrocatalysts to accelerate the both electrode reactions. Currently, nickel based catalysts are widely regarded as an effective electrocatalyst for OER due to their low cost, high stability, good redox properties, and high electrocatalytic performance. Herein, iron/nickel based sulfide supported on Ni foam were simply synthesized using two step hydrothermal method and was used as a bifunctional electrocatalyst for OER and HER. The iron/nickel based sulfide only require the low overpotentials of as smaller as 281 and 222 mV for HER and OER, respectively, at current density of 50 mA cm?2 in 1 M KOH. Assembled as an electrolyzer for overall water splitting, this bifunctional catalyst also indicates excellent low onset potential of only 1.41 V and deliver a current density of 10 mA cm?2 at a very low cell voltage of 1.59 V. The outstanding electrochemical performance of iron/nickel based sulfide on Ni foam is mainly attributed to the synergistic effect of the binary metal system, leading to increasing the electroconductivity, active surface area, and intrinsic catalytic activity. These iron/nickel based sulfide materials can be widely applied to fabricating efficient energy conversion and storage.