Environmental Science-Nano
·
2023
·Vol. 11
·期 1
·459-469
·
IF 7.3
Hu Meng,Zhiwen Liu,Xiaoxin Wang,Liang Feng
Compared with carbon dioxide, fluorinated greenhouse gases (F-type gases), such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6), have a stronger greenhouse effect, and their global warming potential can reach thousands or even tens of thousands of times that of carbon dioxide. Thus, the rapid online accurate detection of fluorinated greenhouse gases is highly desired and it can provide a basis for the evaluation of the greenhouse effect and a yardstick for the formulation of emission reduction measures. Unfortunately, these highly noble chemical gas molecules, especially at trace concentration levels, are extremely difficult to detect with conventional rapid screening methods. The use of the most common gas sensing techniques, semiconducting metal oxides, in the detection of HFCs and PFCs has not appeared within the scope of our knowledge. Herein, we report a novel N-doped tin oxide semiconducting metal oxide prepared by using a facile hydrothermal method. The experimental characterization results showed that the as-prepared materials were uniform spherical nanoparticles. The doping ratio of N-doped tin oxide was further optimized, and gas-sensing tests using these materials were carefully conducted. The results showed that the sensor had good detection performance for F-type gases, represented by SF6, C2F6 and C2H2F4, including low working temperature (200 °C), high selectivity, good repeatability, relatively high response, and low limit of detection (LOD ∼7 ppb). To the best of our knowledge, this is the first report on an F-type gas sensor based on semiconductor metal oxide. The ultra-fine particle size and uniform morphology of spherical particles, high concentration of oxygen vacancy defects and N doping contribute to the excellent performance of the sensor.
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Catalysts
·
2021
·Vol. 11
·期 6
·738
·
IF 4.146
Yimeng Xing,Mengyao Ouyang,Lingling Zhang,Ming Yang,Xiaodong Wu,Rui Ran,Duan Weng,Feiyu Kang,Zhichun Si
Copper catalysts were widely developed for CO2conversion, but suffered severe sintering at temperatures higher than 300 °C. Platinum was the most active and stable metal for RWGS reactions. However, the high price and scarcity of platinum restrained its application. Downsizing the metal particles can significantly improve the atom efficiency of the precious metal but the size effect of Pt on RWGS reactions was still unclear. In the present work, the single atomic Pt on SrTiO3was prepared using an impregnation leaching method, and the catalyst showed significant activity for an RWGS reaction, achieving a CO2conversion rate of 45%, a CO selectivity of 100% and a TOF of 0.643 s−1at 500 °C. The structures of the catalysts were characterized using XRD, STEM and EXAFS. Especially, the size effect of Pt in RWGS was researched using in situ FTIR and DFT calculations. The results reveal that single Pt atoms are the most active species in RWGS via a “–COOH route” while larger Pt cluster and nanoparticles facilitate the further hydrogenation of CO. The reaction between formate and H* is the rate determination step of an RWGS reaction on a catalyst, in which the reaction barrier can be lowered from 1.54 eV on Pt clusters to 1.29 eV on a single atomic Pt.Keywords:size effect;single Pt atoms;SrTiO3;reverse water gas shift (RWGS)
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JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Xiujuan Zhang,Xinlu Zhang,Bangyao Du,Xiaokun Wang,Xuehua Ruan,Wenji Zheng,Yan Dai,Minggang Guo,Gaohong He
While extracorporeal oxygenation (ECMO) is regarded as the golden weapon for patients with cardiopulmonary failure in critical care, its clinical use is usually complicated by the blood coagulation on the hydrophobic surface of the artificial membrane for gas exchange. Herein, amphiphilic polydimethylsiloxane‐hydroxyethyl methacrylate (PDMS-HEMA) material was firstly synthesized from chemical reaction between HEMA and the vinyl group on the side chains of PDMS via a simple process, and then coated on the microporous polyethersulfone (PES) base membrane to obtain PDMS-HEMA/PES composite membrane . Structure characterizations demonstrated that HEMA and PDMS were successfully copolymerized, and PDMS-HEMA/PES composite membranes were well prepared with a flat dense PDMS-HEMA layer coated on the surface of microporous PES substrate. Surface property analyses confirmed much smoother membrane surface, phase-separated morphology, and significant decrement in water contact angles for PDMS-HEMA obtained. More importantly, the PDMS-HEMA/PES composite membrane exhibited a CO 2 /O 2 gas selectivity of ∼6.5 in comparison to ∼5.5 of PDMS/PES, indicating improved gas exchange efficiency. Nevertheless, the PDMS-HEMA/PES composite membrane also displayed excellent and much improved performance in hemocompatibility and long-term stability for storage as well as against blood wetting. Therefore, side-chain modification of hydrophobic PDMS with hydrophilic HEMA through simple chemical copolymerization process is an easy and feasible method to make the membrane surface with long-term amphiphilicity less thrombogenic in contact with blood and more efficient in gas exchanges.
