APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Junnan Wei,Ting Wang,Xuejuan Cao,Huai Liu,Xing Tang,Yong Sun,Xianhai Zeng,Tingzhou Lei,Shijie Liu,Lu Lin
Biomass-derived furanyl ethers, such as 5-alkoxymethylfurfurals (AMFs) and 2,5-bis(alkoxymethyl)furans (BAMFs), can be employed as promising biofuels or additives. The development of multifunctional catalysts for the efficient production of furanyl ethers from sugars through 5-hydroxymethylfurfural (HMF) as an intermediate is highly desirable but challenging, because multiple reactions including dehydration, etherification and hydrogenation get involved and the side reaction of sugars and HMF to form humins is inevitable. In this contribution, we found that the introduction of CuO resulted in the generation of Lewis acid sites at the cost of Bronsted acid sites over CuO-USY catalysts through the formation of Al-O-Cu(II) species. The dispersity of CuO particles and the amount of Lewis acid sites could be manipulated by adjusting the loading of CuO. If 5 wt% CuO was supported on USY zeolite to give a CuO(5)-USY catalyst, CuO particles with a high dispersity (36.4%) afforded abundant Lewis acid sites (457.1 μ mol/g). Lewis acid over CuO(5)-USY greatly promoted the acid-catalyzed dehydration of fructose to HMF and HMF etherification to AMFs, resulting in a HMF yield up to 86.2% from fructose and AMFs yields greater than 90% from HMF. Interestingly, a combination of CuO(5)-USY and a small amount of metallic Cu powder was able to offer desirable BAMFs yields by the reductive etherification of HMF under hydrogen atmosphere. As a result, 5-methoxymethylfurfural (MMF) of 79.6% and 2,5-bis(methoxymethyl)furan (BMMF) yield of 74.5% were achieved from fructose through HMF as an intermediate in the presence of CuO(5)-USY alone or with metallic Cu as a co-catalyst. Therefore, the above Cu-based catalyst system holds the promise to flexibly produce a family of AMFs or BAMFs from fructose via a facile two-step approach.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2019
·
IF 3.218
Di Chen,Rong-Hua Zhang,QingYun Hu,Yi-Fei Guo,Shao-Na Chen,Xin-Wen Zhou,Zhong-Xu Dai
The high electrocatalytic activity of Cu@PdCo icosahedrons were synthesized via a facile, one-pot seed co-reduction method. Subsequent X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis reveal that as-synthesized Cu@Pd-1, Cu@Pd-2 and Cu@PdCo-1 catalysts have core-shell structure and the average particle size reached 18.84 nm, 16.34 nm and 16.88 nm, respectively. By compared with Cu@Pd-1, Cu@Pd-2 and commercial Pd black, icosahedron morphology, special core-shell structure, surface etching exposed Pd active sites can be used to explain the superior ethanol oxidation performance of as-synthesized Cu@PdCo-1 nanocatalysts. This method is expected to lead the preparation of more multielement icosahedral core-shell catalysts for more catalytic applications.
