Highly Sensitive and Stable Humidity Nanosensors Based on LiCl Doped TiO2 Electrospun Nanofibers

Alan G. MacDiarmid Institute, Jilin University, Chang Chun 130012, PR China.
Journal of the American Chemical Society (Impact Factor: 12.11). 05/2008; 130(15):5036-7. DOI: 10.1021/ja800176s
Source: PubMed


A new type of humidity nanosensor based on LiCl-doped TiO2 nanofibers with poly(vinyl pyrrolidone) (PVP) nanofibers as sacrificial template has been fabricated through electrospinning and calcination. The sensor exhibited excellent sensing characteristics, such as ultrafast response and recovery times, good reproducibility, linearity, and environmental stability, which are of importance for applications in humidity monitoring and control.

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Available from: Zhenyu Li, Jul 23, 2014
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    • "In addition, the electrospinning method is incredibly effective for low-cost mass production with the minimal usage of materials, which makes it the most suitable method for industrial applications on the commercial scale. For these reasons, electrospun NFs have been employed in a diverse range of sensing materials [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]. Possessing a wide bandgap (3.37 eV) with a large exciton energy (60 meV) [15], ZnO NFs-based semiconductors are one of the most promising sensing materials and have been extensively studied for the past several years [16] [17] [18]. "
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    ABSTRACT: We have fabricated sensors with reduced graphene oxide (RGO) nanosheets (NSs)-loaded ZnO nanofibers (NFs) via an electrospinning method. The RGO NSs-loaded ZnO NFs were comprised of nanograins with an average diameter of 20 nm. Transmission electron microscopy and X-ray diffraction both revealed the presence of RGO NSs in the ZnO NFs. The sensing properties of RGO NSs-loaded ZnO NFs were examined after exposure to various gases, including O2, SO2, NO2, CO, C6H6, and C2H5OH. The sensor responses showed a bell-shaped behavior with respect to the weight ratio of RGO NSs. It is remarkable that our sensors exhibited significantly higher responses than pure ZnO NFs. We propose a novel hybrid sensing mechanism for the drastic improvement in the sensing behavior that is caused by loading RGO NSs into ZnO NFs. This hybrid sensing mechanism combines the resistance modulation of ZnO/ZnO homointerfaces and RGO-NSs/ZnO heterointerfaces in addition to the radial modulation of the surface depletion layer of ZnO NFs. In the heterointerfaces, the creation of local heterojunctions plays a significant role in raising the sensitivity of RGO-loaded ZnO NFs.
    Sensors and Actuators B Chemical 08/2015; DOI:10.1016/j.snb.2015.07.120 · 4.10 Impact Factor
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    • "Generally, nanoparticles are used for the fabrication of mesoporous structure of TiO 2 . However, nanocrystalline TiO 2 is a promising semiconducting material that have attracted considerable interest for their applications as electrodes [12], electronics [13], capacitors [14], optics [15] [16], sensors [17] [18], ceramics [19], solar cells [20] [21] [22], catalysis [23] [24] and photocatalysis [25] [26] [27] [28]. Therefore, many research scientists are now-a-days involved in the research work on the photocatalytic activity of TiO 2 doped with different metal ions such as Ag [29], Au [30], Mn [31], Fe [32] [33], Co [34], Ni [35] [36], Cu [37] [38], and Pd [39] etc. "
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    ABSTRACT: Spherical mesoporous titania modified iron-niobate nanoclusters FNT1 [FexNbxTi1−2xO2−x/2 (x = 0.01)], with relatively small particle size 10 ± 2 nm and SBET 145 m2 g−1 were prepared using a sol-gel method, from the reaction of titanium and niobium tartrate with triethanol amine and ferric nitrate solution. HRTEM of FNT1 shows coexistence of porous mesostructure and high symmetric order of crystallinity in the nanoparticles. The mesopore size is in the range of 4-5 nm and the lattice fringes of 0.37 nm is observed in the mesopore walls which correspond to the d-spacing between adjacent (101) crystallographic planes of FNT1 phase. This is supported by XRD studies. In the presence of UV light, FNT1 (0.1 g/50 mL) reduces the 4-nitrophenol (4-NP) (0.0139 g L−1) to 4-aminophenol by using NaBH4 (0.054 g L−1) in contrast to pure TiO2 and other composites of FexNbxTi1−2xO2−x/2 photocatalysts. The 4-NP is reduced to 4-aminophenol within 10 min in the presence of FNT1 and UV light, but in the absence of the catalysts, it takes approximately 82 min. The catalytic activity of FNT1 is enhanced significantly in the presence of UV light compared to the absence of UV light. We observed that the catalytic activity of the prepared catalyst also depends on crystal size, particle morphology and particle porosity, and dopant concentrations.
    Journal of Materials Research and Technology 12/2014; 4(2). DOI:10.1016/j.jmrt.2014.11.005
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    • "Although the literature is abound with humidity sensors8, those with fast response form only a small subset (see Supplementary Table S1). The subset includes those based on inorganic materials in the form of nanowires9, nanotubes1011, thin films of oxides121314 and of few sulfides1516 as well. Similarly, there are examples from organic and composite materials, a notable one being nafion persulphonate4 with tens of milliseconds of response time. "
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    ABSTRACT: Measuring humidity in dynamic situations calls for highly sensitive fast response sensors. Here we report, a humidity sensor fabricated using solution processed supramolecular nanofibres as active resistive sensing material. The nanofibres are built via self- assembly of donor and acceptor molecules (coronene tetracarboxylate and dodecyl methyl viologen respectively) involved in charge transfer interactions. The conductivity of the nanofibre varied sensitively over a wide range of relative humidity (RH) with unprecedented fast response and recovery times. Based on UV-vis, XRD and AFM measurements, it is found that the stacking distance in the nanofibre decreases slightly while the charge transfer band intensity increases, all observations implying enhanced charge transfer interaction and hence the conductivity. It is demonstrated to be as a novel breath sensor which can monitor the respiration rate. Using two humidity sensors, a breath flow sensor was made which could simultaneously measure RH and flow rate of exhaled nasal breath. The integrated device was used for monitoring RH in the exhaled breath from volunteers undergoing exercise and alcohol induced dehydration.
    Scientific Reports 02/2014; 4:4103. DOI:10.1038/srep04103 · 5.58 Impact Factor
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