PhD Thesis (M/F): Development of nanostructured electrocatalysts for the conversion of nitrate waste into green ammonia

Job Description

Thesis Subject

This doctoral contract is part of the BOOOST project, which is funded by the ANR from 2025 to 2029. The project aims to develop a new methodology for engineering electrodes decorated with electrocatalytically active nanostructures that also exhibit high Raman scattering efficiency. Many candidate electrocatalysts that are validated in preliminary three-electrode configurations on very small surfaces and/or in catalytic ink formulations fail to pass the validation stage in an electrolyzer because the synthesis methods are difficult to scale up. The idea is therefore to retro-engineer electrocatalysts directly onto industrial electrode substrates (GDEs, GDLs) to eliminate the intermediate step of preparing catalytic inks, thereby overcoming persistent bottlenecks in a realistic testing environment without compromising replicability.

In addition to the reverse engineering aspects guiding the development of new electrocatalysts on customizable GDE supports (e.g., 10-100 cm2) compatible with electrolyzers, this thesis topic lies at the intersection of electrocatalysis and environmental science. The ultimate goal is to develop low-cost systems capable of selectively converting nitrates into green ammonia. The primary aim of this process is to remove nitrates from wastewater to prevent health issues. The secondary aim is to offer an alternative to the current Haber-Bosch process, which accounts for 1.5% of global CO₂ emissions and approximately 2% of global energy consumption [2].

Although the electrolysis strategy is an elegant approach powered by renewable electricity from various sources (e.g., solar, wind, and hydro), the operation of electrocatalysts for the relatively complex nitrate reduction reaction involving coupled proton and electron transfer (NO3RR: NO3– + 6H2O + 8e– → NH3 + 9OH–) is not yet well understood in terms of balancing the three parameters of activity, selectivity, and stability. For instance, nitrogen exists in its most oxidized and reduced states (N(+V) and N(-III), respectively) between nitrate and ammonia, which implies the formation of several other compounds (NO2–, NO, N2O, NH2OH, N2, etc.). The fundamental objective of this thesis project is thereby to determine the performance parameters (activity, selectivity, and stability) that govern NO3RR. The project aims to achieve efficient macroscopic-scale conversion in electrolyzers and to conduct mechanistic studies using time-resolved in situ electrochemical and Raman measurements. The synthesis strategy hinges on controlled electrodeposition of metal nanostructures with complementary catalytic effects (M, M1@M2, M = Cu, Au, Ag, etc.) on inexpensive GDE electrodes intended for electrolysis and carbon ultramicroelectrodes (UME) for fundamental studies, all without organic surfactants, which block access to certain active sites. Our goal is to provide as precise as possible experimental evidence on a single fiber (i.e., UME) and on a set of fibers (i.e., GDE) regarding the initial mechanistic steps of NO₃RR. The current literature on this topic is divided: (1) Are all N-O bonds broken in the nitrate prior to hydrogenation to NH3? Or (2) does hydrogenation begin after the first or second N-O bond in the nitrate is broken?

The thesis will leverage the supervisory team's unique expertise in materials synthesis, including electrochemistry, electrocatalysis and atomic layer deposition (ALD), as well as instrumental methods, such as coupling electrochemistry and Raman spectroscopy [4]. Final validation will be performed on a pre-industrial electrolyzer prototype designed at IEM Montpellier.
The work will be conducted in collaboration with a postdoctoral researcher affiliated with the Paris Institute of Molecular Chemistry (IPCM, Sorbonne University), under the guidance of Professor Emmanuel Maisonhaute.

Reading:
[1] D. Siegmund et al., JACS Au 2021, 1, 527, https://doi.org/10.1021/jacsau.1c00092.
[2] P. H. van Langevelde et al., Joule 2021, 5, 290, https://doi.org/10.1016/j.joule.2020.12.025.
[3] H. Yin et al., ACS Nano 2023, 17, 25614, https://doi.org/10.1021/acsnano.3c10058; F.-Y. Chen et al., Nat. Nanotechnol. 2022, 17, 759, https://doi.org/10.1038/s41565-022-01121-4; W. Jung et al., Mater. Chem. Front. 2021, 5, 6803, http://dx.doi.org/10.1039/D1QM00456E.
[4] Z. Hagheh Kavousi et al., J. Mater. Chem. A 2025, 13, 34231, http://dx.doi.org/10.1039/D5TA02374B; Y. Holade et al., ACS Catal. 2022, 12, 12563, https://doi.org/10.1021/acscatal.2c03399; B. A. Karamoko et al., ChemElectroChem 2025, 12, e202500338, https://doi.org/10.1002/celc.202500338; Z. Hagheh Kavousi et al., ChemSusChem 2024, 17, e202400996, https://doi.org/10.1002/cssc.202400996.
[5] T. Touzalin et al., Curr. Opin. Electrochim 2017, 6, 46, https://doi.org/10.1016/j.coelec.2017.10.016; X. S. Zhou et al., Chem. Commun. 2016, 52, 251, http://dx.doi.org/10.1039/C5CC07953E; T. Touzalin et al., Anal. Chem. 2017, 89, 8974, https://doi.org/10.1021/acs.analchem.7b01542.

Your Work Environment

The PhD student will be enrolled in the Balard Doctoral School of Chemical Sciences (No. 459) at the University of Montpellier. The thesis research will take place at the European Institute of Membranes (IEM, UMR 5635, Univ. of Montpellier, ENSCM, CNRS), an internationally renowned laboratory specializing in membrane materials and processes with a multiscale and multidisciplinary approach. IEM, ICGM, IBMM, and ICSM are part of the Balard Chemistry Cluster, a center of excellence dedicated to bridging research, education, and business. The doctoral student will benefit from a supportive work environment within the framework of research-based training, in addition to over 100 hours of supplementary training from the courses offered by the Doctoral School.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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