A classification and ranking system on the H2 gas sensing capabilities of nanomaterials based on proposed coefficients of sensor performance and sensor efficiency equations

A coefficient of performance is defined based on the traditional definitions of response, S, of a chemoresistive sensing material to a specific gas from resistance–time data. The new definition not only considers the Sresponse and Srecovery but also the temperature, T, and the relative humidity, H, at which the sensor operates and the response time, τres, and recovery time, τrec. Resistance–time data at various temperatures in a H2 atmosphere for six samples of different materials, including WO3 nanoparticles, SnO2 nanoparticles, SnO2 nanoparticles mixed with carbon nanotubes, TiO2 nanorods, TiO2 nanotubes and VO2 nanobelts, are presented in this report. The VO2 nanobelts were the best sensing materials when these materials were ranked according to the temperatures at which they operate; however, the SnO2 nanoparticles are the superior sensing materials when they are ranked by the defined coefficient of performance.