<p>Oxygen evolution reaction (OER) is the key step
involved both in water splitting devices as well as in rechargeable metal-air
batteries and there is an urgent requirement for a highly stable and low-cost
material for efficient OER. In this article, for the first time, electrocatalyst
based on high entropy alloy (HEA) of FeCoNiZnGa has been reported for OER. Nano-crystalline high
entropy alloys materials withdrew the attention of the research academia due to
their emerging unique properties due to the cocktail effect and synergetic
effect between the constituent elements. The existing materials (IrO<sub>2</sub>,
RuO<sub>2</sub>, etc.) being utilized in the OER reaction contain precious
metals. Thus, high entropy alloy made up of low-cost elements has been
formulated and tested for the OER, which is found to be highly stable and more
efficient. The formulation of nanocrystalline HEA (FeCoNiZnGa) utilized a unique recipe
casting-cum-comminution (CCC). After electrochemical CV activation, transition
metal oxides formation at the HEA surface helps in OER activities. HEA exhibits
a low overpotential of 370 mV to achieve a current density of 10 mA cm<sup>-2</sup>
with a very small Tafel slope of 71 mV dec<sup>-1</sup> and exceptional long
term stability of electrolysis for over 10 h in 1 M KOH alkaline solution,
which is extremely stable in comparison to the state-of-the-art OER
electrocatalyst RuO<sub>2</sub>. Transmission
electron microscopic (TEM) studies after 10 h of long term chronoamperometry
testing confirmed high stability of HEA as no change in the crystal structure
observed. Our work highlights the great potential of HEA towards oxygen
evolution reaction which is primary reaction involved in water splitting.</p>
High intrinsic activity of the oxygen evolution reaction in low-cost NiO nanowall electrocatalysts