Nanostructured Ni-Fe-P Alloy for Alkaline Electrolyzer

Abstract

In recent years, the interest towards green hydrogen has drastically increased due to the global decarbonization process. Electrochemical water splitting is considered an attractive solution to convert and store the surplus energy from renewable energy sources. However, hydrogen production by water electrolysis is not economically sustainable. To reduce the cost of produced hydrogen, it is necessary to switch from noble-metal catalyst (Pt, Pd…) to cheap alternatives with a lower per unit energy cost but at the same time able to guarantee a high electrocatalytic activity for both oxygen and hydrogen evolution reactions. Among transition metals, nickel was selected as active material for its low cost and high chemical stability in alkaline media. Currently, the most investigated transition metal catalyst includes alloy of nickel with sulfide, phosphide, and nitride. In this work, a ternary alloy of Nickel-Iron-Phosphorus with nanowires morphology was investigated and compared to the binary alloy of Nickel-Iron. Ni-Fe-P NWs electrodes were obtained by potential-controlled pulse electrochemical deposition using polycarbonate membrane as template. Electrodes morphology and structure were studied by scanning electrode microscopy (SEM), energy diffraction spectroscopy (EDS) and X-ray diffraction (XRD). Electrodes were tested both as cathodes as anodes by Quasi Steady State Polarization (QSSP) and Galvanostatic Test. All the tests were performed in 30% w/w KOH aqueous solution at room temperature. Preliminary results showed better performance of the ternary alloy compared to the binary one.