A Combinatorial Approach to the Study of Particle Size Effects on Supported Electrocatalysts: Oxygen Reduction on Gold

Abstract

A novel high-throughput technique has been developed for the investigation of the influence of supported metal particle size and the support on electrocatalytic activity. Arrays with a gradation of catalyst particle sizes are fabricated in a physical vapor deposition system that also allows selection of the support material. Simultaneous electrochemical measurements at all electrodes in the array, together with determination of the actual particle size distribution on each of the electrodes by transmission electron microscopy (TEM), then allows rapid determination of the activity as a function of catalyst center size. The procedure is illustrated using data for the reduction of oxygen on gold nanoparticles supported on both substoichiometric titanium dioxide (TiO(x)()) and carbon and the conclusions are verified using voltammetry at rotating disk electrodes. Gold centers with diameters in the range 1.4-6.3 nm were investigated and it is demonstrated that, with both supports, the catalytic activity for oxygen reduction decays rapidly for particle sizes below 3.0 nm. This may be observed as a decrease in current at constant potential or an increase in the overpotential for oxygen reduction.

Developments in electrode materials and electrolytes for aluminium–air batteries

“…Combinatorial chemistry would allow the simultaneous synthesis and screening of a large number of alloys under identical conditions relevant to the aluminiumeair environment. This technique is growing in popularity to optimise the composition of materials having specific physical or chemical properties [147]. Using this technology, a 10 Â 10 array of individually addressable aluminium alloy electrodes could be fabricated onto a silicon nitride capped silicon wafer in a high-throughput physical vapour deposition system.…”

“…Using this technology, a 10 Â 10 array of individually addressable aluminium alloy electrodes could be fabricated onto a silicon nitride capped silicon wafer in a high-throughput physical vapour deposition system. The array would contain a gradient of varying aluminium alloy composition [147,148].…”

“…Screening would involve carrying out simultaneous half-cell tests on each of the Al alloy electrodes [147]. This would allow identification of the alloying elements, either in binary or ternary alloys that enhance the anodic behaviour of aluminium in alkaline solutions at different temperatures, ranging from 20 to 60 C. This is important since previous published research has focused on identifying alloys suitable for use at 60 C. A similar high-throughput screening technique has been used for the evaluation of micro zinceair [149] and tineair cells [150].…”

The influence of support and particle size on the platinum catalysed oxygen reduction reaction

“…12 Following characterization of the particle size distributions, the activity of the supported catalysts was evaluated using silicon micro-fabricated arrays of 100 electrodes. 13 Of particular interest has been the effect of the support material and the particle size on the activity of the electrocatalysts. We have so far focused our attention on supported gold particles, and indeed recently demonstrated that there is a strong substrate and particle size effect for the electrooxidation of carbon monoxide on reduced titania (TiO x ) supported gold.…”

Inkjet Printing Meets Electrochemical Energy Conversion

“…Each jetted ink droplet has a known composition and by controlling the number of droplets from the different inks, arrays of catalyst spots with gradient compositions can easily be prepared. After post-processing, the catalytically most active composition can be identified by using different screening methods including fluorescence, [17] employing electrode arrays, [18,19] scanning electrochemical microscopy [20,21] and electrochemical scanning droplet cells. [22] Inkjet printed electrocatalyst libraries were reported first by Reddington et al who printed Pt, Ru, Os and Ir based halide salts.…”