DEVELOPMENT OF ADSORBENTS FOR THE CAPTURE AND STORAGE OF HYDROGEN AND CARBON DIOXIDE BY MAGNETRON SPUTTERING
Concerns about climate change have rejuvenated global efforts in reducing carbon dioxide (CO2) emissions. Tactics include capture and sequestration of CO2 from point sources and the promotion of hydrogen (H2) as a “transport fuel”. Current H2 vehicles use high pressure H2 tanks which lack the convenience of their fossil fuel counterparts and present potential safety hazards. Development of adsorbent materials that reduce the energetic costs of H2 and CO2 capture, facilitating reversible storage under safer conditions, are hoped to increase the viability of these technologies for industrial application. This thesis is the first to utilise magnetron sputtering, a technique allowing fine control over nano-material synthesis, for the design of novel solid adsorbents and deposition of novel dopants for H2 storage and CO2 capture. Work includes an in-depth study of the influence of nitrogen as a sputter gas on the growth of carbonaceous films, and is the first to explore these films performance as H2 and CO2 adsorbents. Several conflicting nitrogen effects were identified, their influence on the films growth dependent upon the nitrogen fraction of the sputter gas. Performance of the deposited films as adsorbents was also dependent on the growth conditions. The H2 storage capacity at 77 K and 20 bar of an optimised adsorbent, synthesised by magnetron sputtering, was 4.7 wt.%, comparable in performance to alternatives from the literature. Further work provides the first evidence that cerium, deposited by magnetron sputtering, can function as an adsorbent catalyst and identified that sputtering is a worthwhile, yet slow process for adsorbent doping as it facilitates intimate binding between the adsorbent and the dopant. The novel synthesis of graphene by magnetron sputtering was also attempted. Whilst tests failed, results collected could provide guidance for more successful attempts in the future.
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