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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高影响因子
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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CHEMOSPHERE
·
2019
·
IF 5.108
Xinze Bian,Yi Xia,Tingting Zhan,Lin Wang,Wan Zhou,Qizhou Dai,Jianmeng Chen
This work investigated the electrochemical degradation of amoxicillin (AMX) in aqueous solution with Cu-PbO 2 electrode. The main influence factors on the degradation of AMX, such as Na 2 SO 4 concentration, initial AMX concentration, current density and initial pH value, were analyzed in detail. Under the optimal conditions, the removal rates of AMX and chemical oxygen demand (COD) reached 99.4% and 46.3% after 150 min treatment. The results indicated that the electrochemical degradation of AMX fitted pseudo-first-order reaction kinetics. Compared with undoped PbO 2 electrode, Cu-PbO 2 electrode had a smaller crystal size, more proportion of hydroxyl oxygen species, greater AMX and chemical oxygen demand (COD) removal efficiency, higher average current efficiency (ACE) and lower electrical efficiency per log order (EE/O). Electrochemical oxidation using Cu-PbO 2 electrodes was an effective way to eliminate amoxicillin in aqueous solution. Moreover, a possible degradation pathway including ring open and mineralization was proposed by intermediate products determined by GC-MS method. This paper could provide basic data and technique reference for the amoxicillin wastewater pollution control .
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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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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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REACTIVE & FUNCTIONAL POLYMERS
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2019
·
IF 3.074
Xiaoyi Zhang,Xubao Jiang,Xiaoli Zhu,Xiang Zheng Kong
The pollution by metal ions has been a key issue in environmental protection. Amine-rich porous polyurea (PPU), prepared by a simple one-step precipitation copolymerization of diisocyanate and diamine, is highly selective for Cu 2+ adsorption, but associated with a poor reusability. We report here a chemically modified PPU by simply turning the amine groups of PPU to aminoacetic carboxyls. The results indicate that this carboxylation is an easy and effective pathway to polymer adsorbent, with high performance for Cu 2+ adsorption and reusability superior to most of the reported adsorbents. Cu 2+ adsorption capacity on PPU-M, i.e. PPU after carboxylation, increased to 2.84 mmol/g, an increase by 22% in comparison with PPU. The chemical modification process was optimized. The porosity and morphology of PPU-M were characterized using N 2 adsorption, mercury intrusion, and scanning electron microscopy. The high Cu 2+ adsorption was interpreted through a complex coordination mechanism of Cu 2+ based on XPS analysis . The high performance of reusability of PPU-M, thanks to enhanced desorption of 99.5% or more of the adsorbed Cu 2+ after each recycled use, was also interpreted based on the stability constants of acid-base equilibrium of amine and carboxyl towards Cu 2+ and protons. Adsorption kinetics modelling demonstrated this adsorption followed the pseudo-second-order model. The adsorption analysis by isothermal adsorption showed this adsorption was well fitted by Freundlich equation and in good agreement with the suggested adsorption mechanism.
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MATERIALS & DESIGN
·
2019
·
IF 5.77
Tianhao Ge,Wenjie Zhao,Xuedong Wu,Yangmin Wu,Lu Shen,Xiaojing Ci,Yanlin He
To make good use of the barrier effect of graphene nanosheets and to reduce the uneven dispersion of zinc particles caused by its sedimentation, coating with alternate structure containing rGO was developed to provide Cu a long-term corrosion protection. Ionic liquid was used to obtain a better dispersion of rGO in solvent, which was proved by TEM, SPM images and sedimentation experiment. The enhanced long-term anti-corrosion protection of alternate coating was revealed by electrochemical tests. OCP and EIS results showed enhanced barrier performance of epoxy-G compared with epoxy and improved sacrificial anode protection of epoxy-Zn-G compared with epoxy-Zn. Tidal range-corrosion simulation test was also performed to show that the alternate coating can stick on copper substrate without peeling off even in harsh corrosive environment for 432 h. Furthermore, EIS, XRD, and XPS spectra together proved that the excellent anti-corrosion property of alternate coating was originated from the combination of sacrificial anode protection provided by zinc-rich-epoxy layer with barrier protection provided by rGO-doping-epoxy layer. This combination makes it reality to protect copper substrate from corrosion for longer time immersion in 3.5 wt% NaCl solution compared with epoxy-Zn-G.
