Interfacial Dynamics and Solar Fuel Formation in Dye-Sensitized Photoelectrosynthesis Cells (original) (raw)
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The replacement of fossil fuels by a clean and renewable energy source is one of the most urgent and challenging issues our society is facing today, which is why intense research has been devoted to this topic recently. Nature has been using sunlight as the primary energy input to oxidise water and generate carbohydrates (solar fuel) for over a billion years. Inspired, but not constrained, by nature, artificial systems can be designed to capture light and oxidise water and reduce protons or other organic compounds to generate useful chemical fuels. This tutorial review covers the primary topics that need to be understood and mastered in order to come up with practical solutions for the generation of solar fuels. These topics are: the fundamentals of light capturing and conversion, water oxidation catalysis, proton and CO 2 reduction catalysis and the combination of all of these for the construction of complete cells for the generation of solar fuels.
Molecular artificial photosynthesis
Chemical Society Reviews, 2014
The replacement of fossil fuels by a clean and renewable energy source is one of the most urgent and challenging issues our society is facing today, which is why intense research has been devoted to this topic recently. Nature has been using sunlight as the primary energy input to oxidise water and generate carbohydrates (solar fuel) for over a billion years. Inspired, but not constrained, by nature, artificial systems can be designed to capture light and oxidise water and reduce protons or other organic compounds to generate useful chemical fuels. This tutorial review covers the primary topics that need to be understood and mastered in order to come up with practical solutions for the generation of solar fuels. These topics are: the fundamentals of light capturing and conversion, water oxidation catalysis, proton and CO 2 reduction catalysis and the combination of all of these for the construction of complete cells for the generation of solar fuels.
The Light Reactions of Photosynthesis as a Paradigm for Solar Fuel Production
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The overall process of photosynthesis can be deconstructed into four distinct stages, each of which can be mimicked as a first step towards developing robust, integrated, supra-molecular systems or devices capable of using solar energy to produce a reduced product, fuel. This process is necessary because natural photosynthesis is rather inefficient. In this short review we outline the steps that would be required to produce systems capable of using solar energy to make fuels more efficiently. It is emphasised that these aims will require an extended multidisciplinary effort that will undoubtedly involve close collaboration between academic and industrial scientists.
Finding the Way to Solar Fuels with Dye-Sensitized Photoelectrosynthesis Cells
Journal of the American Chemical Society, 2016
The dye-sensitized photoelectrosynthesis cell (DSPEC) integrates high bandgap, nanoparticle oxide semiconductors with the light-absorbing and catalytic properties of designed chromophore-catalyst assemblies. The goals are photoelectrochemical water splitting into hydrogen and oxygen and reduction of CO2 by water to give oxygen and carbon-based fuels. Solar-driven water oxidation occurs at a photoanode and water or CO2 reduction at a cathode or photocathode initiated by molecular-level light absorption. Light absorption is followed by electron or hole injection, catalyst activation, and catalytic water oxidation or water/CO2 reduction. The DSPEC is of recent origin but significant progress has been made. It has the potential to play an important role in our energy future.
