Optimizing electrochemical reactions is essential to improving the energy efficiency of many renewable energy technologies, such as for increasing their competitive advantage across many sectors of the market. The oxygen evolution reaction (OER) is of particular importance for its applicability to chemical generation and energy storage, and its reliance on low cost materials, such as nickel based catalysts. Nickel electrodes with surface oxides (NiO_x) are frequently used as anodes in these systems because they also offer reduced activation energies, exhibit sufficient catalytic activity, and durability under alkaline conditions. Persistent bubble accumulation on highly active electrodes can, however, result in blocked active sites and reduced system performance for these and other OER catalysts. The identification and development of surface morphologies that can effectively evolve and remove oxygen bubbles from the electrode surfaces could be a highly beneficial technology to further enhance the efficiency of the OER.

In this work, regular dimpled Ni surfaces were prepared using self-assembled poly(styrene) templates with a distinct diameter (e.g., 1 μm). The electrodeposition of Ni into these assembled templates was tuned to produce four types of dimpled surface textures. The electrochemical activity of these regular features were evaluated for the OER to investigate their influence on the mass transport properties. Enhancements to the OER efficiency were demonstrated for these systems when compared to flat Ni electrodes. The wettability of the dimpled Ni electrodes was characterized by contact angle measurements acquired both before and after electrochemical cycling. Theoretical wetting models were applied to the surface morphologies to correlate the results with adhesion of the oxygen bubbles and partial wetting with the electrolyte. The regular design of these micro- and nanostructured surfaces enables further correlation of structural morphologies in Ni based electrodes to their electrochemical performance.