Surface-ruthenated tin oxide as a novel hydrocarbon sensor

A surface-functionalized gas-sensing material capable of better sensitivity and selectivity to hydrocarbons is demonstrated by grafting some Ru-O linkages on the surface of tin oxide. For example, the sensitivity towards 1000 ppm liquid petroleum gas (LPG) is found to be dramatically enhanced from 4 to 320 at 300 degrees C after this type of surface modification using ruthenium species. A systematic evaluation of the surface coverage, morphology, oxidation state and thermal stability using different techniques like EDAX, cyclic voltammetry, SEM, XPS and TGA indicates the crucial role of the optimum distribution of Ru species (0.27 wt.%) in dictating both selectivity and sensitivity. The response time of the surface-modified sensor has also been found to be significantly improved in comparison with pure tin oxide as a result of surface functionalization. (C) 1998 Elsevier Science S.A.