High performance bimetal decorated PtNix-WO3 sensors and the cross-sensitivity investigation

Gas sensors play an essential bridge in connecting humans and health by helping people monitor the gas quality in their living spaces. In this work, PtNi3-WO3 gas sensors were fabricated and demonstrated superior selectivity, sensitivity, and stability to formic acid, which was sufficient for indoor air gas monitoring. The response to 100 ppm formic acid was as high as 591, with a response time of only 3 s, and detection range down to the ppb level. The bimetal PtNi3 decorated sensors showed a 30 times improvement in formic acid response compared to pure WO3 sensors. The cross-sensitivity was investigated, and we observed that the response initially decreased and then increased in a mixed gas with a constant concentration of carboxylic acid and increasing gradually con-centration of formaldehyde. The adsorption and desorption mechanisms were studied, which implied that the decomposition and adsorption behavior of the gas could change and produce different intermediate products under different mixing environments. The results of the energy surface testing and density functional theory supported the proposed sensing mechanism. A machine-learning framework was developed for gas identification and concentration prediction, which achieved ultra-high identification accuracy. In addition, Bluetooth-based portable gas sensors were demonstrated, showing promising practical applications.