Potential-Controlled Current Responses from Staircase to Blip in Single Pt Nanoparticle Collisions on a Ni Ultramicroelectrode

Collisions of electrocatalytic platinum (Pt) single nanoparticles (NPs) with a less electrocatalytic nickel (Ni) ultramicroelectrode (UME) surface were detected by amplification of the current by electrocatalysis of NPs. Two typical types of current responses, a current staircase or blip (or spike), in single NP collision experiments were observed at a time with a new system consisting of Pt NP/Ni UME/hydrazine oxidation. The staircase current response was obtained when the collided NPs were attached to the electrode and continued to produce electrocatalytic current. On the other hand, the blip current response was believed to be obtained when the NP attached but was deactivated. The different current responses depend on the different electrocatalytic reaction mechanism, characteristics of the NP, or the electrode material. How the deactivation of the electrocatalytic process affects on the current response of NP collision was investigated using the Ni UME. The current response of a single Pt NP collision is controllable from staircase to blip by changing the applied potential. The current response of the Pt NP was observed as a staircase response with 0 V (vs Ag/AgCl) and as a blip response with 0.1 V (vs Ag/AgCl) applied to the Ni UME.