Regulating electrolytic Fe0.5CoNiCuZnx high entropy alloy electrodes for oxygen evolution reactions in alkaline solution

The properties of high entropy alloys(HEAs) depend on their phase structures and compositions. However, it is difficult to control the composition of the HEAs that contain highly volatile metals by the conventional arc melting method. In this paper, homogeneous powdery face centered cubic(FCC) phase Fe0.5CoNiCuZnxHEAs were prepared by the electrolysis of metal oxides in molten Na2CO3-K2CO3using a stable Ni11Fe10Cu inert oxygen-evolution anode. The use of oxide precursors and relatively low synthetic temperature are beneficial to efficiently preparing HEAs that contain highly volatile elements such as Zn.Moreover, the microstructures and compositions of the electrolytic HEAs can be easily tailored by adjusting the components of oxide precursors, then further regulating its properties. Thus, the electrocatalytic activity of Fe0.5Co NiCuZnxHEAs towards oxygen evolution reactions(OER) was investigated in 1 M KOH.The results show that Zn promotes the OER activity of Fe0.5CoNiCuZnxHEAs, i.e., the HEA(Zn0.8) shows the best OER activity exhibiting a low overpotential of 340 m V at 10 m A/cm~2 and excellent stability of 24 h. Hence, molten salt electrolysis not only provides a green approach to prepare Fe0.5CoNiCuZnxHEAs but also offers an effective way to regulate the structure of the alloys and thereby optimizes the electrocatalytic activities for water electrolysis.