Plasma-assisted synthesis of transition metal-based nanostructures for zinc-air batteries

Rechargeable zinc-air batteries, which present the advantages of low cost, high theoretical energy density and intrinsic safety, have been considered as a promising energy storage device to replace the current lithium-based batteries. The practical performance of rechargeable zinc-air batteries is strongly related to the reaction rate of the oxygen-involved reaction at their air cathodes, including the oxygen evolution reaction (OER) during the charge process and the oxygen reduction reaction (ORR) during the discharge process. Although noble-metal-based materials exhibit the highest electrocatalytic activities for these reactions, their high prices and poor stability still hinder them for future applications. Therefore, finding an efficient bifunctional electrocatalyst is necessary for the commercial applications of rechargeable zinc-air batteries.

Transition metal-based catalysts have been accepted as promising candidates to replace these noble-metal-based catalysts owing to their low cost, natural abundance and high stability. In this thesis, a self-supported catalyst of spinel NiCo₂O₄ nanowires coated on the commercial carbon paper was synthesized by a hydrothermal method followed by an annealing process. To further enhance the electrocatalytic performance of the catalyst, the low-pressure plasma treatments based on different gases were conducted to tune its electronic structure and optimize its surface properties.