Solar driven electrochemical nitrogen fixation for ammonia refinery

Projektinformationen

SuN2rise

ID Finanzhilfevereinbarung: 948769

DOI

10.3030/948769

Projekt abgeschlossen

EK-Unterschriftsdatum 23 September 2020

Startdatum 1 Februar 2021

Enddatum 31 Januar 2026

Finanziert unter

• EXCELLENT SCIENCE - European Research Council (ERC)

Gesamtkosten

€ 1 498 750,00

EU-Beitrag

€ 1 498 750,00

Koordiniert durch

POLITECNICO DI TORINO
Italy

Periodic Reporting for period 4 - SuN2rise (Solar driven electrochemical nitrogen fixation for ammonia refinery)

Berichtszeitraum: 2025-08-01 bis 2026-01-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

Solar-driven processes using H2O, CO2 and N2 as feedstocks offer a pathway to produce sustainable “solar fuels” capable of replacing fossil-based energy carriers. Among these routes, nitrogen conversion into ammonia is particularly strategic.
Ammonia is produced at a scale of ~200 million metric tons per year and is essential for fertilizers sustaining global food production. It is also widely used in plastics, fibers, resins, explosives and refrigeration. Increasingly, ammonia is recognized as a carbon-free energy carrier and hydrogen vector, with applications emerging in heavy transport, power generation and distributed energy storage. However, its production still relies almost entirely on the fossil-based Haber–Bosch process, which is energy-intensive and responsible for significant CO2 emissions. A renewable alternative is therefore urgently needed.
SuN2rise addressed this challenge by developing a renewable-driven electrochemical platform for nitrogen-to-ammonia conversion under mild conditions. The core objective was to advance a lithium-mediated N2 reduction concept, enabling ammonia production in reactors powered by renewable electricity and fed by air and water. By combining lithium electrochemistry with nitrogen activation strategies, the project aimed to establish a new paradigm for decentralized, low-carbon ammonia synthesis.
In parallel, SuN2rise developed sustainable energy-harvesting technologies aligned with this vision, including aqueous solar cells and advanced polymer electrolytes, targeting integrated solar-to-ammonia systems.
In conclusion, the project contributed to redefining ammonia production from a centralized fossil-based process to a potentially distributed, renewable-powered electrochemical technology, laying the foundations for a future solar-driven ammonia economy.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

Since its inception, SuN2rise pursued the development of a fully renewable-driven platform for sustainable nitrogen fixation, moving from aqueous solar harvesting to lithium-mediated electrochemical ammonia synthesis and ultimately toward integrated solar-powered NH₃ production.

WP1 – Aqueous Solar Cells
WP1 redefined dye-sensitized solar cells (DSSCs) according to strict sustainability criteria. Fully water-based photovoltaic devices were developed using organic sensitizers and heavy/rare-metal-free redox shuttles and cathodes.
Key results include:
- Six sensitized photoanodes and five Pt-free cathodic alternatives optimized for aqueous environments while maintaining >65% transparency.
- Three polymeric aqueous electrolytes ensuring long-term stability. UV-induced polymerization enabled quasi-solid membranes without organic solvents or catalysts. Design of Experiments (DoE) was introduced to optimize membrane formulation.
- A screen-printing protocol for 10×10 cm modules and an IEC-compliant photovoltaic testing bench for long-term characterization.
These advances enabled Q1 publications (IF >10) and established the photovoltaic foundation of the project.

WP2 – Lithium-Mediated N2 Reduction
WP2 constituted the scientific core: developing a reproducible lithium-mediated nitrogen reduction (Li-NRR) platform.
Building on lithium battery expertise, the project exploited electroplated lithium reactivity toward N2 to form Li₃N, followed by protonolysis to NH₃.
Main achievements:
- Custom airtight electrochemical reactors ensuring gas isolation and isotopic validation.
- Advanced electrolyte engineering through systematic screening of salts and solvents. Tailored fluorinated salts enabled controlled SEI engineering.
- Introduction of multivariate chemometric optimization (Doehlert design and response surface modelling) to rationally optimize Li-NRR parameters.
- Development of self-healable polymer electrolytes compatible with lithium metal.
- Li-NRR progressed from exploratory research to a system-engineered and reproducible platform, consolidated by high-impact publications.

WP3 – Toward a Solar NH₃ Refinery
WP3 integrated renewable harvesting with nitrogen electroreduction:
- Conceptual and experimental prototypes coupling aqueous solar cells and electrochemical reactors.
- System-level durability assessment and preliminary life-cycle considerations.
- Investigation of in situ ammonium capture for fertilizer production.

Overall, SuN2rise delivered:
- A new generation of aqueous photovoltaics.
- A mechanistically clarified and statistically optimized Li-mediated N2 reduction platform.
- Advanced self-healing polymer electrolytes.
- Integrated renewable-driven electrochemical concepts.

Results were disseminated through Q1 publications, keynote and plenary lectures, and international collaborations. Methodological innovations generated cross-field impact, supporting two ERC Proof-of-Concept projects and fostering industrial dialogue. SuN2rise met and in several aspects exceeded its objectives, laying the foundation for decentralized renewable ammonia production.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

Electrochemical ammonia synthesis has become highly competitive in recent years. Within this context, SuN2rise delivered advances beyond the state of the art in materials design, system engineering and methodology.
First, sustainability criteria for solar-driven electrochemical systems were redefined by demonstrating fully aqueous DSSCs using water-based electrolytes, organic sensitizers and heavy/rare-metal-free components, including waste-derived biomass such as lignin. Interfaces and redox chemistry were redesigned for 100% aqueous operation, embedding circular economy principles into device architecture.
Second, in lithium-mediated nitrogen reduction (Li-NRR), the project shifted the focus from empirical catalyst screening to interfacial and electrolyte engineering. Polymeric electrolytes capable of conducting Li⁺ in Li–N2 cells were developed while remaining compatible with lithium metal batteries. A quantitative protocol correlating self-healing behavior with electrochemical performance transformed self-healing from a qualitative concept into a measurable functional parameter.
Third, a paradigm shift in optimization strategies was introduced through multivariate chemometric methodologies (Design of Experiments and Response Surface Modelling). This systems-level approach revealed hidden interactions governing Faradaic efficiency and selectivity, enabling predictive optimization rather than trial-and-error improvements.
Finally, SuN2rise bridged renewable energy harvesting and lithium-mediated electrosynthesis through integrated concepts toward a solar ammonia refinery. The project not only improved performance metrics but advanced the field toward system-level sustainability and renewable-powered chemical manufacturing.

Graphical abstract of M1-18 activity