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Membranes
·
2023
·Vol. 13
·期 11
·858
·
IF 4.2
Qing Wang,Huiyuan Chen,Feiyang He,Qiao Liu,Nong Xu,Long Fan,Chuyan Wang,Lingyun Zhang,Rongfei Zhou
In this study, high-performance FAU (NaY type) zeolite membranes were successfully synthesized using small-sized seeds of 50 nm, and their gas separation performance was systematically evaluated. Employing nano-sized NaY seeds and an ultra-dilute reaction solution with a molar composition of 80 Na2O: 1Al2O3: 19 SiO2: 5000H2O, the effects of synthesis temperature, crystallization time, and porous support (α-Al2O3or mullite) on the formation of FAU membranes were investigated. The results illustrated that further extending the crystallization time or increasing the synthesis temperature led to the formation of a NaP impurity phase on the FAU membrane layer. The most promising FAU membrane with a thickness of 2.7 µm was synthesized on an α-Al2O3support at 368 K for 8 h and had good reproducibility. The H2permeance of the membrane was as high as 5.34 × 10−7mol/(m2s Pa), and the H2/C3H8and H2/i-C4H10selectivities were 183 and 315, respectively. The C3H6/C3H8selectivity of the membrane was as high as 46, with a remarkably high C3H6permeance of 1.35 × 10−7mol/(m2s Pa). The excellent separation performance of the membrane is mainly attributed to the thin, defect-free membrane layer and the relatively wide pore size (0.74 nm).
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PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Jundan Tang,Lihua Shen,Kunpeng Zhao,Jiaming Peng,Qili Chen,Chunxia Yu,Yuangang Li,Azhar Abbas,Shan Wang,Zhifang Liu
Nanomaterials-based gas sensors are conducive to online, real-time monitoring and large-scale production due to their simplicity, low energy consumption and miniaturization. Conventional nanomaterial-based (metal oxide semiconductor or two-dimensional nanomaterials) gas sensors are less sensitive (ppm-ppb level). So, it is significantly meaningful to develop new gas-sensing materials. Herein, Ag@sulfur nanosheets (S-NSs) nanocomposite-based sensor is explored for ultrasensitive detection of NH 3 in dry air at room temperature at parts per trillion (ppt) level. Introducing Ag nanoparticles (NPs) on S-NSs, improved electrical conductivity and created more effective adsorption sites, leading to a high response rate of 1.92 for 3 ppt NH 3 . The developed Ag@ S-NSs sensor showed a linear response to NH 3 in the range of 3–70 ppt with correlation coefficient of 0.996. Moreover, the developed Ag@S-NSs sensor showed fast response and recovery time (28/7 s) to NH 3 . The probable sensing mechanism is supposed that the polarization-induction of NH 3 changed of electronic energy level of Ag@S-NSs, and the changed energy is at approximately the same energy level of the Ag@S-NSs itself. Thus, a response signal caused by NH 3 with low concentration can also be felt by Ag@S-NSs sensing materials itself.
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ENERGY
·
2023
·
IF 9
Ningtao Zhang,Shuxia Li,Litao Chen,Yang Guo,Lu Liu
The characteristics of gas-liquid two-phase flow in hydrate-bearing sediments (HBS) are critical for natural gas hydrate production . This study experimentally investigates the flow patterns in the presence of hydrates and employs the phase field method for accurate simulations. Additionally, flow pressure differences in a capillary model were analyzed, and the impacts of occurrence patterns, saturation, and wettability of hydrates were investigated by numerical simulation. The results show that flow patterns are predominantly influenced by flow velocity. At high flow rates (Reynolds number >10), different gas-liquid ratios result in a variety of flow patterns, including annular, Taylor, and bubble flow. However, at lower flow rates (Reynolds number <10), the flow pattern consistently manifests as Taylor flow, regardless of gas-liquid ratio variations. Notably, the Jamin effect (a significant pressure differential caused by hydrates within the flow) was observed, which intensifies with increasing hydrate saturation and decreasing contact angle. Pore-filling hydrate patterns, in contrast to grain-coating, exhibit a greater number of gas-liquid interfaces, leading to larger pressure differences and a more evident Jamin effect. These findings aid in understanding the fluid migration in HBS and help estimate the natural gas production capacity.
