CuO-based gas sensor decorated by polyoxometalates electron acceptors: From constructing heterostructure to improved sensitivity and fast response for ethanol detection

In this paper, polyoxometalates (POMs) electron acceptors were introduced into a classical p-type gas sensitive ceramic-copper oxide (CuO). Then, we investigated the effect of phosphomolybdic acid (PMA) on the sensing performance of CuO gas sensors. The results show that by introducing PMA, the response of CuO gas sensor to 100 ppm ethanol gas can be effectively improved to 2.78. This promotion may be due to the electron trapping effect of PMA, which promotes the carrier migration and inhibits its recombination. Simultaneously, the response and recovery time of the sensor is only 5 s and 4 s. Other gas sensing parameters of the sensors were also comprehensively investigated. The mechanism analysis shows that PMA, as an electron-transport mediator, can trap electrons in the conduction band of CuO, generate shallow electron traps, and effectively inhibit the recombination of electrons and holes in CuO, thereby enhancing gas sensing performance. This work provides a new idea for the advance of CuO-based gas sensors with enhanced sensing sensitivity using polyoxometalates as electron acceptors .