Bias-free high-performance solar NH3 production by perovskite-based photocathode and in-situ valorisation of glycerol

Project Information

PECSolFuel

Grant agreement ID: 101107294

DOI

10.3030/101107294

Project closed

EC signature date 20 March 2023

Start date 1 April 2024

End date 31 March 2026

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 181 152,96

Coordinated by

UNIVERSIDAD DE SANTIAGO DE COMPOSTELA
Spain

Periodic Reporting for period 1 - PECSolFuel (Bias-free high-performance solar NH3 production by perovskite-based photocathode and in-situ valorisation of glycerol)

Reporting period: 2024-04-01 to 2026-03-31

Summary of the context and overall objectives of the project

Ammonia (NH₃) is the second most produced chemical worldwide (~175 Mtons annually), essential for fertilizers and increasingly recognized as a promising carbon-free energy carrier due to its high volumetric energy density. However, its industrial production via the Haber–Bosch process consumes ~2% of global energy and contributes ~1.6% of CO2 emissions, creating an urgent need for sustainable alternatives aligned with European Green Deal objectives. This project addresses this challenge by developing energy-efficient and environmentally benign routes for solar-driven ammonia production.
Photoelectrochemical (PEC) ammonia synthesis offers a compelling pathway, operating under ambient conditions with no direct CO2 emissions. However, current systems suffer from low solar-to-ammonia efficiency (<1%), primarily due to the lack of selective and stable catalysts and the sluggish kinetics of nitrogen activation. In this project, I developed highly selective electrocatalysts and PEC photoelectrodes achieving Faradaic efficiencies above 90%, significantly advancing the state of the art.
To further improve system efficiency, the project tackles the bottleneck of the energy-intensive water oxidation reaction. By replacing conventional oxygen evolution with thermodynamically favorable organic oxidation reactions, the system reduces energy demand and enhances overall techno-economic feasibility. In parallel, durability challenges associated with catalyst degradation are addressed through the design of strongly coupled metal–support systems, preventing nanoparticle coalescence and maintaining long-term catalytic performance.
The project contributes to the transition toward sustainable chemical manufacturing and renewable energy storage, with potential impact at both industrial and societal scales. By enabling efficient solar-to-chemical energy conversion, it supports EU climate neutrality goals while opening new pathways for decentralized ammonia production.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the project, a comprehensive set of experimental and analytical activities was carried out to develop efficient and durable electrocatalysts for nitrate reduction to ammonia. First, the electrocatalytic performance of Ru nanoparticles supported on titanate nanosheets was optimized by tuning Ru loading and operational parameters. The reaction mechanism was investigated using operando techniques, including in situ Raman and infrared spectroscopy, complemented by density functional theory (DFT) calculations to establish the reaction energy pathways. In parallel, Cu-based electrocatalysts were developed, including Cu–Ru alloys and hybrid structures, to enhance selectivity and yield. These catalysts were systematically evaluated in electrochemical systems, achieving Faradaic efficiencies exceeding 90%. Furthermore, coupling electrocatalytic nitrate reduction to ammonia with anodic organic oxidation reactions, such as formaldehyde or glycerol oxidation, significantly reduces the overall energy demand compared to the conventional oxygen evolution reaction. This approach not only lowers the required cell potential but also enables the generation of value-added products at the anode instead of oxygen. In this context, Cu-based catalysts were developed and optimized for organic oxidation, achieving high activity and selectivity. This integrated strategy enhances the overall efficiency and techno-economic feasibility of the system while simultaneously enabling the co-production of ammonia and valuable chemicals.
To enable solar-driven ammonia production, photoelectrochemical systems photocathodes were developed. To address the intrinsic instability of aqueous environments, a protective layer was introduced, improving both stability and interfacial charge transfer. In addition, with deposition of a selective catalyst on the surface of photoelectrode not only high selectivity obtained, but also light-blocking effects become minimized.
Advanced characterization techniques, including electrochemical impedance spectroscopy, in situ Raman spectroscopy, and structural analysis, were employed to identify performance-limiting factors and elucidate catalytic mechanisms.
The main outcomes include the development of highly selective and stable catalytic systems, and the design of robust catalyst architectures (e.g. Cu–Ru alloys and heterostructures). These results have led to multiple publications and manuscripts under preparation in high-impact journals, establishing a strong scientific foundation for further development.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project has generated significant scientific and technological advances toward sustainable ammonia production. Highly selective and stable electrocatalysts based on Ru and Ti/Cu heterostructures and alloys were developed, achieving high selectivity for nitrate reduction to ammonia. In parallel, photoelectrochemical systems based on protected photocathodes were successfully demonstrated, enabling efficient solar-driven ammonia production. Mechanistic understanding was advanced through operando spectroscopy and density functional theory, providing insights into reaction pathways and catalyst–support interactions. The observed structure-dependent catalytic performance offers a promising strategy for the rational design of bimetallic catalysts for nitrate reduction as well as other electrochemical reactions such as CO2 and nitrogen reduction.
The project also contributed to capacity building through the supervision of PhD and Master’s students and the establishment of international collaborations, strengthening interdisciplinary research networks. Furthermore, catalyst design strategies based on heterostructure engineering and alloying have opened new directions for advanced electrochemical applications.
Regarding potential impact, the developed catalyst architectures and protective layers provide a basis for low-carbon chemical production and renewable energy storage, supporting European sustainability goals. To ensure further uptake, additional research is needed to explore new bimetallic systems and optimize catalyst integration on photoelectrodes. Scaling up catalyst synthesis and device fabrication is also essential.
Further work should focus on improving long-term stability, increasing current densities, and optimizing system integration. Coupling nitrate reduction with alternative anodic reactions, such as organic oxidation, could enhance efficiency and generate value-added products. These efforts will facilitate the translation of the project results into practical solutions for sustainable ammonia production.