Mapping of Electrocatalytic Sites on a Single Strand of Carbon Fiber Using Scanning Electrochemical Microscopy (SECM)

Abstract

A novel use of scanning electrochemical microscopy (SECM) to study electrocatalytic heterogeneities present on a single strand of carbon fiber (SSCF) is presented. The SECM investigations on an SSCF have been carried out in a feedback mode using α-methyl ferrocene methanol as a redox mediator. Array scan investigations revealed substantial enhancement in the positive feedback response at specific locations on the SSCF. These locations appeared as high-contrast morphological heterogeneities in the optical micrographs. The probe-approach curves, recorded near a variety of predefined locations on the SSCF, were fitted in the analytical expressions. From this analysis, the apparent pseudo-first-order rate constant keff for the electron-transfer reaction was estimated. The electroactive locations resulted in a keff as high as 0.1 cm s–1. The confocal micro-Raman spectra recorded on the identical portions of the fiber indicated a larger proportion of the distorted sp2-hybridized structure near the electroactive sites and thus implied enhanced local electrocatalytic activity on the fiber.