Research

13 pages, 4420 KiB

Open AccessArticle

Microgravimetric Modeling—A New Method for Extracting Adsorption Parameters of Functionalized MIL-101(Cr)

by Xu Zhang, Bo Tian, Zhiheng Ma, He Wang, Zhixuan Cheng and Jiaqiang Xu

Nanomaterials 2023, 13(14), 2072; https://doi.org/10.3390/nano13142072 - 14 Jul 2023

Viewed by 932

As a volatile air pollutant, formaldehyde can enter people’s living environment through interior decoration, furniture and paint, causing serious harm to human health. Therefore, it is necessary to develop a sensor for the real-time detection of formaldehyde in low concentrations. According to the [...] Read more.

As a volatile air pollutant, formaldehyde can enter people’s living environment through interior decoration, furniture and paint, causing serious harm to human health. Therefore, it is necessary to develop a sensor for the real-time detection of formaldehyde in low concentrations. According to the chemical interaction between amino groups and formaldehyde, a MIL-101(Cr) aminated-material-based formaldehyde cantilever sensor was prepared, of which ethylenediamine- functionalized MIL-101(Cr) named ED-MIL-101(Cr)) showed the best gas sensing performance. Using quasi-in situ infrared spectroscopy, ED-MIL-101(Cr) was found bound to formaldehyde through a Schiff base. The adsorption enthalpy of formaldehyde-bound ED-MIL-101(Cr) was −52.6 kJ/mol, which corresponds to weak chemical adsorption, so the material showed good selectivity. In addition, ED-MIL-101(Cr) has the most active sites, so its response value to formaldehyde is larger and it takes longer to reach saturation adsorption than bare MIL-101(Cr). Through the research on the gas sensing performance of functionalized MIL-101(Cr) material, we found that it has a strong application potential in the field of formaldehyde monitoring, and the material performance can be quantitatively and accurately evaluated through combining calculation and experimentation for understanding the gas sensing mechanism. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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11 pages, 3901 KiB

Open AccessArticle

Mesoporous-Structure MOF-14-Based QCM p-Xylene Gas Sensor

by Zhiheng Ma, Tongwei Yuan, Yu Fan, Yang Chen, Yueling Bai and Jiaqiang Xu

Nanomaterials 2023, 13(11), 1743; https://doi.org/10.3390/nano13111743 - 26 May 2023

Cited by 3 | Viewed by 1548

Abstract

In this work, a facile synthesis method was adopted to synthesize MOF-14 with mesoporous structure. The physical properties of the samples were characterized by PXRD, FESEM, TEM and FT-IR spectrometry. By coating the mesoporous-structure MOF-14 on the surface of a quartz crystal microbalance [...] Read more.

In this work, a facile synthesis method was adopted to synthesize MOF-14 with mesoporous structure. The physical properties of the samples were characterized by PXRD, FESEM, TEM and FT-IR spectrometry. By coating the mesoporous-structure MOF-14 on the surface of a quartz crystal microbalance (QCM), the fabricated gravimetric sensor exhibits high sensitivity to p-toluene vapor even at trace levels. Additionally, the limit of detection (LOD) of the sensor obtained experimentally is lower than 100 ppb, and the theoretical detection limit is 57 ppb. Furthermore, good gas selectivity and fast response (15 s) and recovery (20 s) abilities are also illustrated along with high sensitivity. These sensing data indicate the excellent performance of the fabricated mesoporous-structure MOF-14-based p-xylene QCM sensor. On the basis of temperature-varying experiments, an adsorption enthalpy of −59.88 kJ/mol was obtained, implying the existence of moderate and reversible chemisorption between MOF-14 and p-xylene molecules. This is the crucial factor that endows MOF-14 with exceptional p-xylene-sensing abilities. This work has proved that MOF materials such as MOF-14 are promising in gravimetric-type gas-sensing applications and worthy of future study. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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15 pages, 5376 KiB

Open AccessArticle

Utilizing Imine Bonds to Create a Self-Gated Mesoporous Silica Material with Controlled Release and Antimicrobial Properties

by Yuyang Lu, Xutao Li, Jiaqi Xu, Huimin Sun, Jie Sheng, Yishan Song and Yang Chen

Nanomaterials 2023, 13(8), 1384; https://doi.org/10.3390/nano13081384 - 16 Apr 2023

Cited by 2 | Viewed by 1488

Abstract

In recent years, silica nanomaterials have been widely studied as carriers in the field of antibacterial activity in food. Therefore, it is a promising but challenging proposition to construct responsive antibacterial materials with food safety and controllable release capabilities using silica nanomaterials. In [...] Read more.

