Combinatorial Electrochemical Screening of Fuel Cell Electrocatalysts

Abstract

Combinatorial methods have been applied to the preparation and screening of fuel cell electrocatalysts. Hardware and software have been developed for fast sequential measurements of cyclic voltammetric and steady-state currents in 64-element half-cell arrays. The arrays were designed for the screening of high-surface-area supported electrocatalysts. Analysis software developed allowed the semiautomated processing of the large quantities of data, applying filters that defined figures of merit relevant to fuel cell catalyst activity and tolerance. Results are presented on the screening of carbon-supported platinum catalysts of varying platinum metal loading on carbon (and thus, particle size) in order to demonstrate the speed and sensitivity of the screening methodology. CO electro-oxidation, oxygen reduction, and methanol oxidation on a series of such catalysts reveal clear trends in characteristics and activities. Catalysts with smaller particle sizes reveal structure in the CO stripping voltammetry that can be associated with edge sites in addition to the closely packed planes, and this is concomitantly reduced as particle size is increased. Specific activity for steady-state methanol oxidation and oxygen reduction at room temperature in H(2)SO(4) electrolyte is found to be a maximum for the largest particle sizes, in agreement with the literature. These trends in activity are significantly smaller than the differences in activities of promoted platinum-based alloy catalysts for the same reaction.

Combinatorial and High‐Throughput Materials Science

“…[292] Guerin and co-workers developed both hardware and software for the fast sequential measurement of cyclic voltammetric and steady-state currents in 64-element halfcell arrays. [293] It is interesting to note that the 64-cell array uses only one reference and one counterelectrode (Figure 28). This setup allows the parallel screening of all 64 electrodes and catalysts deposited on these electrodes for various fuelcell applications.…”

A Parallel Optical Screen for the Rapid Combinatorial Electrochromic Analysis of Electrochemical Materials

“…The working-electrode array consisted of 64 equally sized (3 mm diameter) vitreous carbon cylinders supported in a glass-filled poly(tetrafluoroethylene) (PTFE) plate and described elsewhere [1]. In the experiments described here not all the available electrode array was used, instead subarrays of 7 × 8 or 2 × 2 electrodes were used.…”

“…The thin-layer cell was connected to a single potentiostat, whereby each element in the array was at the same potential, and to a pseudoparallel 64-channel current follower described previously [1].…”

“…[1][2][3][4] However, measuring the current or potential variations across a large array is limited by complex and costly hardware, and this is restricting the size of material libraries that can be screened in one experiment. Consequently, an optical technique that allows a discrete array of samples, or even a continuous but compositionally varying sample, to be monitored in a single snapshot could have significant advantages as a first screen.…”

Kombinatorische und Hochdurchsatz‐Techniken in der Materialforschung

“…[292] Guerin und Mitarbeiter entwickelten sowohl Instrumentierung als auch die Computerprogramme zur schnellen sequenziellen Messung von CV-Kurven und Gleichgewichtsströmen in Halbzellen-Arrays mit 64 Einzelzellen. [293] Dabei ist es bemerkenswert, dass für die 64-Zellen-Anordnung nur eine Referenz-und eine Gegenelektrode verwendet wird (Abbildung 28 [300,301] Mithilfe genetischer Algorithmen wurden weiterhin lösungsmittelresistente Nanofiltrationsmembranen auf Polyimidbasis über HT-Techniken weiterentwickelt. [302] [311] HTT wurden auch für die Testung von Mischungen aus drei Katalysatoren zur Ethylenpolymerisation entwickelt.…”