SENSORS AND ACTUATORS B-CHEMICAL
·
2022
·
IF 9.221
Haiyan Zhang,Fei Feng,Yangyang Zhao,Bin Zhao,Lei Li,Dan Zheng,Xinxin Li
Increasing the aspect ratio of the microchannels of microfabricated gas chromatographic columns (μGCCs) can allow analytes to quickly reach equilibrium between the stationary phase and mobile phase , which helps improve their separation performance. In this paper, an all-silicon microfabricated gas chromatographic column (AS-μGCC) with a high aspect ratio was proposed and fabricated using deep reactive-ion etching (DRIE) and silicon direct bonding. Two AS-μGCCs with the lengths of 2 m and the aspect ratios of 6.6 (100 µm-width × 660 µm-depth) and 25 (30 µm-width × 750 µm-depth) were successfully fabricated. The effects of different aspect ratios on the column efficiency of AS-μGCCs were studied. A separation experiment showed that the column efficiency of the AS-μGCC with an aspect ratio of 25 (AS-μGCC-25) was 12 times higher than that of the AS-μGCC with an aspect ratio of 6.6 (AS-μGCC-6.6). The column efficiency of the AS-μGCC-25 was 1961 plates/m, and a heavy hydrocarbon mixture (C8–C20) could be separated using AS-μGCC-25 within 4.5 min
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高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Chengqin Dai,Maosheng Chen,Yujing Lin,Ruijuan Qi,Chunhua Luo,Hui Peng,Hechun Lin
Metal oxide semiconductor have been widely used as sensing materials for detecting various gases with trace concentrations. However, the sensing properties of layered cobaltites with metallic conductivity have not been investigated to date. In this work, we developed a convenient preparation method of Na x CoO 2 nanoflakes via aqueous ultrasonic exfoliation of Na x CoO 2 single crystals. The sensor based on Na x CoO 2 nanoflakes was fabricated, whose resistance is obviously smaller than that of the typical metal oxide based sensors. It shows less response to n -hexane, toluene, xylene, ammonia, methanol, ethanol and acetone. However, it exhibits excellent sensing performance to n -butanol and good moisture-resistance, and the sensitivity to 50 ppm n -butanol is up to 4.48 with the response time of 95 s and the recovery time of 154 s at the optimum working temperature of 200 °C. Owning to the high electric conductivity of Na x CoO 2 layers, the sensor presents a very low noise and a high signal-to-noise ratio value with the detection limit at ppb level. The layered cobaltites exhibit the rich phase diagram and the nanoflakes are versatile surface functionalization. This work provides insight for layered cobaltites to be employed as highly sensitive sensors.
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高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
YaHui Cai,ShuYi Ma,TingTing Yang,Li Wang,Ni Na Ma,Miao Miao Liu
The pure YVO 4 and heterostructured YVO 4 /V 2 O 5 gas sensitive materials were prepared by simple and economic hydrothermal path. A variety of characterization methods were used to study the morphology, specific surface area and binding state of YVO 4 /V 2 O 5 composites. The results show that the YVO 4 /V 2 O 5 composites has smaller particle size (reduced from 200 nm to 50 nm) and larger specific surface area, which is increased from 7.738 m 2 /g to 26.586 m 2 /g). Compared with pure YVO 4 , the n-type sensor based on YVO 4 /V 2 O 5 composites has higher response value (increased from 12.29 to 42.15), lower optimal operating temperature (reduced from 200 °C to 140 °C), and shorter response/recovery time (reduced from 11 s/25 s–6 s/14 s). The YVO 4 /V 2 O 5 composites gas sensor has excellent selectivity and good long-term stability for triethylamine gas. The study of gas sensing mechanism shows that n-n heterojunctions and large specific surface area conduce excellent gas-sensitive property of YVO 4 /V 2 O 5 composites. This work provides a valuable direction for low-cost preparation of TEA sensors with excellent performance and long-term stability.
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高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2022
·
IF 10.53
Shan Xu,Ning Zhao,Lei Wu,Shuanyan Kang,Zhiguang Zhang,Guolong Huo,Zhongde Dai,Nanwen Li
Tuning the relationship between the microporous structure of carbon molecular sieve (CMS) membranes and the corresponding gas permeability performance enables optimization for gas separation applications. The pre-crosslinked structure of the precursor plays a key role in improving the performance of the CMS membrane. Herein, the thermally crosslinkable brominated 6FDA-based polyimide (BMPI) by debromination is prepared and selected as the precursor to fabricate high performance CMS gas separation membranes . By heat-treating the BMPI membrane at 350 °C for 10 h, the debromination-induced crosslinking exhibited higher permeability over the uncrosslinked precursors, as it forms a pre-crosslinked structure that is more stable at 550 °C. A representative BMPI-350/10h-550 °C CMS membranes pyrolyzed at 550 °C had CO 2 and O 2 permeabilities of 11169 and 2182 Barrer with a CO 2 /CH 4 and O 2 /N 2 ideal selectivity of 26.5 and 5.4. These values are much higher than that of the un-crosslinkable precursor (6FDA-DAM) derived CMS membrane (P CO2 = 3465, α CO2/CH4 = 21.1). Even at the high carbonization temperature of 800 °C, the as-obtained CMS membrane still show a promising CO 2 permeability of 1119 Barrer and a CO 2 /CH 4 ideal gas selectivity of 41.2. Importantly, the excellent gas separation performance of CMS membranes obtained in this work exceeds the Robeson's upper-bound. This work outlines a new protocol to tailor CMS membrane microstructures to meet high permeability performance needs. These CMS membrane materials hold great potential in corrosive natural gas purification applications.
