Ni-Co-O anodes for the alkaline oxygen evolution reaction: Multistage electrode optimization and plasma-assisted activity enhancement enabled by a coherent workflow
Vineetha Vinayakumar, Timo Wagner, Christian Marcks, Jacob Johny, Garlef Wartner, Ahyoun Lim, Marc F. Tesch, Ioannis Spanos, A. Ghafari, Adarsh Jain, Oleg Prymak, Ignacio Sanjuán, Ahammed Suhail Odungat, Osama Anwar, Mohit Chatwani, Aneeta Jose, Vimanshu Chanda, Axel Knop‐Gericke, Corina Andronescu, Anna K. Mechler, Nicolas Wöhrl, Doris Segets
Abstract
Improving the performance of oxygen evolution reaction (OER) catalysts through proper catalyst design and processing represents a critical step toward enhancing the efficiency of water electrolysis. While many studies focus on structure-activity relationships and mechanistic insights confined to a particular stage during the anode fabrication, an integrated approach covering all process steps is crucial to optimize performance-relevant properties such as composition, morphology, and electrode architecture. In this study, we demonstrate a comprehensive approach for developing Ni-Co-O anodes as a model system through the entire process chain. Starting from the initial powder characterization through operando to post-catalysis analyses, we first underpin the critical impact of catalyst ink optimization through solvent matrix screening, enabling high-quality electrode layers via ultrasonic spray coating on Ni plates. This enables us to uncover the effects of post nitrogen plasma treatment integrated into our coherent workflow yielding binder-free Ni-Co-O anode surfaces with enhanced redox reversibility, Fe uptake, porosity, and wettability. These improvements reduce the OER overpotential by ~43 mV at 100 mA/cm 2 compared to untreated counterparts. The durable performance of these electrodes is further demonstrated in a single cell configuration. Our holistic approach from catalyst powder to post-mortem analysis highlights the benefits of a coherent anode development strategy employing plasma post-processing which is broadly applicable and easily transferable to other benchmark electrocatalysts.