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 cross-disciplinary approach ranges from synthetic and materials to biological chemistry.
More information about our main projects:
Christian Doppler Laboratory and ERC Consolidator Grant project
For a poster summary of our work made by Katherine Orchard - click here
group is a member of the following networks and
Cambridge Centre for Doctoral Training in Functional and Sustainable Nano
Cambridge Centre for Doctoral Training in Graphene Technology
Cambridge Bioenergy Initiative - The Algal Biotechnology Consortium
UK Solar Fuels Network
EU COST Action CM1202 (PERSPECT-H2O) - Supramolecular photocatalytic water splitting
EU COST Action TD1102 (PHOTOTECH) - Photosynthetic proteins for technical applications
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 metallo-enzymes. 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) 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._______________________________________________
Below please find an overview of some of our ongoing projects (last update: Dec 2015)
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 the fuel H2 from water (instead of producing electricity). Solar-light driven H2 production was achieved by co-attaching a cobaloxime or DuBois-type 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 in water 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: Willkomm, J.; Orchard, K. L.; Reynal, A.; Pastor, E.; Durrant, J. R.; Reisner, E. Chem. Soc. Rev., 2016, 45, 9–23 (review - pdf); Willkomm, J.; Muresan, N. M.; Reisner, E. Chem. Sci., 2015, 6, 2727–2736 (pdf); Reynal, A.; Willkomm, J.; Muresan, N. M.; Lakadamyali, F.; Planells, M.; Reisner, E.; Durrant, J. R. Chem. Commun., 2014, 50, 12768–12771 (pdf); Gross, M. A.; Reynal, A.; Durrant, J. R.; Reisner, E. J. Am. Chem. Soc., 2014, 136, 356–366 (pdf); Reynal, A.; Lakadamyali, F.; Gross, M. A.; Reisner, E. Durrant, J. R. Energy Environ. Sci., 2013 , 6, 3291–3300 (pdf); Lakadamyali, F.; Reynal, A.; Kato, M.; Durrant, J. R.; Reisner, E. Chem. Eur. J., 2012 , 18, 15464–15475 (pdf); Lakadamyali, F.; Reisner, E. Chem. Commun., 2011, 47, 1695–1697 (pdf).
Photocatalysis with novel hybrid materials: towards new chemical transformations
Here, we study unexplored light-absorbing materials in photocatalysis and explore new redox chemistry. For example, we have recently established that carbon quantum dots (CQDs) are excellent photosensitisers in combination with a molecular Ni catalyst for solar light driven hydrogen production in aqueous solution (Figure, left). Another example is the selective photocatalytic conversion of formic acid into either H2 or CO was achieved with CdS nanocrystals under visible light irradiation (Figure right). In this system, product selectivity can be controlled by the solvent and particle capping ligand. As final example, we succeeded in the coupling of a [NiFeSe]-hydrogenase and a bioinspired synthetic nickel catalyst with a heptazine carbon nitride polymer, melon (CNx) for solar H2 generation.
References: Martindale, B. C. M.; Hutton, G. A. M.; Caputo, C. A.; Reisner, E. J. Am. Chem. Soc., 2015, 137, 6018–6025 (carbon dots - pdf); Kuehnel; M. F.; Wakerley, D. W.; Orchard, K. L.; Reisner, E. Angew. Chem. Int. Ed., 2015, 54, 9627–9631 (CdS dots - pdf); Caputo, C. A.; Gross, M. A.; Lau, V. W.; Cavazza, C.; Lotsch, B. V.; Reisner, E. Angew. Chem. Int. Ed., 2014, 53, 11538–11542 (carbon nitrides - pdf).
Photoelectrochemistry of the water oxidation enzyme photosystem II
In this project, we immobilize photosystem II on an electrode surface and study its photocatalytic activity with different techniques. We address basic questions about the effect of an exogenous substrate and an artificial enviroment on the electron transfer kinetics in photosystem II. We showed that photosystem II can be integrated in transparent and porous indium-tin oxide electrodes and observed direct electron transfer from photosystem II to the electrode via the natural QB and an unnatural QA electron transfer pathway. Controlled and covalent orientation of photosystem II on the nanostructured electrodes was achieved by exploiting electrostatic interactions of the dipole of the enzyme with a self-assembled monolayer on the electrode. Recently, full water splitting into H2 and O2 was achieved by wiring of photosystem II to a hydrogenase in a photoelectrochemical cell. This project is executed in collaboration with the group of Bill Rutherford at Imperial College London and Richard Friend's group at Cambridge.
