Scanning electrochemical microscopy at the nanometer level.

This review describes how one can perform nanometer (nm)-scale SECM experiments through advances in tip fabrication and positioning and instrumentation design. Basic SECM methodology including instrumentation and feedback and generation/collection modes are discussed. Aspects of nanoscale SECM including fabrication of nm-sized electrodes and nano SECM instrumentation are also described. State of the art applications related to nanogaps (i.e., rapid homogeneous reactions and short-lived intermediates; heterogeneous electron transfer kinetics; nanoparticles (NPs) and clusters) and nanoscale imaging (e.g., single NPs, single biological samples, combined methods) are described. Future possibilities and prospects are suggested that might lead to even better resolution, thus introducing SECM electrochemical imaging to the single atom level.