Encapsulation of metal hydride nanoparticles

Parr, GP

Abstract

Hydrogen is likely to play a significant role in future low and zero carbon energy infrastructures. Alkali metal hydride nanoparticles could provide a route to an efficient lightweight hydrogen storage technology for automotive applications. However, a particular issue with alkali metal hydrides is their sensitivity to air/moisture, making their characterisation extremely difficult. In addition to unwanted changes to the materials on contact with air/moisture, reaction products that can be released such as hydroxides and ammonia, could cause significant damage to expensive analytical instrumentation. To address these issues, a method for encapsulating metal hydride nanoparticles in spherical polysulfone microcapsules has been developed, offering an environment for both safe storage and handling of moisture-sensitive nanoparticles.

A methodology for producing spherical polysulfone microcapsules with a typical diameter between 1-2mm is presented. Microcapsules are produced with a solid outer wall structure, preventing moisture permeation, but being soft enough to allow easy access to the internal structure for characterisation of the nanoparticle morphology. In addition to the design of the microcapsules, a robust preparation technique to allow the study of their internal structure, without exposing the nanoparticles to moisture, using high-resolution Scanning Electron Microscopy (SEM) is defined. The established technique allows the microcapsules to be cross-sectioned under vacuum with an additional option of purging the reactive particles with argon gas. In order to examine the encapsulated nanoparticles, Energy Dispersive X-ray Analysis (EDX) was used, for which lithium-containing hydrides are not suited. Therefore, the main focus of the research presented involves the encapsulation of sodium borohydride (NaBH4) nanoparticles. In addition, this technology could be considered for the storage of other air/moisture sensitive materials.

Citation

Parr, G. Encapsulation of metal hydride nanoparticles. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Apr 12, 2022
• Publicly Available Date: Apr 12, 2022