The decoration of TiO2/reduced graphene oxide by Pd and Pt nanoparticles for hydrogen gas sensing

Esfandiar, Ali; Ghasemi, Shahnaz; zad, Azam Iraji; Akhavan, Omid; Gholami, Majid

doi:10.1016/j.ijhydene.2012.08.011

Cited by 136 publications

(44 citation statements)

References 49 publications

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“…This spin doublet can be assigned due to spin-orbital splitting of Ti 4+ in the TiO 2 lattice, since splitting between two peaks are 5.7 eV. 15,25,55 Moreover, presence of Ti 3+ can act as colour centres to actively absorb visible light, which is as shown in the XPS peak at 457.5 eV.…”

Section: D5 Hr-temmentioning

confidence: 95%

“…The emission peak around 382 nm in the UV range originates from near band edge (NBE) free excitation emission i.e., direct transition from VB to CB. 44,55 The latter additional emission signals at 450, 468, 482, and 492 nm originate from the charge transfer transition from oxygen vacancy trapped electrons. 61 This effective quenching in PL spectra is observed by two tracks: rst, created electrons trapped by oxygen vacancy and holes by doped nitrogen in a TiO 2 lattice and, second, excited electron transfer from the valence band to a new existing energy level introduced by nitrogen incorporation.…”

Section: D7 Photoluminescence (Pl) Spectramentioning

confidence: 99%

“…The lowest peak binding energy (529.5 eV) is assigned to oxygen bound to Ti 4+ of TiO 2 (Ti-O-Ti) i.e., lattice oxygen, whereas the peak around 531.9 eV is ascribed to hydroxy groups adsorbed at the surface of TiO 2 (Ti-OH). 51,55,57 Further, the peak around 533.4 eV is attributed to presence of carboxyl oxygen (C-O/C]O). Quantitative estimation of the N/O ratio was also made by XPS measurements with both TiO 2 and 1NTFA samples.…”

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confidence: 99%

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Green sol–gel route for selective growth of 1D rutile N–TiO₂: a highly active photocatalyst for H₂ generation and environmental remediation under natural sunlight

et al. 2017

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We report selective growth of N-TiO 2 1D nanorods using a green aqueous sol-gel method followed by hydrothermal treatment. Titanium tetraisopropoxide, diethanolamine, and H 2 O 2 were used as precursors for preparing an aqueous gel. Trifluoroacetic acid (TFA) was used as a growth regulator for selective growth of desired structure and morphology. Effects of TFA on the structure and morphology of N-TiO 2 were studied by varying concentration of TFA between 1-10% by volume. Structural characterization using XRD confirmed formation of a specific rutile phase with slight crystal disorder with N-doped TiO 2 samples. FESEM and HRTEM analysis showed formation of 1D rice grain shaped N-TiO 2 in the presence of 1% TFA solution. One directional growth along the (211) A. IntroductionAmong transition metal oxide photocatalysts, titania (TiO 2 ) has been an intensively investigated candidate within the ambit of various potential applications such as photocatalytic water splitting, 1-3 organic pollutant degradation, 4-7 supercapacitors, 8 dye sensitized solar cells (DSSC), 9-12 Li-ion battery photo anodes, 13,14gas-sensors, 15,16 and super-hydrophilicity. 17 This can be ascribed to its fascinating electronic and optical properties, namely, favourable electronic band structure, non-toxicity, biocompatibility, long term chemical stability towards photo-corrosion, and, importantly, commercial cost-effectiveness.18,19 However, photocatalytic quantum efficiency of TiO 2 in solar applications is still limited due to its broad bandgap (3.0 and 3.2 eV for rutile and anatase phases, respectively) responding to UV radiation only (l < 387 nm).20 But, UV radiation accounts for merely 5% of solar photons. Subsequently, another important drawback with TiO 2 is a high recombination rate of photogenerated electron-hole pairs. To compensate for the above challenges, many attempts have been made to decrease the threshold energy of TiO 2 or photo-excitation by red-shiing its photo-response to visible light having a wavelength (l) range between 400-800 nm.

