The Effect of rGO-Doping on the Performance of SnO2/rGO Flexible Humidity Sensor

Abstract

The development of a flexible and high-performance humidity sensor is essential to expand its new applications, such as personal health monitoring and early diagnosis. In this work, SnO2/rGO nanocomposites were prepared by one-step hydrothermal method. The effect of rGO-doping on humidity sensing performance was investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the nanostructure, morphology and chemical composition of SnO2/rGO nanocomposites. The SnO2/rGO humidity sensitive film was prepared by electrospinning on a polyimide film modified with gold electrodes. The humidity test results show that different doping ratios of rGO have different effects on humidity sensing properties. Among them, the sensor with 2 wt% rGO-doping has a high sensitivity (37,491.2%) within the humidity range as well as the fast response time (80 s) and recover time (4 s). Furthermore, the sensor with 2 wt% rGO-doping remains good flexibility and stability in the case of bending (1000 times). The sensitivity of the 2 wt% rGO-doping sensor at the bending radius (8 mm and 4 mm) is 48,219% and 91,898%, respectively. More importantly, the sensor could reflect different breathing states clearly and track breathing intervals as short as 3 s. The SnO2/rGO flexible humidity sensor with accuracy, flexibility and instantaneity as well as the facile fabrication strategy is conceivable to be applied in the potential application for human health real-time monitoring.

Composite Nanoarchitectonics with CoS2 Nanoparticles Embedded in Graphene Sheets for an Anode for Lithium-Ion Batteries

“…The detail information of chemical reagent in this experiment were shown in Table S1. After referring to the classic literature on this subject, graphene oxide was prepared by an improved version of the graphene modified Hummer method [1,6]. The specific synthesis method was as follows: 3.0 g flake graphite was added into a beaker containing 60 mL concentrated H 2 SO 4 (98%), and 1.5 g KNO 3 was added under stirring condition.…”

“…Lithium-ion batteries (LIBs) have attracted wide attention due to their high energy density, good cycling stability, and no memory effect [1,2]. Since their introduction in 1991, graphite has been the dominant commercial anode materials for lithium-ion batteries, due primarily to the low theoretical specific capacity of graphite (372 mAhg −1 ).…”

SnO2-Based Ultra-Flexible Humidity/Respiratory Sensor for Analysis of Human Breath

“…Nevertheless, conventional metal oxide (MOx)based sensors usually require a high annealing temperature (>200 • C) and high operating temperature (>100 • C) [38]. Recently, noble metals (Au/ZnO, Ag/SnO 2 ) [35,39] and carbonbased nanomaterials (GO/ZnO, SnO 2 /rGO, g-C 3 N 4 /ZnO) [40][41][42] have been incorporated into metal oxides to realize room-temperature-operated MOx-based sensors. In Table S2, recently-published metal-oxide-based humidity sensors with a low annealing temperature (<100 • C) are listed [25,26,35,[41][42][43][44].…”

“…Recently, noble metals (Au/ZnO, Ag/SnO 2 ) [35,39] and carbonbased nanomaterials (GO/ZnO, SnO 2 /rGO, g-C 3 N 4 /ZnO) [40][41][42] have been incorporated into metal oxides to realize room-temperature-operated MOx-based sensors. In Table S2, recently-published metal-oxide-based humidity sensors with a low annealing temperature (<100 • C) are listed [25,26,35,[41][42][43][44]. It is noticed that, compared to composite MOx, pure MOx sensors show lower responses [26,35,[42][43][44] under a low annealing temperature.…”

“…It is noticed that, compared to composite MOx, pure MOx sensors show lower responses [26,35,[42][43][44] under a low annealing temperature. The drop-casting or sputtered MOx/carbon nanomaterial composite-based humidity sensors such as In 2 O 3 /GO, SnO 2 /rGO, and g-C 3 N 4 /ZnO-based sensors on flexible epoxy and PI substrate are fabricated at a particularly low annealing temperature such as 60 • C [26,41,42]. As shown in Table S2, in our experiment, pure SnO 2 was used as the sensing layer, and the low annealing temperature (<41 • C) was realized by using NIR laser annealing.…”