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Title: Titania-based photoelectrochemical H2 production from water involving economic sacrificial agents
Author: Ibadurrohman, Muhammad
ISNI:       0000 0004 6496 1054
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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H2 is considered as a crucial factor for future energy prosperity due to its high energy density and the carbon-free feature it offers. A sustainable route towards H2 is therefore paramount, and it necessitates avoiding fossil-based sources and/or costly technology. This opportunity has paved the way for H2 production via semiconductor-based photoelectrochemical (PEC) water splitting, which exploits charge carriers extracted from the semiconductors that are exposed to photons, driving redox generation of O2 and H2. Titania-based films, notwithstanding their excellent chemical stability which make them favoured photoanode materials in most PEC systems, still suffer from several limitations, including restricted surface area, high recombination rate of photo-carriers, and visible-light-inactivity. By identifying scope for improvements based on literature survey, this PhD project revolved around syntheses, characterisations, and modifications of titania-based films as photoanode materials for PEC H₂ production involving economic sacrificial agents. Titania materials were deposited on F:SnO2 via a spray pyrolysis method. PEC results revealed photocurrents of anatase TiO2 control films in the realm of ca. 40 μA at 0.8 V vs HgO|Hg with PEC efficiency of ca. 0.40% (120 W/m2 white light intensity, exposing 0.3 cm2 geometric area). Morphological modifications were successfully accomplished via a one-step polyethylene glycol (PEG)-templating technique, leading to generation of nano-sized features and improved roughness while maintaining the original superstructure. PEC efficiency of up to 1.23% was revealed by PEG-modified films, attributed to improved surface area and betterment of carrier transport facilitated by the morphological structure. A series of organic compounds were introduced as anodic sacrificial agents, leading to better carrier transport and current-doubling effects, the significance of which were more noticeable in the use of rough-surface photoanodes. Key factors related to the functionalities of sacrificial agents in PEC H2 production were stipulated. Suppression of carrier recombination was also pursued by incorporating highly conductive graphene into the film network, which successfully increased PEC efficiency by 70% as compared to unmodified TiO2. Efforts on modifying TiO2 band gap were made with the purpose of extending the usable portion of light spectrum, which included doping with impurities (anions and cations) and synthesis of bismuth titanates. While obtaining satisfactory results in this context remains a challenge, difficulties associated with the undesired outcome and possible adjustments for future studies are suggested.
Supervisor: Hellgardt, Klaus Sponsor: Menteri Negara Riset dan Teknologi ; Indonesia
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral