(A) study on the synthesis of octahedral Au@Pt nanoparticles and their catalytic application to hydrogen generation reaction of ammonia borane

Abstract

Recently, majority of transport methods use fossil fuel as their energy source. However, exces-sive use of fossil fuel causes severe environmental problems, so finding and using of alternative energy source becomes important. Among several alternative energy sources, hydrogen is one of the strongest candidates due to its high energy content and clean burning. However, safe and efficient way to hydrogen storage and transport is still challenging. As an efficient approach chemical hydrogen storage using ammonia borane is intensively investigated due to its various advantages. In this thesis, hydrogen generation from hydrolysis of ammonia borane was investigated using octahedral Au@Pt nanoparticles (NPs) as catalysts. The octahedral Au@M (M = Pt, Au, Pd) nanoparticles (NPs)were synthesized via a polyol method. Pt NPs were successfully fabricated on the octahedral Au NPs with different atomic ratios of Pt to Au and at different temperatures. The presence of poly(diallyldimethylammonium chloride) as a capping agent is crucial for the successful formation of Pt NPs on the Au nanooctahedra. However, other octahedral Au core - metal shell NPs was not successively synthe-sized. The synthesized octahedral Au@Pt NPs showed a moderate performance toward hydrolysis of $NH_3BH_3$. The highest catalytic activity of the Au@Pt NPs for hydrolysis was observed with activation energy of 44.28 kJ/mol when the Pt coverage on the Au NPs was optimized at the Pt/Au ratio of 1 and the Pt syn-thetic temperature of $160^\circ C$.