Three-Dimensional Mesoporous Graphene Aerogel-Supported SnO₂ Nanocrystals for High-Performance NO₂ Gas Sensing at Low Temperature

Abstract

A facile and cost-efficient hydrothermal and lyophilization two-step strategy has been developed to prepare three-dimensional (3D) SnO2/rGO composites as NO2 gas sensor. In the present study, two different metal salt precursors (Sn(2+) and Sn(4+)) were used to prepare the 3D porous composites. It was found that the products prepared from different tin salts exhibited different sensing performance for NO2 detection. The scanning electron microscopy and transmission electron microscopy characterizations clearly show the macroporous 3D hybrids, nanoporous structure of reduce graphene oxide (rGO), and the supported SnO2 nanocrystals with an average size of 2-7 nm. The specific surface area and porosity properties of the 3D mesoporous composites were analyzed by Braunauer-Emmett-Teller method. The results showed that the SnO2/rGO composite synthesized from Sn(4+) precursor (SnO2/rGO-4) has large surface area (441.9 m(2)/g), which is beneficial for its application as a gas sensing material. The gas sensing platform fabricated from the SnO2/rGO-4 composite exhibited a good linearity for NO2 detection, and the limit of detection was calculated to be as low as about 2 ppm at low temperature. The present work demonstrates that the 3D mesoporous SnO2/rGO composites with extremely large surface area and stable nanostructure are excellent candidate materials for gas sensing.

A 3D Chemically Modified Graphene Hydrogel for Fast, Highly Sensitive, and Selective Gas Sensor

“…In addition to chemical modification of sensing materials, the performance of chemical sensors can also be enhanced through newly designed material structures. For example, recently 3D Gr/RGO porous structures have been utilized to significantly improve the gas sensing performance compared with the 2D counterparts 1, 4, 15, 28, 29. This is because the unique porous structure coupled with the inherent properties makes 3D RGO exhibit a higher surface area and much more “space” for the transportation or storage of electron/hole and gas, leading to an improved sensitivity 30…”

Versatile Aerogels for Sensors

“…Graphene is a promising candidate for the gas sensors for detecting individual gas due to its exceptionally low‐noise property, however, the graphene‐based sensors without any modification always exhibit an inferior selectivity . The chemical modification and introduction of heterostructure materials in the 3D graphene network have been proved to be efficient ways to prepare high‐performance gas sensors . For example, HSO 3 − with lone‐pair electrons was used to modify the graphene sheets, and the resultant modified graphene network showed an enhanced selectivity of NO 2 due to the weak interaction between HSO 3 − and NO 2 .…”

“…Through the density‐functional calculation, Yuan and co‐workers theoretically simulated gas adsorption on the chemical modification of graphene with B‐, N‐, Al‐, and S‐doping, indicating that B‐ and S‐doped graphene could be a selective senor for NO and NO 2 . As for the introduction of heterostructure materials in graphene aerogels, the graphene aerogels serve as a 3D porous supporting materials that can enhance the electron transfer between the sensing materials and the target gases or vapors, and improve the gas diffusion in the entire sensors; moreover, the 3D scaffold can stabilize the heterostructure materials avoiding its aggregation, thus a fine grain size can be obtained, resulting in an enhanced sensing performance . Zhang and co‐workers and Chen and co‐workers prepared the 3D graphene aerogel‐supported SnO 2 for NO 2 sensing via the hydrothermal treating of the mixed suspension of GO and the metal salt precursors (Figure e).…”

“…As for the introduction of heterostructure materials in graphene aerogels, the graphene aerogels serve as a 3D porous supporting materials that can enhance the electron transfer between the sensing materials and the target gases or vapors, and improve the gas diffusion in the entire sensors; moreover, the 3D scaffold can stabilize the heterostructure materials avoiding its aggregation, thus a fine grain size can be obtained, resulting in an enhanced sensing performance . Zhang and co‐workers and Chen and co‐workers prepared the 3D graphene aerogel‐supported SnO 2 for NO 2 sensing via the hydrothermal treating of the mixed suspension of GO and the metal salt precursors (Figure e). Both of the aerogel‐based sensors exhibited a low detection limit of 10 and 2 ppm, as well as a decreased operating temperature of room temperature and 55 °C, respectively.…”

Gas sensors based on ultrathin porous Co3O4 nanosheets to detect acetone at low temperature

“…7(a) shows the response time of S250-S450, decreasing from 150 s to 41 s. And the recovery time of S250-S450 decreases from 300 s to 65 s, as shown in Fig. [31][32][33] To conrm the stability of the samples, the responses of S300 at 150 C to 100 ppm acetone (RH $ 50%) were investigated 20 times over two months. 8 presents the acetone-selective characteristics of S300 with respect to other typical interfering gases such as ethanol, ammonium, methanol, toluene, and p-xylene with response values toward each gas at 150 C. The gas response to 100 ppm acetone vapour is signicantly higher than all the other gases at the same concentration, which demonstrates that the sensors based on ultrathin porous Co 3 O 4 nanosheets show a high anti-interference performance that is a precondition for becoming a useful sensor to detect breath acetone for diabetes detection.…”