New Electrocatalysts with Pyrolyzed Siloxane Matrix

In a first screening, platinum nanoparticles in pyrolyzed siloxane matrices with additional carbon fillers were developed and tested for their use as electrocatalysts. The influence of various parameters - type of carbon filler, carbon content, pyrolysis temperature, and siloxane composition - on structural properties and on electrochemical activity was investigated. Homogeneous distributions of platinum nanoparticles could be obtained for most of these electrocatalysts. Uniform platinum particles were generated with average particle sizes of 2.5–4.7 nm. At a temperature of 300 °C, the siloxane-based electrocatalysts exhibit high thermal stabilities with maximum weight losses of around 8 wt% after 20 h. The electrochemical behavior of the siloxane-based electrocatalysts in contact with 0.1 M H 2 SO 4 was studied by cyclic voltammetry. Electrocatalytic activities were studied by CO adlayer oxidation, which also served for determining the electrochemical active surface area. High electrochemically active surface areas with up to 50 m 2 g −1 Pt were obtained, which are in the same range as carbon-based electrocatalysts. Interestingly, some siloxane-based electrocatalysts showed a slightly higher catalytic activity for CO adlayer oxidation than carbon-based materials.