References: Mersch, D.; Lee, C.-Y.; Zhang, J. Z.; Brinkert, K.; Fontecilla-Camps, J. C.; Rutherford, A. W.; Reisner, E. J. Am. Chem. Soc., 2015, 137, 8541–8549 (pdf); Kato, M.; Zhang, J. Z.; Paul, N.; Reisner, E. Chem. Soc. Rev., 2014, 43, 6485–6497 (review - pdf);
Kato, M.; Cardona, T.; Rutherford, A. W.; Reisner, E. J. Am. Chem. Soc., 2013, 135, 10610–10613 (pdf); Kato, M.; Cardona, T.; Rutherford, A. W.; Reisner, E. J. Am. Chem. Soc., 2012, 134, 8332–8335 (pdf).
Catalytic fuel generation with enzymes: Hydrogenase & Formate Dehydrogenase
Enzymes are notable benchmark catalysts for fuel forming reactions such as the reduction of protons to H2 by hydrogenases and CO2 to formic acid by formate dehydrogenase. Here, we aim to gain a better understanding of the functino of these enzymes and employ them as 'ideal' model catalysts in photocatalytic schemes, where the enzyme electrocatalyst is coupled to a light-harvestor. We are particularly interested in the selenocysteine-containing enzymes [NiFeSe]-hydrogenase from Desulfomicrobium baculatum (argubaly, the best H2 evolution catalyst known in water splitting) and the molybdenum-containing formate dehydrogenase H from the model organism Escherichia coli (EcFDH-H; a formidable CO2 to formate reduction catalyst once the enzyme is immobilised on an electrode). This work is executed in collaboration with Juan C. Fontecilla-Camps in Grenoble and Judy Hirst in Cambridge.
References: Wombwell, C.; Caputo, C. A.; Reisner, E. Acc. Chem. Res., 2015, 48, 2858–2865 (review on NiFeSe-hydrogenase - pdf); Caputo, C. A.; Wang, L.; Beranek, R.; Reisner, E. Chem. Sci., 2015, 6, 5690–5694 (hydrogenase - pdf); Bassegoda, A.; Madden, C.; Wakerley, D. W.; Reisner, E.; Hirst, J. J. Am. Chem. Soc., 2014, 136, 15473–15476 (FDH - pdf); Sakai, T.; Mersch, D.; Reisner, E. Angew. Chem. Int. Ed., 2013, 52, 12313–12316 (hydrogenase - pdf).
Synthetic catalysts & enzymes for fuel generation under demanding atmospheres
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. The state-of-the art catalyst 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 and other potential inhibitors. We found that a water soluble cobaloxime catalyst operates electro- and photocatalytically in pH neutral water and at room temperature, but also in the presence of atmospheric O2. We extended this work to hydrogenases, which were also found to generate H2 in homogenous photocatytic systems under O2. We have recently extended our work to CO-inhibition and found that a DuBois Ni catalyst is CO-tolerant.
References: Wakerley, D. W.; Reisner, E. Energy Environ. Sci., 2015, 8, 2283–2295 (review - pdf); Wakerley, D. W.; Gross, M. A.; Reisner, E. Chem. Commun., 2014, 50, 15995–15998 (pdf); Sakai, T.; Mersch, D.; Reisner, E. Angew. Chem. Int. Ed., 2013, 52, 12313–12316 (pdf); Lakadamyali, F.; Kato, M.; Muresan, N. M.; Reisner, E. Angew. Chem. Int. Ed., 2012, 51, 9381–9384 (pdf).
Synthetic molecular catalysts for fuel generation
We develop new synthetic electrocatalysts for the reduction of protons to H2 and CO2 to valuable fuels (in particular CO and formic acid) and specialise on their integration in electrodes and photocatalytic systems (see above). Two molecular H2 production catalysts developed and extensively studied in our laboratory are now commercially available via Strem Chemicals (see here for CoP and NiP and Figure below). Both catalysts operate under mild aqueous conditions and have phosphonated groups in the ligand periphery to allow for immobilisation on a range of solid state materials. We have also synthesised the first dinuclear synthetic model of the [NiFeSe] hydrogenase active site through classic biomimetic chemistry (see Figure below). A phosphonated Re catalyst (ReP) for CO2 to CO conversion has also been recently reported (not shown).
