POLYMER COMPOSITES
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2022
·Vol. 43
·期 10
·7200-7210
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IF 3.531
Feng Gao,Jiahao Shi,Xiaorui Zhang,Xuan Wang,Ling Weng,Xue Sun,Lida Yu,Chenhao Li
Bismaleimide resin (BMI) is a thermosetting resin with excellent properties. However, due to its poor toughness as a cured product, this paper uses hyperbranched polyimide (HBPI) and nano-SiO 2 in a synergistic manner to improve the performance of BMI. Isophorone diisocyanated tripolymer (IPDI trimer) and methyl nadic anhydride (MNA) were used to synthesize HBPI, and then we investigated the effect of the synergistic modification on the mechanical and thermal properties and the modification mechanism of HBPI and nano-SiO 2 . The experiments showed that the most significant improvements were achieved at the addition of 40 and 3 wt% of HBPI and nano-SiO 2 respectively, with the impact strength of the materials increasing by 97.2%, fracture toughness indexes G IC and K IC increased by 36.7% and 34.6% respectively and glass transition temperature ( T g ) was reduced. The SEM results showed that the nanoparticles were uniformly dispersed and further validated the synergistic modification mechanism.
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RENEWABLE ENERGY
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2022
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IF 8.634
Wenjing Song,Mengxue Song,Wenqing Cai,Weichu Li,Xingmao Jiang,Weiping Fang,Weikun Lai
Development of highly active and stable catalyst for C–O bonds cracking is important in biomass conversion , in this work, we report a SiO 2 -encapsulated NiPt/HY core-shell catalyst for phenethoxybenzene (PEB) catalytic cracking . The as-grown silica shell with defined pores serves as a ‘storage’ to enhance local concentration of PEB and intermediate isomers and promotes catalytic cracking on NiPt/HY core. With the increase of silica shell thickness from 0 to 40 nm, PEB reaction rate has increased more than five times, and the major cracking product selectivity is raised to above 90%, which is attributed to the continuous conversion of PEB isomers within the shell. This designed structure endows the NiPt/HY@SiO 2 with a high activity and no obvious deactivation in PEB cracking to corresponding phenol and aromatics. The outstanding performance benefit from the enrichment effect on the unique core-shell structure, as well as the moderate acidity originated from silica regulation. This work can be extended to the modulation of microenvironment to promote the catalytic behavior of core-shell catalysts.
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Frontiers in Chemistry
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2022
·
IF 5.545
Jia Hongyan,Lv Qing,Xia Qineng,Hu Wanpeng,Wang Yanqin
Efficient conversion of biomass-derived 5-hydroxymethylfurfural (HMF) to renewable fuels such as 2,5-dimethylfuran (DMF) and 2,5-dimethyltetrahydrofuran (DMTHF) is of significance for sustainable energy supply. For efficient catalyst design, it is important to understand the catalytic behavior and clarify the influence of physico-chemical properties of catalyst on reaction performance. Herein, to study the structure-activity relationships of monometallic Cu catalysts for HMF hydrogenolysis, a series of Cu/SiO2 catalysts with different physico-chemical properties were prepared and compared for their catalytic performance in HMF hydrogenolysis. It was found that Cu/SiO2-HT-8.5 catalyst prepared by hydrothermal method showed excellent activity in HMF hydrohydrolysis reaction. Under the optimal reaction condition, the total yield of liquid fuels reaches 91.6% with 57.1% yield of DMF and 34.5% yield of DMTHF in THF solvent. Characterizations such as XRD, H2-TPR, N2-adsorption/desorption, TEM and XPS revealed that the Cu particles in the Cu/SiO2-HT-8.5 catalyst have uniform size and high dispersion. The Cu species and the SiO2 support have relatively weak interaction and are easy to be reduced to Cu0, which makes it show excellent activity in the hydrogenolysis of HMF.
