Holistic design of hybrid electrocatalysts as electrodes in and of themselves for sustainable energy conversion – HOLYCAT

In the context where electrocatalyst materials play a determinant role in the cost, performance and lifetime of various key electrochemical systems of conversion and storage of energy, the successful integration of low cost, active and stable catalyst materials in practical systems is urgently needed. However, promising catalysts developed in laboratory environment (liquid electrolytes) systematically underperform in practical systems using mostly solid electrolytes.
The HOLYCAT project aims at developing a new concept of hybrid functional nanostructures able to address most of the issues that have been identified for the state-of-the-art electrodes design regarding initial performance and long-term stability. The originality of the project relies on the holistic approach followed, consisting in exploiting the particular continuous structure of an emerging and promising class of nanocatalyst, that are metal aerogels, as a lever to redesign an alternative three-phase boundary interface allowing high ionic and mass transport rates. By supporting metal aerogels on skeleton matrixes composed of electrospun ionomer nanofibers, the ionomer-free surfaces of the intrinsically very active aerogel catalysts are expected to be preserved in practical electrodes. In addition, this design allows the removal of highly corrosive materials from the electrode, such as commonly employed carbon black supports and unstable metal alloy elements from the catalysts.
Through judicious combinations of the ionomer matrixes transport functions (cationic or anionic) and the chemistry of the metal aerogels at the synthesis stage, the proposed design is in principle transposable to many electrochemical devicesg. To demonstrate this versatility, the project targets (i) the reduction of precious metal (Iridium) used at proton exchange membrane water electrolyzer anode and (ii) the performance improvement of non-precious group metal-based (here Nickel) anion exchange membrane fuel cell anode.