title: Nanoelectrochemical approach to detecting short-lived intermediates of electrocatalytic oxygen reduction.
abstract: Development of better catalysts for the oxygen reduction reaction (ORR) and other electrocatalytic processes requires detailed knowledge of reaction pathways and intermediate species. Here we report a new methodology for detecting charged reactive intermediates and its application to the mechanistic analysis of ORR. A nanopipette filled with an organic phase that is immiscible with the external aqueous solution was used as a tip in the scanning electrochemical microscope to detect and identify a short-lived superoxide (O2(●-)) intermediate and to determine the rate of its generation at the catalytic Pt substrate and its lifetime in neutral aqueous solution. The voltammogram of the O2(●-) anion transfer to the organic phase provides a unique signature for unambiguous identification of superoxide. The extremely short attainable separation distance between the pipette tip and substrate surface (∼1 nm) makes this technique suitable for detecting and identifying charged intermediates of catalytic processes with a lifetime of a few nanoseconds.
authors.affiliation: Department of Chemistry and Biochemistry, Queens College, City University of New York, Flushing, New York 11367, United States.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Department of Chemistry and Biochemistry, Queens College, City University of New York, Flushing, New York 11367, United States.
authors.forename: Yun
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Chemistry and Biochemistry, Queens College, City University of New York, Flushing, New York 11367, United States.
authors.forename: Keke
authors.initials: K
authors.lastname: Hu
authors.affiliation: Department of Chemistry and Biochemistry, Queens College, City University of New York, Flushing, New York 11367, United States.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Mirkin