GREENH3 – Laboratoire CEISAM // CEISAM Institute

The GREENH3 project tackles the grand challenge of (photo)electrochemical production of ammonia (NH3) from atmospheric N2 without using H2 or emitting CO2, as an alternative to the current Haber-Bosch process which consumes 1% of the world energy and emits nearly 1.5% of the CO2. Indeed, (photo)electrosynthesis ((photo)Power-to-X) is the most promising choice for a green, onsite and decarbonized production of NH3 (that can be decomposed to produce decarbonized H2). NH3 is a chemical with strategic, societal and economic importance for various industrial applications such as fertilizers, power plants and fuel cells. For decades, scientists have dreamed to use atmospheric N2 to produce NH3 without using H2 nor generating CO2. This attractive scenario remains beyond reach due to the lack of fundamental knowledge regarding the parameters that dictate the activity, selectivity and durability of catalysts. The nitrogen reduction reaction (NRR, N2 + 6H+ + 6e-  2NH3) is an electrochemical process that needs six electrons and six protons, implying a cascade of elementary steps that require a delicate balance of reactivity at the metal active site M. Such active site should indeed be able to cleave the N-N triple bond without creating a too strong, poisoning M-N interaction, and simultaneously avoid competitive reduction of protons to H2. Seminal studies have shown that both a control of the catalyst structure and the nature of the electrolytic medium are key to achieve a good Faradaic efficiency. We therefore propose paradigm shifts rooted in the development of unexplored molecular and heterogeneous (photo)electrocatalysts exclusively based on non-noble metals, as well as novel ionic liquid electrolytes. With these innovative catalytic systems, we will: (i) identify the most promising phases, (ii) provide atomic and molecular scale understanding of the catalytic mechanisms and accurately model the prepared (photo)electrocatalysts by including an explicit description of the solvent and the inclusion of relevant molecules of the electrolyte, (iii) optimize the NRR catalysts and insert them into (photo)electrolyzers with unprecedented performance. GREENH3 will decipher the mechanisms that lock today’s direct (photo)electrochemical conversion of atmospheric N2 to high-value ammonia. We will experimentally and computationally unravel how catalyst structures affect (photo)electrocatalytic functions and determine structure-activity relationships by combining cutting-edge electrochemical, photocatalytic and computational approaches. The innovation in the ionic liquids as electrolytes with a control over the proton source will provide the basis for achieving high efficiency in the conversion of N2 to NH3, avoiding the too slow kinetics and the competitive H2 evolution reaction, the main drawbacks of current catalysts. The multidisciplinary and collaborative GREENH3 project is based on a close synergy between experiment and theory. It will involve researchers from eight public research institutes with highly complementary expertise in molecular chemistry, electrocatalysis, photocatalysis, materials science, semi-conductive materials, chemical engineering, theoretical (electro)chemistry and analytical chemistry. The project will bring significant elements of fundamental understanding to the scientific community involved in green (photo)electrosynthesis technologies. It will have important social and economic impact because ammonia is an energy carrier with strategic, societal and economic stakes to store and transport hydrogen, the dreamed fuel for the decarbonized production of energy, while additionally being an essential feedstock for nourishing the planet (fertilizer industries).

GREENH3 - Direct (photo)electrochemical conversion of atmospheric N2 to ammonia

Project summary

Project members

External partners