Metal Oxides as low loaded nano-Iridium Support for competitive water Electrolysis – MOISE

To reach this ambitious goal, our strategy consists in replacing the IrO2 particles conventionally used by IrOx nanoparticles deposited on a support with high electronic conductivity and electrochemical stability, presenting an appropriate morphology: porous doped tin dioxide.
The novelty comes from our ability to elaborate this catalyst support with two different and innovative «competing« microstructures: aerogels and nanofibers/tubes.
Different innovations and improvements will result from this project: (i) elaboration of catalyst supports of appropriate composition and morphology, (ii) development of optimized processes for the deposition of iridium dioxide on these supports, (iii) formulation of an appropriate ink and (iv) fabrication of optimized membrane-electrode assemblies.
After optimization and validation (in terms of initial performance and durability), these innovative materials were tested in short stacks under real application conditions with a view to their commercialization.

Two types of catalysts were developed, iridium oxide nanoparticles deposited on antimony or tantalum doped tin dioxide as aerogels or nanofibers. Good electrocatalytic activities could be obtained with iridium levels 5 to 7 times lower than with reference catalysts, based on iridium oxide alone. The tantalum doping also allowed to significantly improve the stability of the catalyst under electrolysis operating conditions. The nanofiber based catalyst having given the best results, 4 large surface area (250 cm²) MEAs were prepared and tested in stack. The performances obtained exceeded those of the Elogen reference containing 6 times more iridium and tested under the same conditions within the stack.

Following the excellent results obtained in the MOISE project, a follow-up will be undertaken with the objective of optimizing the catalyst, evaluating new architectures and integrating new thinner and stronger membranes into MEAs in order to further improve the performance of PEM electrolyzers to help their deployment.

The work carried out has given rise to the publication of 6 scientific articles (4 multi-partners), 13 communications in national and international conferences (5 multi-partners).

Water Electrolysis is potentially one of the most environment-friendly hydrogen production processes. However, the large-scale deployment of PEM water electrolysis will be prevented in the near future by limited iridium resources (IrO2 is the conventional catalyst used at the anode side for water oxidation into molecular oxygen).

Hence, the objective of the MOISE project is to decrease the necessary amount of Ir by a factor of 5, improving the mass activity of oxygen-evolving PEM anodes compared to the state-of-art (SoA). Such an evolution will participate to the developement of efficient and cost-effective PEM Water Electrolysdis for large scale H2 production

To reach this ambitious goal, our strategy is to replace SoA unsupported IrO2 particles with IrO2 nanoparticles or M-rich core@Ir-rich shell nanoparticles (with M a transition metal element) coated on a substrate of appropriate electronic conductivity, morphology and electrochemical stability: porous doped tin dioxide used as catalyst support.

The novelty will come from our ability to elaborate this catalyst support with two different and innovative microstructures that will be compared: aerogels and nanotubes/fibers. Different innovations and improvements will result from this project:
(i) elaboration of catalyst supports of appropriate composition and morphology;
(ii) development of optimized processes for iridium dioxide deposition;
(iii) determination of appropriate ink composition;
(iv) manufacturing of optimized membrane-electrode assemblies.

After optimization and validation (in terms of initial performance and durability) these innovative materials will be tested in short stack configuration in real application conditions in view of commercial applications.