CHINESE JOURNAL OF CATALYSIS
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2021
·
IF 8.271
Fang Li,Xiaoyang Yue,Haiping Zhou,Jiajie Fan,Quanjun Xiang
The active site amount of photocatalysts, being the key factors in photocatalytic reactions, directly affects the photocatalytic performance of the photocatalyst. Pristine graphitic carbon nitride (g-C 3 N 4 ) exhibits moderate photocatalytic activity due to insufficient active sites. In this study, cyano-modified porous g-C 3 N 4 nanosheets (MCN-0.5) were synthesized through molecular self-assembly and alkali-assisted strategies. The cyano group acted as the active site of the photocatalytic reaction, because the good electron-withdrawing property of the cyano group promoted carrier separation. Benefiting from the effect of the active sites, MCN-0.5 exhibited significantly enhanced photocatalytic activity for CO 2 reduction under visible light irradiation. Notably, the photocatalytic activity of MCN-0.5 was significantly reduced when the cyano groups were removed by hydrochloric acid (HCl) treatment, further verifying the role of cyano groups as active sites. The photoreduction of Pt nanoparticles provided an intuitive indication that the introduction of cyano groups provided more active sites for the photocatalytic reaction. Furthermore, the controlled experiments showed that g-C 3 N 4 grafted with cyano groups using melamine as the precursor exhibited enhanced photocatalytic activity, which proved the versatility of the strategy for enhancing the activity of g-C 3 N 4 via cyano group modification. In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations were used to investigate the mechanism of enhanced photocatalytic activity for CO 2 reduction by cyano-modified g-C 3 N 4 . This work provides a promising route for promoting efficient solar energy conversion by designing active sites in photocatalysts.
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Nature Catalysis
·
2021
·Vol. 4
·期 3
·202-211
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IF 41.813
Liu Hongfei,Xia Jun,Zhang Nan,Cheng Han,Bi Wentuan,Zu Xiaolong,Chu Wangsheng,Wu HengAn,Wu Changzheng,Xie Yi
Conventional strategies for modifying electrocatalysts for efficient CO 2 reduction are mainly based on doping, defect/morphology engineering, substrate design and so on. In most cases, these methods can only tune their structures, electronic states and thereby catalytic properties in a gradual way. Here we report that the solid–liquid phase transition of Ga–Sn/Ga–In alloys can induce an instant and radical transformation of their atomic and electronic structures during electrocatalysis, which dramatically impacts their catalytic properties. The transition of Sn/In active components from phase-segregated clusters to dispersed single atoms during melting results in a unique electronic structure through further reduction of both metallic Sn/In and Ga. Such atomic/electronic structure transitions can correlate well with suppression of the hydrogen evolution reaction and an enhanced formate Faradaic efficiency from <35% to >95%. This two-state switching strategy may be extended to other catalytic reactions to determine correlations between their structures and catalytic properties.
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Materials Science & Engineering C-Materials for Biological Applications
·
2021
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IF 7.328
Xiangping Wen,Guangming Wen,Wenyan Li,Zhonghua Zhao,Xine Duan,Wenjun Yan,John F. Trant,Yingqi Li
Fluorescent carbon dots (CDs) were hydrothermally synthesized from a mixture of frozen tofu, ethylenediamine and phosphoric acid in an efficient 64% yield. The resulting CDs exhibit good water solubility, low cytotoxicity, high stability, and excellent biocompatibility. The CDs selectively and sensitively detect Co 2+ through fluorescent quenching with a detection limit of 58 nM. Fluorescence can be restored through the introduction of EDTA, and this phenomenon can be used to quantify EDTA in solution with a detection limit of 98 nM. As both analytes are detected by the same CD platform, this is an “off-on” fluorescence sensor for Co 2+ and EDTA. The technique's robustness for real-world samples was illustrated by quantifying cobalt in tap water and EDTA in contact lens solution. The CDs were also evaluated for in vivo imaging as they show low cytotoxicity and excellent cellular uptake. In a zebrafish model, the CDs are rapidly adsorbed from the intestine into the liver, and are essentially cleared from the body in 24 h with no appreciable bioaccumulation. Their simple and efficient synthesis, combined with excellent physical and chemical performance, renders these CDs attractive candidates for theranostic applications in targeted “smart” drug delivery and bioimaging.
