Effect of low temperature composite catalyst loading (LTC2L) on sensing properties of nano gas sensor

Abstract Effect of low temperature composite catalyst loading (LTC2L) method on sensing properties of nano gas sensor to 500–10 000  ppm CH4 gas was investigated. The LTC2L method is to load Pd–Pt composite catalyst onto the SnO2 nanoparticle of which mean size is 15 nm below 300 °C. Sensing materials were synthesized using the LTC2L method and were applied to thick film nano gas sensor for characterization. The thick film sensing layer was fabricated by screen printing the paste including sensing material and organic solvents on alumina substrate and heat-treating at 500 and 600 °C, respectively. Composition ratio of Pd:Pt was controlled to 1 wt.%:2 wt.%, 2 wt.%:1 wt.%, and 3.5 wt.%:1.5 wt.%, respectively. The sensitivity is defined as the ratio of R3500/R1000, the resistance at 3500 ppm CH4 gas divided by the resistance at 1000 ppm. As a result, nano gas sensor with Pt rich catalyst showed the enhanced sensitivity. Also, an excellent sensitivity of 0.58 could be achieved by the nano gas sensor with the ratio of 3.5 wt.%:1.5 wt.%. Accordingly, the LTC2L method was successfully applied to the synthesis of ultrafine gas sensing material, and the nano gas sensor with good sensing properties could be fabricated by applying the LTC2L method.