Electrocatalysis on 2-D chiral & conducting surfaces

For the transition towards a more sustainable world, the energy costs have to be reduced amongst the industrial processes. Electrochemistry and electrocatalysis are crucial in that regards. For example, the Oxygen and Hydrogen Evolution Reactions resulting from water electrolysis are one of the cornerstone for energy storage under a chemical form. These reactions have their downsides and bottlenecks, such as the high potential required and their sluggish kinetics. While many strategies have been developed to improve electrocatalytical processes over the years, through fine tuning of the metals used and their coordination spheres, it is only lately that a new approach based on the direct control of the electron spin emerged. Spin directed electrocatalysis has the potential to significantly improve the performance of the reactions.

The combination in an array of molecules of chirality and conductivity generates exotic physical effects such as the Chirality Induced Spin Selectivity (CISS effect). This recently discovered effect states that the transport of electrons through a chiral material is correlated to the spin of the electron and the handedness of the chiral molecules. The material is therefore acting as a spin polarizer. Most of the reported examples are based on the adsorption of chiral molecules on a metallic surface, and not on a stronger covalent bonding. However, when immobilizing a chemical structure, the properties expression is related to the molecule accessibility, its interaction with the substrate and the organization of molecular buildings.

This project aims to prepare nanometric organic layers grafted via the diazonium electroreduction technique and perform physico-chemical characterization to obtain structural information. We will target the deposition of Helicenes, a class of chiral molecules renowned for their typical helicoidal structure and exceptional chiroptical properties.

The project will start with the synthesis of the target molecules, followed by their deposition on surfaces and the characterization of the surfaces through advanced electrochemical methods. [4]helicene will be first used as a model structure to assess the grafting process and further studies will be conducted with racemic and then chiral [6]helicene. Structure/properties relationships will be studied in the field of chiral electrocatalytical processes, such as OER, HER, or CO₂ electro-reduction.

The project will involve strong collaborations between specialists of chiral synthesis and surface modification in MOLTECH-Anjou and measurement of the CISS effect at the Hebrew University of Jerusalem. MOLTECH-Anjou is a renowned laboratory located in the lovely city of Angers, specialized in organic chemistry, electrochemistry, photovoltaics and material chemistry, with about 80 co-workers. Pr. Breton holds a strong background in the field of electrochemistry, surface chemistry and electrode functionalization, while Dr. Zigon has a strong background in material analysis, chirality and helicene-based chemistry. A 4-months stay in HUJI (Partner: Dr. Y. Paltiel) will be made during the PhD to develop the spin-based devices. The laboratories are fully equipped for organic synthesis, electrochemical measurements and surface characterizations. Participation to national and international conferences will be encouraged.

The work will be divided in two parts: synthesis and resolution of targeted diazotizated helicenes, and then grafting and physicochemical characterization of the layers formed by electrochemical measurements, spectroscopic techniques and atomic force microscopy. The student, holder of a master 2, must therefore have a strong affinity for electrochemistry and surface characterization techniques. A good knowledge in organic synthesis will be appreciated.

Taking this PhD topic will provide the applicant a broad knowledge of organic synthesis, and an expertise in surface chemistry, electrochemistry, electrocatalysis, and chirality related physical phenomenons. His/her abilities to communicate scientific results (writing and oral), monitor the scientific literature, or work as part of a larger team in an international environment will also be developed.