A UHV chamber incorporating an infra-red window and a high sensitivity thermal camera has been use to image a high-throughput screening chip. The chamber allows the chip to be exposed to mixtures of gases of up to several mBar. Planar model catalysts synthesised on the chip, when catalysing exothermic reactions, cause an increase in temperature of the substrate which is detected using the camera. Combinatorial synthesis of the catalysts on the array allow up to ca. 100 different catalysts to be screened for their activity simultaneously.
The screening chips comprise of arrays of ca. 1mm x 1mm fields of silicon nitride membranes supported on back etched silicon. These membraned have both a low thermal capacity and poor thermal conductivity enabling small temperature changes associated with reactions taking place at model catalysts synthesised on them to be detected.
Combinatorial synthetic methods have been developed to produce a variation of particle size on a support. The latter can be changed independently and simultaneously. To demonstrate the effectiveness of the thermographic screening method, a range of titania supported gold and platinum model catalysts were synthesised. The ability of these catalysts to sustain the catalytic oxidation of CO was investigated. The results below summarise a few of the results for titania supported gold. The results clearly show that the CO activity monotonically increases with the decrease in gold particle size in the range and conditions studies.