Single Particle Nanoelectrochemistry Reveals the Catalytic Oxygen Evolution Reaction Activity of Co3O4 Nanocubes.

Abstract

Co 3 O 4 nanocubes are evaluated concerning their intrinsic electrocatalytic activity towards the oxygen evolution reaction (OER) by means of single-entity electrochemistry. Scanning electrochemical cell microscopy (SECCM) provides data on the electrocatalytic OER activity from several individual measurement areas covering one Co 3 O 4 nanocube. We were able to evaluate a comparatively high number of individual particles with sufficient statistical reproducibility. Single-particle-on-nanoelectrode measurements performed with the same Co 3 O 4 nanocubes provide, on the one hand, an accelerated stress test at highly alkaline conditions with current densities of up to 5.5 A∙cm -2 , and on the other hand, allows to derive TOF values of up to 2.8 x 10 4 s -1 at 1.92 V vs. RHE for surface Co atoms of a single cubic nanoparticle. Obtaining such current densities combined with identical-location transmission electron microscopy allows monitoring structural changes during electrocatalysis, specifically the formation of an oxy(hydroxide) surface layer. Combining the information from two independent single-entity electrochemistry measurements provides the basis for elucidating structure-activity relations of single electrocatalyst nanoparticles with well-define surface structure.