(Invited) Using Single Nanoparticle Electrochemistry to Better Understand the Oxygen Evolution Reaction at Cobalt Oxide Nanocatalysts

Transition metal oxides are highly promising catalysts for alkaline water splitting thanks to their relatively high abundancy and high catalytic activity. Due to their limited electrical conductivity they are often used as nanoparticles and their catalytic performance is assessed based on experiments at composite electrodes. Besides the nanocatalyst of interest, these electrodes contain catalytically inactive binders and conductive additives. This makes it highly challenging – if not impossible – to distinguish influences of catalyst properties from matrix effects. For example, observed effects of particle morphology on electrocatalytic activity may simply originate from different wetting/blocking of catalyst active sites by the used additives or by different iR drop across the composite film, instead of signifying different charge transfer kinetics [1]. To overcome this limitation, we use single nanoparticle electrochemistry and study electrocatalysis at individual catalyst nanoparticles [2]. Employing this approach, we are able to clearly reveal that Co 3 O 4 nanocubes are more active for the oxygen evolution reaction (OER) than spheres. Moreover, we can link our experimental data to theory data obtained from DTU+U calculations, thanks to the comparably small size of the electrochemical system [3]. For OER catalysis at single Co 3 O 4 nanocubes in KOH(aq), we demonstrate and rationalize the effect of support materials on catalyst activity that had been debated previously [4]. References [1] N. Blanc, C. Rurainsky, K. Tschulik, J. Electroanal. Chem. 872(2020)114345 [2] A. El Arrassi, Z. Liu, M. V. Evers, N. Blanc, G. Bendt, S. Saddeler, D. Tetzlaff, D. Pohl, C. Damm, S. Schulz, K. Tschulik, J. Am. Chem. Soc. 141 ( 2019 ) 9197 [3] Z. Liu, H. M.A. Amin, Y. Peng, M. Corva, R. Pentcheva, K. Tschulik, Adv. Funct. Mater., ( 2022) accepted. [4] Z. Liu, M. Corva, H.M.A. Amin, N. Blanc, J. Linnemann, K. Tschulik, Int. J. Mol. Sci. 22 ( 2021 )13137. Figure 1: Single nanoparticle electrochemistry shows higher OER activity for cobalt oxide cubes than spheres [3]. Figure 1