Intriguing Aspects of of Oxygen Evolution Electrocatalyst Dissolution: Towards Stability Descriptors

Widespread deployment of sustainable energy technologies is facing limitations due to relatively low efficiency of key energy conversion processes:conversion of renewable energy to electricity, conversion of renewable electricity to chemical energy as well as re-conversion of chemical energy to electricity. One of the essential technologies to convert renewable electricity to chemical energy is water electrolysis. Despite being a topic of investigation for decades, water electrolysis still conceals too many unknowns related to reaction mechanism. That could be the main underlying reason for too many obstacles on the pathway to enhance water electrolysis efficiency. Conversion process is based on two electrocatalytic reactions: facile hydrogen evolution reaction (HER) at the cathode and sluggish oxygen evolution reaction (OER) at the anode. OER is additionally related to severe anode stability issues and therefore it is nowadays more frequently studied. Widely accepted approach to enhance performance of OER anodes is to search for more active electrode materials, while issues related to electrode stability are very often disregarded. Besides gas evolution that has destabilizing effect on electrode surface morphology, very often is lacking significant input to better understanding of intrinsic drivers of electrocatalyst stability. Enhancement of OER anode stability requires existence of straightforward structure-stability relations. In that way, it is possible to tune material properties and interfacial properties of electrode/electrolyte boundary, to achieve long term electrocatalytic performance. Practical precondition for creating link: material properties – interfacial properties – reaction kinetics is to have advanced analytical tools that will allow relevant view on reaction mechanism. Therefore, in this work we propose discussion that will analyse several key aspects of electrode stability in relation to OER electrocatalysis with special focus on what are relevant stability descriptors. Experimental data are gathered using: high-temperature rotating disc electrode (RDE) measurements and scanning flow cell with inductively coupled plasma mass spectrometer (SFCICPMS).