Hybrid nanoarchitecturing of hierarchical zinc oxide wool-ball-like nanostructures with multi-walled carbon nanotubes for achieving sensitive and selective detection of sulfur dioxide

Abstract

Graphical abstract Research highlights Hierarchical 3D wool-ball-like ZnO nanostructures were synthesized via a solvothermal method. 3D wool-ball like ZnO/MWCNT composites with different ratios (3:1, 5:1, and 10:1) were prepared. The 3D wool-ball like ZnO/MWCNT composite showed high response and good selectivity to SO2 gas. AbstractThis work reports a facile glycerol-assisted solvothermal method for synthesizing hierarchical three-dimensional (3D) wool-ball-like zinc oxide (ZnO) nanostructures and their subsequent modifications with multi-walled carbon nanotubes (MWCNTs) as modifiers for achieving sensitive and selective detection of toxic sulfur dioxide (SO2) gas.Structurally, the as-synthesized 3D wool-ball-like ZnO is assembled of two-dimensional (2D) plate-like structures, which 3 themselves are arranged by numerous small nanoparticles. Furthermore, in this work we observed an interesting new phenomenon in which when a high concentration of MWCNTs is introduced, many small nanorods grew on the surface of the plate-like structures which assemble the 3D wool-ball-like ZnO nanostructures. When evaluated for SO2 detection, the ZnO/MWCNTs (10:1) composite (ZnO:MWCNTs= 10:1) shows a high response of 220.8 to 70 ppm of SO2 gas (approximately three times higher than the response of pure wool-ball-like ZnO) at an optimum operating temperature of 300 °C. Additionally, the composite also displays good stability and selectivity to SO2 with the response to 50 ppm of SO2 being 7-14 times higher than the responses to other tested gases at a similar concentration. The excellent sensing performance of the wool-ball-like ZnO/MWCNTs (10:1) composite is mainly attributed to: (i) the formation of p-n heterojunctions at the ZnO/MWCNTs interfaces, which greatly enhances the resistance changes upon exposure to SO2 gas and (ii) the increased amount of adsorption sites for O2 and SO2 gas molecules owing to the larger surface area of the composite and defects sites generated by the functionalization process of MWCNTs.

Wearable Carbon Monoxide Sensors Based on Hybrid Graphene/ZnO Nanocomposites

“…Consequently, electron transfer from CO to the system during exposure time may reduce the potential and then deliver sensor responses as the change of resistance (Fig. 8(b)) [62]. Aside from the graphene role in the graphene/ZnO interface, graphene also can act as an electron channel in the composite system and cause to lower the ZnO resistance.…”

Ionic Liquid and f‐MWCNTs Fabricated Glassy Carbon Electrode for Determination of Amygdalin in Apple Seeds

“…All the isotherms can be recognized as type IV according to the IUPAC classification. In addition, there hysteresis loops are Type H3, and this indicates the sample were in crystalline form [36]. The obtained surface area of ZnONPs‐f‐MWCNTs nanocomposite sample (110.27 m 2 /g) is greater than that of f‐MWCNTs (29.75 m 2 /g).…”

Advanced Strategies to Improve Performances of Molybdenum-Based Gas Sensors

“…Several studies show that low dimensional of MoO 3, such as nanorods [ 78 – 80 ], nanowires [ 48 , 81 ], nanobelts [ 82 , 83 ], nanoflakes [ 26 , 84 ], and nanosheets [ 45 , 49 , 85 ] have good performance as sensitive materials for toxic gas detection. However, some works reported that hierarchical 3D structures assembled by their low dimensional form offer higher performance due to their low density, high surface area, and porosity that allow more adsorption sites [ 86 , 87 ]. Huo’s group compared the TEA sensor performance of α -MoO 3 nanoparticles, nanobelts, and nanobelt-assembled hierarchical flower-like [ 87 ] at 170 °C.…”