Single Palladium Nanoparticle Collisions Detection through Chronopotentiometric Method: Introducing a New Approach to Improve the Analytical Signals

Abstract

In the present research, the chronopotentiometric method and hydrazine, as a suitable probe, were used to detect single Pd nanoparticle (Pd-NP) collisions to the surface of a carbon fiber ultramicroelectrode (CFUME). The change in the potential, which is due to the electrocatalytic oxidation of hydrazine exactly at the time of Pd-NP collision to the CFUME surface, was used to detect each collide. It was shown that the amplitude and the frequency of the potential steps, produced through the nanoparticles collisions at the CFUME surface, are respectively proportional to their radius and concentration in an analytical solution. For the first time, a new approach is introduced for extraction of current-time plots (chronoamperograms) from experimental potential-time plots (chronopotentiograms). It is demonstrated that the signal-to-noise ratio (S/N) increases significantly based on the proposed method. Also, by using the chronoamperograms that resulted from the experimental chronopotentiograms, a higher number of collisions is achievable and, thus, the collision frequency, f, increases and the limit of detection decreases. Interestingly, the collision frequency resulted from the chronoamperograms, that has been derived from chronopotentiograms, is closer to the collision frequency calculated by using the theoretical model.