Design of Nanostructured Nickel Hydroxide-based Materials for Renewable, Electrochemical Energy Applications

Abstract

This contribution investigates the synthesis and characterization of nickel and nickel hydroxide-based materials with intended applications as electrode materials and electrocatalysts in clean, renewable energy technologies. A diverse range of nickel-based nanostructures are studied to identify candidates with high surface area and significant electrocatalytic activities towards the relevant hydrogen and oxygen redox reactions. The structures studied in this work include nickel hydroxide nanocages, nickel-based layered double hydroxide (LDH) nanoparticles, and nickel-based mesoporous metal oxides (MMO). To evaluate these materials, a complete characterization of the synthesized nanostructures is presented, comprising a combination of thermal analyses, surface science techniques and electrochemical analyses to gain a fundamental understanding of their chemical composition and structural features. Based on these results, we propose a tunable methodology for the preparation of nickel-based LDH nanoparticles including various historically relevant, hybrid nickel materials (i.e. Ni-Al, Ni-Zn, Ni-Fe, etc.). Tripodal ligands are applied in this technique to act as particle growth control agents, resulting in the successful isolation of nanoparticles as small as 30 nm and 15 nm (diameter), in the cases of Ni and Ni-Fe, respectively. Assembly of these nanoparticles into larger mesoporous structures was also performed using a soft polymer-templating method, and a comprehensive overview of this technique is presented. Successful conversion of hybrid nickel hydroxide nanoparticles to the corresponding mesoporous nickel oxide was confirmed by electron microscopy and electrochemical measurements. The foundation for further exploration of a vast series of nickel hydroxide and nickel oxide functional nanomaterials is established based on the novel research presented in this work.