Since the global energy demand shows rapid expansion from last several decades, coping with serious environmental pollution and searching for renewable energy sources have been the pan-international problems. Among the various renewable energy sources, hydrogen is considered as a noticeable candidate, since hydrogen combustion does not discharge any air-pollutant.

There are still many obstacles for hydrogen to alternate the existing fuels, however, mainly due to its difficulties in large-scale production. Indebted with this, electrochemical water splitting attracted a great attention since it shows excellent efficiency to obtain hydrogen from water. Among the all sorts of electrocatalysts, iridium oxide and ruthenium oxide are ranked as the uppermost standard for the oxygen evolution reaction (OER). These catalysts have ultimate disadvantages; nevertheless, extremely high prices limit their usage on the mass production of hydrogen.

Recently, many researches were focused on transition-metal-based catalysts because of their low cost, good stability and high catalytic activity on OER. Not only transition metals, but also many derivatives such as phosphorous-alloy-based have been suggested. These alloy catalysts often deliver higher catalytic activity than separated single-metal-based ones, due to synergetic effects induced by transition of valence state and enhanced electrical conductivity.

In this study, we discovered the effect of alloying another element on the Ni OER catalyst. Phosphorous, which is known as good alloying element for improvement of OER activity, was directly incorporated via electrodeposition method. Electroplating enables facile synthesis of the electrocatalyst layer in wet condition without any high temperature process. Furthermore, we introduced Cu as another alloying element and confirmed its catalytic behavior toward OER, compared to conventional Ni phosphorous electrocatalyst.