title: One at a time: counting single-nanoparticle/electrode collisions for accurate particle sizing by overcoming the instability of gold nanoparticles under electrolytic conditions.
abstract: In response to an increasing demand for understanding electrochemical processes on the nanometer scale, it now becomes possible to monitor electron transfer reactions at the single-nanoparticle level, namely particle collision electrochemistry. This technique has great potential in the development of research tools towards single-particle electrocatalysis and selective and multiplexed particle sizing. However, one existing problem that may discourage these applications is the relatively weak colloidal stability of nanoparticles in an electrolytic solution. Here we report on a facile but efficient way to achieve a good stability of gold nanoparticles in an acidic media so that 'zero-aggregation' collisions can be achieved at a carbon ultramicroelectrode. This allows us to obtain anodic dissolution currents from individual nanoparticles in a 'one particle at a time' manner, based on which accurate particle sizing with a resolution of 1-2 nm can be achieved. Our work strongly suggests that to maintain a well dispersed nanoparticle solution during a particle impact electrochemical experiment is critically important for accurate particle sizing, as well as other applications that require information to be extracted from individual nanoparticles (not their aggregates).
authors.affiliation: CAS Key Laboratory of Soft Matter Chemistry & Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Danfeng
authors.initials: D
authors.lastname: Qiu
authors.forename: Song
authors.initials: S
authors.lastname: Wang
authors.forename: Yuanqin
authors.initials: Y
authors.lastname: Zheng
authors.forename: Zhaoxiang
authors.initials: Z
authors.lastname: Deng