Potential synergy between NH3 and NaBH4 for improved H2 density and enhanced safety
The thesis focuses on the study of the hybrid ammonia–sodium borohydride system (NH3–NaBH4) as an innovative chemical energy carrier. The objective is to investigate the combination of ammonia (NH3), recognised for its high hydrogen density and mature industrial infrastructure, with sodium borohydride (NaBH4), a high-capacity chemical hydrogen storage material, in order to overcome certain limitations associated with each vector when considered separately.
The proposed work specifically addresses the safer storage and transport of ammonia through its coupling with sodium borohydride, enabling a reduction in vapour pressure (compared to 8.88 bar at 21 °C for liquid ammonia) and less restrictive operating conditions. In parallel, the thesis aims to improve the stability (relative to the H2O–NaBH4 system) and operability of sodium borohydride which, when combined with ammonia molecules (acting as inert species), forms stable liquid or viscous phases that are potentially pumpable, thereby facilitating integration into energy-related processes.
The fundamental goal of the thesis is to understand the physicochemical mechanisms governing this hybrid system, particularly the role of dihydrogen interactions between the N–H bonds of ammonia and the B–H bonds of borohydride, and their influence on stability, reactivity, transport properties, and hydrogen release pathways (thermal and/or hydrolytic).
Beyond its storage function, the thesis also explores the potential of the NH3–NaBH4 system as a novel hybrid material with high gravimetric and volumetric hydrogen capacity, while considering realistic operational constraints relevant to energy applications in a dual-use context. At this stage, exhaustive optimisation is not the primary objective.
Optimising the enzymatic degradation of polylactic acid (PLA) to produce biohydrogen (BioH2) through photofermentation.
This thesis project presents a novel method of producing biohydrogen (BioH2) through the enzymatic breakdown of polylactic acid (PLA), a bioplastic which is challenging to recycle. The aim is to optimise the hydrolysis of PLA into lactic acid, which can be metabolised directly by purple non-sulfur bacteria (PNSB) to produce BioH2 in anoxic conditions. The work will entail selecting high-performance esterases in collaboration with Génoscope CEA, expressing them in soluble form in model hosts such as E. coli, yeasts and PNSB, and optimising reaction conditions such as pH, temperature and concentration to maximise lactic acid production. The second phase will focus on enhancing photofermentation in a photobioreactor (PBR) with advanced control systems (LED, AI and CFD). Funded by the CEA and PUI Grenoble Alpes, this project is part of a circular economy approach, aiming to develop a scalable process for converting PLA waste into renewable energy in line with the challenges of the energy transition.
development of a NET (Negative Emission Technologie) process combining CO2 capture and hydrogenation into synthetic fuel
Until recently, CO2 capture technologies were developed separately from CO2 utilization technologies, even though coupling the CO2 desorption stage with the chemical transformation of CO2, which is generally exothermic, would yield significant energy savings.
The first coupled solutions have recently been proposed, but they are mainly at moderate temperatures (100-180°C) [1], or even recently close to 225°C [2].
The objective of this doctoral thesis is to study, both experimentally and theoretically, a coupled system in the 250-325°C temperature range that allows via Fischer-Tropsch-type catalytic hydrogenation the direct production of higher value-added products
Understanding Lithium Recovery Mechanisms through the Application of Electrochemical Pumping on Battery Leachates
The economical, environmental and geopolitical context recently pushed Europe to issue a regulation on battery recycling. By 2031, 80% of lithium in batteries should be recovered. In this context, CEA is interested in Electrochemical Lithium-Ion Pumping (ELIP): this process uses battery electrodes to selectively insert and disinsert lithium, allowing to extract it from a complex solution. Unlike more common lithium recovery processes, ELIP allies a high selectivity towards lithium, does not require the use of toxic chemicals during the process and offers the possibility to be used in a continuous flow mode, practical for industrial applications. A first PhD work on the subject, in our team, evidenced for the relevance of such a process for the separation of lithium from other alkali cations (sodium and potassium). Real battery leachates are however more complex and can include transition metal cations and organic species besides alkaline cations. The proposed PhD subject has the aim to precisely understand the effect of these solutions on the ELIP process in order to choose the best position in the recycling loop (upstream or downstream), and to adapt to adverse effects encountered in such conditions. The impact of the other species present in solution will be evaluated on selectivity, efficiency and durability at different scales: material, electrode and membrane. Chemical (ICP-AES, EDX), structural (XRD) and morphological (SEM, TEM) characterizations will be correlated with electrochemical results in order to identify side reactions and species which impact the most the performances. Based on these results, the PhD student will have to test different improvement protocols (additive incorporation, pH control, change of the electrochemical method, etc...) and to understand the physico-chemical reasons governing these improvements. The PhD work will allow to propose a thoughtful integration of the ELIP process in conventional battery recycling steps, as well as highlighting the relevance, or not, of such a process for lithium extraction from real leachates.
Physicochemical Properties of Antimony-containing Photovoltaic (PV) Glass
The proposed PhD thesis is part of the ANR GRISBI project (2026–2030), which aims to optimize the recycling of glass from photovoltaic (PV) panels. These glasses, predominantly manufactured in China, are doped with antimony oxide (Sb2O3) to ensure high transparency while keeping production costs low. However, the presence of antimony currently prevents the recycling of these glasses within the European flat glass industry, which would otherwise greatly benefit from this secondary raw material to reduce its environmental footprint — particularly its greenhouse gas emissions, in line with the carbon neutrality targets set by the Paris Agreement (2015). To make the recycling of PV glass into flat glass production feasible, it is therefore essential to gain a deeper understanding of the physicochemical behavior of antimony in glass, and more generally, within the float process, which involves a hot glass / liquid tin interface.
The core scientific objective of the PhD is to determine the redox equilibria between the multivalent species present in PV glasses, in particular the Sb2O3/Sb and Fe2O3/FeO couples. The work will involve preparing glasses with different Sb2O3 contents, then determining the mechanisms of antimony incorporation into the glass structure, as well as the temperature and oxygen partial pressure (pO2) conditions leading to the reduction of Sb³? to metallic Sb°. Experimental results, based on advanced materials characterizations such as SEM, XRD, EXAFS, and XANES, will be used to enrich thermodynamic databases and to develop a methodology enabling the recycling of Sb-doped PV glasses in flat glass production.
The PhD will be conducted at CEA Marcoule, in collaboration with IMPMC (Sorbonne Université) — two laboratories internationally recognized for their expertise in glass science. All glass samples will be synthesized by the PhD student, and their characterization will primarily rely on facilities available at CEA and IMPMC.
A background in Materials Science is required. This research project will provide the PhD candidate with the opportunity to develop strong expertise in applied glass science and industrial recycling technologies.