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Section: D5 Hr-temmentioning

confidence: 95%

Section: D7 Photoluminescence (Pl) Spectramentioning

confidence: 99%

mentioning

confidence: 99%

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Green sol–gel route for selective growth of 1D rutile N–TiO₂: a highly active photocatalyst for H₂ generation and environmental remediation under natural sunlight

et al. 2017

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“…[4][5][6][7][8] Over the past decades, semiconductor metal oxide (SMO)-based gas sensors for toxic and explosive volatile organic compounds (VOCs) have drawn much Pt, Pd) by further sputtering or solution processes, which increased the fabrication time and cost of the gas sensor. [29][30][31] Compared with other nanostructures, nanorod arrays are very promising for use as gas sensors because of their high surfaceto-volume ratio and reaction rate with surface-adsorbed species resulting from the 3D structure that is less agglomerated than the bulk material. [32][33][34] SMO nanorod arrays composed of WO 3 , ZnO, and SnO 2 have been demonstrated to be very sensitive to VOC vapors.…”

Section: Introductionmentioning

confidence: 99%

Diverse Adsorption/Desorption Abilities Originating from the Nanostructural Morphology of VOC Gas Sensing Devices Based on Molybdenum Trioxide Nanorod Arrays

Cong

Sugahara

Wei

et al. 2016

Adv Materials Inter

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attention from researchers because of their advantages of sensitivity, rapid response, and inexpensive production. [9,10] Recently, considerable effort has been devoted to developing much simpler routes to control the shape and grain size of SMO to achieve a higher surface-to-area ratio and unique surface chemistry behavior to improve sensing performance. [11][12][13] Among the metal oxides, molybdenum trioxide (MoO 3 ) is one of the most desirable for use in gas sensors because of its indirect wide band gap of 3.5 eV. [14][15][16][17] MoO 3 -based gas analyzing devices show excellent gas sensing properties for several kinds of gas species [18][19][20][21][22][23][24] because of their special quantum size effect, surface effect, high reactivity, and the polyvalency of molybdate. In particular, MoO 3 nanostructures, such as MoO 3 nanobelts, flower-like microstructured MoO 3 , and net-like MoO 3 porous architectures synthesized by the hydrothermal route, exhibit appealing sensing properties for VOC vapors. [25][26][27] The gas sensing properties of MoO 3 thin film fabricated by radiofrequency (RF) sputtering have also been investigated. [28] These reports showed the nanostructures possessed typical sensing performance for VOC vapors; however, these nanostructures need to be processed with two or more steps, which is time consuming. For instance, these nanostructures need to be transferred or arranged on a ceramic substrate and then annealed to obtain substantial growth/adhesion on the substrate. To increase the VOC gas sensing performance of nanostructures, they needed to be loaded with noble metal particles (e.g., Au, Nanorod arrays gas sensors are attracting much scientific and engineering interest because of their excellent sensing performance arising from their unique nanostructures. In this work, large-scale random 3D networks of ultrafine single-crystal α-MoO 3 nanorod arrays are applied as gas sensors. The arrays are spontaneously grown by a simple single-step solution route. A prompt response and obvious discrimination of ethanol, methanol, isopropanol, and acetone vapors at 573 K are investigated via the modulation of the resistance of the gas sensors. The sensitivity, response time, and recovery time of the sensors strongly depend on the specific morphologies of the nanorod arrays, such as length, number, and coverage of nanorods in the 3D network. A reaction mechanism in which the 3D-network nanorod arrays adsorb and react with the target molecules more readily than the seed layer is proposed to explain the different response and recovery times of the sensors. These random 3D-network nanorod arrays with functionally tunable morphology are promising for universal application as gas sensors for detecting various vapors, and provide valuable insights for the production of fast, largescale, low-cost, and simple synthesis of sensing devices.

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“…More recently, graphene functionalized with semiconductor metal oxidess, especially TiO 2 [68] (Figure 4(e)), due to the synergistic effect of Cu 2 O (higher surface activity) and FGS (greater electron transfer efficiency). In addition, gas sensor based on graphene decorated with polymer have been repoted [74,75].…”

Section: Detection For Toxic Gases In Airmentioning

confidence: 99%

Applications of graphene-based materials in environmental protection and detection

Yang

et al. 2013

Chin. Sci. Bull.