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高影响因子
Separation Science Plus
·
2022
·Vol. 5
·期 9
·513-519
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IF 0
Yanni Huang,Jia Chen,Gafang Fu,Chi Zhang,Hongdeng Qiu
This work reported the preparation and evaluation of a 2D porous graphene as the stationary phase for gas chromatography with high-resolution performance from non-polar to polar structural isomers. As a result, the dynamically coated porous graphene capillary column has a film thickness of about 16 μm. After aging treatment at different temperatures, the porous graphene capillary column exhibited high thermal stability up to 300°C. In addition, the porous graphene capillary column has good column repeatability and reproducibility. The retention time RSDs are 2.61–3.90% ( n = 3) during the days and 4.58–4.78% ( n = 3) column-to-column. This work demonstrates the advantageous separation performance of a good potential for the porous graphene as a new stationary phase for gas chromatography analysis.
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JOURNAL OF ELECTRONIC MATERIALS
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2022
·Vol. 51
·期 12
·7009-7019
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IF 2.047
Ma Xin,Ying Zhihua,Wen Fei,Li Lili,Zheng Xiaolong,Zheng Peng,Wang Gaofeng
Since cobalt-containing spinel oxides have good prospects for the detection of toxic gases, they also have great potential for applications in the field of gas sensors. However, ZnCo 2 O 4 -based gas sensors have the disadvantages of low response values and poor selectivity in formaldehyde detection. In this study, we attempted to prepare formaldehyde gas sensors by varying the addition of sodium citrate for hydrothermal synthesis of ZnCo 2 O 4 . During the fabrication process, it was found that an appropriate amount of sodium citrate content could produce ZnO on the surface of ZnCo 2 O 4 , and that the gas sensitivity of ZnO-ZnCo 2 O 4 to formaldehyde was better compared to that of pure ZnCo 2 O 4 . The sensor has a response rate of 17 at 20 ppm formaldehyde at 200°C. It also has good selectivity, repeatability, and stability. These results can provide foundational knowledge for the implementation of spinel oxide materials in the field of gas sensors.
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高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Jie Hu,Xueqing Xiong,Wangwang Guan,Haizhu Long
To realize a synergistic effect between composition engineering and morphology modulation, PdO–Fe 2 O 3 heterojunction architectures with various morphologies were fabricated by facile hydrothermal and solution impregnation methods. Afterwards, gas sensing devices were constructed from the as-prepared PdO–Fe 2 O 3 composites, and their parameters were systematically investigated. The obtained results revealed that all PdO–Fe 2 O 3 sensors exhibited excellent selectivity properties and high responses to target gases. Importantly, an urchin-like PdO–Fe 2 O 3 sensing device produced the largest response of 75 to 50 ppm hydrogen sulfide at a PdO concentration of 4 wt%, which was approximately four times greater than that of a spherical PdO–Fe 2 O 3 sensor. The urchin-like sensor was also characterized by the highest response recovery efficiency, water resistance, and long-term stability. Furthermore, the sensing mechanism of the fabricated PdO–Fe 2 O 3 composite-based gas sensors was discussed comprehensively.
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高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2021
·
IF 7.46
Ning Lu,Shurui Fan,Yaxu Zhao,Boxuan Yang,Zhongqiu Hua,Yi Wu
In this work, a selective methane gas sensor was prepared based on In 2 O 3 to eliminate the serious cross-sensitive sensitivity to VOCs, NO 2 , and CO, which are typical interfering gases for methane detection in domestic. The catalytic films of Pt-TiO 2 , Pt-CeO 2 , and Pt-ZrO 2 were placed on the top of the sensing layer, i.e., In 2 O 3 loaded with Pd. Catalytic films were designed as filters to catalytically oxidize the interfering gases, such as VOCs, to prevent them reaching the surface of the sensitive layers. Thanks to this design, our sensors showed a high selectivity to methane, even in the presence of ethanol, CO, and NO 2 . In addition, we confirmed via the power-law response of oxygen that the basic sensing mechanism between Pd-In 2 O 3 and the sensor-printed catalytic films are kept the same. Both follow the general model with MOS sensors, which involves an electron transfer process resulting from the adsorption of oxygen on the surface and interaction with methane molecules. The present study showed that catalytic filter films (Pt-TiO 2 , Pt-CeO 2 , and Pt-ZrO 2 ) printed on Pd-In 2 O 3 sensors could enhance the selective response to methane for methane monitoring.