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Nanomaterials
·
2021
·Vol. 11
·期 3
·694
·
IF 5.076
Ruoxin Yuan,Hao Wen,Li Zeng,Xi Li,Xingang Liu,Chuhong Zhang
Supercritical CO2(scCO2) is often used to prepare graphene/metal oxide nanocomposite anodes for high performance lithium-ion batteries (LIBs) by the assisted solvothermal method due to its low viscosity, high diffusion, zero surface tension and good surface wettability. However, the formation mechanism of metal oxides and the combination mechanism between metal oxides and graphene in this system are superficial. In this work, a cobalt monoxide/graphene (CoO/G) nanocomposite is fabricated via the scCO2assisted solvothermal method followed by thermal treatment. We elucidate the mechanism that amorphous intermediates obtain by the scCO2assisted solvothermal method, and then ultrafine CoO nanoparticles are crystallized during the heat treatment. In addition, scCO2can promote CoO to be tightly fixed on the surface of graphene nanosheets by interfacial chemical bonds, which can effectively improve its cycle stability and rate performance. As expected, the CoO/G composites exhibit higher specific capacity (961 mAh g−1at 100 mA g−1), excellent cyclic stability and rate capability (617 mAh g−1after 500 cycles at 1000 mA g−1) when applied as an anode of LIB.Keywords:lithium-ion battery;anode;supercritical carbon dioxide;cobalt monoxide;graphene
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RSC Advances
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2021
·Vol. 11
·期 46
·28535-28541
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IF 3.361
Peng Wang,Mingzhi Wang,Jianqiao Lu
Direct conversion of CO2 to high value-added carbon products based on molten salt electrochemistry has been proven to be a feasible approach to solve the climate problem and achieve carbon neutrality. In this work, carbon nanotubes (CNTs), carbon spheres (CSs) and honeycomb carbon are synthesized by electrolysis of a single or multiple alkali metal carbonate electrolyte. The elemental composition, morphology and structure, crystallinity and graphitization degree of carbon products are characterized by electron dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman microspectroscopy (RAM). The results demonstrate that a high yield of CNTs is obtained in Li2CO3 electrolyte by regulating the electrolysis temperature and current density. Compared to pure Li2CO3, Li–Na carbonate electrolyte with 1 wt% stannic oxide/cerium oxide (SnO2/GeO2) favors CS formation rather than CNT formation. Additionally, honeycomb carbon products are generated in Li–Na–K electrolyte, when the electrolysis temperature is lower than 600 °C. Overall, this work provides a novel carbon neutral strategy where high value-added carbon products are synthesized using CO2 as a carbon source.
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RSC Advances
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2021
·Vol. 11
·期 28
·17197-17205
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IF 3.361
Bin Liu,Yanling Wang,Lei Liang,Yijin Zeng
Supercritical carbon dioxide (SC-CO2) fracturing technology has the characteristics of a large amount of fixed CO2 and anhydrous fracturing. It has great application potential for developing unconventional oil and gas resources and mitigating the greenhouse effect. However, the low viscosity of SC-CO2 limits the development of this technology. In this work, HS series thickeners were prepared via a ring-opening polymerization and hydrosilylation reaction by a molecular simulation-aided design method. The simulation results of cohesive energy density, interaction energy, and radial distribution function are consistent with the visualization experimental results, which proves that HS (hyperbranched siloxane) series thickeners have excellent solubility in SC-CO2. HS-3 is the best thickener in the HS series. At 305.15 K and 10 MPa, 5 wt% HS-3 (60 s−1) increases the viscosity of SC-CO2 by 151 times, and the apparent viscosity is 3.024 mPa s. The apparent viscosity of SC-CO2 was positively correlated with the pressure and concentration but negatively correlated with the temperature and shear rate. The results indicate that it is feasible to introduce an aliphatic group and polysiloxane into a SC-CO2 thickener by hydrosilylation.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2021
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IF 5.316
Lei Xue,Aiai Zhang,Jinfang Wu,Qi Wang,Yang Liu,Yuansong Zhao,Shangpeng Liu,Ze Liu,Ping Li,Shanghong Zeng
Surface chemistry can be modified by introducing another component on the surface of catalyst due to the regulation of configuration and electronic properties. Herein, the nanostructured ZnO hollow microspheres were fabricated for selective CO 2 reduction to CO. The addition of CuO weakens the strength of adjacent Zn-O bond and improves the formation of more zero-valence Zn. Small CuO entities can provide the active sites for CO 2 adsorption, and the presence of surface defects due to Zn 2+ reduction could enhance initial dissociation from CO 2 to CO. More interestingly, the 3CuO/ZnO catalyst underwent reconstruction during electrocatalysis , and multi-shelled hollow spheres evolved into a thin flaky structure. The extended surface area of flaky morphology enhances the catalytic stability despite the occurrence of ZnO reduction. This study highlights the importance of surface modification for CO 2 selective reduction to CO but also provides some insights on reconstruction during electrochemical reduction of CO 2 .
