Direct measurement of metal surface temperature during catalytic dissociation of ozone for sensor application

Temperature variation of a catalytic metal surface exposed to ozone produced in an atmospheric-pressure dielectric barrier discharge is examined by using a very thin thermocouple. The metal sheet is heated initially to a certain temperature (T₁) using a resistive heater and, then, the ozone concentration is increased with the heater current unchanged. When T₁ is room temperature, the temperature of the metal sheet remains almost constant independent of ozone concentration. When T₁ is increased up to 80 °C, the temperature of the metal sheet decreases clearly with increasing ozone concentration due to enhanced catalytic dissociation of ozone at the metal surface. The rate of decrease in temperature for a stainless steel sheet is increased from nearly 0% to ∼ 5.7 % with increasing T₁ from room temperature to 80 °C, while that for a platinum sheet is increased further to ∼ 17.5 % at 80 °C due to stronger catalytic activity of platinum. The results confirm that the sensitivity for ozone is improved with a stronger catalytic metal heated to a higher temperature as the sensor body.