Transition metals (Fe/Mn)-doped g-C3N4 and ZnO nanosheet composite sensors for efficient detection of BTEX

In this study, the solid-phase precursor synthesis method was used to prepare Fe-C3N4/ZnO and Mn-C3N4/ZnO nanocomposites to attain effective detection of BTEX. The crystal structure, micro-morphology and chemical bonding states of the samples were analyzed by using XRD, SEM, TEM and XPS. The gas-sensitive properties of ZnO-based sensors for BTEX in the range of 200-370 degrees C were systematically investigated. Compared with pristine ZnO, the sensing capabilities of the composites were significantly enhanced. It was worth mentioning that the sensors exhibited superior performances to three forms of xylene. In particular, the optimal responses of the sensors to 100 ppm o-xylene were about 5.8 times (Fe-C3N4/ZnO) and 7.1 times (Mn-C3N4/ZnO) that those of pristine ZnO at 370 degrees C. Besides, the responses of the sensors to target gas did not decay in four weeks. These above results indicated that the sensors had good potential for rapid detection of BTEX. The improvements in gas- sensitive performances were mainly attributed to the construction of heterojunction and the catalytic effect of highly dispersed transition metal active sites.