100

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Many efficient adsorbents and sensors based on graphene and functionalized graphene have been constructed for the removal and detection of environmental pollutants due to its unique physicochemical properties. In this article, recent research achievements are reviewed on the application of graphene-based materials in the environmental protection and detection. For environmental protection, modified graphene can adsorb heavy metal ions in a high efficiency and selectivity, and thus reduces them to metals for recycling. High adsorption capacity of graphene-based materials to kinds of organic pollutants in water was also presented. Several graphene-based sensors with high limit of detection were reported to detect heavy metal ions, toxic gases and organic pollutants in environment. Finally, a perspective on the future challenge of adsorbents and detection devices based on graphene is given. Environmental pollution especially toxic gases, heavy metal ions and organic pollutants in air and water, caused by industry and agricultural activities, severely threaten ecological balance and human health, and have received extensive attention worldwide. For example, the heavy metal ions in bodies accumulated from the food chains will cause various chronic diseases. Therefore, it is necessary to develop simple, sensitive and inexpensive methods to remove and detect these pollutants. Currently, many efficient adsorbents and sensitive detection devices based on nanomaterials especially graphene have been designed due to their unique chemical, thermal, electronic, and mechanical properties. Graphene, a two-dimensional (2D) one atom thick nanomaterial consisting of sp 2 -hybridized carbon, has attracted great interest among scientists due to its unique properties, including high specific surface area (SSA) of 2600 m 2 g −1 [1], excellent thermal conductivities of 5000 W mhigh-speed electron mobility of 200000 cm 2 V −1 s −1 at room temperature [3], high stiffness and strength with Young's modulus of around 1000 GPa and break strength of 130 GPa [4], extraordinary electrocatalytic activity [5] and optical properties [6]. These outstanding physicochemical properties indicate its potential application in many research fields. For example, considering the high surface area and strong adsorption capacity of graphene, many efficient adsorbents [7] and photocatalysts [8] are developed for the removal and photocatalytic degradation of pollutants. Moreover, based on the excellent electrical conductivity and optical properties of graphene, many sensitive electrochemical [9] and fluorescent [10] sensors are also designed for the detection of pollutants. However, aggregations of graphene decrease its available surface area and further reduce its adsorption capacity. Functionalization of graphene with molecules, which have water-solubility and affinity toward target analytes, will improve the selectivity of adsorbents or detection devices, as well as prevent the aggregation. Based on this

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The decoration of TiO2/reduced graphene oxide by Pd and Pt nanoparticles for hydrogen gas sensing

Cited by 136 publications

References 49 publications

Green sol–gel route for selective growth of 1D rutile N–TiO₂: a highly active photocatalyst for H₂ generation and environmental remediation under natural sunlight

Green sol–gel route for selective growth of 1D rutile N–TiO₂: a highly active photocatalyst for H₂ generation and environmental remediation under natural sunlight

Diverse Adsorption/Desorption Abilities Originating from the Nanostructural Morphology of VOC Gas Sensing Devices Based on Molybdenum Trioxide Nanorod Arrays

Applications of graphene-based materials in environmental protection and detection

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The decoration of TiO2/reduced graphene oxide by Pd and Pt nanoparticles for hydrogen gas sensing

Cited by 136 publications

References 49 publications

Green sol–gel route for selective growth of 1D rutile N–TiO2: a highly active photocatalyst for H2 generation and environmental remediation under natural sunlight

Green sol–gel route for selective growth of 1D rutile N–TiO2: a highly active photocatalyst for H2 generation and environmental remediation under natural sunlight

Diverse Adsorption/Desorption Abilities Originating from the Nanostructural Morphology of VOC Gas Sensing Devices Based on Molybdenum Trioxide Nanorod Arrays

Applications of graphene-based materials in environmental protection and detection

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Green sol–gel route for selective growth of 1D rutile N–TiO₂: a highly active photocatalyst for H₂ generation and environmental remediation under natural sunlight

Green sol–gel route for selective growth of 1D rutile N–TiO₂: a highly active photocatalyst for H₂ generation and environmental remediation under natural sunlight