In recent years, silica nanomaterials have been widely studied as carriers in the field of antibacterial activity in food. Therefore, it is a promising but challenging proposition to construct responsive antibacterial materials with food safety and controllable release capabilities using silica nanomaterials. In this paper, a pH-responsive self-gated antibacterial material is reported, which uses mesoporous silica nanomaterials as a carrier and achieves self-gating of the antibacterial agent through pH-sensitive imine bonds. This is the first study in the field of food antibacterial materials to achieve self-gating through the chemical bond of the antibacterial material itself. The prepared antibacterial material can effectively sense changes in pH values caused by the growth of foodborne pathogens and choose whether to release antibacterial substances and at what rate. The development of this antibacterial material does not introduce other components, ensuring food safety. In addition, carrying mesoporous silica nanomaterials can also effectively enhance the inhibitory ability of the active substance. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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11 pages, 2201 KiB

Open AccessArticle

New Application of Quartz Crystal Microbalance: A Minimalist Strategy to Extract Adsorption Enthalpy

by Zhiheng Ma, Tongwei Yuan, Yu Fan, Yang Chen, Yueling Bai, Zhixuan Cheng and Jiaqiang Xu

Nanomaterials 2022, 12(22), 4035; https://doi.org/10.3390/nano12224035 - 17 Nov 2022

Cited by 1 | Viewed by 1356

Abstract

The capture and separation of CO₂ is an important means to solve the problem of global warming. MOFs (metal–organic frameworks) are considered ideal candidates for capturing CO₂, where the adsorption enthalpy is a crucial indicator for the screening of materials. [...] Read more.

The capture and separation of CO₂ is an important means to solve the problem of global warming. MOFs (metal–organic frameworks) are considered ideal candidates for capturing CO₂, where the adsorption enthalpy is a crucial indicator for the screening of materials. For this purpose, we propose a new minimalist solution using QCM (quartz crystal microbalance) to extract the CO₂ adsorption enthalpy on MOFs. Three kinds of MOFs with different properties, sizes and morphologies were employed to study the adsorption enthalpy of CO₂ using a QCM platform and a commercial gas sorption analyzer. A Gaussian simulation calculation and previously data reported were used for comparison. It was found that the measuring errors were between 5.4% and 6.8%, proving the reliability and versatility of our new method. This low-cost, easy-to-use, and high-accuracy method will provide a rapid screening solution for CO₂ adsorption materials, and it has potential in the evaluation of the adsorption of other gases. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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10 pages, 4753 KiB

Open AccessArticle

A Novel 3D-Morphology Pyrene-Derived Conjugated Fluorescence Polymer for Picric Acid Detection

by Yu Fan, Yang Chen, Yueling Bai, Baoli An and Jiaqiang Xu

Nanomaterials 2022, 12(22), 4034; https://doi.org/10.3390/nano12224034 - 17 Nov 2022

Cited by 1 | Viewed by 1264

Abstract

Aggregation-induced quenching (ACQ) is a hard problem in fluorescence material, leading to a poor utilization rate of fluorophores. In this work, 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) was synthesized and used as a precursor to build two kinds of fluorescence polymer. The TFFPy molecule with D2h symmetry [...] Read more.

Aggregation-induced quenching (ACQ) is a hard problem in fluorescence material, leading to a poor utilization rate of fluorophores. In this work, 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) was synthesized and used as a precursor to build two kinds of fluorescence polymer. The TFFPy molecule with D2h symmetry can easily form polymers with C3 symmetry amines through the Schiff base reaction, making the resulting polymer a 3D amorphous material. Thus, ACQ of fluorophore can be reduced to minimum, making the most usage of the fluorescence of pyrene core. Fluorescence titration and DFT calculation can clearly prove this conclusion. The resulting CPs showed a highly sensitivity to picric acid, down to 3.43 ppm in solution, implying its potential in explosive detection. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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11 pages, 1832 KiB

