Pd-modified SnO2 octahedrons for humidity-independent ethanol vapor gas sensing

The type and amount of oxygen adsorption species under varying humidity conditions are key factors in improving the sensitivity of SnO₂-based resistive gas sensors to combustible gases and their stability against humidity changes. We investigated the effect of Pd metal surface modification on the sensitivity stability and oxygen adsorption species of octahedral SnO₂ nanoparticles under humid conditions. The results show that, at a working temperature of 124°C and a testing temperature of 25°C, the 4 % Pd/SnO₂ sensor maintains stable sensitivity to ethanol within the relative humidity (RH%) range of 11–95 %, with a response value of approximately 42. In contrast, the unmodified SnO₂ sensor shows a gradual decrease in response as humidity increases. Pd modification effectively enhanced the sensor's response under humid conditions while maintaining good stability against humidity changes. Therefore, we have successfully improved the sensitivity stability of SnO₂ nanoparticles during humidity variations, marking an important advancement in the development of high-performance, practical resistive-type gas sensors.