The increasing production and application of nanoparticles necessitates a highly sensitive analytical method for the quantification and identification of these potentially hazardous materials. We describe here an application of surface plasmon microscopy for the individual detection of each adsorbed nanoparticle and for visualization of its electrochemical conversion. Whereas the adsorption rate characterizes the number concentration of nanoparticles, the potential at which the adsorbed nanoparticles disappear during an anodic potential sweep characterizes the type of material. All the adsorbed nanoparticles are subjected to the potential sweep simultaneously; nevertheless, each of the up to a million adsorbed nanoparticles is identified individually by its electrochemical dissolution potential. The technique has been tested with silver and copper nanoparticles, but can be extended to many other electrochemically active nanomaterials.
All‐seeing: The detection of each adsorbed nanoparticle (NP) and visualization of their electrochemical conversions is possible with surface plasmon microscopy. Whereas the adsorption rate gives the concentration of NPs, the potential at which the adsorbed NPs disappear during an anodic potential sweep characterizes their chemical composition. Each adsorbed NP is identified individually.