ISBN 9783843926003

978-3-8439-2600-3, Reihe Anorganische Chemie

Ali Kaouk
Plasma Enhanced Chemical Vapour Deposition of Graphene-Hematite Nanocomposite Films as Photoanodes in Water-Splitting Reactions

140 Seiten, Dissertation Universität Köln (2016), Softcover, A5

Zusammenfassung / Abstract

Solar hydrogen as a renewable source of energy has been the focus of research for the past decade. Enhancement of the properties of photo active metal oxide anodes for better bias-free production of solar hydrogen through photoelectrochemical water splitting continues to be a thrust area in the quest for sustainable energy solutions. Among foremost materials, challenges for this application such as highly efficient photo catalysts, cost factor and long term stability are the main factors for material selection. Earth abundant metal oxides such as Fe2O3 and TiO2 are promising candidates in terms of their stability and cost. However, their poor electrical properties are major limiting factor for using them as possible photoanodes. Last decades, multiple improvement techniques have been employed for overcoming these challenges such as carbon/MOx material, doping, surface functionalization, multi-layer systems and nano-structuring of the metal oxides.

The major research objective of this thesis was to establish plasma-assisted chemical vapor deposition techniques for growing high-quality graphene on various substrates due to its excellent electrical properties. Availability of fabrication procedures enabling direct growth of graphene would allow convenient handling (no need of post-synthesis transfer) and enable the combination of graphene with other functional material. Low-pressure plasma-chemical decomposition of hydrocarbons (primarily methane) was fully investigated as viable approach. Graphene growth in conjunction with transition metal oxide films (Fe2O3 and TiO2) was investigated to design bi- and multilayer electrodes for better light harvesting and superior charge transport. In addition to thorough material characterization graphene-based nanocomposite electrodes were tested as photoanode material for photoelectrochemical splitting of water.