MECHANISM OF HYDROGEN SENSING BY PD TIO2 SCHOTTKY DIODES/

The mechanism of hydrogen sensing by Pd/TiO2 Schottky diodes has been investigated by measuring the shift of the current-voltage curve, DELT A(I-V), and the Pd surface work function change, DELTAphi. The kinemat ic analysis of the plots of DELTA(I-V) versus DELTAphi shows that the formation of adsorbed water from adsorbed oxygen at the Pd/TiO2 interf ace is the dominant reaction for the Pd/TiO2(001) diodes throughout th e hydrogen concentration region investigated (0-3000 ppm), while, for the Pd/TiO2(100) diodes, this reaction is dominant only in the low hyd rogen concentration region below 100 ppm and the hydrogen adsorption o n bare Pd atoms becomes dominant in the higher hydrogen concentration region.