Tuning the Electrode Activity to Expose Transformational and Electrocatalytic Characteristics of Individual Nanoparticles by Nanoimpact Electrochemistry.

Nanoimpact electrochemistry (NIE) is a straightforward analytical technique to study at high throughput the reactivity of single nanoparticles (NPs) colliding with a biased ultramicroelectrode (UME). As NIE can reveal both NP size and catalytic activity, this strategy can be employed to establish relationships between these two NP descriptors. Herein, it is shown that the electrode material is crucial for visualizing simultaneously electrocatalytic processes and NP transformation, which can size the NPs. UMEs made of gold (Au) or glassy carbon (GC), were employed to study the reduction of AgBr NPs and the electrocatalytic activity of the resulting Ag NPs for the oxygen reduction reaction (ORR). With Au UME, only the transformation process is probed, allowing a quantitative analysis of the overpotential effect on the reduction dynamics of the AgBr NPs. When a GC UME is employed, the AgBr NPs reduction and subsequent ORR activity can be quantified for the very same NPs. [ABSTRACT FROM AUTHOR]