The effects of Co doping for Fe metal on boosting hydrogen and oxygen evolution reactions

[Display omitted] •Co doped Fe metal catalysts were prepared by one-step electrodeposition method.•Co atoms weaken the adsorption of Fe to H and enhance the HER performance.•Co doping enhances the adsorption of oxygen-containing intermediates and OER.•Co doped Fe metal can be used as bifunctional catalyst for water splitting. In alkaline water splitting, the hydrogen evolution reaction (HER) has high overpotential with the oxygen evolution reaction (OER). To develop a bifunctional water electrolytic catalyst with high performance, a cobalt-doped iron (Co-Fe) metal catalyst was synthesized on nickel foam (NF) through a one-step of electrodeposition method. The introduction of Co atoms can obviously promote HER and OER performance of Fe metal. The overpotential of HER and OER is only 51 mV and 268 mV at the current density of 10 mA cm−2, respectively, and it can maintain long-term stability. In the alkaline water splitting system constructed with Co-Fe/NF electrodes, the battery voltage is only 1.61 V at the current density of 10 mA cm−2 with long-term stability. The experimental and theoretical results disclose that the strong interaction between Co and Fe, the addition of Co atoms changes the electronic structure of Fe metal, optimizes the electrons transfer and the adsorption of Fe on H and H2O, thus promoting the HER process. In addition, Co doping also enhances the adsorption of Fe on oxygen-containing intermediates, thereby improving the OER performance.