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NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 10
·4611-4616
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IF 3.591
Zheng Wang,Da Li,Shangqing Chen,Jiayin Hu,Yanxi Gong,Yafei Guo,Tianlong Deng
The green basic IL [DBUH][BO2] was easily synthesized for the first time and used to catalyze the cycloaddition of CO2 and epoxides under solvent- and halogen-free conditions at atmospheric pressure and room temperature with high target product yields. Moreover, this IL could be easily recovered and reused at least five times without activity loss. The basic anion and the cation with N–H had excellent synergistic catalytic effects on promoting these reactions. Particularly, this basic IL, the anion of which had a strong nucleophilic ability, was also very effective for the reactions of CO2 and 2-aminobenzonitriles into quinazoline-2,4(1H,3H)-diones, giving the desired products in high yields at atmospheric pressure and room temperature.
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MACROMOLECULAR MATERIALS AND ENGINEERING
·
2020
·Vol. 306
·期 3
·2000643
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IF 3.853
Yaoyu Pan,Qiongfang Song,Yalin Zhu,Yun Wang,Zhengguang Sun,Xueqin Chen,Ziqiang Xu,Cao Li,Bingbing Jiang
Large-scale and simple strategies to flexibly preparing materials with industrial application potential attract people's attention. Layer-by-layer (LBL) self-assembly technology is a typical preparation method for current nanomaterials to address the large-scale concern and achieve the possibility of a simple, streamlined and controllable process. Here, a novel and simple strategy is developed to fabricate microporous polymeric film (MPF) based on poly(styrene-hydroxyethyl methylacrylate) (P(St-HEMA)) microspheres, in combination with LBL self-assembly technology and hypercrosslinked microporous post-treatment. To improve the mechanical properties of the film, the buffer layer of polyethyleneimine (PEI) and poly(sodium- p -styrenesulfonate) (PSS) are used to avoid swelling of nanoparticles and the methacryloxyethyltrimethyl ammonium chloride (DMC) is chosen to increase the force between the nanoparticles via UV-crosslinking. The MPF has well CO 2 capture capabilities up to 46.21 wt% (10.52 mmol g −1 ), large-scale feature and certain improved mechanical properties. It is hoped that the research could display a successful strategy to prepare the large-scale film for the application of industrialization.
