Abstract
In recent years, the demand for advanced materials with enhanced properties has grown significantly across various industries. Metallic nanostructures have emerged as a promising class of materials due to their unique atomic structures and tailored chemical compositions. These metallic nanostructures offer excellent electrocatalytic performance, high corrosion resistance and exceptional mechanical strength. However, their widespread adoption is hindered by high production costs associated with complex processing techniques and expensive raw materials. This limitation poses a significant obstacle to their commercialization and impact on sectors such as energy, electronics, aerospace and automotive.To address these challenges, this thesis focuses on the development of cost-effective nanostructured materials via physical metallurgy and nanomechanical methods for electrocatalysis. In the second chapter, an easy-to-implement nanomechanical method termed polymer surface buckling enabled exfoliation (PSBEE), which our group developed previously, was utilized to create ultrathin platinum (Pt) nanomembranes. These Pt nanomembranes consist of highly distorted Pt nanocrystals with heterogeneous elastic strains, a characteristic rarely seen in conventional nanocrystals. This unique feature results in significantly higher electrocatalytic efficiency than conventional Pt catalysts, including Pt/C and Pt foils. This research offers a promising approach to develop highly efficient and cost-effective low-dimensional electrocatalysts for sustainable hydrogen production.
In addition to PSBEE, the third chapter explores the use of dealloying as a strategy to fabricate nanostructured materials. Electrochemical dealloying of a eutectic multi-principal element alloy (MPEA) was employed to produce a porous C15 intermetallic alloy. The controlled formation of a three-dimensional bi-continuous porous framework through electrochemical dealloying, followed by cyclic voltammetry (CV) activation, results in a porous structure with a remarkable catalytic activity in electrochemical hydrogen evolution reactions (HER). The stability of this porous intermetallic structure at high industry current densities is attributed to its chemical stability and the operando formation of an amorphous oxide layer. These findings contribute to the advancement of high entropy intermetallic oxide catalysts for energy applications.
Furthermore, by electrochemical dealloying of a ternary eutectic MPEA, the fourth chapter explored the fabrication of a corrosion-resistant porous intermetallic alloy with a unique topologically-close-packed (TCP) phase. The porous structure exhibited both good catalytic activity in acidic HER and superior long-term stability owing to the corrosion resistance inherent to the surface oxides formed during dealloying. Notably, we observed in-situ reconstruction of the surface oxides, alongside the outstanding catalytic performance and stability in acidic HER. In addition, unlike conventional TCP alloys, this porous TCP intermetallic structure was malleable, enabling its potential use as self-supported catalytic materials for energy applications.
| Date of Award | 2 Jan 2025 |
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| Original language | English |
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| Supervisor | Yong YANG (Supervisor) |