Frontiers in Chemistry
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2020
·
IF 3.693
Zhou Xinfeng,Qi Weihong,Yin Kai,Zhang Ning,Gong Shen,Li Zhou,Li Yejun
Highly efficient and low-cost non-noble metal based electrocatalysts for oxygen evolution reaction (OER) have attracted more and more attention in recent years. However, the current research has been focused on the construction of novel OER electrocatalysts themselves, little attention has been paid to the modification of the substrates. In this work, a different strategy is proposed via laser ablation to fabricate the Cu foams with rich micro/nano-structures as OER substrates. Later, the precipitation conversion method was utilized to grow cobalt hydroxide on the laser fabricated Cu foams. The as-produced Cu/Cu oxides/Co(OH)2 electrocatalysts exhibit high OER activity in 1 M KOH, requiring an overpotential of only 259 mV at a current density of 50 mA cm−2 with excellent mild-term durability. The improved catalytic performance of the prepared samples can be attributed to the increased surface area, rich active sites, and the superhydrophilicity of the laser produced micro/nano-structures.
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ACS Sustainable Chemistry & Engineering
·
2019
·
IF 6.97
Changhui Zhu,Haiyong Wang,Hu Li,Bijuan Cai,Wei Lv,Chiliu Cai,Chenguang Wang,Long Yan,Qiying Liu,Longlong Ma
Alloyed Cu−Ni encapsulated in carbon was prepared by loading Ni and Cu onto biochar (BC) through an initial wetness impregnation method under mild conditions. The bimetallic catalysts were exploited to perform selective hydrodeoxygenation (HDO) of 5-hydroxymethylfurfural (HMF). 2,5-Dimethylfurfural (DMF), a promising liquid fuel/fuel additive, could be obtained from HMF with the highest yield of 93.5% under the optimized conditions. During HMF HDO, two key intermediates, 5-methylfurfural (MFF) and 2,5-dihydroxymethylfuran (DHMF), dominating two distinct conversion pathways were systematically investigated by Arrhenius kinetics analysis. In addition, the turnover frequencies (TOFs) of HDO reaction over Cu−Ni/BC corresponding with Cu amount were thoroughly discussed, finding that the electron transfer from Cu to Ni in the alloy structure was beneficial to the HDO reaction and the conversion pathways can be regulated by reaction temperature variation. Importantly, the synergy of HDO of HMF by alloyed Cu−Ni metal and Lewis acid sites from oxide NiOx were hence clarified by systematic catalyst characterizations. The Cu−Ni/BC catalyst is stable for at least five consecutive runs to obtain the stabilized 81.9% of DMF since the third run.
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CARBOHYDRATE POLYMERS
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2019
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IF 6.044
Yongjian Xu,Yun Shi,Feng Lei,Lei Dai
Cellulose-based materials are widely used in the biomedical field. However, the lack of antibacterial activities of cellulose fibers inevitably causes bacterial infection damages. In this study, Schiff base was first introduced to endow the cellulose fibers good antibacterial property and copper ions were complexed with Schiff base to form a complex. The prepared complex greatly enhanced the antibacterial properties of the cellulose fibers. FT-IR, XRD, UV–vis and SEM-EDS results proved the successful synthesis of Schiff base and its copper (II) complex. The antibacterial tests indicated that the width of the inhibition zone of the as-prepared cellulose-based Schiff base-Cu (II) complex against E. coli and S. aureus increased by 472 % and 823 %, respectively, in comparison to the Schiff base ligand. This significant increase could be attributed to the incorporation of the copper ions (II). This Schiff base-Cu (II) complex containing cellulose-based antibacterial materials are expected to be widely used for biomedical application.
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CHEMOSPHERE
·
2019
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IF 5.108
Yufan Chen,Yong Feng,Huaqiang Chu,Deli Wu,Yalei Zhang
Cu(II) enhanced the oxygen activation by Fe(II) to increase the yield of oxidants. However the factors controlling the catalytic performance and indeed the underlying influencing mechanisms remained unclear. Here, we presented the detailed study of Cu(II)-Fe(II) reactions for a range of pH and Cu(II)/Fe(II) ratios. From the results obtained, we provided insight into the factors controlling the redox reactions of Fe-Cu and the catalytic behaviours of active species. A reaction scheme for the Fe(II)/Cu(II) system was developed in which the in-situ formed Cu(I) mainly contributed to producing H 2 O 2 and Fe(II) dominantly decomposed H 2 O 2 to hydroxyl radical (HO ) [see companion article] (Yufan Chen). Circumneutral conditions facilitated the catalytic processes; under acidic conditions, the reverse reaction between Fe(III) and Cu(I) was strongly favoured; alkaline conditions improved the reducing capacity, which subsequently enhanced the generation of Cu(0) instead of Cu(I). There was a saturated Cu(II)/Fe(II) ratio above which further addition of Cu(II) could not be reduced, and then excessive Cu(I) and Cu(II) consumed HO and O 2 – , respectively. Therefore, the highest removal efficiency of organic pollutants was achieved when the stoichiometric Cu(II)/Fe(II) ratio was 60% at circumneutral pH. The new findings have implications for the treatment of mixed wastewater where copper and organic pollutants coexist.
