The slow kinetics of the oxygen evolution reaction (OER) limits the performance of proton exchange membrane (PEM) electrolysers. Only iridium-based oxides are both reasonably active and stable for the OER in acidic electrolytes [1], and high amounts of Ir are needed at the anode of PEM electrolysers. In addition, the lack of stable support materials limits the utilisation of Ir. Designing novel electrocatalysts with enhanced OER activity and stability in acidic media remains a great challenge. In this talk, I will present some recent strategies aiming to understand and engineer the interfacial structure and properties for oxygen evolution electrocatalysis. We have developed self-supported high surface area nanostructured Ir-based networks as highly active electrocatalysts for OER [2]. These networks, prepared by alternating sputtering of Ir and Co, followed by selective Co leaching, show a unique morphology and combine excellent mass activity with promising stability [2]. In addition, our group is working in the development of an easy and affordable method to prepare IrO_x catalysts by controlled electrodeposition of Co and Ni in a deep eutectic solvent followed by galvanic displacement [3]. By controlling the conditions during the galvanic displacement, we tune the morphology and thus the electrocatalytic properties for OER. Finally, we have investigated the role of both composition and concentration of the acidic electrolyte (perchloric and sulphuric acid) on the OER electrocatalytic performance of Ir nanoparticles [4]. Our work highlights the key role the electrolyte plays in the performance of Ir-based electrocatalysts during rotating disc electrode measurements.

REFERENCES

[1] M. Escudero-Escribano et al., Journal of Physical Chemistry B 2018, 122, 947.

[2] A.W. Jensen, G.W. Sievers, K.D. Jensen, J. Quinson, J.A. Arminio-Ravelo, V. Brüser, M. Arenz, M. Escudero-Escribano, Journal of Materials Chemistry A 2020, 8, 1066.

[3] F.B. Holde, K.N. Dalby, H. Falsig, P. Sebastián-Pascual, M. Escudero-Escribano, in prep., 2022.

[4] J.A. Arminio-Ravelo, A.W. Jensen, K.D. Jensen, J. Quinson, M. Escudero-Escribano, ChemPhysChem 2019, 20, 2956.