Porous Anatase TiO2 Thin Films for NH3 Vapour Sensing

Ponnusamy, Dhivya; Sridharan, M.

doi:10.1007/s11664-015-4099-4

Cited by 11 publications

(6 citation statements)

References 31 publications

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“…Response = Z' NH 3 ⁄Z' air (1) It should be noted that for low NH 3 concentrations the sensing units exhibited similar responses, with low error associated to the measurements. That is an important issue to develop sensors able to detect NH 3 below 50 ppm [15][16][17]. In addition, the larger errors at higher concentrations of NH 3 may be associated with the lower stability of the measuring system, since gas injection can cause small turbulences in the airflow system, as observed in the calibration curve of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…According to the regulatory agency in Brazil, the ammonia exposure level at working places should not exceed 20 ppm within 48 h/week [13], while in England the ammonia exposure should not exceed 25 ppm in 8 h [14]. The human olfactory limit of detection for ammonia is 55 ppm, but loss of sensitivity occurs after long and repeated exposure [15][16][17]. Therefore, designing robust ammonia sensors with low limits of detection is necessary to increase safety and health in such environments [18].…”

Section: Introductionmentioning

confidence: 99%

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Hybrid layer-by-layer (LbL) films of polyaniline, graphene oxide and zinc oxide to detect ammonia

André

Shimizu

Miyazaki

et al. 2017

Sensors and Actuators B: Chemical

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Reliable gas sensors operating at room temperature are in demand for monitoring the environment for hazardous pollutants, such as ammonia (NH 3) gas that may become toxic to humans and animals above a threshold concentration. In this paper we report on the combination of three materials, namely polyaniline (PANI), graphene oxide (GO) and zinc oxide (ZnO), to produce hybrid layer-by-layer (LbL) films used for sensing NH 3 with impedance spectroscopy measurements. The deposition of tetralayered PANI/GO/PANI/ZnO LbL films was confirmed with UV-vis. absorption and Raman spectroscopies, while atomic force microscopy (AFM) served to investigate film morphology. Exposure of these LbL films to NH 3 caused film roughness to vary, in an effect that depended on the number of tetralayers. Because of synergy in the materials properties, the films with 3 tetralayers were found to be the most adequate for detecting NH 3 in the range from 25 ppm to 500 ppm with a response time of 30 s. These figures of merit are adequate for monitoring working environments regarding gas exposure, and highlight the usefulness of the control of film architecture provided by the LbL technique.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hybrid layer-by-layer (LbL) films of polyaniline, graphene oxide and zinc oxide to detect ammonia

André

Shimizu

Miyazaki

et al. 2017

Sensors and Actuators B: Chemical

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“…Gas sensing characteristics such as response, selectivity, stability, and detection limit were studied at room temperature and repeated 3 times at different time pattern. Sensing response can be calculated using Ra/Rg, in which Ra and Rg are the measured resistance of the sensing elements in ambient atmosphere and target gas, respectively. − …”

Section: Methodsmentioning

confidence: 99%

Monomer: Design of ZnO Nanostructures (Nanobush and Nanowire) and Their Room-Temperature Ethanol Vapor Sensing Signatures

Shankar

Rayappan

2017

ACS Appl. Mater. Interfaces

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Ethanol serves as a biomarker as well as a chemical reagent for several applications and has been predominantly used as an alternative fuel (E10 and E85). Development of sensors for the detection and monitoring of ethanol vapor at lower operating temperatures has gathered momentum in the recent past. In this work, we reported the synthesis of self-assembled ZnO nanowires using electrospun technique without using any external surfactants or capping agents and their room temperature ethanol sensing properties. An inherent template namely monomer of the polymer poly(vinyl alcohol) (PVA) with two different molecular weights (14 000 and 140 000 g mol) was used along with the precursor zinc acetate dihydrate. The ZnO-PVA nanofibers have been tranformed to ZnO nanospheres and nanowires after calcination. The ratio of zinc precursor concentration to PVA polymer led to the enhanced carrier concentration of the resultant ZnO nanowire that enhanced, in turn, the sensing response toward ethanol vapor. The developed sensing elements have been systematically characterized to correlate their structural, morphological, and electrical properties with the respective room-temperature ethanol-sensing characteristics. The role of grain features and low activation energy of ZnO nanowires in coordination with the low dipole moment of ethanol resulted in the excellent response of 78 toward 100 ppm at room temperature with ultra-sensitive response and recovery times (9 and 12 s, respectively).

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“…The photocatalytic activity of TiO 2 -anatase may be improved by increasing the porosity of the material [24]. This porosity may be achieved by supporting the TiO 2 on intrinsically porous surfaces, such as, zeolites, inverse opal-like structures, tiles, ceramics or asphalt pavement [8,[25][26][27][28] or by the preparation of porous TiO 2 materials [29][30][31][32][33][34][35][36][37][38][39]. The molecular layer deposition (MLD) technique is a variation of ALD (atomic layer deposition) that makes use of molecular organic and inorganic precursors, thus allowing for the formation of molecular layers or the preparation of hybrid inorganic-organic films.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Activity in the In-Flow Degradation of NO on Porous TiO2–Coated Glasses from Hybrid Inorganic–Organic Thin Films Prepared by a Combined ALD/MLD Deposition Strategy

Azpíroz

Borraz²,

González

et al. 2022

Coatings

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A combined ALD/MLD (where ALD and MLD stand for atomic and molecular layer deposition, respectively) deposition strategy using TiCl4, H2O and HQ (hydroquinone) as precursors has been applied for the preparation of inorganic–organic thin films on soda-lime glasses. The alternate deposition of TiO2 layers, by pulsing TiCl4/H2O (ALD), and hybrid layers, using TiCl4/HQ (MLD), results in the formation of thin films that are precursors for porous TiO2-coatings after removal of the HQ template by annealing. The coated-glassed show good photocatalytic activity in the degradation of NO with up to 15% reduction of NO concentration in three successive photocatalytic cycles of 5 h each. Surface Scanning Electron Microscopy (SEM) images show that the TiO2-coating is composed of large grains that are made up of finer subgrains resulting in a porous structure with an average pore size of 3–4 nm. Transmission Electron Microscopy (TEM) images show two regions, a porous columnar structure on top and a denser region over the glass substrate. Energy Dispersive X-Ray (EDX) analysis, nanocrystal electron diffraction and Raman spectroscopy confirm the presence of the anatase phase, which, together with the porosity of the material, accounts for the observed photocatalytic activity.

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Porous Anatase TiO2 Thin Films for NH3 Vapour Sensing

Cited by 11 publications

References 31 publications

Hybrid layer-by-layer (LbL) films of polyaniline, graphene oxide and zinc oxide to detect ammonia

Hybrid layer-by-layer (LbL) films of polyaniline, graphene oxide and zinc oxide to detect ammonia

Monomer: Design of ZnO Nanostructures (Nanobush and Nanowire) and Their Room-Temperature Ethanol Vapor Sensing Signatures

Photocatalytic Activity in the In-Flow Degradation of NO on Porous TiO2–Coated Glasses from Hybrid Inorganic–Organic Thin Films Prepared by a Combined ALD/MLD Deposition Strategy

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