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高影响因子
Chemistry-An Asian Journal
·
2021
·Vol. 16
·期 21
·3413-3418
·
IF 4.568
Yuxiao Li,Ting Wang,Dahuan Liu
Graphical In this work, we report the fabrication of ultrathin and defect-free Zr-BTB membranes constructed by the assembly of monolayer MOF nanosheets with tunable gas separation performance. H 2 /CO 2 selectivity of the membranes can be enhanced by increasing the membrane thickness or by introducing the thermal disturbance during the membrane fabrication process. Two-dimensional (2D) metal-organic frameworks (MOF) nanosheets have emerged as novel membrane materials for gas separation. However, the development of ultrathin MOF membranes with tunable separation performances is still a challenge. Herein, we developed a facile GO-assisted restacking method to fabricate defect-free membranes with monolayer Zr-BTB nanosheets. Obtained ultrathin membranes ranging from 130 nm to 320 nm show tunable separation performances and exceed the 2008 Robeson upper bound by changing the amount of nanolayers in vertical stacking direction. Furthermore, a heating filtration method was used to change the restacking process of nanosheets in the horizontal direction. As a result, H 2 /CO 2 selectivity can be enhanced by two times with the same membrane thickness (130 nm) and H 2 permeance is almost maintained to be 7.0×10 −7 mol m −2 s −1 pa −1 . This method may provide a possible way to efficiently tune the gas separation performances of MOF membranes.
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PubMed
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2021
·
IF 4.094
Cao Cheng,Hongyan Zhang,Fan Li,Shuguo Yu,Yan Chen
In this study, a gas sensor based on TiO 2 /WO 3 ·H 2 O (TW) heterojunction with high sensitivity, excellent selectivity and long-term stability for ammonia (NH 3 ) detection was successfully prepared by hydrothermal method . Compared with WO 3 ·H 2 O and TiO 2 , TW heterojunction shows excellent selective to NH 3 and the response varies by 3 orders of magnitude to 500 ppm NH 3 at room temperature (RT, 25 ± 3 °C). The lowest response limit of TW is 0.5 ppm and the response/recovery time is 2.35 s/1.95 s. The main reason for improving the performance of TW heterojunction to NH 3 detection is that TiO 2 nanoparticles cause more oxygen free radicals on the surface of TW heterojunction, which can react with more NH 3 molecules to release more electrons. Therefore, heterojunction structure increases the electrons and reduces the width of electron depletion layer in TW gas sensor. In addition, TW heterojunction has small and uniform particle size which can provide more active sites for the reaction between NH 3 and oxygen free radicals to release more electrons. This work provides a heterojunction structure composed of TiO 2 and WO 3 ·H 2 O to effectively improve the performance of sensor for NH 3 detection at RT, which is beneficial to the development of high-performance gas sensors.
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Journal of Materials Chemistry A
·
2021
·Vol. 9
·期 33
·17821-17829
·
IF 12.732
Ling-Yu Dong,Xu Hu,Yun-Zhe Du,Rui Ge,Guang-Ping Hao,An-Hui Lu
Electrochemically catalytic conversions have attracted worldwide interest as promising routes to reach a sustainable and green energy cycle. The exploration of efficient electrocatalysts is one of the key tasks, in which the majority has focused on devising new active centers; however, mass transport that determines the reactant supply and the conductance of electrolyte ions and electrons is often overlooked. Here, we report on spatially locating active centers into parallelly bimodal mesopores by precisely engineering mesopore geometries, through which the contribution of the paralleled transport channels to the activity of gas-consuming reactions was quantitatively determined. Under identical conditions, bimodal mesoporous carbon-based electrocatalysts displayed a 2.9 times higher CO partial current density than monomodal mesoporous catalysts for CO2-to-CO conversion in the kinetic region of −1.1 V vs. RHE. Likewise, the strong correlation between the activity enhancement and the bimodal mesopore geometry was verified for supported molecular catalysts and applicable to other gas-consuming reactions such as the O2 reduction reaction. These encouraging results offer a fresh and general idea to advance electrocatalysts by pore geometry engineering on the mesoscale.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
IF 3.573
Tong Zhang,Liming Deng,Pei Li
Previous studies demonstrate that decarboxylation cross-linking improves both the plasticization resistance and gas separation properties of a polymer precursor. However, when the decarboxylation reactions were carried out at low temperatures (350–400 °C), gas permeability was low because of the intrinsically low gas permeability of the polymer precursor. In this work, we synthesized a series of highly permeable polymer precursors having a triptycene-based Tröger’s base (TB) backbone structure and different amounts of carboxylic acid side groups. The TB polymer precursors were heated in a temperature range of 275–400 °C to induce cross-linking. After cross-linking, a more open polymer structure was obtained, resulting in an increase in the free volume fraction and gas permeability. The lowest cross-linking temperature was 350 °C and the separation performances of the cross-linked polymers surpassed the “2008 Robeson Upper Bound” for the CO2/CH4 and O2/N2 gas pairs. Moreover, the cross-linked polymers were not plasticized by CO2 at a pressure up to 30 bar.
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高影响因子
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