▎ 摘 要
Formaldehyde (HCHO) is a colorless and pungent pollutant gas in both indoor and outdoor air, which poses a significant threat on ambient environment and human health at ppm level. In this work, an ionic-conduction composite film featuring reduced graphene oxide (rGO), nitrogen-doped MXene Ti3C2Tx (N-MXene), and titanium oxide (TiO2) was firstly proposed to detect 4-40 ppm HCHO vapor at room temperature (20 degrees C) in the presence of humidity, preceding its counterparts comprised of single or binary components. Among various humidity cases toward 4 ppm HCHO, the ternary sensor reached a mean and reversible response of 26 % at 54 % RH. Moreover, favorable repeatability, long-term stability and selectivity were revealed. When under wet atmospheres, rGO nanosheets served as excellent conduction platform to transport and collect charge carriers. Layered N-MXene benefitted co-adsorption and diffusion of both HCHO and water molecules. TiO2 nanoparticles provided rich sorption sites and facilitated the dissociation of adsorbed water. The HCHO. H2O formation upon HCHO adsorption eliminated conductive H+ and H3O+ ions on TiO2 nanoparticles and thus increased the resistance of the ternary sensors. This work enriched the sensing mechanism and expanded the room-temperature gas detection of MXene based materials.