Pine needle-like FeCo@C grown in situ on nickel foam to enhance the oxygen evolution reaction

The design and synthesis of efficient, stable, and inexpensive oxygen evolution reaction (OER) catalysts is crucial for improving the energy efficiency of water electrolysis for hydrogen production. Herein, we propose a novel composite prepared by a one-step hydrothermal method as an OER catalyst: Fe3O4 and Co3O4 coated on carbon and grown on nickel foam (denoted as FeCo@C/NF). The added Ketjen black (KB) exhibits a unique branched-chain shape, resulting in a homogeneous pine needle-like structure of the catalyst with increased active sites. The overpotential of FeCo@C/NF is only 167 mV at a current density of 10 mA cm−2 in 1.0 M KOH electrolyte, a very low value compared with the conventional catalysts. The formation of the dense conductive network and heterojunctions inside the catalyst allows electrons to move freely across the carbon black and effectively reduces the carrier transfer resistance. Meanwhile, FeCo@C/NF also exhibits high electrochemical stability. These results show an effective thought for the design and synthesis of highly-efficient non-noble metal composite electrocatalysts.