Abstract
A gas sensor was prepared by calcining rhodium nitrate supported on aluminium nitride at various temperatures in a N2 stream. The sensitivity of the gas sensor increased linearly with CO gas concentration below 3000 ppm at 180°C and 220°C, while addition of rhodium nitrate over 3 wt% was not effective. The sensor calcined at 1000°C was twice as sensitive as that calcined at 600°C. Rhodium nitrate decomposed to RH2O3 at 600°C and to Rh at 1000°C in N2 stream. From these results, Rh was better than RH2O3 as a catalyst. The apparent porosity of the gas sensor was about 50% and this value was kept constant after annealing. It is considered that aluminium nitride is a good material as a support.
