ZnO-Reduced Graphene Oxide Composites Sensitized with Graphitic Carbon Nitride Nanosheets for Ethanol Sensing

In this work, we reported a ternary sensing material using graphitic carbon nitride (g-C3N4) nanosheets as sensitization modifier for zinc oxide (ZnO)/reduced graphene oxide (rGO) rather than widely reported noble metal nanoparticles. The nanostructures of 2D graphene oxide (GO)-hybridized by g-C3N4 were synthesized in advance by combining ultrasonic dispersion and electrostatic self-assembly strategy. ZnO nanoparticles were coated on GO/g-C3N4 through a hydrothermal process, in which GO was totally reduced to rGO. Compared with pure ZnO and ZnO/rGO, the ZnO/rGO/g-C3N4 nanocomposites exhibited a remarkable enhancement in the responses to ethanol vapor. The ternary nanocomposites showed the highest response of 178 (Ra/Rg) to 100 ppm ethanol at 300 °C with a detect limitation lower than 500 ppb, which was about 2-fold and 9-fold higher than ZnO/rGO and pure ZnO samples, respectively. The enhancement was attributed to the sensitization of g-C3N4 and the ample interfacial contact between rGO and g-C3N4. The ethanol sensing mechanism associated with ZnO nanoparticles and GO/g-C3N4 2D hybrid structure was also discussed in detail.