Development of sustainable energy has recalled highly efficient energy storage technology because it generates the electricity stochastically from the sources such as solar and wind. The water electrolysis has been considered as the one of the promising options to convert and store electrical energy as the form of hydrogen. However, relatively large overpotential from anodic half reaction, that is, oxygen evolution reaction (OER) has hindered commercial use of hydropower.

The recent studies about OER have focused on finding out non-noble metal catalyst because the RuO₂ and IrO₂, ideal catalysts for OER, are scarce and expensive. Among the non-noble metal oxides, cobalt (III, IV) oxide has been received great attention since it is anticipated to be second best ideal catalyst for OER from theoretical calculations. With this respect, the number of nano-sized cobalt oxide electrodes with different morphologies have been prepared and utilized as the anode of electrolytic water splitting system.

In this work, copper-cobalt oxides nanosheets catalyst layer was electrochemically prepared on the nickel foam substrate. To achieve nano-porous morphology of deposit, cobalt oxide was co-deposited with copper oxide. The structural and spectroscopic analyses revealed that cobalt-copper oxides nanosheet array consists of mixture of Co₃O₄ and Cu_xCo_3-xO₄. As the catalyst for OER, the resulting catalyst showed exceptional catalytic activity thanks to its nano- to micro-porous structure, which allows facile transport of active species. Furthermore, it showed great long-term stability.

In this presentation, the catalytic activity of cobalt-copper oxides will be discussed in terms of electrochemical properties. In particular, several electrochemical parameters such as anodic Tafel slopes and overpotentials at different current densities will be suggested and compared to that of other nanostructured catalysts reported in literature. Furthermore, the effect co-deposition of copper and cobalt oxides on growth habit of overall deposit and its OER performance will be discussed.