Three-dimensional conductive networks based on stacked SiO₂@graphene frameworks for enhanced gas sensing

Abstract

Graphene is an ideal candidate for gas sensing due to its excellent conductivity and large specific surface areas. However, it usually suffers from sheet stacking, which seriously debilitates its sensing performance. Herein, we demonstrate a three-dimensional conductive network based on stacked SiO@graphene core-shell hybrid frameworks for enhanced gas sensing. SiO spheres are uniformly encapsulated by graphene oxide (GO) through an electrostatic self-assembly approach to form SiO@GO core-shell hybrid frameworks, which are reduced through thermal annealing to establish three-dimensional (3D) conductive sensing networks. The SiO supported 3D conductive graphene frameworks reveal superior sensing performance to bare reduced graphene oxide (RGO) films, which can be attributed to their less agglomeration and larger surface area. The response value of the 3D framework based sensor for 50 ppm NH and 50 ppm NO increased 8 times and 5 times, respectively. Additionally, the sensing performance degradation caused by the stacking of the sensing materials is significantly suppressed because the graphene layers are separated by the SiO spheres. The sensing performance decays by 92% for the bare RGO films when the concentration of the sensing material increases 8 times, while there is only a decay of 25% for that of the SiO@graphene core-shell hybrid frameworks. This work provides an insight into 3D frameworks of hybrid materials for effectively improving gas sensing performance.

Co3O4 nanosheet-built hollow dodecahedrons via a two-step self-templated method and their multifunctional applications

“…10). However, the chemisorption of oxygen on Co 3 O 4 creates the hole accumulation layer on the surface of Co 3 O 4 , different from that of n-type semiconductor [46][47][48], where the electron depletion layer is created at the grain boundaries. In general, the atmospheric oxygen is adsorbed in ionic forms at the surface as O 2 − (<100°C), O − (100-300°C) and O 2− (>300°C) in the air [49].…”

Room‐Temperature Solid‐State Grown WO3−δ Film on Plastic Substrate for Extremely Sensitive Flexible NO2 Gas Sensors

“…In order to demonstrate the sensing capability of the GSV‐WO 3–δ flexible sensing device, we measured its resistance change under exposure to analyte gases. The response factor is defined as R = Δ R/R 0 = ( R g − R 0 )/ R 0 , where R g and R 0 represent resistance of the sensor to be exposed (respectively) to analytic gas and N 2 . As shown in Figure c, the resistance of the device exposed to NO 2 gas was strongly dependent on the operating temperature.…”

“…Most importantly, the response/recovery time for oxidizing NO 2 gas (17/25 s), as depicted in Figure b, was fast enough for practical applications. The long recovery time after exposure to reducing gas might be due to a complex sensing mechanism that slows down the desorption rate of the detected gas . Meanwhile, specific response factors to the gases of the GSV‐WO 3–δ sensor device were compared in Figure c.…”

Hydrothermal Synthesis and Electrochemical Performance of Amorphous SiO&lt;sub&gt;2&lt;/sub&gt; Nanospheres/Graphene Composites

“…From 100˚C to 300˚C, the TGA curve declines slowly because of the decomposition of a small amount of oxygen containing functional groups of graphene [15].…”