Electrospun nanostructured composite fibres for hydrogen storage applications.
Doctoral thesis, UCL (University College London).
The urgent realisation of the low carbon economy requires the development of cheap, safe and lightweight hydrogen storage, both for commercialisation of hydrogen fuel cell vehicles, and for the use of hydrogen as a reservoir of energy from intermittent renewable energy sources. The primary motivation of this PhD project was to investigate (co)electrospinning, a cheap and scalable fibre production technique, for nanostructuring potential solid state hydrogen storage materials. Solid state storage of hydrogen is being extensively investigated worldwide. However, many of the candidate materials are still not able to meet the practical requirements for mobile applications. The principal drawbacks are that these materials either have low capacity for hydrogen storage (physisorption systems), even at cryogenic temperatures, or high release temperatures with slow release rates (chemisorption systems). Because kinetic and thermodynamic properties can be improved by nanoscale processing, nanoengineering of selected materials has emerged as one of the most effective ways of overcoming their associated performance barriers. In this thesis I present two successful approaches to nanostructuring using electrospinning: firstly, by encapsulating chemical hydrides in polymeric nanofibres, as demonstrated by the development of co-axial ammonia borane-encapsulated polystyrene (AB-PS) fibres, and secondly, by post-processing of single-phase electrospun PAN fibres, resulting in the synthesis of potassium-intercalated graphitic nanofibres (K-GNFs). The results show that the micro and nano-structure imparted through electrospinning, can have the effect of reducing dehydrogenation temperatures in AB-PS fibres (from 110 to ~85 °C) and improving the (de)hydrogenation rates by an order of magnitude in both composite fibres (from ~50 to <5 mins in K-GNFs and from ~150 minutes to as low as 15 minutes in AB-PS fibres). The details of co-axial electrospinning as a novel approach to nanoengineering chemical hydrogen storage materials and as a way of possibly overcoming issues regarding reversibility, stability and clean hydrogen release from many of these materials is discussed. The solution selection method I have developed for use in the synthesis of co-axial composite fibres can be applied as an efficient solution selection formula for multi-phase electrospinning in general.
|Title:||Electrospun nanostructured composite fibres for hydrogen storage applications|
|Open access status:||An open access version is available from UCL Discovery|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy|
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