Nanostructured, Glassy-Carbon-Supported Pt/GC Electrodes: The Presence of Secondary Pt Nanostructures and How to Avoid Them

Abstract

Nanostructured, glassy carbon ͑GC͒ supported Pt/GC electrodes, with Pt nanostructures ͑nanodisks͒ of controlled size ͑100-140 nm in diameter͒ and separation homogeneously distributed on a planar GC substrate, were recently shown to be interesting model systems for electrocatalytic reaction studies ͓M. Gustavsson, H. Fredriksson, B. Kasemo, Z. Jusys, C. Jun, and R. J. Behm, J. Electroanal. Chem., 568, 371 ͑2004͔͒. We present here electron microscopy and electrochemical measurements which reveal that the fabrication of these nanostructured electrodes via colloidal lithography, in addition to the intended nanodisks, results in a dilute layer of much smaller Pt nanoparticles ͑diameter ϳ5 nm͒ on the GC surface in the areas between the Pt nanodisks. We further demonstrate that by using the developed, related method of hole-mask colloidal lithography ͑HCL͒ ͓H. Fredriksson, Y. Alaverdyan, A. Dmitriev, C. Langhammer, D. S. Sutherland, M. Zäch, and B. Kasemo, Adv. Mater. (Weinheim, Ger.), 19, 4297 ͑2007͔͒, similar electrodes can be prepared which are free from these Pt nanoparticles. The effect of the additional small Pt nanoparticles on the electrochemical and electrocatalytic properties of these nanostructured electrodes, which is significant and can become dominant at low densities of the Pt nanodisks, is illustrated and discussed. These results leave HCL the preferred method for the fabrication of nanostructured Pt/GC electrodes, in particular, of low-density Pt/GC electrodes.

Oscillatory behaviour in Galvanostatic Formaldehyde Oxidation on Nanostructured Pt/Glassy Carbon Model Electrodes

“…[19,[41][42][43][44][45] employing CL. The polished (alumina paste down to 0.3 mm grain size) GC substrates (disk diameter 9 mm, Sigradur G from Hochtemperatur Werkstoffe GmbH), were cleaned by immersion in 5 m KOH, rinsing with Millipore MilliQ water, subsequent immersion in concentrated H 2 SO 4 solution and again rinsing with Millipore MilliQ water, before they were dried in a N 2 stream.…”

“…The large-scale images of the nanostructured Pt/GC samples (Figures 1 b,c) underline the homogeneous and narrow size distribution of the disk-shaped nanostructures as it was demonstrated in previous studies. [41,42,44,45,51,52] High-resolution SEM images are included as insets in Figures 1 b,c. As we reported recently, the preparation of nanostructured Pt/GC electrodes via the CL-route results in Pt nanoparticles distributed between the Pt nanostructures, [45] which are poorly resolved in Figures 1 b, c in the present SEM images.…”

“…[41,42,44,45,51,52] High-resolution SEM images are included as insets in Figures 1 b,c. As we reported recently, the preparation of nanostructured Pt/GC electrodes via the CL-route results in Pt nanoparticles distributed between the Pt nanostructures, [45] which are poorly resolved in Figures 1 b, c in the present SEM images. Therefore, we cannot rule out the absence of Pt nanoparticles in between the Pt nanostructures.…”

“…These Pt nanoparticle features were assumed to originate from Pt clusters which are formed during the Ar + sputtering procedure (Experimental Section) for removal of the unprotected Pt film between the adsorbed PS-colloid mask. [45] The physical characterization via SEM was used for determination of the Pt coverage, the mean Pt nanostructure diameter and nanostructure density. For a (Table 1).…”

Novel, Highly Conductive Pt/TiO2 Thin‐Film Model Catalyst Electrodes: The Role of Metal–Support Interactions

“…6d on the GC substrate the H2O2 yield increases. [58] The authors explained that by a decreasing probability of re-adsorption and further reduction of H2O2 which had been formed in a first step and desorbed into the electrolyte. Comparable results were reported later also by Inaba et al for disperse Pt/C catalysts with decreasing amount of Pt deposited.…”