Multifunctions of Net Surface Charge in the Reaction on a Single Nanoparticle

Electric charge can determine where and how reaction occurs, but the relationship between net surface charge and activity is unclear because of the difficulty in simultaneously detecting charge and activity at the single nanoparticle level. In this study, we use ions as probes to detect the distribution of net surface charge and track galvanic replacement reaction on single Ag nanowire in situ and in real time by dark-field microscopy. The two ends of a single Ag nanowire are found to possess more net surface charges than the middle part. The unevenly distributed net surface charge performs multifunctions in determining the reaction activity, selectivity, and product shape. Owing to the interaction between the net surface charges and ions in solution, many clusters are generated on the Ag nanowires. The locations of generating these clusters are where faster deposition reaction happens. Furthermore, larger size Ag compounds with clear shape are produced near the two ends by attracting Ag⁺ at lower [HAuCl₄], but larger size Ag–Au alloy clusters with veiled shape are produced near the center by repelling AuCl₄^– at higher [HAuCl₄]. Given that net surface charge generally exists in nanoscience, the methodology and results obtained from this research can be widely used in other single-shaped nanomaterials