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RSC Advances
·
2019
·Vol. 9
·期 61
·35524-35531
·
IF 3.049
Xinyu Mao,Liqun Zhu,Huicong Liu,Haining Chen,Pengfei Ju,Weiping Li
Directly dispersing graphene into an electrolyte still remains a crucial difficulty in electrodepositing a graphene enhanced composite coating onto electrical contact materials. Herein, graphene was synthesized via electrochemical exfoliation in an N,N-dimethylformamide (DMF)/H2O solution containing (NH4)2SO4. The electrochemically exfoliated graphene nanosheets (GNs) were directly dispersed by sonication. In comparison with graphene synthesized from aqueous solution, the GNs electrochemically exfoliated in the DMF/H2O–(NH4)2SO4 solution exhibit a lower degree of oxidation. Cu/graphene composite coatings were subsequently electrodeposited onto Cu foils by adding Cu2+ into the as-fabricated graphene solution. The surface nanostructure of the Cu/graphene composite coatings was transformed from loose pine needles to a uniform and compact structure with an increase in the concentration of Cu2+, which indicated that the controllable synthesis of Cu/graphene composite coatings with different performances could be achieved in graphene dispersions after adding Cu2+. In order to synthesize graphene via electrochemical exfoliation and directly electrodeposit a Cu/graphene composite coating without adding CuSO4 or any other additive, an attempt was made to directly electrodeposit a Cu/graphene composite coating in CuSO4/DMF/H2O solution after electrochemical exfoliation.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2019
·Vol. 30
·期 21
·19598-19608
·
IF 2.195
Li Pengfei,Zhang Hong,Gao Caiyun,Jiang Guoxiang,Li Zhicheng
N egative temperature coefficient (NTC) ceramics based on simple ZnO were prepared and investigated in present work, where slight amount of Al- and La- ions were added as semiconductor dopants, and Cu-ions were selected as the sintering agent and property modificator. All the prepared ZnO-based ceramics have a wurtzite structure and show typical NTC characteristic. For various contents of Al-, La- and Cu- ions in ZnO-based ceramics, ρ 25 can be adjusted from 0.65 kΩ cm to 3.28 MΩ cm, and B values were obtained in range of 2500 K to 5850 K. The ageing treatment at 125 °C for 600 h in air revealed that the ZnO-based ceramics have high thermal stability with the resistance shift < 2%. The complex impedance spectra were applied to analyze the electrical performance.
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JOURNAL OF POWER SOURCES
·
2018
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IF 6.945
Xiaogeng Feng,Xiangjie Bo,Liping Guo
Rational synthesis and development of earth-abundant materials with efficient electrocatalytic activity and stability for water splitting is a critical but challenging step for sustainable energy application . Herein, a family of bimetal (CoFe, CoCu, CoNi) embedded nitrogen-doped carbon frameworks is developed through a facile and simple thermal conversion strategy of metal-doped zeolitic imidazolate frameworks. Thanks to collaborative superiorities of abundant M-N-C species, modulation action of secondary metal, cobalt-based electroactive phases, template effect of MOFs and unique porous structure , bimetal embedded nitrogen-doped carbon frameworks materials manifest good oxygen and hydrogen evolution catalytic activity . Especially, after modulating the species and molar ratio of metal sources, optimal Co 0.75 Fe 0.25 nitrogen-doped carbon framework catalyst just requires a low overpotential of 303 mV to achieve 10 mA cm −2 with a low Tafel slope (39.49 mV dec −1 ) for oxygen evolution reaction , which even surpasses that of commercial RuO 2 . In addition, the optimal catalyst can function as an efficient bifunctional electrocatalyst for overall water splitting with satisfying activity and stability. This development offers an attractive direction for the rational design and fabrication of porous carbon materials for electrochemical energy applications.
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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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