Metal Oxide Gas Sensors with Au Nanocluster Catalytic Overlayer: Toward Tuning Gas Selectivity and Response Using a Novel Bilayer Sensor Design

Moon, Young Kook; Jeong, Seong‐Yong; Kang, Yun Chan; Lee, Jong Heun

doi:10.1021/acsami.9b11079

Cited by 95 publications

(56 citation statements)

References 54 publications

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“…Figure 14 shows four different examples that demonstrate the selectivity control of bilayer design sensors with nanoscale catalytic overlayers. [444][445][446] The thick films (thickness: ≈30 µm) with SnO 2 hollow spheres showed relatively low responses (R a /R g = 3.7-13.7) to 5 ppm ethanol, xylene, toluene, and benzene at 350 °C (Figure 14a1). [444] The decoration of SnO 2 film with Au nanoclusters by an e-beam coating of 0.5 nm thick (nominal thickness) Au and subsequent thermal annealing substantially enhanced the gas responses toward xylene and toluene (Figure 14a2).…”

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

“…[444][445][446] The thick films (thickness: ≈30 µm) with SnO 2 hollow spheres showed relatively low responses (R a /R g = 3.7-13.7) to 5 ppm ethanol, xylene, toluene, and benzene at 350 °C (Figure 14a1). [444] The decoration of SnO 2 film with Au nanoclusters by an e-beam coating of 0.5 nm thick (nominal thickness) Au and subsequent thermal annealing substantially enhanced the gas responses toward xylene and toluene (Figure 14a2). The responses toward xylene and toluene became the highest (R a /R g = 61.4 and 56.2) when the thickness of the predeposited Au layer increased to 1.0 nm (Figure 14a3).…”

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

“…In bilayer sensors, the catalytic overlayer is outlying and thus barely affects the conduction at the lower part of the sensing film close to the sensing electrodes. [36,444,446] Thus, the gas selectivity and response can be tailored without affecting the baseline sensor resistance. For artificial olfaction, diverse sensing materials are essential, and it is better to control the gas selectivity of sensors easily and precisely at a constant temperature Figure 14.…”

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

“…a) Adapted with permission. [444] Copyright 2019, American Chemical Society. b) Gas responses (R g /R a ) of pure and TiO 2 -coated Co 3 O 4 thick films (thickness: ≈5 µm) to 5 ppm E, X, T, and B at 225 °C: b1) pure Co 3 O 4 , b2) TiO 2 (2 nm)-coated Co 3 O 4 , b3) TiO 2 (5 nm)-coated Co 3 O 4 , b4) TiO 2 (20 nm)-coated Co 3 O 4 , and b5) sensing mechanism.…”

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

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Rational Design of Semiconductor‐Based Chemiresistors and their Libraries for Next‐Generation Artificial Olfaction

2020

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With rapid progress in device integration and computing power, the realization of highly miniaturized one-chip artificial olfaction with superior performance is close and should be further supported by the rational design of chemical sensors and chemical sensing materials. The number of gas sensors tends to increase in order to sniff more complex odors with the progress of civilization. This explains the evolution from a single chemical sensor to complicated artificial olfaction using sensor arrays. At the advent of oxide chemiresistive gas sensors in the 1960s and 1970s, a single gas sensor was widely used to detect toxic, explosive, dangerous, and harmful gases, such as CO, C 3 H 8 , CH 4 , H 2 S, and NO 2 , in a selective manner. [26,27] However, a single sensor is often insufficient for recognizing most of the natural odors encountered in daily life, which consist of hundreds to thousands of different chemicals. [28] In the mammalian olfactory system, odorants are initially detected by olfactory receptors (ORs) covering the surface of the cilia projected from olfactory sensory neurons (OSNs), which are located in the olfactory epithelium lining the nasal cavity. These signals are transmitted to the glomeruli in the olfactory bulb, where a high degree of signal integration happens (Figure 1a). [29] Finally, the signals are sent through mitral cells to a higher brain region (olfactory cortex), and the signals are subsequently combined or modified in a variety of ways by parallel processing for analysis and interpretation (Figure 1b). [30] Each OR can detect various kinds of odorants, and similarly, each odorant can also be recognized by a number of ORs. That is, the olfactory system determines multiple odorants from various combinations of ORs (Figure 1c). [31] For better olfaction, both OSNs and ORs should be abundant. A larger number of OSNs is advantageous for detecting trace concentrations of analytes and ligands. [32] For instance, dogs with more OSNs are better than humans at detecting explosives, searching and rescuing, diagnosing disease, and assessing agricultural products. [33] If a mammal can detect larger numbers of faint gas components within odors, he can perceive and identify the odors more accurately. From this perspective, gas sensors with lower detection limits would be assembled to the stronger artificial olfaction. Kinds of ORs are also important. Mammals are known to have ≈1000 different kinds of ORs, and combinations of dissimilar ORs enable the discrimination of a myriad of odorants. [29] To mimic this, sensor arrays consisting of small number (5-20) of sensors that show Artificial olfaction based on gas sensor arrays aims to substitute for, support, and surpass human olfaction. Like mammalian olfaction, a larger number of sensors and more signal processing are crucial for strengthening artificial olfaction. Due to rapid progress in computing capabilities and machinelearning algorithms, on-demand high-performance artificial olfaction that can eclipse human olfaction becomes inevitable onc...

