ENGINEERING NANOSTRUCTURED MATERIALS FOR FUEL CELLS  AND WATER SPLITTING

Qiurong Shi

The objective of my research is to rationally design and engineer high efficient electrocatalysts for energy conversion reactions, including oxygen reduction/evolution reaction (OR/ER), and alcohol oxidation reaction (AOR) happened in fuel cells and proton exchange membrane water electrolyzers (PEMWEs). Firstly, the as-synthesized zero-dimensional (0D) mesoporous and core-shell structured Au@PtNi nanoparticles (NPs) demonstrated improved catalytic performances toward ORR over commercial Pt/C in acidic solution. Then, one dimensional ultra-thin IrTe nanotubes (NTs) were synthesized, which showed smaller overpotential and higher stability toward OER than commercial IrO2 due to its dendritic and hollow structures. Finally, three-dimensional (3D) noble-metal based systems including metallic hydrogels/aerogels (MH/As) and nanowire networks (NNs) were successfully constructed via wet-chemical synthesis strategies. From the macro-scope, the as-obtained Au@Pt3Pd, Au2Cu@Pd, AuPt MAs and Pd3Pb NNs possessed inter-connected nanowires and hybrid pore system that provided numerous free paths for electron transfer and mass diffusion. Besides, the self-supported backbone is more robust than carbon support for enhancing the long-term stability. From the micro-scope, the morphology, compositions and atomic structure of the building blocks were rationally designed for further boosting the catalytic performances. For example, Au@Pt3Pd MAs were built with core-shell and dendritic structured NPs, which increased the number of active sites and generated the synergistic effects. The surface of Au2Cu nanowires were anchored with well-modified Pd ensembles, which significantly boosted the mass activity toward ethanol oxidation; the Pd3Pb NNs were composed with intermetallic structures, which exhibited remarkable enhanced catalytic activity, durability and selectivity toward ORR. The remarkably enhanced catalytic efficiency and durability are attributed to two major reasons: i) the introduction of non-precious metals to form bi- or multi-metallic systems could generate geometric effect and electronic effect for boosting their catalytic activity; ii) the construction of 3D architecture with hybrid pore systems and inter-connected nanowires are effective in improving the catalytic efficiency due to the fast electron/mass transfer rate, and long-term stability due to the self-supported backbone of high resistance to corrosion in harsh conditions.

ENGINEERING NANOSTRUCTURED MATERIALS FOR FUEL CELLS AND WATER SPLITTING

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