EXSOLUTION-BASED NANOPARTICLES FOR LOWEST COST GREEN HYDROGEN VIA ELECTROLYSIS

Project Information

EXSOTHyC

Grant agreement ID: 101137604

DOI

10.3030/101137604

EC signature date 5 December 2023

Start date 1 January 2024

End date 31 December 2026

Funded under

• Climate, Energy and Mobility

Total cost

€ 2 495 480,00

EU contribution

€ 2 495 480,00

Coordinated by

OU STARGATE HYDROGEN SOLUTIONS
Estonia

Periodic Reporting for period 1 - EXSOTHyC (EXSOLUTION-BASED NANOPARTICLES FOR LOWEST COST GREEN HYDROGEN VIA ELECTROLYSIS)

Reporting period: 2024-01-01 to 2025-06-30

Summary of the context and overall objectives of the project

Alkaline electrolysers typically operate above 2 V per cell, consuming over 54 kWh/kg, to reach commercial current densities. This is due to limited electrode activity, high diaphragm gas permeability improving hydrogen purity at high currents, simple flow fields not optimised for low currents, and the need for high currents to lower capital costs per kW. However, green hydrogen costs are now driven mainly by operational expenditure, which depends on efficiency. Therefore, prioritising efficiency over current density is essential to reduce the levelised cost of hydrogen.

EXSOTHyC will optimise electrolyser operation towards lower voltages and higher efficiencies. Within the project, a breakthrough concept for catalyst materials, processes and sub-components for an alkaline electrolyser stack is being proposed. This results in a novel stack design including disruptive components like Zirfon membranes with reduced HTO, catalyst coated diaphragm (CCD), and novel materials, which remarkably improve the voltage efficiency. The scientific innovation is three-fold and addresses all listed reasons for today’s used higher voltages:

• Alternative pathways to the O2 and H2 evolution reactions by new anode and cathode approaches
• Novel concepts of membranes and membrane electrode assemblies with integrated components
• Novel cell design to enhance overall cell efficiency by integrating disruptive concepts

Target KPIs by end of 2026
• Electricity consumption @ nominal capacity 48 kWh/kg
• CAPEX (€/(kg/d) and €/kW) values will be provided by M24
• O&M cost N/A €/(kg/d)/y
• Current density 1.0 A/cm2
• Use of critical raw materials as catalysts <0.3 for alkaline cells and 0.0 for novel materials

Pathway to Impact
EXSOTHyC will lower the levelised cost of hydrogen by reducing electricity use, enabling cost-competitive green hydrogen production, supporting industrial decarbonisation, and reducing dependence on critical raw materials. Large-scale adoption could save over 500 GWh/year per GW of capacity compared to current norms, directly contributing to the EU’s 10 Mt/year renewable hydrogen target by 2030.

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

WP1 – Electrode Development: Transition metal phosphide catalysts were synthesised on perovskite oxides through solid-state and solution routes. Two integration strategies, CCS and DSE, were pursued with optimisation of deposition on Ni foam. Extensive structural and electrochemical characterisation guided selection.
Achievement: highly active, stable electrodes were obtained, with DSE catalyst 1 showing the best performance.

WP2 – Membrane Development: Thin polymer coatings and recombination catalyst concepts were applied to Zirfon diaphragms. Screening and ex-situ/in-situ testing assessed stability, resistance, permeability and HTO.
Achievement: two membrane candidates reduced gas crossover, though stability–resistance trade-offs limited progress.

WP3 – Catalyst-Coated Diaphragms: Benchmark CCDs were spray- or stencil-coated, enabling precise layer control and rapid application.
Achievement: double coatings lowered cell voltage by >330 mV; Raney Ni outperformed Pt for HER.

WP4 – Dynamic Stability: Models for shunt/reverse currents were combined with advanced I–V/EIS methods using a reference electrode.
Achievement: accelerated stress tests revealed significant degradation of bare Ni, guiding material optimisation.

WP5 – Integration & Validation: Optimised electrodes and membranes were integrated into single cells and short-stack prototypes, validated under industrial conditions.
Achievement: designs and tests confirmed feasibility for scale-up towards 10 kW class stacks.

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)

Expected Results Until the End of the Project

A new class of catalyst materials for alkaline electrolysers based on PGM-free perovskites with exsolution ability and excellent electrochemical activity, when coated into electrodes.
Diaphragms with reduced gas crossover, enabling wide operating windows and smoother integration of alkaline electrolysers with renewable energy sources.
Easily stackable, high-performance catalyst coated diaphragm (CCD) providing intimate contact between diaphragm and catalysts.
Advanced stack diagnostics based on the reverse current model and impedance spectroscopy.
An electrolyser stack incorporating the above innovations, demonstrating electricity consumption below 48 kWh/kg @ 1 A/cm², suitable for operation at 5-100% load.

Impact
Economically, the project strengthens EU industrial leadership by driving innovation in hydrogen production materials and standards, enabling cost reductions that support broader green hydrogen adoption across renewable energy sectors and related industries. Societally, the widespread uptake of green hydrogen facilitated by EXSOTHyC could drastically cut greenhouse gas emissions and air pollution, improve public health, and promote sustainable energy systems.

EXSOTHyC consortium

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