Gas-sensing properties and sensitivity promoting mechanism of Cu-added SnO2 thin films deposited by ultrasonic spray pyrolysis

Liu, Jianqiao; Lu, Yiting; Cui, Xiao; Geng, Yuncong; Jin, Guohua; Zhai, Zhaoxia

doi:10.1016/j.snb.2017.01.057

Cited by 38 publications

(9 citation statements)

References 31 publications

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“…To date, mesoporous SMOs can be synthesized through template‐free method or templating method. The former includes sol–gel synthesis procedure, spray pyrolysis, and chemical vapor deposition,[3b] which usually lead to materials with ill‐defined porous structures and uncontrollable morphologies. By using hard‐templating methods, highly ordered mesoporous metal oxides materials can be produced through a structure replication from hexagonal SBA‐15 silica or cubic KIT‐6 silica .…”

Section: Introductionmentioning

confidence: 99%

Pt Nanoparticles Sensitized Ordered Mesoporous WO₃ Semiconductor: Gas Sensing Performance and Mechanism Study

Ren

Zhou

et al. 2017

Adv Funct Materials

260

173

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In this study, a straightforward coassembly strategy is demonstrated to synthesize Pt sensitized mesoporous WO 3 with crystalline framework through the simultaneous coassembly of amphiphilic poly(ethylene oxide)-b-polystyrene, hydrophobic platinum precursors, and hydrophilic tungsten precursors. The obtained WO 3 /Pt nanocomposites possess large pore size (≈13 nm), high surface area (128 m 2 g −1 ), large pore volume (0.32 cm 3 g −1 ), and Pt nanoparticles (≈4 nm) in situ homogeneously distributed in mesopores, and they exhibit excellent catalytic sensing response to CO of low concentration at low working temperature with good sensitivity, ultrashort response-recovery time (16 s/1 s), and high selectivity. In-depth study reveals that besides the contribution from the fast diffusion of gaseous molecules and rich interfaces in mesoporous WO 3 /Pt nanocomposites, the partially oxidized Pt nanoparticles that chemically and electronically sensitize the crystalline WO 3 matrix, dramatically enhance the sensitivity and selectivity.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201705268. metal oxides (SMOs), such as WO 3 , [1] ZnO, [2] SnO 2 , [3] In 2 O 3 , [4] have attracted much attention for their wide applications in monitoring gas leakage, air quality, food safety, and medical diagnosis, [5][6][7][8][9] owing to their excellent properties including easy production, low-cost, long-term stability, and compact size. [10] A fast responserecovery dynamics, high sensitivity, and high selectivity are indispensable to highperformance gas sensors based on SMOs because some toxic and flammable gases (e.g., carbon monoxide), are colorless, odorless and tasteless, and extremely poisonous even at low concentrations. Considering that the gas-sensing process strongly relies on surface reactions between target gases and surface-chemisorbed oxygen species on the sensing layers, rational and controlled synthesis of nanomaterials with high surface areas, tailor-designed structure [11][12][13][14] combined with effective catalytic sensitization [15,16] is a promising approach to develop high-performance sensing sensors.SMO nanomaterials with mesoporous structures are promising candidates for gas sensing nanodevices due to their high specific surface area, highly depleted region in thin pore walls, and highly interconnected and adjustable ordered mesopores. [11,12] The high surface area favors the interaction between gas molecules and the solid porous oxide wall as well as the surface catalytic reaction. Moreover, the well-connected channels and a mesoscale (2−50 nm) pore size are advantageous to gas diffusion due to the facile penetration of gas molecules dominated by Knudsen diffusion. [12] To date, mesoporous SMOs can be synthesized through template-free method or templating method. The former includes sol-gel synthesis procedure, [17] spray pyrolysis, [18] and chemical vapor deposition, [3b] which usually lead to materials with ill-defined porous structur...

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Section: Introductionmentioning

confidence: 99%

Pt Nanoparticles Sensitized Ordered Mesoporous WO₃ Semiconductor: Gas Sensing Performance and Mechanism Study

Ren

Zhou

et al. 2017

Adv Funct Materials

260

173

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“…The successful invention of ZnO gas sensors by Seiyama in 1962 started the new era of the application of semiconductor in a gas detecting field [ 1 ]. From then on, several kinds of semiconductors were put into practice to develop advanced gas sensors, which contained a variety of sensing materials such as SnO 2 [ 2 , 3 , 4 ], ZnO [ 5 , 6 ], and WO 3 [ 7 ] as well as in different forms such as bulk [ 8 ], thick film [ 9 , 10 ], and thin film [ 11 , 12 , 13 ]. Recently, semiconductor quantum dots were also introduced into the investigation of gas sensors [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Oxygen Vacancy Behaviors in Cooling Process on Semiconductor Gas Sensors: A Numerical Analysis

Liu

Wang

Zhai

et al. 2018

Sensors

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The influence of oxygen vacancy behaviors during a cooling process in semiconductor gas sensors is discussed by the numerical analysis method based on the gradient-distributed oxygen vacancy model. A diffusion equation is established to describe the behaviors of oxygen vacancies, which follows the effects of diffusion and exclusion in the cooling process. Numerical analysis is introduced to find the accurate solutions of the diffusion equation. The solutions illustrate the oxygen vacancy distribution profiles, which are dependent on the cooling rate as well as the temperature interval of the cooling process. The gas-sensing characteristics of reduced resistance and response are calculated. Both of them, together with oxygen vacancy distribution, show the grain size effects and the re-annealing effect. It is found that the properties of gas sensors can be controlled or adjusted by the designed cooling process. The proposed model provides a possibility for sensor characteristics simulations, which may be beneficial for the design of gas sensors. A quantitative interpretation on the gas-sensing mechanism of semiconductors has been contributed.

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“…The defects on the grain surface provide adsorption sites for aerial oxygen. The types of adsorbed oxygen are found to be O − , O 2 − and O 2 − , which are dependent on the operating temperature [ 65 , 66 , 67 , 68 ]. They also determine the sensor sensitivity, which is usually known as the power law exponent for semiconductor gas sensors.…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

Liu

Gao

et al. 2017

Sensors

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The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

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Gas-sensing properties and sensitivity promoting mechanism of Cu-added SnO2 thin films deposited by ultrasonic spray pyrolysis

Cited by 38 publications

References 31 publications

Pt Nanoparticles Sensitized Ordered Mesoporous WO₃ Semiconductor: Gas Sensing Performance and Mechanism Study

Pt Nanoparticles Sensitized Ordered Mesoporous WO₃ Semiconductor: Gas Sensing Performance and Mechanism Study

Influence of Oxygen Vacancy Behaviors in Cooling Process on Semiconductor Gas Sensors: A Numerical Analysis

Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

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Gas-sensing properties and sensitivity promoting mechanism of Cu-added SnO2 thin films deposited by ultrasonic spray pyrolysis

Cited by 38 publications

References 31 publications

Pt Nanoparticles Sensitized Ordered Mesoporous WO3 Semiconductor: Gas Sensing Performance and Mechanism Study

Pt Nanoparticles Sensitized Ordered Mesoporous WO3 Semiconductor: Gas Sensing Performance and Mechanism Study

Influence of Oxygen Vacancy Behaviors in Cooling Process on Semiconductor Gas Sensors: A Numerical Analysis

Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

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Pt Nanoparticles Sensitized Ordered Mesoporous WO₃ Semiconductor: Gas Sensing Performance and Mechanism Study

Pt Nanoparticles Sensitized Ordered Mesoporous WO₃ Semiconductor: Gas Sensing Performance and Mechanism Study