Iron doped Ni3S2 nanorods directly grown on FeNi3 foam as an efficient bifunctional catalyst for overall water splitting

The development of high-performance and inexpensive bifunctional electrocatalysts to replace precious metal catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a thorny issue in the field of electrochemical water splitting. Here, a three-dimensional rods array catalysts of Ni3S2 doped with trace amount of Fe on foam FeNi3 (Fe-Ni3S2@FeNi3) are synthesized. It is found experimentally that Fe-Ni3S2@FeNi3 has excellent catalytic activity and corrosion resistance in both acidic, neutral and alkaline solutions. In 1.0 M KOH solution, only small overpotentials of 105 mV and 213 mV are required to achieve the current densities of 10 mA cm−2 for HER and OER respectively. In addition, Fe-Ni3S2@FeNi3-8 also exhibits excellent catalytic activity in 0.5 M H2SO4 solution (η10 = 48 mV) and 1.0 M PBS solution (η10 = 83 mV) for HER. In 1.0 M KOH and 0.33 M urea solution, Fe-Ni3S2@FeNi3-8 requires only 1.40 V to provide the current density of 10 mA cm−2 for urea oxidation reaction (UOR). As evidenced, doping Fe element into catalyst can significantly increase the catalytic activities for HER and OER. This work demonstrates a new and facile approach to prepare novel bimetallic transition metal catalysts as inexpensive alternatives to precious metal catalysts for efficient hydrogen production.