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

Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS 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/MoS 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/MoS sensors showed higher sensitivities than rGO sensors, which was attributed to the enhanced HCHO adsorption and electron transfer mediated by MoS. Furthermore, two kinds of MoS nanosheets were prepared by either hydrothermal synthesis or chemical exfoliation and were compared for their detection of HCHO, which revealed that the hydrothermally produced MoS nanosheets with rich defects led to enhanced sensitivity of the rGO/MoS sensors. Moreover, these fabricated flexible sensors can be applied for the HCHO detection in food packaging.