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Journal of Energy Storage
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2022
·
IF 8.907
Lei Liu,Xiwang Miao,Xiang Cheng,Huigang Wang,Min Guo,Fangqin Cheng,Mei Zhang
In this work, PCM nanocapsules composed of ZnO/SiO 2 shell and n-octadecane core were successfully synthesized by emulsion polymerization and hydrothermal method . The crystallinity of ZnO was enhanced on the SiO 2 shell by MPTS modification. The granule-like ZnO were distributed on the SiO 2 shell. The encapsulation rate of n-octadecane in nanocapsules was about 45.2 % with enthalpy of 95.0 J/g melting at room temperature 28.3 °C. Furthermore, due to the presence of ZnO, the synthesized PCM nanocapsules had excellent UV absorption properties for whole wavelengths, and the absorbed UV light can be converted into heat energy for storage, and the photothermal conversion efficiency had reached 25.0 %. Hence, the prepared ZnO/SiO 2 @n-octadecane nanocapsules had broad application prospects due to its thermal energy storage , UV protection and photothermal conversion performance.
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APPLIED CATALYSIS A-GENERAL
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2022
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IF 5.723
Feifei Li,Mingyue Wang,Jinming Zhang,Xingtao Lin,Dazhi Wang,Weijie Cai
The design of highly efficient catalysts for CO 2 reforming with ethanol is of great interest due to the serious coke deposition and the sintering of active metal. In this work, sandwich-type Co core@shell catalyst (SiO 2 @Co@CeO 2 ) with Co nanoparticles between SiO 2 core and CeO 2 shell was synthesized by strong electrostatic adsorption method. Interestingly, SiO 2 @Co@CeO 2 catalyst exhibited the outstanding activity/stability toward CO 2 reforming of ethanol in comparison with Co-SiO 2 catalyst. A bi-functional mechanism involving active sites on CeO 2 shell was proposed. Indeed, cobalt nanoparticles between SiO 2 core and CeO 2 shell maintained the high dispersion because of the confinement effect, which supplied a stable Co-ceria interface area where the reaction occurred. In addition, CO 2 could readily react with the O vacancies in CeO 2 shell to form surface oxygen species and CO, which allowed a continuous cleaning of coke. These positive factors could make it as an attractive candidate for dry reforming process.
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CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Huijuan Liu,Keyan Wei,Chao Long
Y zeolite with high specific surface area and peculiar microporous channels has been regarded as a promising adsorbent in volatile organic compounds (VOCs) control. However, a scalable strategy for improving the hydrophobicity and mass diffusion of Y zeolite to remove VOCs remains a challenge. In this study, we successfully synthesized two NaY@ meso -SiO 2 core–shell composites with different shell thicknesses by coating NaY zeolite with mesoporous SiO 2 (NaY@ meso -SiO 2 -0.8 and NaY@ meso -SiO 2 -1.2), which significantly improved the hydrophobicity of NaY zeolite and diffusion of VOCs into NaY zeolite. The results of XRD, SEM, TEM, FTIR and BET confirmed the successful synthesis of core–shell composites. The adsorption equilibrium experiments showed that coating NaY zeolite with mesoporous SiO 2 effectively enhanced the hydrophobicity of NaY zeolite. Under RH = 0, the adsorption capacity of pristine NaY zeolite was the highest; while under RH = 50%, NaY@ meso -SiO 2 -1.2 exhibited stronger adsorption ability and excellent hydrophobicity. The adsorption diffusion indicated that coating NaY zeolite with mesoporous SiO 2 remarkably promoted the diffusion of VOCs into composites. Compared with the pristine NaY, core–shell composites showed higher diffusion coefficients and lower diffusion activation energy under RH = 0, particularly NaY@ meso -SiO 2 -1.2. In addition, linear solvation energy relationships (LSERs) revealed that π-/n-electron pairs interaction became weak and dipolar interactions were enhanced when water was adsorbed on the surface of NaY@ meso -SiO 2 -1.2. Hydrogen bonding decreased when RH level reached 50% and then increased with the increase of RH from 50% to 90%.
