Effect of polyoxometalates electron acceptor decoration on NO2 sensing behavior of ZnS microspheres toward rapid and ultrahigh response

High sensitivity and rapid response are important for environment monitoring of gas sensors. Herein, we introduced polyoxometalates (POMs) as electron acceptors into a low-resistance sulfide gas sensitive material, ZnS, for the first time, and prepared a group of heater-type gas sensors by using ZnS/PW 12 composite microspheres. The sensor performances to NO 2 gas were comprehensively explored. The optimized ZnS/1 %PW 12 composite sensor exhibited an ultrahigh response of 358.1 to 50 ppm NO 2 gas, which is 4.86 times greater than that of pure ZnS sensor, and higher than performances of most reported ZnS-based NO 2 sensors in literatures. Simultaneously, the ZnS/1 %PW 12 composite sensor also exhibited accelerated response and recovery time of only 82 and 30 s, respectively, much faster than pure ZnS sensor (147 and 72 s). The reason for the improvement of the sensing performance was explored via mechanism study, and it was found that the introduction of PW 12 into ZnS sensor contributed to its enhanced performance. PW 12 , as an electron acceptor, increased carrier mobility and reduced electron-hole recombination, and thus enhanced gas sensing properties. Moreover, other gas sensing parameters such as selectivity, repeatability, long-term stability were investigated. Hence, this study contributed to the literature on the development of polyoxometalates-based gas sensors.