Semiconducting Nanoparticles: Single Entity Electrochemistry and Photoelectrochemistry

Semiconducting nanoparticles (SC NPs) play vital roles in several emerging technological applications including optoelectronic devices, sensors and catalysts. Recent research focusing on the single entity electrochemistry and photoelectrochemistry of SC NPs is a fascinating field which has attained an increasing interest in recent years. The nano-impact method provides a new avenue of studying electron transfer processes at single particle level and enables the discoveries of intrinsic (photo) electrochemical activities of the SC NPs. Herein, we review the recent research work on the electrochemistry and photoelectrochemistry of single SC NPs via the nano-impact technique. The redox reactions and electrocatalysis of single metal oxide semiconductor (MOS) NPs and chalcogenide quantum dots (QDs) are first discussed. The photoelectrochemistry of single SC NPs such as TiO₂ and ZnO NPs is then summarized. The key findings and challenges under each topic are highlighted and our perspectives on future research directions are provided.

Single Particle Electrochemistry of Collision

A novel electrochemistry method using stochastic collision of particles at microelectrode to study their performance in single-particle scale has obtained remarkable development in recent years. This convenient and swift analytical method, which can be called "nanoimpact," is focused on the electrochemical process of the single particle rather than in complex ensemble systems. Many researchers have applied this nanoimpact method to investigate various kinds of materials in many research fields, including sensing, electrochemical catalysis, and energy storage. However, the ways how they utilize the method are quite different and the key points can be classified into four sorts: sensing particles at ultralow concentration, theory optimization, kinetics of mediated catalytic reaction, and redox electrochemistry of the particles. This review gives a brief overview of the development of the nanoimpact method from the four aspects in a new perspective.