|
|
| Functional
Hybrid Systems for Sustainable Chemistry. Natural
photosynthesis serves as an inspiration for the
development of sustainable fuel producing systems.
We create such functional systems by integrating enzyme
and synthetic catalysts in nanostructured, often
photoactive materials. Our approach from
synthetic and materials to biological chemistry is
highly cross-disciplinary.
|
The group
currently collaborates with the following laboratories: Department of Chemistry, Cambridge: Dominic S. Wright Cavendish Laboratory, Cambridge: Richard H. Friend, Ullrich Steiner & Sumeet Mahajan Medical Research Council, Mitochondrial Biology Unit, Cambridge: Judy Hirst Imperial College London, UK: James R. Durrant & A. William Rutherford University of York, UK: Robin Perutz University of East Anglia, UK: Julea Butt University of Leeds, UK: Lars Jeuken Universite Joseph Fourier, Grenoble, France: Juan C. Fontecilla-Camps World Premier Institute, Advanced Institute for Materials Research, Japan: T. Adschiri & N. Asao |
|
| Combining the
Strenghts of Synthesis, Chemical Biology and Materials. Synthesis.
We synthesize and exploit physical and
chemical catalysts in our hybrid systems. The
former allows us to harvest light in the form
of a dye and the latter catalyses the formation of an
energy-rich compound, a fuel. We are particularly
interested in bio-inspired catalysts for proton
and carbon dioxide reduction.
Chemical
Biology. Nature provides us with highly
efficient and selective enzymes, which contain
inexpensive transition metals in their catalytic active
site. We are interested in understanding how these
enzymes work, and applying these principles to design
biomimetic catalysts and photochemical systems. We also
use enzymes such as hydrogenases (proton to H2
conversion), photosystem II (water to O2) and
formate dehydrogenase (CO2 to formic acid)
directly as catalysts in biotechnologically relevant
devices.
Materials.
Our synthetic and biological redox catalysts
will ultimately end up on an electrode, where they will
be interrogated by different electrochemical and
photoelectrochemical techniques. This
approach allows us to study their intrinsic catalytic
properties and how the catalyst
modification improves the electro- or photocatalytic
perfomance of the solid-state material. We
are currently particularly interested in catalysts
integrated in nanostructured semiconductor electrodes.
_______________________________________________Below please find a short summary of our latest projects: |
 |
|
| Photocatalytic
fuel generation with molecular
catalysts on dye-sensitized TiO2. Here, we build up
on the reasonably well understood principles of
dye-sensitised TiO2
(as used in dye-sensitised solar cells) and incorporate
3d transition metal catalysts to evolve H2
from water (instead of producing electricity).
Solar-light driven H2 production
was achieved by co-attaching a cobaloxime H2
evolution catalyst and a ruthenium
photosensitiser to a TiO2
nanoparticle in an aqueous sacrificial electron donor
buffer medium. The solar H2
evolution system operates under visible light
irradiation at pH 7 and room temperature. We study the
electron transfer rates in this colloidal systems in
collaboration with the group of James Durrant at
Imperial College London.
 References: Lakadamyali, F.; Reynal, A.; Kato, M.; Durrant, J. R.; Reisner, E. Chem. Eur. J 2012, 18, 15464–15475; Lakadamyali, F.; Reisner, E. Chem. Commun. 2011, 47, 1695–1697. |
Photoelectrochemical
water oxidation with nature's water oxidizer
photosystem II.
In this
project, we immobilize photosystem II on electrode
surfaces and study its photocatalytic activity with
different techniques. The project addresses basic
questions about the effect of an exogenous substrate
on the electron transfer kinetics in photosystem II
and the activity of the resulting hybrid electrodes
serves as an inspiration and benchmark for related
synthetic systems. We showed recently that
photosystem II can be integrated in a transparent
and mesoporous indium-tin oxide electrode.
We observed direct electron transfer from
photosystem II to the electrode via the natural QB
and an unnatural QA
electron transfer pathway. This project is executed
in collaboration with the group of Bill Rutherford
at Imperial College London and kinetic
investigations are in progress with Richard Friend's
group at Cambridge.
 Reference: Kato, M.; Cardona, T.; Rutherford, A. W.; Reisner, E. J. Am. Chem. Soc., 2012, 134, 8332-8335. |
|
|
Oxygen-tolerant
synthetic catalysts for fuel generation.