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Journal of CO2 Utilization
·
2020
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IF 5.993
Haihong Zhao,Ning Zhao,Qin Wang,Feng Li,Feng Wang,Subing Fan,Ekaterina V. Matus,Zinfer R. Ismagilov,Lei Li,Fukui Xiao
In this work, a series of HK/MCFs-x sorbents consisting of metal organic framework (HKUST-1) and mesocellular foams (MCFs) were prepared using solvothermal method. The samples were characterized by various techniques including XRD, N 2 adsorption/desorption, TG, SEM, FT-IR, and water vapor adsorption, respectively. The CO 2 adsorption isotherms and adsorption kinetic curves at different temperatures were obtained. Results showed that the Langmuir-Freundlich model and pseudo-first-order equation could be used to describe the CO 2 adsorption isotherms and kinetic curves, thus proving the exothermic, multilayer, physical adsorption processes. The isosteric heats of adsorption of the pure HKUST-1 and HK/MCFs-1 were in the range of 19–26 KJ/mol. The mass-transfer coefficient increased along with the temperature. The adsorption activation energies of the pure HKUST-1 and HK/MCFs-1 were 4.150 and 4.203 KJ/mol, respectively. Compared with the pure HKUST-1, HK/MCFs-1 had a substantially equivalent amount of CO 2 adsorption capacity under the same conditions, while the water resistance was improved. The CO 2 mass-transfer rate was higher than the pure HKUST-1. Meanwhile, HK/MCFs-1 also showed better recyclability.
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FUEL PROCESSING TECHNOLOGY
·
2020
·
IF 4.982
Muhammad Masood Khan,Lijun Jin,Muhammad Mahmood Khan,Yang Li,Hammad Saulat,Yun Zhang,Muhammad Sarfraz,Jialong Zhu,Haoquan Hu
The composite catalysts AC-Ni/MgO-Al 2 O 3 were prepared by the co-precipitation method with activated carbon (AC) and [Ni,Mg,Al]-hydrotalcite as the precursors, and characterized by XRD , TG-DTG, N 2 adsorption, H 2 -TPR and SEM, respectively. The resultant catalysts were examined for CO 2 reforming of methane. The results showed that the introduction of AC into Ni/MgO-Al 2 O 3 catalyst improved the textural properties, especially the surface area and pore volume of mesopores , and decreased the size of metal Ni. Compared with Ni/MgO-Al 2 O 3 , the composite AC-Ni/MgO-Al 2 O 3 exhibited higher catalytic activity , stability and H 2 /CO ratio. But the AC content obviously influenced the catalytic performances. High AC loading resulted in the decline of catalytic activity owing to lower surface area and fewer active Ni content in the catalyst. 10AC-Ni/MgO-Al 2 O 3 with 10% AC displayed the best catalytic activity and stability compared with Ni/MgO-Al 2 O 3 . About 86.2% conversion of CH 4 , 91.3% conversion of CO 2 and above 0.95 ratio of H 2 /CO were achieved over 10AC-Ni/MgO-Al 2 O 3 sample for the reaction time of 5430 min. This work provides a route to improve catalytic performances of Ni-based catalysts in CO 2 reforming of methane.
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ACS Applied Materials & Interfaces
·
2021
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IF 9.229
Dechao Wang,Yangyang Xin,Xiaoqian Li,Hailong Ning,Yudeng Wang,Dongdong Yao,Yaping Zheng,Zhuoyue Meng,Zhiyuan Yang,Yuting Pan,Peipei Li,Hongni Wang,Zhongjie He,Wendi Fan
Porous liquids (PLs), an emerging kind of liquid materials with permanent porosity, have attracted increasing attention in gas capture. However, directly turning metal–organic frameworks (MOFs) into PLs via a covalent linkage surface engineering strategy has not been reported. Additionally, challenges including reducing the cost and simplifying the preparation process are daunting. Herein, we proposed a general method to transform Universitetet i Oslo (UiO)-66-OH MOFs into PLs by surface engineering with organosilane (OS) and oligomer species via covalent bonding linkage. The oligomer species endow UiO-66-OH with superior fluidity at room temperature. Meanwhile, the resulting PLs showed great potential in both CO2 adsorption and CO2/N2 selective separation. The residual porosity of PLs was verified by diverse characterizations and molecular simulations. Besides, CO2 selective capture sites were determined by grand canonical Monte Carlo (GCMC) simulation. Furthermore, the universality of the covalent linkage surface engineering strategy was confirmed using different classes of oligomer species and another MOF (ZIF-8-bearing amino groups). Notably, this strategy can be extended to construct other PLs by taking advantages of the rich library of oligomer species, thus making PLs promising candidates for further applications in energy and environment-related fields, such as gas capture, separation, and catalysis.
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