Photothermal hydrogen sensor: the technique, experimental process, and physicochemical analysis

The kinetics of hydrogen adsorption and desorption on palladium thin films was studied via photomodulated thermoreflectance measurements. The subsequent analysis based on a Langmuirian isothermal model supports dissociative adsorption of hydrogen on palladium followed by molecular desorption. Furthermore, the rate constants of adsorption and desorption were determined and their values are discussed. The response and recovery times of the sensor were measured and their dependence on hydrogen concentration is also explored and discussed.