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DALTON TRANSACTIONS
·
2019
·Vol. 48
·期 26
·9631-9638
·
IF 4.052
Weiwei Zhao,Weikang Wang,Jiali Peng,Tiantian Chen,Beibei Jin,Shujuan Liu,Wei Huang,Qiang Zhao
Two-dimensional (2D) metal porphyrin frameworks (MPFs) with a π-conjugated skeleton, high surface area, and more accessible active sites have been applied as active materials for supercapacitors, but the poor electrical conductivity limits the enhancement of electrochemical performance. Moreover, MPF-based flexible supercapacitors have been rarely reported. Here, for the first time, we fabricated wrinkled 2D ultrathin 5,10,15,20-tetrakis(4-carboxylphenyl)porphyrin copper(II) (Cu-TCPP) nanosheets through the surfactant-assisted synthetic method. The as-obtained wrinkled Cu-TCPP nanosheets were further composited with conductive polypyrrole (PPy) to construct a flexible Cu-TCPP/PPy film through the combination of the electrophoretic deposition method and electrochemical polymerization technology. The wrinkled 2D ultrathin Cu-TCPP nanosheets not only offer macroporous channels for fast ion/electron transport, but also effectively reduce the transmission path of electrolyte ions. The PPy affords 3D conductive networks for rapid electron transport and enhances the electrochemical kinetics. The synergistic effect of Cu-TCPP and PPy leads to the enhanced supercapacitive performance of Cu-TCPP/PPy in comparison with the individual components. As a result, the freestanding Cu-TCPP/PPy electrode shows a capacitance of 340.6 mF cm−2 at 1 mA cm−2, 71.14 F cm−3 at 0.1 A cm−3, and 163.34 F g−1 at 0.2 A g−1, more than 45% greater than that of the pristine PPy film of 224.6 mF cm−2, 48.15 F cm−3 and 92.2 F g−1 at the corresponding current densities. Moreover, the fabricated binder-free symmetric supercapacitor possesses a maximum energy density of 2.27 μW h cm−2 at the highest power density of 50 μW cm−2. This work provides a new strategy to design 2D metal–organic framework-based flexible all-solid-state supercapacitors with high energy storage performances.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Han Jiang,Bin Guan,Xuesong Peng,Reggie Zhan,He Lin,Zhen Huang
This study focuses on investigating the influence of ion-exchange method (ION-F and ION-A) and one-pot method (ONE-F and ONE-A) on catalytic properties and hydrothermal stability of Cu/SSZ-13. It was found that ONE-F catalyst showed better SCR activity, especially at low temperature range below 400 °C. After hydrothermal aging, ION-A exhibited higher low temperature efficiency than ONE-A. The effect of synthesis method on the physicochemical structure, acidity intensity, and Cu species migration or transformation of the fresh and aged Cu/SSZ-13 catalysts were comprehensively characterized by NH 3 -TPO, H 2 -TPR, NH 3 -TPD, ICP, XRF, BET, XRD, SEM, and TEM. ONE-F has more isolated Cu 2+ sites, higher ratio of active sites Cu 2+ -2Z/[Cu(OH)] + -Z, more Lewis acid sites, and smaller particle size than ION-F. However, hydrothermal aging had severe effect on Cu/SSZ-13 prepared by one-pot method, leading to particle aggregation and decrease of active copper sites. According to NH 3 -SCR kinetic studies, smaller particle size and more uniformly distributed active sites over ONE-F resulted in less effect of pore diffusion limitation. Furthermore, in situ DRIFTS results indicated that more monodentate nitrates adsorbed sites and Lewis acid sites existed in ONE-F. On the other hand, monodentate nitrates were identified to be the most active nitrate species, and Lewis acid sites were ascertained to be more active than Brønsted acid sites. Therefore, ONE-F showed more excellent SCR performance than ION-F. However, hydrothermal aging resulted in loss of majority of nitrate adsorbed sites and acid sites over catalyst prepared by one-pot method, leading to lower SCR performance. In conclusion, Cu/SSZ-13 prepared by ion-exchange method has higher hydrothermal stability, however, fresh Cu/SSZ-13 prepared by one-pot method has excellent catalytic properties.
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ELECTROANALYSIS
·
2019
·Vol. 31
·期 6
·1002-1008
·
IF 2.691
Baolong Ma,Hao Guo,Mingyue Wang,Li Li,Xueyan Jia,Huiqin Chen,Rui Xue,Wu Yang
A nanocomposite of HKUST-1 (MOF) and electroreduction graphene oxide (ERGO) is prepared and applied as an electrochemical sensor for the simultaneous determination of paracetamol and dopamine by means of one-step electrodeposition. The MOF/ERGO composite displays excellent electrochemical catalytic activities towards the paracetamol and dopamine, which is attributed to the synergistic effect of big surface area, porosity and high electrocataytic activity of the MOF and good conductivity of ERGO. The modified electrode could be applied to determine simultaneously paracetamol and dopamine in biochemical samples with wide linear ranges (0.2 μM to 160 μM for paracetamol and 0.2 μM to 300 μM for dopamine) and low detection limits (0.016 μM for paracetamol and 0.013 μM for dopamine). Meanwhile, the proposed sensor still displays high sensitivity, good selectivity and excellent stability.
