Rapid electrodeposition of Fe-doped nickel selenides on Ni foam as a bi-functional electrocatalyst for water splitting in alkaline solution

An efficient and rapid electrochemical method was applied to in-suit deposit Fe-doped Ni-Se on Ni foam (FexNi-Se/NF) as a bi-function electrocatalyst for over water splitting. Here, the unique three-dimensional (3D) structure of NF substrate can not only offer large surface area to load more active materials, but also benefit gas products releasing. The hybrid structure of Ni-Se material including NiSe and Ni3Se2 can regulate the surface electronic structure and reconstruct the electrode/solution interface. The doping of Fe can change the surface morphology, increase the electroactive area and reduce the charge transfer resistance. Moreover, an outstanding electrocatalyst Ni/Fe(OOH) formed during the water splitting process further improves the catalytical performance. Thanks to the synergistic effects of 3D structure from NF, the combination of NiSe and Ni3Se2, the doping of Fe and the generation of Ni/Fe(OOH), Fe4Ni-Se/NF electrode showed an excellent electrocatalytic performance. Without IR correction, low overpotential of 93 and 207 mV were needed to reach 10 mA cm−2 with small Tafel slopes of 90.6 and 36.7 mV dec−1 for HER and OER, respectively. Moreover, Fe4Ni-Se/NF electrode delivered a very low cell voltage of 1.55 V for water splitting and possessed an outstanding stability during 70 h continuous operation.