Single-Entity Electrocatalysis of Individual "Picked-and-Dropped" Co O Nanoparticles on the Tip of a Carbon Nanoelectrode.

Nano-electrochemical tools to assess individual catalyst entities are critical to comprehend single-entity measurements. The intrinsic electrocatalytic activity of an individual well-defined Co O nanoparticle supported on a carbon-based nanoelectrode is determined by employing an efficient SEM-controlled robotic technique for picking and placing a single catalyst particle onto a modified carbon nanoelectrode surface. The stable nanoassembly is microscopically investigated and subsequently electrochemically characterized. The hexagonal-shaped Co O nanoparticles demonstrate size-dependent electrochemical activity and exhibit very high catalytic activity with a current density of up to 11.5 A cm at 1.92 V (vs. RHE), and a turnover frequency of 532±100 s at 1.92 V (vs. RHE) towards catalyzing the oxygen evolution reaction.