Plasmon mediated electrochemical synthesis of nitrogen compounds

Artificial nitrogen fertilizers sustain nearly half of the global population and are indispensable to modern agriculture. Each year, over 150 million tons of nitrogen ends up in fertilizer, primarily through the Haber-Bosch process, which converts atmospheric nitrogen (N₂) into ammonia (NH₃); the key precursor for all nitrogen-based fertilizers and compounds. Despite its scale and importance, this process comes with a significant environmental burden. It relies heavily on fossil-derived hydrogen, typically obtained via methane reforming, which results in nearly 500 million tons of CO₂ emissions annually. Furthermore, the Haber-Bosch process is highly energy-intensive and centralized, carried out in only a few hundred large-scale plants worldwide. This centralized infrastructure leads to high transportation costs and limited accessibility for farmers in remote regions. Efforts to decarbonize ammonia synthesis focus on replacing fossil hydrogen with green hydrogen produced via water electrolysis. While this substitution eliminates CO₂ emissions from hydrogen production, it substantially increases the overall energy demand of the process. Ammonia must now be synthesized from two low-energy molecule, water and nitrogen, rather than methane, and additional costs arise from hydrogen storage and distribution, especially in decentralized settings.

This PhD project proposes a fundamentally different approach: electrochemical nitrogen activation, which could enable decentralized, low-carbon fertilizer production without the need for hydrogen. By directly converting N₂ into reactive intermediates using electricity, this method offers a promising route toward more sustainable and distributed ammonia synthesis. However, molecular nitrogen is notoriously difficult to activate. Its apolar nature and the strength of the N≡N triple bond make it one of the most inert molecules in chemistry, typically requiring extreme conditions such as high temperatures, pressures, or plasma environments to initiate bond cleavage. Even within the Haber-Bosch process, the dissociative adsorption of N₂ on catalytic metal surfaces remains the rate-limiting step.

By coupling thermal activation with plasmonic enhancement, we aim to activate electrochemical reaction pathways and improve turnover rates at moderate temperatures. At imec, we have developed gas-diffusion electrodes with nanostructured metal electrodes and solid proton conducting electrolytes operating at elevated temperatures. Through modelling, it has been predicted that metals such ruthenium and silver have plasmonic effects for nitrogen activation. In this PhD project, you will investigate and optimize the plasmonic effects on these nanostructured electrodes to enhance the reaction kinetics and facilitate electrochemical oxidation of nitrogen.

As a PhD researcher, you will be embedded in imec’s interdisciplinary ecosystem, working at the intersection of electrochemistry, materials science, and engineering. You will gain hands-on experience in electrochemical analysis, membrane electrode assembly design, material synthesis and characterization, spectroscopic techniques for reaction monitoring, and prototype development and testing. This position offers a unique opportunity to contribute to pioneering research in sustainable fertilizer production and help shape the future of decentralized chemical manufacturing.