Molecular catalysts for artificial photosynthesis: general discussion
Faraday discussions, 2017
Leif Hammarström opened discussion of the paper by Licheng Sun: You indicated using separate panels for PV and solar heating on the same roof top which compete for space in the sun. Instead, have you considered using the heat that is generated from the PV and circulating the water to the electrolyzer? Then you also increase the efficiency of the PV. Licheng Sun responded: That is an even better idea, and solves the problem of competing roof area. Masayuki Yagi asked: I am interested in the temperature dependence of the water oxidation catalysis. The linear relationship between the current density and temperature shows that the enhanced water oxidation is not ascribed to an activation process. If it involves the usual activation process, there is a linear relationship between the logarithm of the current density and the inverse of the temperature. How could you explain the enhancement of the water oxidation catalysis? Licheng Sun replied: In addition to the thermodynamic reasons, kinetics processes are the major contributors to these temperature effects. Masayuki Yagi remarked: Diffusion of H + and proton acceptors (if needed) could be important for electrochemical water oxidation. Is the enhanced water oxidation catalysis temperature due to diffusion of H + and proton acceptors? Did
Light-induced water oxidation in photosystem II
Frontiers in Bioscience, 2011
Introduction 3. Excitation enery transfer, charge separation, and quinone reduction 3.1. Excitation energy transfer and charge separation 3.2. Non-heme iron and quinones 3.3. Creation of a strong oxidant 4. Redox states of the Mn4Ca-cluster 4.1. Kok-cycle and S-states 4.2. X-ray spectroscopy 4.3. Electron paramagnetic resonance (EPR) spectroscopy 4.4. Electron nuclear double resonance (ENDOR) spectroscopy 4.5. Chemical reduction of the Mn4Ca-cluster 4.6. Net charge changes of the Mn4Ca-cluster 5. Structure of the Mn4Ca-cluster 5.1. X-ray crystallography 5.2. Extended X-ray absorption fine structure (EXAFS) 5.3. Ca site and Ca/Sr exchange 5.4. EPR/ENDOR spectroscopy 5.5. Ligand sphere of the Mn4Ca-cluster 5.5.1. Asp A170 5.5.2. Glu A189 5.5.3. His A332 5.5.4. Glu A333 5.5.5. His A337 5.5.6. Asp A342 5.5.7. C-terminal Ala A344 5.5.8. Glu C354 6. Educt and product channels 6.1. Channel proposals 6.2. Channel calculations 6.3. Noble gas pressurization 7. Chloride binding sites 8. Redox-active tyrosines 8.1. YZ 8.2. Metalloradical signals of YZ 8.3. YD 9. Proton release 10. Water binding, water consumption, and oxygen release 10.1. Water binding sites 10.2. Water insertion and consumption 10.3. Dioxygen formation and release 11. Conclusion and Perspectives 12. Acknowledgments 13. References
Photoelectrochemical kinetics of a photosynthetic cell
Journal of Electroanalytical Chemistry, 1994
A photosynthetic semiconductor electrochemical cell which spontaneously fiies CO, into an organic molecule such 'as benzyl chloride to form phenyl acetic acid was constructed. The photosynthetic cell supplies electric power to the outer circuit as well as converting the organic compound to higher quality molecules under illumination. The competitive reaction between photoelectrochemical CO, fixation and charge recombination on the photocathode is analyzed using the information provided by the variation of the short-circuit photocurrent with irradiation intensity and benzyl chloride concentration.
Journal of Photochemistry and Photobiology B: Biology, 1998
Two artificial photosynthetic reaction centers consisting of a porphyrin (P) covalently linked to both a carotenoid polyene (C) and a fullerene derivative (Coo) have been prepared and found to transfer triplet excitation energy from the fullerene moiety of C-P-3Cto to the carotenoid polyene, yielding 3C-P-COO. The transfer has been studied both in toluene at ambient temperatures and in 2-methyltetrahydrofuran at lower temperatures. The energy transfer is an activated process, with E, = 0.17 eV. This is consistent with transfer by a triplet energy transfer relay, whereby energy first migrates from C-p-3C6o to the porphyrin, yielding C-3p-C6o in a slow, thermally activated step. Rapid energy transfer from the porphyrin triplet to the carotenoid gives the final state. Triplet relays of this sort have been observed in photosynthetic reaction centers, and are part of the system that protects the organism from damage by singlet oxygen, whose production is sensitized by chlorophyll triplet states. The fullerene-containing triads can also demonstrate stepwise photoinduced electron transfer to yield long-lived C'+-P-COO "-charge-separated states. Electron transfer occurs even at 8 K. Charge recombination of C'+-P-C6o "-yields 3C-p~oo, rather than the molecular ground state. These photochemical events are reminiscent of photoinduced electron transfer in photosynthetic reaction centers.
Artificial photosynthesis: biomimetic approaches to solar energy conversion and storage
Using sun as the energy source, natural photosynthesis carries out a number of useful reactions such as oxidation of water to molecular oxygen and fixation of CO2 in the form of sugars. These are achieved through a series of light-induced multielectron- transfer reactions involving chlorophylls in a special arrangement and several other species including specific enzymes. Artificial photosynthesis attempts to reconstruct these key processes in simpler model systems such that solar energy and abundant natural resources can be used to generate high energy fuels and restrict the amount of CO2 in the atmosphere. Details of few model catalytic systems that lead to clean oxidation of water to H2 and O2, photoelectrochemical solar cells for the direct conversion of sunlight to electricity, solar cells for total decomposition of water and catalytic systems for fixation of CO2 to fuels such as methanol and methane are reviewed here.