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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
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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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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ENERGY
·
2020
·
IF 6.082
Xiaoya Zang,Xuebing Zhou,Lihua Wan,Jing Wang,Deqing Liang
Cyclopentane (CP) is an alkane that combines with water to form hydrates. Here, we investigate the hydrate thermal dynamics and formation kinetics of a synthesized ternary gas mixture of CH 4 /CO 2 /N 2 with CP additives. The results indicated that CP shifts the phase equilibrium conditions of ternary gas mixture hydrates to higher temperature and lower pressure. Under a constant pressure, the largest temperature offset can be approximately 20 K. Meanwhile, the ternary gas mixture of CH 4 /CO 2 /N 2 formed structure II hydrates with added CP. The kinetics study indicated that the hydrate reaction started immediately when accompanied by stirring. The consumption of CO 2 gas was greater than that of CH 4 and N 2 . The ratio of the volume of CP to the volume of water had a considerable influence on the effective reaction time, CH 4 recovery factor (R CH4 ), and CO 2 split ratio (S CO2 ) under all experimental conditions. R CH4 and S CO2 were higher when the CP-to-water volume ratio was 0.308. The largest values of R CH4 and S CO2 were 3.098 and 0.908, respectively, when the CP-to-water volume ratio was 0.308 at 7.0 MPa and 280.1 K. These results favor the use of CP as an additive to separate CO 2 and purify CH 4 in gas mixtures.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Guanjun Liu,Fan Yang,Wenbo Liu,Weicheng Jiao,Xiaodong He,Rongguo Wang
High gas barrier polyethylene (PE) composites containing non-oxidized graphene flakes (GFs) were fabricated through solution blending. GFs were synthesized through ultrasonic-assisted electrochemical exfoliation of graphite. Then, GFs were functionalized via directly inducing PE molecular crystallization along their surface under proper temperature and PE/GFs ratio. The composites with only 0.5 wt% GFs gave a helium leak rate of 6.29 × 10 −8 Pa m 3 /s at 0.6 MPa, outperforming pure PE with a decrease of 83.4%. In addition, the interface interaction between PE and GFs is very weak, and the cohesive energy is only 0.1448 J m −2 . Therefore, at high GFs concentrations (>0.5 wt%), the continuous weak interfaces between the GFs interconnected networks and PE will reduce the effective diffusion path to a certain extent, leading to the reduction of gas barrier efficiency. In general, this method offers great promise for barrier materials that can be utilized in lightweight high-pressure gas storage vessels.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Boxuan Yang,Zheng Zhang,Chen Tian,Wenjing Yuan,Zhongqiu Hua,Shurui Fan,Yi Wu,Xuemin Tian
Gas sensors based on Pd-loaded SnO 2 were prepared with printed zeolite films on the top of the sensor layer to enhance selective response to methane. As expected, Pd-loaded SnO 2 has a sensitive response to CH 4 and VOCs, such as ethanol and acetone vapors. Pt catalyst was dispersed onto the surface to promote the catalytic activity of zeolite. According to the catalytic characterizations, it was indicated that interfered gases, CO and ethanol were catalytically oxidized into CO 2 and water vapor. Whereas the catalytic combustion of methane is a negligible and sensitive response to the interested analyte was significantly promoted. Thus, the selective response to CH 4 was greatly improved even in a mixture of CO and VOCs. Based on the power-law response to oxygen, it was found that the resistive responses of all sensors were highly oxygen-dependent, suggesting that oxygen adsorbates on the surface were involved in the sensing process and no difference with zeolite coated sensors. Thus, it can be concluded that zeolite films printed onto the sensing layer surface serve as a catalytic filter and responsible for the enhanced sensitive and selective response of methane.
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