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Analytical Methods
·
2022
·Vol. 14
·期 17
·1721-1729
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IF 3.532
Di Deng,Xiaoyu Fang,Ding Duan,Kang Li
There is a critical need for the rapid detection of p-chlorophenol produced by pesticide abuse and industrial wastewater discharge, which has been an urgent problem in the realm of environmental protection. Here, a green and environmentally friendly method was developed to prepare stable and low toxicity quantum dots. First, blue-green fluorescent FeS2 quantum dots (B-FeS2 QDs) were prepared with FeCl3·6H2O (an iron source) and L-cysteine (a capping agent) by the solvothermal method. By combining B-FeS2 QDs with orange carbon dots (O-CDs), a CDs@SiO2/FeS2@MIPs visual fluorescence sensor for the selective detection of p-chlorophenol was constructed. Under optimum conditions, this sensor exhibited a detection limit of 1.265 μM with a linear range of 5.00–50.00 μM and was successfully applied to detect p-chlorophenol in real samples. Moreover, this sensor was successfully applied to visual semi-quantitative detection of p-chlorophenol. This work demonstrated that these sensors, based on FeS2 QDs and CDs, had potentials for in situ and visual detection of environmental contaminants.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2022
·
IF 9.965
Chaohu Xiao,Qimeige Hasi,Shanshan Wang,Yuhan Zhang,Hailing Li,Lu Zhang,Lihua Chen,An Li
Solar steam generation (SSG) is one of the promising technologies for seawater desalination and contaminated water purification . However, SSG devices are always restricted by poor insulation performance, insufficient solar spectrum absorption and serious salt-fouling. Here, a double-layered novel SSG system was fabricated by using poly(ionicliquid)s gels with hollow SiO 2 microspheres in-situ doping to enhance the thermal insulation of lower layer, and co-modified the top surface by polypyrrole (PPy) and silver particles to strengthen the solar absorption capability. Benefiting from the low thermal conductivity (0.082 W m −1 k −1 ), strong light absorption ( ca . 96%) and adequate water transport capability of poly(ionic liquid)s gels. As SSG device, a superb photothermal conversion efficiency of 90.5% is achieved under 1 sun illumination. Moreover, the poly(ionic liquid)s gels based SSG system also shows good desalination performance in artificial sea water and high concentration brine, and the purified water from artificial seawater can achieve the WHO's standard for drinking water . Therefore, this work combined attractive in-situ doping and co-modified strategies for fabricating high performance and thus shows significant potential for real applications.
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Catalysis Science & Technology
·
2022
·Vol. 12
·期 7
·2257-2264
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IF 6.177
Fei Zhang,Chunzheng Wu,Shuibo Wang,Shiwei Wang,Tong Li,Laixi Zou,Hongbo Yu,Hongfeng Yin
Although supported Rh nanoparticles (NPs) are one of the best catalysts for the selective hydrogenation of phenol to cyclohexanol, they still suffer from poor selectivity problems. In this study, we promoted the selectivity of Rh NPs with CoOx through an in situ transformation of the bimetallic RhCo NPs on SiO2. Among the obtained Rh–CoOx/SiO2 catalysts, the one with a Co/Rh molar ratio of 1/3 exhibited the highest phenol conversion (i.e., 98.1%) and the highest selectivity to cyclohexanol (i.e., 99.4%). Our study showed that CoOx promoters modified the electronic states of Rh and created new active sites at their interface, which are beneficial to the activation of phenol and the desorption of cyclohexanol. Excessive coverage of Rh by CoOx, however, would cause deactivation due to the less exposure of the Rh–CoOx interface.
