Flexible room-temperature formaldehyde sensors based on rGO film and rGo/MoS₂ hybrid film

Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS₂ hybrid films were fabricated on polyethylene naphthalate substrates by a simple self-assembly method, which yielded flexible devices for detection of formaldehyde (HCHO) at room temperature. The sensing test results indicated that the rGO and rGO/MoS₂ sensors were highly sensitive and fully recoverable to a ppm-level of HCHO. The bending and fatigue test results revealed that the sensors were also mechanically robust, durable and effective for long-term use. The rGO/MoS₂ sensors showed higher sensitivities than rGO sensors, which was attributed to the enhanced HCHO adsorption and electron transfer mediated by MoS₂. Furthermore, two kinds of MoS₂ nanosheets were prepared by either hydrothermal synthesis or chemical exfoliation and were compared for their detection of HCHO, which revealed that the hydrothermally produced MoS₂ nanosheets with rich defects led to enhanced sensitivity of the rGO/MoS₂ sensors. Moreover, these fabricated flexible sensors can be applied for the HCHO detection in food packaging. (paper)