Kinetic modelling of the H sub 2 -O sub 2 reaction on Palladium and of its influence on the hydrogen response of a hydrogen sensitive Palladium metal-oxide-semiconductor device

A model for the water forming reaction on Pd in the temperature range 350-475K was established. The model takes into account the possibility that hydrogen may absorb and adsorb at interface sites on supported Pd catalysts. It is shown that already at modest conditions interface adsorption may significantly affect reaction rates. The model may also be used to quantify the response of a hydrogen sensitive Pd-MOS device during hydrogen sensing in oxygen. In the case of Pd supported on SiO sub 2 , the concentration of interface sites is so low that interface hydrogen adsorption will have only a minor influence on a catalytic reaction. The fact that a Pd-MOS device may be used as a very sensitive hydrogen detector at atmospheric oxygen conditions, despite a steric oxygen blocking of hydrogen dissociation sites, is predicted by the model.