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FOOD CHEMISTRY
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2023
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IF 8.8
Maosai Zhang,Ye Yang,Wenchuan Guo
In this work, a simple electrochemical sensing platform based on acid-treated Fe 3 O 4 @SiO 2 nanoparticles was successfully prepared for nitrite and sulfite detection. Fe 3 O 4 @SiO 2 nanoparticles were synthesized through the sol–gel and hydrothermal methods. Fe 3 O 4 @SiO 2 presented positive charges after acid treatment, which could enhance the electrostatic attraction between Fe 3 O 4 @SiO 2 and nitrite and sulfite. The Fe 3 O 4 @SiO 2 (acid-treated) modified magnetic glassy carbon electrode (MGCE) was applied to detect nitrite and sulfite using differential pulse voltammetry and cyclic voltammetry. Under optimized conditions, the developed electrochemical sensor presented good analytical properties for nitrite and sulfite detection with detection limits of 3.33 μmol/L and 31.57 μmol/L, respectively. The good recoveries varied from 85.18% to 111.02%, with a relative standard deviation of 0.23–4.80%. Furthermore, the Fe 3 O 4 @SiO 2 (acid-treated) modified MGCE showed better selectivity, reproducibility, and repeatability in nitrite and sulfite detection. Therefore, this proposed electrochemical sensor provides a new method for developing a nitrite and sulfite detection sensor.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
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IF 6.2
Xinli Ye,Jianqing Xu,Shan Li,Xiaomin Ma,Bangxiao Mao,Junxiong Zhang,Kai Zheng
With the widespread application of radar detection systems in the military field, the development of radar stealth technology can effectively reduce the characteristic signals of targets, which was of great significance for the protection of important military targets. In this paper, the resorcinol/formaldehyde (RF) reinforced silica aerogel (RF/SiO 2 ) was synthesized successfully. The RF was introduced into the sol/gel technology to build a porous skeleton, and the SiO 2 aerogel was prepared by atmospheric pressure drying. The RF/SiO 2 aerogel was then heat treated, and the microstructure and physical properties of the RF/SiO 2 aerogel before and after heat treatment were characterized to study the influence of the heat treatment temperatures on the RF/SiO 2 aerogel. With the increase of the heat treatment temperature, its electromagnetic wave absorption performance had been significantly improved. When the heat treatment temperature reached 1500 ℃, the RF/SiO 2 aerogel possessed a minimum reflection loss of − 36.42 dB at 1.95 mm and an effective bandwidth of 2.94 GHz at 2.00 mm within the radar band of 8.00–12.00 GHz. In addition, this paper used CST software to optimize and design the periodic structure of metamaterial based on the RF/SiO 2 aerogel. The optimization design of the patch size and substrate thickness on the substrate surface provided a reference for the future application of this material in specific radar stealth fields.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2023
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IF 5.2
Hongding Zhang,Sifei Wu,Yihan Li,Beibei Tao,Ningning Wu,Hai-Bo Wang,Linxia Fang
Fluorescent probes usually face the issue of photobleaching and premature leakage when they are directly exposed to exterior environment, causing poor photostability and low sensitivity. In this paper, Ru(bpy) 3 2+ encapsulated fluorescent SiO 2 nanoparticles (Ru@SiO 2 NPs) were synthesized and used as fluorescent probe. The SiO 2 nanoparticles were used as carriers to prevent the leakage of the probe. Triangular Ag nanoparticles (T-Ag NPs) were prepared as quenchers to construct a quenching system (Ru@SiO 2 -T-Ag NPs) with Ru@SiO 2 NPs through inner filter effect (IFE). In this quenching system, T-Ag NPs were also designed as recognize units for glutathione (GSH) detection. When GSH existed, the GSH bond with T-Ag NPs to form Ag-S bonds, making the T-Ag NPs etched. In this case, the fluorescent signal of Ru@SiO 2 NPs quenched by T-Ag NPs restored. The fluorescence recovery of the Ru@SiO 2 NPs depended on GSH concentrations and thus it could realize the quantitative analysis of GSH. Under optimized conditions, the proposed assay had good analytical performance for the detection of GSH in the concentration range of 0.01–1 µM with a limit of detection (LOD) as low as 2.8 nM. This assay was also used to measure GSH levels in human serum samples. This work provides a new way for the fluorescent analysis of thiol biomolecules.
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