Bifunctional petal-like carbon–nitrogen covered NiFeOx/nickel foam nanohybrid electrocatalyst for efficient overall water splitting

NiFe-based compounds have attracted increasing attention due to their availability and excellent catalytic performance for the hydrogen evolution (HER) and oxygen evolution reaction (OER). Based on the structure of bulk NiFe-LDH, dispersed interlayer stacking facilitates the diffusion of proton receptors and expose more active sites. Then, nitrogen and graphite domains are controllably introduced by carbonization to improve the conductivity. In this paper, carbon–nitrogen covered NiFeO x was prepared by carbonizing the modified precursor, NiFe layered double hydroxide (NiFe-LDH) with ethylenediaminetetraacetic acid (EDTA). The as-synthesized NiFe EDTA exhibits good bifunctional activity with overpotentials of 163 mV and 249 mV to achieve current densities of 10 mA·cm −2 in 1.0 M KOH for HER and OER, respectively, which is ascribed to the structural advantages of polycrystalline interface and carbon encapsulation structure. Moreover, by using NiFe EDTA as cathode and anode electrodes for overall water splitting (OWS), the cell voltage only needs 1.51 V at 10 mA·cm −2 . The NiFe EDTA has good OWS stability and works at 1.6 V for 70 h.