FeCoNiS Nanoparticles Integrated with Nitrogen−Doped Vertically Oriented Graphene via Single−Step Electrodeposition: An Efficient Bifunctional Catalyst for Overall Water Splitting

The development of transition metal electrocatalysts to replace precious metal electrocatalysts is essential for the development of sustainable water splitting technology for the mass production of clean hydrogen. FeCoNiS/NVG (N-doped vertically oriented graphene) is fabricated via single-step electrodeposition. Benefiting from the vertical structure of FeCoNiS/NVG and intrinsic catalytic activity of FeCoNiS, FeCoNiS/NVG displays excellent catalytic activities toward the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), with overpotentials of 126 and 347 mV at 10 mA cm−2, respectively. The overpotentials of FeCoNiS/NVG are similar to those of commercial Pt/C (100 mV) and IrO2 (329 mV). The Faraday efficiency of FeCoNiS/NVG for overall water splitting is about 95%. FeCoNiS/NVG also exhibits long-term stability for HER and OER. This work demonstrates the great potential of iron-group metal sulfides for overall water splitting.