KINETIC MODELING OF THE H-2-O-2 REACTION ON PD AND OF ITS INFLUENCE ON THE HYDROGEN RESPONSE OF A HYDROGEN SENSITIVE PD METAL-OXIDE-SEMICONDUCTOR DEVICE

We have established a model for the water forming reaction on Pd in th e temperature range-350-475 K. Importantly, the model takes into accou nt the possibility that hydrogen may absorb and adsorb at interface si tes on supported Pd catalysts. It is shown that already at modest cond itions interface adsorption may significantly affect reaction rates. T he model may also be used to quantify the response of a hydrogen sensi tive Pd-MOS device during hydrogen sensing in oxygen. In the case of P d supported on SiO2, the concentration of interface sites is so low th at 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 ve ry sensitive hydrogen detector at atmospheric oxygen conditions, despi te a steric oxygen blocking of hydrogen dissociation sites, is predict ed by the model.