An obvious
requirement for water splitting is the need for an H2
evolution catalyst that operates in the presence of
O2.
However, there has been little progress in the
development of homogeneous catalysts that operate
under significant O2
levels. Efficient catalysts such as the noble metal
platinum and hydrogenases suffer from
cross-selectivity for O2
reduction and typically high O2
sensitivity, respectively. Here, we address this
challenge and study the catalytic activity of
homogeneous catalysts in the presence of O2.
We recently found that a water soluble cobaloxime
catalyst not only operates in pH neutral water and
at room temperature, but also in the presence of
atmospheric O2.
 Reference:
Lakadamyali, F.; Kato, M.;
Muresan, N.M.; Reisner, E. Angew. Chem. Int. Ed.,
2012,
51, 9381–9384.
|
Polyoxometallate
nanocages as single source materials for electro- and
photocatalysis.
We recently started work to investigate heterobimetallic polyoxotitanates as precursors for the deposition of stoichiometrically-controlled doped TiO2 films. We found that Co-doped TiO2 cages (TiCo) are excellent precursors for the preparation of CoOx water oxidation electrocatalyst with a novel conducting metal oxide architecture. The TiCo cages are a reservoir for cobalt ions in a titania matrix on fluoride-doped tin oxide electrodes and form in situ the active CoOx catalyst for O2 evolution in an aqueous pH neutral phosphate buffer. This project is executed in collaboration with the group of Dom Wright at Cambridge.  References: Lai, Y.-H.; Lin, C.-Y.; Lv, Y.; King, T.C.; Steiner, A.; Muresan, N. M.; Gan, L.; Wright, D. S.; Reisner, E. Chem. Commun., 2013, 49, 4331-4333; Lv, Y.; Willkomm, J.; Steiner, A.; Gan, L.; Reisner, E.; Wright, D.S. Chem. Sci., 2012, 3, 2470-2473. |
|
|
Electrocatalytic
H2 evolution with
molecular catalysts on
nanostructured electrode.
The low overpotential
electrolysis of water with inexpensive and efficient
materials allows for the affordable conversion of
electricity into the fuel H2. To achieve this
goal, we have developed a high-yield multi-step
synthesis of a robust cobaloxime H2
evolution catalyst that can be integrated in a
nanostructured indium-tin oxide (ITO) environment. The
novel backbone of the Co catalyst allows for
site-specific immobilization on the nanostructured ITO
surface with excellent stability via phosphonic
acid anchors. The hybrid electrode
showed high current densities, and
spectroelectrochemical studies and extensive surface
characterization demonstrate that the immobilized
molecular catalyst remained intact on the electrode when
applying a low potential.
 Reference: Muresan, N. M.; Willkomm, J.; Mersch, D.; Vaynzof, Y.; Reisner, E. Angew. Chem. Int. Ed., 2012, 51, 12749-12753. |
Nanocomposite materials
for electro- and photocatalytic fuel generation. Solar fuel generation, in
particular the development of inexpensive and
efficient photoelectrochemical (PEC) cells for sunlight-driven water
splitting is of considerable current interest. We have
developed a PEC system that consists of a novel p-type
Cu2O/NiOx nanocomposite
photocathode coupled to an n-type WO3
nanosheet photoanode. The
complementary band gap of Cu2O (2 eV) and
WO3 (2.6 eV) permits for complementary
light absorption and solar water splitting without
external bias. We demonstrated that a Cu2O-based
electrode for H2 evolution
can be prepared free of noble metals and we show its
utilisation in a PEC water splitting cell made solely
from earth abundant elements.
|
|
| Information about more ongoing projects will become available soon. | ||
|
- Engineering
and Physical Sciences Research Council (EP/H00338X/2
Career Acceleration
Scholarships
for postgraduate studies: - Marshall/EPA scholarship (MPhil
scholarship for Christina Chang) Postdoctoral
fellowships: - Japan
Society for the Promotion of Science (for Masaru Kato) - National
Science Council of Taiwan (for Chia-Yu Lin) - Marie Curie fellowship from European Union (for Jenny Zhang) - Isaac Newton Trust
(Trinity College, Cambridge) & German Research
Foundation (for Moritz Kuehnel) |
_____________________________ 
   |
