Artificial Photosynthesis: from CO2 to Fuels – PhotoCarb
artificial photosynthesis: a photoelectrochemical cell for production of fuels from carbon dioxide, water and sun
Photocarb aims at integrating various molecular components for collecting solar energy, storing multiple electrons and catalyzing reduction reactions within a technological device, a photoelectrochemical cell, in order to transform CO2 into fuels, using exclusively sunlight as a source of energy as photosynthetic microoraganisms do. This research will specifically lead to the development of an original molecular photocathode.
From molecular components towards a molecular photocathode within an original photoelectrochemical cell
With PhotoCarb we intend to demonstrate that it is possible to develop a photocathose using exclusively molecular components. Molecular systems have indeed the advantage that their performances (efficiency, selectivity, stability) can be quite easily and finely controlled via synthetic modifications. Most previously reported photocathodes are almost exclusively based on solid materials (semiconductors and heterogeneous catalysts). The first critical component is the catalyst. Photocarb focusses on the design and development of new molecular catalysts for the (photo)electroreduction of CO2 into CO and/or HCOOH. More specifically, a bioinspired approach is used which consists in mimicking the active sites of formate dehydrogenases and CO-dehydrogenases. The second challenge very specific to this kind of systems which catalyze multielectronic processes is related to the requirement for transiently storing multiple electrons and delivering them at the same time. This is adressed here with combinations of catalysts and polyoxometallates since the latter are well-known for their ability to accumulate several electrons. The last step in the integration of the catalyst/polyoxometallate assemblies onto electrodes that are functionalized with molecular photosensitizers (alternatively on semiconductors). The project thus combines very fundamental approaches in order to find new molecular catalysts for CO2 reduction and technological developments aiming at integrating them into devices. The new photocathode will be coupled to a standard photoanode in order to build an original photoelectrochemical cell.
The various approaches developped within the PhotoCarb project are: (i) synthesis of organic ligands and synthesis of corresponding coordination and organometallic complexes; (ii) synthesis of supramolecular systems combining catalysts, polyoxometallates and photosensitizers; (iii) exploitation of grafting methods to attach the best supraolecular systems on solid electrodes based on transparent metal oxides (ITO/FTO); (iv) electrochemical characterization (cyclic voltammetry, controlled potential electrolysis) and phtochemical (under irradiation) characterization of the various new molecular assemblies in solution and as attached to a surface; (v) analysis of gaseous and liquid reaction products; (vi) development of a photoelectrochemical cell.
Discovery of a new class of molecular catalysts based on dithiolene ligands for the electro- and photo-reduction of CO2; synthesis and characterization of the first bioinspired Mo complex, mimicking the active site of formate dehydrogenase, that catalyzes the photochemical reduction of CO2; functionnalisation of diphosphine ligands allowing corresponding Co(Cp)-diphosphine catalysts to be soluble in water; synthesis of the first supramolecular complexes associating a molecular catalyst and a polyoxometallate demonstrating a stimulating effect of the polyoxometallate on CO2 electroreduction; first photocathodes combining a molecular photodsensitizer and a polyoxometallate demonstrating an effect of the polyoxometallate on photocurrents. All these results will serve for further integration of molecular components into a photocathode and will fracilitate further progress towards a molecular photoelectrochelmical cell.
The main results have been described above. All these results will serve for further integration of molecular components into a photocathode and will fracilitate further progress towards a molecular photoelectrochemical cell, allowing production of solar fuels from CO2.
«A Bioinspired Nickel(bis-dithiolene) Complex as a Novel Homogeneous Catalyst for Carbon Dioxide Electroreduction
T. Fogeron, T. K. Todorova, J.-P. Porcher, M. Gomez-Mingot, L.-M. Chamoreau, C. Mellot-Draznieks, Y. Li, M. Fontecave
ACS Catalysis 2018, 8, 2030-2038
Pyranopterin Related Dithiolene Molybdenum Complexes as Homogeneous Catalysts for CO2 Photoreduction
T. Fogeron, P. Retailleau, L.-M. Chamoreau, Y. Li, M. Fontecave
Angew. Chem. Int. Ed. Engl. 2018 in press
Nickel complexes based on molybdopterin-like dithiolenes: catalysts for CO2 electroreduction
T. Fogeron, P. Retailleau, M. Gomez-Mingot, Y. Li, M. Fontecave
Organometallics 2018 (submitted)«
The development of solar energy requests new technologies for energy storage. One fascinating option resides in the selective reduction of CO2 into energy-dense organic compounds. This strategy is used in photosynthetic organisms which have evolved a unique mechanism to convert CO2 and H2O into biomass under sunlight. PhotoCarb is aimed at developing novel energy storage systems via an artificial photosynthesis approach. This consists in the preparation, characterization, heterogenization of photosensitizer/electron reservoir/catalyst molecular assemblies and their evaluation as catalysts for CO2 photoelectroreduction. The objective of PhotoCarb is the development of a complete PhotoElectrochemical Cell (PEC) based exclusively on non-noble metals. Thus three tasks are proposed. Task 1 is devoted to the optimization of catalysts discovered within the previous CarBioRed ANR project, namely metal-terpy (metal = Co, Ni or Mn) complexes, cobalt-diphosphine-cyclopentadienyl complexes and metal-dithiolene (metal= Mo and Ni) complexes. In addition an original issue, specifically their combination with proton- and electron-reservoirs appropriate for the multi-proton and multi-electron processes at work, is addressed in the PhotoCarb project. Polyoxometalates (POMs) exquisitely fit such properties and are chosen for exploring the potential of POM-catalyst supramolecular systems. Task 2 will select the best systems to engineer and evaluate the performances of molecular-based photocathodes, via their immobilization on low band-gap semiconductors and the elaboration of dye-sensitized photocathodes. Task 3 finally will integrate the best photocathodes within a PEC. This research will not only provide new insights into basic questions regarding multi-electron multi-proton CO2 reduction (photo)catalysis but also translate this knowledge into a practical proof-of-concept device, which is still a challenging issue.
Project coordination
Marc Fontecave adresse erronée (Chimie des Processus Biologiques)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partner
IPCM Institut Parisien de Chimie Moleculaire
LCBM Chimie et Biologie des Metaux
College de France Chimie des Processus Biologiques
Help of the ANR 608,096 euros
Beginning and duration of the scientific project:
November 2016
- 48 Months
