Helium plasma irradiation on Nickel: Nanostructure formation and electrochemical characteristics

Nanotechnology offers new avenues for the design, fabrication, and application of novel materials. Helium plasma exposure is a technique that can be used to fabricate self-supported metallic nanostructures. In this work, we explore the plasma irradiation conditions for fabricating various morphologies on planar nickel surfaces, and evaluate the electrochemical performance of these surfaces for oxygen evolution reaction (OER) in alkaline media. The preferential growth towards certain morphologies such as nano-pillars, nano-blocks, and micro-structures, is found to be primarily influenced by the applied plasma conditions and two counteracting processes of sputtering and annealing. The plasma treatment increased the electrochemical surface area of the modified samples by approximately 3 to 4 times as compared to the planar/unmodified surfaces, along with an increase in the OER performance for all morphologies. However, in addition to the increased surface area, the electrochemical performance was found to be dependent on the shape, size and thickness of the nano/micro-features. Moving ahead, the ability of this technique to achieve control over the feature size along with its effectiveness for a broad range of metals offers new routes for nanostructuring and functionalization of emerging materials.