Towards H2-evolving Photoelectrode Materials
Our group is now engaged in several projects aiming at developing new photocathode materials for H2 evolution and their integration into a fully operative Photo-Electro-Chemical (PEC) cell. Both solid-state and fully molecular-immobilized systems are targeted. In addition hydrid systems combining a molecular catalysts and solid-state semi-conductors are developed in collaboration with Dr. Phong D. Tran and Prof. Jim Barber from the Solar Fuel Lab of Nanyang Technological University in Singapore.
Grafting photosensitizers onto Transparent Conducting Electrodes
To enter this project, we first targeted the preparation and characterization of dye-sensitized nanostructured mesoporous ITO (templated nano-ITO) electrodes. In the framework of a collaboration with the group of Prof. Christel Laberty-Robert and Prof Clément Sanchez, a multi-layer template-directed sol-gel process was successfully applied for the preparation of ITO films with tunable thickness onto glass substrates, resulting in high conductivities and transparencies. Electrochemical and photo-electrochemical characterizations were realized after surface functionalization by a redox active ruthenium dye. Grafting densities as high as 3.6 10-9 mol.cm-2 were measured (100 times higher than on a planar substrate) and cathodic photocurrents with intensities of 50 mA.cm-2 were established under visible light irradiation in presence of a redox mediator in solution. This represents the first step toward the construction of a photoelectrochemical device.
ArtipHyction, a collaborative FCH-JU-funded project
Building on the pioneering work performed in a precedent project based on natural enzymes (Solhydromics, FP7-Energy-2008-FET) and the convergence of the work of the physics, materials scientists, chemical engineers and chemists involved in the project, an artificial device will be developed to convert sun energy into H2 with close to 10% efficiency by water splitting at ambient temperature, including:
- an electrode exposed to sunlight carrying a PSII-like chemical mimic deposited upon a suitable transparent electron-conductive porous electrode material (e.g. ITO, FTO);
- a membrane enabling transport of protons via a pulsated thin water gap;
- an external wire for electron conduction between electrodes;
a cathode carrying an hydrogenase-enzyme mimic over a porous electron-conducting support in order to recombine protons and electrons into pure molecular hydrogen at the opposite side of the membrane (our team is mainly involved in this last task).
A tandem system of sensitizers will be developed at opposite sides of the membrane in order to capture light at different wavelengths so as to boost the electrons potential at the anode for water splitting purposes and to inject electrons at a sufficiently high potential for effective H2 evolution at the cathode. Along with this, the achievement of the highest transparency level of the membrane and the electrodes will be a clear focus of the R&D work. A proof of concept prototype will be assembled and tested by the end of the project.
Web site of ArtipHyction
The ERC-granted PhotoCatH2ode project
The ERC-granted PhotoCatH2ode project
Gathering organic and hybrid photovoltaics with artificial photosynthesis for Photo-Electro-Chemical production of hydrogen. The objective of this project is to design an operating photocathode based on Earth-abundant elements for photo-electro-chemical production of hydrogen answering therefore the sustainability and cost-effectiveness issues. The novelty relies on the approach gathering organic and hybrid photovoltaics with artificial photosynthesis to design original materials and architectures. More precisely, we will combine and immobilize molecular photosensitizers with bio-inspired catalysts on an electrode surface thanks to electronic junctions. This will allow :
- optimizing the light-driven charge separation,
- controlling the successive electron transfer steps from the electrode to the catalyst,
- and limiting charge recombination processes.