title: SEM method for direct visual tracking of nanoscale morphological changes of platinum based electrocatalysts on fixed locations upon electrochemical or thermal treatments.
abstract: A general method for tracking morphological surface changes on a nanometer scale with scanning electron microscopy (SEM) is introduced. We exemplify the usefulness of the method by showing consecutive SEM images of an identical location before and after the electrochemical and thermal treatments of platinum-based nanoparticles deposited on a high surface area carbon. Observations reveal an insight into platinum based catalyst degradation occurring during potential cycling treatment. The presence of chloride clearly increases the rate of degradation. At these conditions the dominant degradation mechanism seems to be the platinum dissolution with some subsequent redeposition on the top of the catalyst film. By contrast, at the temperature of 60°C, under potentiostatic conditions some carbon corrosion and particle aggregation was observed. Temperature treatment simulating the annealing step of the synthesis reveals sintering of small platinum based composite aggregates into uniform spherical particles. The method provides a direct proof of induced surface phenomena occurring on a chosen location without the usual statistical uncertainty in usual, random SEM observations across relatively large surface areas.
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia; Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana, Slovenia.
authors.forename: Milena
authors.initials: M
authors.lastname: Zorko
authors.affiliation: Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana, Slovenia.
authors.forename: Barbara
authors.initials: B
authors.lastname: Jozinović
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia; Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana, Slovenia.
authors.forename: Marjan
authors.initials: M
authors.lastname: Bele
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia. Electronic address: nejc.hodnik@ki.si.
authors.forename: Nejc
authors.initials: N
authors.lastname: Hodnik
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia; Centre of Excellence for Low-Carbon Technologies, Hajdrihova 19, Ljubljana, Slovenia.
authors.forename: Miran
authors.initials: M
authors.lastname: Gaberšček
keywords: Annealing; Degradation; IL-SEM; Identical location; Platinum; SEM