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.

No abstract

Recently, the observation of the electrocatalytic behavior of individual nanoparticles (NPs) by electrochemical amplification method has been reported. For example, the Iridium oxide (IrO x ) NP collision on the Pt UME was observed via electrocatalytic water oxidation. However, the bare Pt UME had poor reproducibility for the observation of NP collision signal and required an inconvenient surface pre-treatment for the usage. In this manuscript, we has been investigated other metal electrode such as Cu UME for the reproducible data analysis and convenient use. The IrO x NP collision was successively observed on the bare Cu UME and the reproducibility in collision frequency was improved comparing with previous case using the NaBH 4 pre-treated Pt UME. Also, the adhesion coefficient between NP and the Cu UME was studied for better understanding of the single NP collision system.