Ultrafast transient electrochemical behavior of single nanoparticles

In this talk, I will discuss our recent research in single-nanoparticle collision electrochemistry. I will describe two separate studies toward understanding the transient collision and electrocatalytic behavior of Pt nanoparticles on a carbon ultramicroelectrode. In the first study, we investigated the electrocatalytic oxidation of hydrazine (N2H4) on Pt NPs, in which we observed an ultrafast current spike at the collision event. In addition, we found the steady-state oxidation current for N2H4 is significantly less than the predicted current based on diffusion limitation. Our experimental and simulation results suggest the current spikes are due to the oxidation of the pre-adsorbed N2H4 on Pt, whereas the reduction in the steady-state current is due to an elevated solution acidity in the vicinity of the NP surface. In the second study, we examined the hydrogen evolution reaction (HER) on Pt NPs and found the collision frequency of NPs can be significantly reduced at higher reduction potentials. We explain the reduced collision frequency by the possible formation of H2 nanobubbles.