New Materials for Photocatalysis and Photovoltaics
By
Abbas Jassim Attia Lafta
BSc, MSc
Submitted in Fulfilment of the Requirements for the
Degree of Doctor of Philosophy
School of Chemistry
College of Science and Engineering
University of Glasgow
March 2013
Abstract
Photocatalytic processes are of widespread interest. Among different types of
photocatalytic material TiO2 is the generally considered amongst the best due to its
favourable physical and chemical properties. In recent decades, photovoltaic devices have
been widely studied to provide alternative routes to energy and reduce dependency upon
fossil fuel. Solar photovoltaic are cells capable of harvesting of sunlight into electrical
power. This technology is one of the most promising routes in the search for sustainable
and renewable sources of energy. The study presented in this thesis relates to the
preparation and characterization of a range of different materials which can be applied in
photocatalytic processes and for photovoltaic devices.
The photocatalysis work has been focused mainly upon modification of the various
phases of titanium dioxide. This has been undertaken via doping with nitrogen by
treatment with ammonia at different temperatures. In addition, samples containing Al, Co
and Cu opants, as well as their N doped counterparts, have been prepared, characterized
and tested. The photocatalytic activity was screened by following photocatalytic
decomposition of an queous solution of methylene blue using a light source containing
various components in the UV and visible regions. For selected samples, the
photocatalytic activity for polymerization of methyl methacrylate and styrene has been
determined with the aim of producing composites.
In terms of potential photovoltaic materials, the synthesis of novel viologen compounds
and polymerization via electrochemical and chemical means has been undertaken.
Different viologen monomers have been synthesized with various moieties in conjugation
to a phenanthroline core to afford novel push-pull systems. These compounds have
incorporated both TCNE and TCNQ moieties as strong electron acceptors and hence
yield chromophore with large dipole moments. In addition, novel ruthenium complexes
were prepared featuring bipyridine and phenanthroline ligands. The optical and redox
properties of these materials have been investigated. DSSCs have been fabricated form
some of these systems and their properties have been compared to dye 719.