References: Wombwell, C.; Reisner, E. Chem. Eur. J., 2015, 21, 8096–8104 (NiFeSe-model - pdf); Willkomm, J.; Muresan, N. M.; Reisner, E. Chem. Sci., 2015, 6, 2727–2736 (pdf); Windle, C. D.; Pastor, E.; Reynal, A.; Whitwood, A. C.; Vaynzof, Y.; Durrant, J. R.; Perutz, R. N.; Reisner, E. Chem. Eur. J., 2015, 21, 3746–3754 (ReP - pdf); Gross, M. A.; Reynal, A.; Durrant, J. R.; Reisner, E. J. Am. Chem. Soc., 2014, 136, 356–366 (NiP - pdf); Scherer, M.; Muresan, N. M.; Steiner, U.; Reisner, E. Chem. Commun., 2013, 49, 10453-10455 (pdf); Muresan, N. M.; Willkomm, J.; Mersch, D.; Vaynzof, Y.; Reisner, E. Angew. Chem. Int. Ed., 2012, 51, 12749-12753 (pdf); Lakadamyali, F.; Reisner, E. Chem. Commun., 2011, 47, 1695–1697 (CoP - pdf).
nanocages as single source materials for energy
We investigate heterobimetallic polyoxotitanates as precursors for the deposition of stoichiometrically-controlled doped TiO2 films. Molecular Co-doped TiO2 (TiCo) Ni-doped TiO2 cage compounds are easy to hydrolyse on a surface in air and the resulting TiNi and TiCo ﬁlms act as precursors to bifunctional hydrogen and oxygen evolution catalysts in aqueous solution. In addition to serving as bifunctional electrocatalysts, TiNi and TiCo also act as single source precursors to form an amorphous TiO2 layer for protecting the semiconductor electrodes, thereby enhancing their photostability. We have therefore demonstrated that a multifunctional material can be integrated with photoelectrodes for application in solar water splitting. Our approach does not require prohibitively expensive or nonscalable materials, techniques, or experimental conditions. This project is executed in collaboration with the group of Dom Wright at Cambridge.
References: Lai, Y.-H.; Palm, D. W.; Reisner, E. Adv. Energy Mater., 2015, 5, 1501668 (pdf); Lai, Y.-H.; Park, H. S.; Zhang, J. Z.; Matthews, P. D.; Wright, D. S.; Reisner, E. Chem. Eur. J., 2015, 21, 3919–3923 12943–12947 (pdf); Lai, Y.-H.; King, T.C.; Wright, D. S.; Reisner, E. Chem. Eur. J., 2013, 19, 12943–12947 (pdf); 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 (pdf).
Solar fuels devices: Photoelectrochemical cells
Solar fuel generation, in particular the development of inexpensive and efficient photoelectrochemical (PEC) or sunlight-driven water splitting is of considerable current interest. We have reported the first tandem PEC cell for water splitting free of prohibitively expensive materials. This system consisted 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. Recently, we demonstrated that a PEC cell with a Si photocathode coupled to a BiVO4 photoanode can generate a total photocurrent of ≈2 mA, which is believed to be the highest operating photocurrent for a dual photoelectrode PEC device to date.
References: Lai, Y.-H.; Palm, D. W.; Reisner, E. Adv. Energy Mater., 2015, 5, 1501668 (pdf); Lin, C.-Y.; Mersch, D.; Jefferson, D. A.; Reisner, E. Chem. Sci. 2014, 5, 4906–4913 (pdf); Zhang, L.; Reisner, E.; Baumberg, J. J. Energy Environ. Sci., 2014, 7, 1402–1408 (pdf); Lin, C.-Y.; Lai, Y.-H.; Mersch, D.; Reisner, E. Chem. Sci., 2012, 3, 3482-3487 (pdf).
- The OMV
group & Christian Doppler Research Association
Members of the group are
currently holders of the following awards:
Members of the group are currently holders of the following awards:
Scholarships for postgraduate