Open AccessArticle

Microwave Synthesized 2D WO₃ Nanosheets for VOCs Gas Sensors

by He Liu, Lingyao Duan, Kedong Xia, Yang Chen, Yunling Li, Shaoxin Deng, Jiaqiang Xu and Zhenyu Hou

Nanomaterials 2022, 12(18), 3211; https://doi.org/10.3390/nano12183211 - 15 Sep 2022

Cited by 11 | Viewed by 2034

Abstract

As an n-type semiconductor material, tungsten oxide (WO₃) has good application prospects in the field of gas sensing. Herein, using oxalic acid (OA), citric acid (CA) and tartaric acid (TA) as auxiliary agents, three homogeneous tungsten oxide nanosheets were prepared by [...] Read more.

As an n-type semiconductor material, tungsten oxide (WO₃) has good application prospects in the field of gas sensing. Herein, using oxalic acid (OA), citric acid (CA) and tartaric acid (TA) as auxiliary agents, three homogeneous tungsten oxide nanosheets were prepared by the rapid microwave-assisted hydrothermal method. The potential exhaled gases of various diseases were screened for the gas sensitivity test. Compared with WO₃-OA and WO₃-TA, WO₃-CA exhibits significant sensitivity to formaldehyde, acetone and various alkanes. Photoluminescence (PL) chromatography and photoelectric properties show that its excellent gas sensitivity is due to its abundant oxygen vacancies and high surface charge migration rate, which can provide more preferential reaction sites with gas molecules. The experiment is of great significance for the sensor selection of the large disease exhaled gas sensor array. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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15 pages, 3780 KiB

Open AccessArticle

Synthesis of Porous Hierarchical In₂O₃ Nanostructures with High Methane Sensing Property at Low Working Temperature

by Huiju Zhang, Jiangnan Chang, Yan Wang and Jianliang Cao

Nanomaterials 2022, 12(17), 3081; https://doi.org/10.3390/nano12173081 - 05 Sep 2022

Cited by 2 | Viewed by 1422

Abstract

Different hierarchical porous In₂O₃ nanostructures were synthesized by regulating the hydrothermal time and combining it with a self-pore-forming method. The gas-sensing test results show that the response of the sensor based on In₂O₃ obtained after hydrothermal reaction [...] Read more.

Different hierarchical porous In₂O₃ nanostructures were synthesized by regulating the hydrothermal time and combining it with a self-pore-forming method. The gas-sensing test results show that the response of the sensor based on In₂O₃ obtained after hydrothermal reaction for 48 h is about 10.4 to 500 ppm methane. Meanwhile, it possesses good reproducibility, stability, selectivity and moisture resistance as well as a good exponential linear relationship between the response to methane and its concentration. In particular, the sensor based on In₂O₃ can detect a wide range of methane (10~2000 ppm) at near-room temperature (30 °C). The excellent methane sensitivity of the In₂O₃ sensor is mainly due to its unique nanostructure, which has the advantages of both porous and hierarchical structures. Combined with the DFT calculation, it is considered that the sensitive mechanism is mainly controlled by the surface adsorbed oxygen model. This work provides a feasible strategy for enhancing the gas sensitivity of In₂O₃ toward methane at low temperatures. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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15 pages, 5992 KiB

Open AccessArticle

Rational Design of SnO₂ Hollow Microspheres Functionalized with Derivatives of Pt Loaded MOFs for Superior Formaldehyde Detection

by Lanlan Guo, Yuanyuan Wang, Hua Zeng, Yanji Feng, Xueli Yang, Saisai Zhang, Yonghao Xu, Guodong Wang, Yan Wang and Zhanying Zhang

Nanomaterials 2022, 12(11), 1881; https://doi.org/10.3390/nano12111881 - 31 May 2022

Cited by 10 | Viewed by 1791

Abstract

In this work, SnO₂ hollow microspheres functionalized with different incorporated amounts of Pt@Co₃O₄ complex catalyst were innovatively designed by using an MOF template. The results show that sensor based on the optimal incorporated amount of Pt@Co₃O₄ [...] Read more.