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JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
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2018
·Vol. 18
·期 12
·8269-8275
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IF 1.354
Wang Manchao,Peng Lin,Wang Jiahui,Li Changqing,Guan Lihao,Lin Yuqing
In this study, hierarchical ternary nanocomposites, i.e., Cu–TiO2-mesoporous silica microspheres (Cu–TiO2-MSM), were synthesized as ternary photocatalyst system to improve the visible light photocatalytic degradation of the environmental pollutant model
dye methylene blue (MB). The innovation of this method is in situ depositing TiO2 and Cu2O nanoparticles sequentially onto the surface of mesoporous silica microspheres to form highly active heterostructure. The improved activity for the degradation of MB is attributed
to: (1) the high adsorption capacity of the porous and interconnected-channel-structure MSM to MB; (2) the valence band electrons of TiO2 released from the conduction band generating abundant highly active free radicals, which directly reacted with adsorbed MB. The photocatalytic
degradation efficiency to MB was found to be 98% in 5 min, and almost 100% in 20 min. This study paves a way for the development of a ternary-doped catalyst for visible light photocatalytic degradation and may exhibit widely application in industry.
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PubMed
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NANO
·
2019
·
IF 1.293
Qian Sun,Chun Zeng,Meng-Meng Xing,Bo Chen,Dan Zhao,San-Guo Hong,Ning Zhang
Deliberately engineering oxide composites on constructing and manipulating interactive structures particularly in surface layers was highly desirable for heterogeneous catalysis. Herein, upon the redox replacement reaction between Ce(IV) precursor (Ce(NO 3 ) 6 2 − ) and Cu 2 O nano-substrate, an attempt to directly engineer the surface structure of Cu-based substrate was performed by the Ce(IV)–Cu 2 O etching-embedding process, then the obtained powders were thermo-treated to get a series of Ce–O–Cu catalysts with different Ce:Cu molar ratios for NH 3 selective catalytic reduction (NH 3 -SCR) of NO. Characterized by ICP-OES, XRD, Raman, XPS, SEM, BET, H 2 -TPR, NO- and NH 3 -TPD measurements, it was demonstrated that the Cu–O–Ce catalysts were structured as CuO matrix with an interactive surface composed by co-present Cu(I)–Cu(II) and Ce(III)–Ce(IV) species, even the introduction of Ce was confined in a quite low loading range (0.83–2.3 wt.%); such a surface exhibited the distinct synergistic effect with positively manipulated physical-chemistry properties such as active site distributions, redox features and surface reactivity compared to pure CuO and traditional Cu–Ce composite catalyst, leading to attractive catalytic performance such as ≥ 9 0 % NO conversion with ≥ 9 5 % N 2 selectivity and the two-fold TOF enhancement versus traditional catalysts, even SO 2 was present in reactant mixture on well-manipulated catalyst (Ce loading at 1.6 wt.%) These results indicated that the etching-embedding strategy illuminated in this work could be referred as a feasible method to directly engineer and construct interactive oxide composite surface for advanced application as well as current efficient Ce–O–Cu catalytic interface for heterogeneous catalysis.
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NANO
·
2019
·
IF 1.293
Yunong Zhou,Chao Hu,Weidong Zhang,Hong Chen,Gang Yu
The ability to control the shape, structure and faceting characteristics of bimetallic alloy nanocrystals (NCs) has been vital for designing a catalyst with excellent activity and durability in fuel cells. However, it has remained a significant challenge to synthesize platinum–copper (Pt–Cu) alloy NCs with controlled structure and exposed facets. Herein, Pt–Cu alloy NCs with different shapes, structures and facets were synthesized via a one-step direct chemical co-reduction method employing various glucose concentrations. The results showed that the prepared Pt–Cu alloy NCs exhibited very interesting facet-dependent electrocatalytic properties for ethylene glycol oxidation. In comparison with other prepared Pt–Cu alloy NCs and commercial Pt/C, Pt–Cu alloy NPs with (111)-dominant facets showed higher electrocatalytic activity and durability for ethylene glycol oxidation. Alloy NPs showing prominent electrocatalytic performance were attributed to the predominant (111) facets on NP surfaces serving as catalytic active sites, in addition to added Cu providing unique electronic and synergistic effects. The present work highlighted that these NPs with (111)-dominant facets were indeed promising candidates as electrocatalysts with excellent activity and superior durability.
