Formation of carbon nanostructures on nickel acetate alcogel by CVD method and its OER electrocatalytic study in alkaline media

Facile and cost-effective methods to synthesize non-noble transition metal with electrically conductive carbon-nanostructured materials are desirable for the possible replacement of noble metals like iridium and ruthenium-based anode materials in alkaline water electrolyzer. Herein, we report a simple method to produce nickel-carbon nanotube (CNT) nanocomposites by CVD method using nickel acetate alcogel. The molar concentration of nickel in acetate alcogel was observed to be controlling factor for the growth of extremely small nickel nanoparticles of the order 2-5 nm in diameter on the tips and walls of the CNTs. Moreover, it was found experimentally that the higher concentration of nickel in acetate alcogel nucleated predominantly big-faceted globular particles presumably composed of nickel nanocrystals of the order 50-1000 nm in diameter and scarce CNTs of the diameter 40-80 nm. In addition, oxygen evolution reaction activities of sample synthesized by CVD of carbon using 0.333 molar nickel in acetate alcogel was found to better than the sample with 0.495 molar concentration of nickel in acetate gel. The better OER performance of the sample was attributed to the presence well-separated distribution of catalytic nickel nanoparticles on the electrically conductive CNTs.