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Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

Section: Bilayer Sensors With a Nanoscale Catalytic Overlayermentioning

confidence: 99%

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Rational Design of Semiconductor‐Based Chemiresistors and their Libraries for Next‐Generation Artificial Olfaction

2020

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“…The research on gold nanoclusters (Au n ) started to attract extensive attention when Haruta et al [1] found that Au n on TiO 2 have a good catalytic activity in CO low-temperature oxidation reaction. Further deep explorations of Au n uncovered that Au n not only exhibited a variety of physical and chemical features [2][3][4], but also had broad applications in many fields, such as catalysis, biological engineering, nanotechnology, and so on [5][6][7][8][9][10]. More importantly, the study on the Au n is still the research focus even now.…”

Section: Introductionmentioning

confidence: 99%

Influences of MgO(001) and TiO2(101) Supports on the Structures and Properties of Au Nanoclusters

et al. 2019

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Due to the unique structures, photoelectric properties, good catalytic activity, and broad potential applications, gold nanoclusters (Au n ) received extensive attention in catalysis, bioengineering, environmental engineering, and so on. In the present work, the structures and properties of Au n adsorbed on the MgO(001) and TiO 2 (101) surfaces were investigated by density functional theory. The results showed that the catalytic properties of Au n will be enhanced when Au n is adsorbed on certain supports. Because the difference of the outer electronic structure of metals in supports, the direction of the charge transfer was different, thus inducing the different charge distribution on Au n . When Au n was adsorbed on MgO(001) [TiO 2 (101)] surface, Au n will have negative [positive] charges and thus higher catalytic activity in oxidation [reduction] reaction. The variation of surface charges caused by the support makes Au n possess different catalytic activity in different systems. Moreover, the electronic structure of the support will make an obvious influence on the s and d density of states of Au n , which should be the intrinsic reason that induces the variations of its structure and properties. These results should be an important theoretical reference for designing Au n as the photocatalyst applied to the different oxidation and reduction reactions.

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A General Solution to Mitigate Water Poisoning of Oxide Chemiresistors: Bilayer Sensors with Tb₄O₇ Overlayer

Jeong

Moon

Kim

et al. 2020

Adv Funct Materials

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Water poisoning, the dependence of gas‐sensing characteristics on moisture, in oxide chemiresistors remains a long‐standing challenge. Various approaches are explored to mitigate water poisoning but they are often accompanied by significant deterioration of sensing capabilities such as gas response deterioration, gas selectivity alteration, and sensor resistance increase up to unmeasurable levels. Herein, a novel sensor design with a moisture‐blocking Tb4O7 overlayer is suggested as a facile and universal strategy to remove moisture poisoning without sacrificing intrinsic sensing properties. A submicrometer‐thick coating of Tb4O7 overlayer on In2O3 sensors effectively eliminates the humidity dependence of the gas‐sensing characteristics without significantly altering the gas response, selectivity, and sensor resistance. Furthermore, the general validity of the water‐blocking effect using the Tb4O7 overlayer is confirmed in diverse gas sensors using SnO2, ZnO, and Pd/SnO2. The negligible moisture interference of the bilayer sensor is explained in terms of the hydrophobic nature of the Tb4O7 overlayer and the prevention of formation of the OH radical by the interaction between Tb4O7 and In2O3. A universal solution to design diverse humidity‐independent gas sensors with different gas selectivities can open up new pathways toward building accurate and robust gas sensors with new functionalities and high‐performance artificial olfaction.

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Metal Oxide Gas Sensors with Au Nanocluster Catalytic Overlayer: Toward Tuning Gas Selectivity and Response Using a Novel Bilayer Sensor Design

Cited by 95 publications

References 54 publications

Rational Design of Semiconductor‐Based Chemiresistors and their Libraries for Next‐Generation Artificial Olfaction

Rational Design of Semiconductor‐Based Chemiresistors and their Libraries for Next‐Generation Artificial Olfaction

Influences of MgO(001) and TiO2(101) Supports on the Structures and Properties of Au Nanoclusters

A General Solution to Mitigate Water Poisoning of Oxide Chemiresistors: Bilayer Sensors with Tb₄O₇ Overlayer

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Metal Oxide Gas Sensors with Au Nanocluster Catalytic Overlayer: Toward Tuning Gas Selectivity and Response Using a Novel Bilayer Sensor Design

Cited by 95 publications

References 54 publications

Rational Design of Semiconductor‐Based Chemiresistors and their Libraries for Next‐Generation Artificial Olfaction

Rational Design of Semiconductor‐Based Chemiresistors and their Libraries for Next‐Generation Artificial Olfaction

Influences of MgO(001) and TiO2(101) Supports on the Structures and Properties of Au Nanoclusters

A General Solution to Mitigate Water Poisoning of Oxide Chemiresistors: Bilayer Sensors with Tb4O7 Overlayer

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A General Solution to Mitigate Water Poisoning of Oxide Chemiresistors: Bilayer Sensors with Tb₄O₇ Overlayer