Evaluation of Pt/In2O3-WO3 nano powder ultra-trace level NO gas sensor

Various nano metal oxide composites were prepared from In2O3-WO3 (4:1) and 0.25% Pt/In2O3-WO3 (4:1) were coated as sensing materials over screen printed gold electrodes as a room temperature nitric oxide sensor. The optimized composite materials were characterized by temperature program reduction (TPR), X-ray diffraction (XRD), transmission electron microscope (TEM) techniques. From the obtained experimental results, we found that In2O3-WO3 (4:1) was better than other ratios. The sensor response (S=RNO/RN2) toward detection of 1000 ppm NO at room temperature was 23.9. Response time (T90) and recovery time (TR90) are 12.5 and 15.3 min, respectively. Further loading with 0.25% Pt, sensor response was increased. The sensor responses for 0.1 ppm and 25 ppb were 330 and 15.2, respectively. Sensor response was good for NO concentration range of 25-100 ppb.