Fast-Scan Cyclic Voltammetry Allows Determination of Electron Transfer Kinetic Constants in Single Nanoparticle Collision

Here we report the use of Fast-Scan Cyclic Voltammetry (FSCV) to study transient nanoparticle (NP) collision experiments and determine the apparent heterogeneous electron-transfer (ET) rate constant k degrees and electrocatalytic activity of single NPs. Continuous potential scanning at fast scan rates, for example, up to 500 V/s, and background subtraction enable voltammetric study of single NPs when they collide on a carbon ultramicroelectrode (UME). The FSCV results indicate a substantial potential shift in the CV response of single NPs due to increased mass transfer and it is necessary to consider this effect when analyzing single NP electrocatalysts. FSCV results also reveal that single particle deactivation is associated with a decrease in peak current and an increase in overpotential. Importantly, the use of FSCV coupled with numerical simulations enabled the determination of k on single NPs, confirming an increase in catalytic activity with decreasing particle size. Moreover, the Gibbs free energy of activation can be estimated from the k. This work further confirms that FSCV is a powerful method in studying dynamic electrochemical processes such as single NP collisions.