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Page 36
allied
academies
November 22-23, 2018 | Paris, France
Journal of Materials Science and Nanotechnology | Volume: 2
Materials Physics and Materials Science
International Conference on
Synthesis of transition metal doped BiVO
4
nano photoanodes from single source precursors
Haijiao Lu
University of Cambridge, UK
A
s global energy demands, and related environmental
concerns grow, there is an urgent requirement to
harness alternative energy sources, such as solar energy.
One attractive opportunity is to utilise sunlight to split water,
forming H
2
which may be used directly as a fuel or as a
reagent for the preparation of liquid fuels. BiVO
4
exhibits a
valence band edge at a suitable position for water oxidation
(2.4eV vs reversible hydrogen electrode (RHE)), and a
conduction band edge located close to RHE. The band gap
of BiVO
4
allows absorption of a significant portion of visible
light, giving a theoretical Solar-to-Hydrogen (STH) efficiency
of 9%. BiVO
4
exhibits good photostability, non-toxicity and is
composed of earth abundant, non-costly elements. It occurs
in three polymorphs, with the monoclinic scheelite structure
as the most effective as a photoanode. However, the low
carrier diffusion length (70-100nm) reduces the efficiency of
photo-absorption due to accumulation and recombination of
charge carriers. Efforts to remediate this issue include doping,
Nano structuring, heterojunction formation. Recent reports
state the necessity for simple scalable routes to deposit thin
films of BiVO
4
onto conductive surfaces for the preparation
of larger photoanodes. Simple solution preparation routes
such as spray pyrolysis or drop casting/spin coating are
particularly attractive due to their simplicity and potential
for scale up. Current methodologies commonly use inorganic
salts and/or metal organic precursors. A challenge when
using a mixture of precursors is the even distribution of
molecular precursors and prevention of phase separation
upon the film prior to annealing. Here we report a one step,
straightforward synthesis with polyoxometalates as suitable
single-source precursors for nanoporous thin films of Co/
Ni/Cu/Zn doped-BiVO
4
, which show good photoactivity and
can be produced on a large scale due to the simplicity of
deposition.
e:
hl509@cam.ac.uk