COMPARATIVE-STUDIES OF DOPED AND SURFACE-MODIFIED TIN OXIDE TOWARDS HYDROGEN SENSING - SYNERGISTIC EFFECTS OF PD AND RU

A surface functionalised gas sensing material capable of giving better sensitivity and selectivity to hydrogen is demonstrated by grafting f ew Ru-O and Pd-O linkages in the surface of tin oxide. A systematic ev aluation of the surface coverage, morphology and thermal stability usi ng different techniques like EDAX, Cyclic voltammetry, SEM and TGA ind icates the importance of an optimum distribution of Ru/Pd ratio (1.28) in dictating both sensitivity and selectivity. A comparison of the op timum performance of conventionally doped (225) and surface modified ( 1350) tin oxide to 1000 ppm hydrogen at 250 degrees C illustrates the clear advantages offered by surface modified tin oxide in enhancing th e sensitivity. Moreover, the synergistic effect by surface functionali sation with both Ru and Pd species is emphasised in comparison to indi vidually modified tin oxide sensors. (C) 1998 Elsevier Science S.A. Al l rights reserved.