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ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Yue Song,Tianran Sun,Long Cang,Song Wu,Dongmei Zhou
Further research into more cost-effective methods to treat toxic metal-ethylenediaminetetraacetate (Me-EDTA) complexes is required due to their high bioavailability. In this study, we compared electrodialysis (ED) with different compartment designs (2-, 3- and 4-compartment designs) and electrochemical oxidation (EO, 1-compartment design) to treat a dilute Cu(II)-EDTA solution (1 mM). After a 48-h treatment with a constant current applied at 32 mA, the Cu removal efficiencies were achieved at 49%, 87%, 79% and 96% for 1-compartment EO and 2- to 4-compartment ED, respectively, and the total organic carbon concentrations decreased from 138 mg/L to 100, 64, 57 and 39 mg/L, respectively. The energy consumptions for 1-compartment EO and 2- to 4-compartment ED were 7.7, 8.4, 13.9 and 15.4 W h, respectively. Based on all above results, the most cost-effective design was determined to be the 2-compartment ED. Moreover, the 3- and 4-compartment ED treatments have faster contaminant removal kinetics than 1-compartment EO and 2-compartment ED. This study clarified the mechanisms of the migration and the transformation of Cu-EDTA during EO and ED with different membrane combinations, which is helpful for improved selection of compartment design for metal-chelate complex removal.
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ACS Omega
·
2019
·
IF 2.584
Caidan Zhang,Haidong Li,Qiaozhen Yu,Lin Jia,Lynn Yuqin Wan
Electrospun nanofiber membrane (ENM) with huge specific surface area is an ideal solid substrate for sensors. However, only a few ENMs are developed into colorimetric sensors and it is even more challenging to fabricate multiple-ion-responsive ENM-based colorimetric sensor. In this study, benefiting from the excellent metal ion adsorption ability of poly(aspartic acid) (PASP) and high specific surface area of nanofibers, a reusable colorimetric sensor utilizing PASP electrospun nanofiber hydrogel membrane (ENHM) was designed to detect Cu2+ and Fe3+ in aqueous solution with simple filtration. The sensor based on PASP–ENHM exhibited high sensitivity and selectivity, and colorimetric responses for Cu2+ and Fe3+ detection could be observed by the naked eye. Upon exposure to Cu2+ aqueous solution, the color of the sensor changed from white to blue with a naked eye detection limit of 0.3 mg/L, while it turned from white to yellow with a detection limit of 0.1 mg/L for Fe3+ detection. Furthermore, this sensor was reusable after metal ion extraction by the desorption process.
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PubMed
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
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2019
·
IF 4.081
Siyuan Guo,Xiang Zhang,Chunsheng Shi,Enzuo Liu,Chunnian He,Fang He,Naiqin Zhao
Poor mechanical interfacial bonding between graphene nanoplatelets (GNPs) and Cu is unfavorable to the comprehensive properties of the GNPs/Cu composites. Molybdenum carbide coating graphene nanoplatelets (Mo 2 C@GNPs) were prepared by impregnation reduction combined with in situ reaction to improve the interfacial bonding of Cu matrix composites . Compared with GNPs/Cu composites, Mo 2 C@GNPs/Cu composites exhibit excellent mechanical properties . It is due to the fact that Mo 2 C not only improves the interface bonding between the GNPs and Cu matrix, but also increases the strength of composites by dislocation strengthening as nanoparticle reinforcing phase. In addition, the conductivity of Mo 2 C@GNPs/Cu composites is higher than that of GNPs/Cu composites due to the improved interfacial bonding. This work sheds light on adding carbides to control the properties of GNPs/Cu composites.
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高影响因子
Reaction Kinetics Mechanisms and Catalysis
·
2019
·Vol. 128
·期 2
·1065-1077
·
IF 1.428
Yu Qifan,Liu Xuesong,Chen Hongfeng,Liu Shuang,Jiang Peng
The regeneration mechanism of sulfated Cu/SAPO-34 catalysts in reducing atmospheres (5% H 2 /Ar and NH 3 /Ar at 600 °C) was investigated by using a series of characterization methods. Hydrogen regeneration improved the catalysts’ NH 3 -SCR activity from 150 to 550 °C remarkably, while ammonia regeneration exhibited relatively less obvious promotion effect. The TPR of hydrogen and EPR spectra data show that the regeneration process affects the amount and the coordination of the active isolated Cu 2+ species significantly. The desulfation increases the amount of isolated copper ions and improves the catalytic activity of SCR.
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