In this work, SnO₂ hollow microspheres functionalized with different incorporated amounts of Pt@Co₃O₄ complex catalyst were innovatively designed by using an MOF template. The results show that sensor based on the optimal incorporated amount of Pt@Co₃O₄ not only greatly enhances the response value of SnO₂ to formaldehyde (R_air/R_formaldehyde = 4240 toward 100 ppm) but also decreases the low detection limit (50 ppb), which is quite outstanding compared with other SnO₂-based formaldehyde sensors. Further analysis proves that the content of oxygen vacancy and chemisorbed oxygen and the catalytic effect of ultra-small Pt play the key roles in improving the formaldehyde sensing performance. Meanwhile, this present work demonstrates that oxide semiconductors functionalized with the derivatives of MOF templated catalysts may lead to the discovery of new material systems with outstanding sensing performance. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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13 pages, 3687 KiB

Open AccessArticle

Ag-Modified Porous Perovskite-Type LaFeO₃ for Efficient Ethanol Detection

by Jiejie Yu, Cong Wang, Quan Yuan, Xin Yu, Ding Wang and Yang Chen

Nanomaterials 2022, 12(10), 1768; https://doi.org/10.3390/nano12101768 - 22 May 2022

Cited by 17 | Viewed by 2220

Abstract

Perovskite (ABO₃) nanosheets with a high carrier mobility have been regarded as the best candidates for gas-sensitive materials arising from their exceptional crystal structure and physical–chemical properties that often exhibit good gas reactivity and stability. Herein, Ag in situ modified porous [...] Read more.

Perovskite (ABO₃) nanosheets with a high carrier mobility have been regarded as the best candidates for gas-sensitive materials arising from their exceptional crystal structure and physical–chemical properties that often exhibit good gas reactivity and stability. Herein, Ag in situ modified porous LaFeO₃ nanosheets were synthesized by the simple and efficient graphene oxide (GO)-assisted co-precipitation method which was used for sensitive and selective ethanol detection. The Ag modification ratio was studied, and the best performance was obtained with 5% Ag modification. The Ag/LaFeO₃ nanomaterials with high surface areas achieved a sensing response value (R_g/R_a) of 20.9 to 20 ppm ethanol at 180 °C with relatively fast response/recovery times (26/27 s). In addition, they showed significantly high selectivity for ethanol but only a slight response to other interfering gases. The enhanced gas-sensing performance was attributed to the combination of well-designed porous nanomaterials with noble metal sensitization. The new approach is provided for this strategy for the potential application of more P-type ABO₃ perovskite-based gas-sensitive devices. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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8 pages, 1982 KiB

Open AccessEditor’s ChoiceArticle

Area-Selective, In-Situ Growth of Pd-Modified ZnO Nanowires on MEMS Hydrogen Sensors

by Jiahao Hu, Tao Zhang, Ying Chen, Pengcheng Xu, Dan Zheng and Xinxin Li

Nanomaterials 2022, 12(6), 1001; https://doi.org/10.3390/nano12061001 - 18 Mar 2022

Cited by 13 | Viewed by 2273

Abstract

Nanomaterials are widely utilized as sensing materials in semiconductor gas sensors. As sensor sizes continue to shrink, it becomes increasingly challenging to construct micro-scale sensing materials on a micro-sensor with good uniformity and stability. Therefore, in-situ growth with a desired pattern in the [...] Read more.

Nanomaterials are widely utilized as sensing materials in semiconductor gas sensors. As sensor sizes continue to shrink, it becomes increasingly challenging to construct micro-scale sensing materials on a micro-sensor with good uniformity and stability. Therefore, in-situ growth with a desired pattern in the tiny sensing area of a microsensor is highly demanded. In this work, we combine area-selective seed layer formation and hydrothermal growth for the in-situ growth of ZnO nanowires (NWs) on Micro-electromechanical Systems (MEMS)-based micro-hotplate gas sensors. The results show that the ZnO NWs are densely grown in the sensing area. With Pd nano-particles’ modification of the ZnO NWs, the sensor is used for hydrogen (H₂) detection. The sensors with Pd-ZnO NWs show good repeatability as well as a reversible and uniform response to 2.5 ppm–200 ppm H₂. Our approach offers a technical route for designing various kinds of gas sensors. Full article

(This article belongs to the Special Issue Advanced Nanomaterials and Nanodevices for VOCs Gas Sensor)

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