Description du sujet de thèse

Green dihydrogen production with nanocomposite materials based on molybdenum carbides or nitrides

The electrochemical production of dihydrogen from water splitting (green hydrogen) is a major challenge for the decarbonization of energy production/storage in Europe. At present, green hydrogen accounts for 4% of the energy mix, and this share must be increased to 13-15% by 2050, while targeting low production costs, according to the roadmap proposed by the EU. The challenges to be met are immense and concern all aspects of electrolysis devices, particularly electrocatalytic electrode materials. The aim of this thesis project is to evaluate the performance of molybdenum carbide/nitride-based materials in water splitting reactions, so-called HER and OER. These materials show good activity in these reactions, and molybdenum is not considered a critical metal by the EU, unlike the noble metals (Pt, etc.) and nickel used in current electrolysis technologies (PEM or alkaline electrolyzers).

Contexte de travail

The work will be carried out at the Institut des Sciences Chimiques de Rennes (UMR 6226, Rennes) as part of a collaborative project supported by the Agence Nationale de la Recherche (ANR 2024, project MONICA), in collaboration with 2 academic partners (NIMBE-CEA, UMR 3685 (Saclay), IRL 3629 LINK (Tsukuba, Japan)) and 1 industrial partner (Nanomakers). An important aspect of the project is the large-scale synthesis of catalytic materials using a laser pyrolysis technique. This aspect represents a real challenge to be met in the context of the deployment of low-carbon H2 production in line with the stakes involved.
The materials, synthesized by our partners, will be characterized in the laboratory using a combination of techniques (DRX analysis, vibrational spectroscopy (IR, Raman), X-ray photoemission spectroscopy (XPS), electron microscopy (SEM and TEM), ATG, porosity measurements, etc.). Fine characterization analyses will also be performed at the LINK laboratory in Japan.
Electrocatalytic performance will be assessed using state-of-the-art electrochemical methods, in half and full cells. Gas production (H2 and O2) will be monitored by gas chromatography coupled to the electrochemical cell. The operational durability of the materials will be assessed. The aim of these studies is to correlate the electrocatalytic performance of nitride or carbide materials with their physico-chemical characteristics (morphology, texture, crystallite size, composition, etc.) with a view to optimizing the synthesis of these materials.

Skills
The candidate will have a keen scientific curiosity and a real motivation to develop robust expertise in the fields of materials chemistry and electrocatalysis. The PhD candidate will be responsible for characterizing nanocomposites, shaping them to optimize their catalytic activity, in particular by formulating electrode materials, and testing their performance in water reduction and oxidation reactions. He or she will also be responsible for analyzing the results, formatting them and keeping abreast of the literature.
With a Master's degree or equivalent in materials chemistry or electrochemistry, the candidate should have a solid background in electrochemistry and/or materials chemistry, and in particular characterization (chemical analysis, X-ray diffraction, microscopy and/or spectroscopy). He or she will participate in the activities of the research teams, and will be required to present his or her work at national and international conferences. A good level of English is required.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.