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CATALYSIS LETTERS
·
2019
·Vol. 149
·期 4
·974-984
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IF 2.372
Zhang Xiaotong,He Ning,Liu Chunyan,Guo Hongchen
Highly dispersed Pt–Cu alloy nanoparticles encapsulated in silicalite-1 were prepared by one-pot method. Taking propane dehydrogenation as a probe reaction, it was found that anti-coke ability was improved by encapsulation. Through H 2 -TPR, CO adsorption DRIFT spectra and X-ray Photoelectron Spectroscopy experiment, enhanced anti-coke ability was ascribed to the electronic environment change of encapsulated metal. And it was further confirmed by in situ coking experiment. Owning to limited acidity, metal encapsulated by silicalite-1 molecular sieve exhibited better anti-coke ability and higher propylene selectivity than that by stronger acidic ZSM-5 molecular sieve. Moreover it was found that the combination of Cu and Pt made better catalytic performance and accelerated dehydrogenation more effectively compared with monometallic catalysts. Therefore, Pt–Cu alloy nanoparticles encapsulated in silicalite-1 molecular sieve core–shell material was a potential coke-resistant catalyst for alkane dehydrogenation reaction. Graphical Abstract
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WATER ENVIRONMENT RESEARCH
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2019
·Vol. 91
·期 8
·770-779
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IF 1.24
Jinhong Fan,Hehe Qin,Yunfei Zhang,Simin Jiang
In this study, Fe/Cu bimetal composite was prepared by high-energy ball milling (BM) method for the removal of refractory organics. The BM Fe/Cu bimetal was characterized by SEM-EDS, XRD, and XPS. Evenly distributed Fe and Cu was observed in the EDS mapping. In contrasting experiments, the removal rate of 4-chlorophenol (4-CP) by BM Fe/Cu materials was about 10-fold faster than that by chemical substitution deposition (CSD) of Fe/Cu material. Complete 4-CP removal and 66.7% of total organic carbon (TOC) mineralization in the BM Fe/Cu–O 2 system were achieved. Dissolved oxygen plays a crucial role for 4-CP degradation through the in situ generation of reactive oxygen species (ROS) such as H 2 O 2 , ·OH, and via oxygen activation reactions. The predominant reactive radicals were identified to be and ·OH through ESR technique and inhibition experiments. The coexistence of oxidation and reduction of 4-CP in the BM Fe/Cu-O 2 system was proposed. Practitioner points 4-CP removal rate by BM Fe/Cu is 10-fold faster than that by CSD Fe/Cu at the same conditions. Complete 4-CP removal and 66.7% of TOC reduction were achieved. All three ROS including ·OH, , and H 2 O 2 coexisted in the BM Fe/Cu-O 2 system. A harmonious coexistence of oxidation and reduction mechanism was proposed.
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Catalysts
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2019
·Vol. 9
·期 6
·538
·
IF 3.444
Lili Liu,Xiaojing Zhou,Li Liu,Shuai Jiang,Yingjie Li,Luxia Guo,Shijuan Yan,Xishi Tai
Three bimetallic Cu–Ni nanoparticle-supported catalysts were synthesized by co-immobilization followed by H2reduction. A chromium(III) terephthalate metal organic framework (MIL-101), titanium dioxide (TiO2), and carbon (C) with different properties (acidity and Brunauer–Emmett–Teller surface area) were selected as supports for studying the effect of the support nature on the catalytic activity and selectivity in the oxidation of benzyl alcohol. The physicochemical properties of the Cu–Ni-supported catalysts were characterized by XRD, NH3-TPD, nitrogen adsorption/desorption, TEM, EDS, XPS, and ICP-OES. Bimetallic Cu–Ni nanoparticles were highly dispersed on the support. The catalytic activities of CuNi/MIL-101, CuNi/TiO2, and CuNi/C were tested in the selective oxidation of benzyl alcohol to benzaldehyde in the presence of molecular oxygen under mild reaction conditions. The highest benzaldehyde yields were achieved with CuNi/TiO2, CuNi/MIL-101, and CuNi/C catalysts at 100 °C within 4 h under 5, 3, and 3 bar of O2, respectively. The bimetallic Cu–Ni-supported catalysts possessed two types of catalytic active sites: acid sites and bimetallic Cu–Ni nanoparticles. The CuNi/MIL-101 catalyst possessed a high number of acid sites and exhibited high yield during selective benzyl alcohol oxidation to benzaldehyde. Importantly, the catalysts exhibited a high functional group (electron-donating and electron-withdrawing groups) tolerance. Cu–Ni-supported catalysts with an Cu:Ni mole ratio of 1:1 exhibited the highest yield of 47% for the selective oxidation of benzyl alcohol to benzaldehyde. Reusability and leaching experiment results exhibited that CuNi/MIL-101 showed better stability than CuNi/TiO2and CuNi/C catalysts due to the large porous cavities of MIL-101 support; these cavities can be used to trap bimetallic Cu–Ni nanoparticles and inhibit nanoparticle leaching.Keywords:Cu–Ni nanoparticles;MIL-101;TiO2;carbon;benzyl alcohol oxidation
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FREE RADICAL BIOLOGY AND MEDICINE
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2019
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IF 5.657
Hong Huang,Xiaobing Lou,Bingwen Hu,Zhongneng Zhou,Jinquan Chen,Yang Tian
In the amyloid plaques , a signature of AD, abnormally high Cu 2+ concentrations are found bound to Aβ. Most of previous studies reported that Cu-Aβ could contribute to oxidative stress , as H 2 O 2 and •OH are catalytically generated by Cu-Aβ with the assistance of biological reductant, with only one recent report stated that free O 2 •- is also generated in the Cu-Aβ catalyzed processes, where an indirect technique was applied. To comprehensively investigate the free radicals produced during this Cu-Aβ-mediated process with a biological reductant, DNA-cleavage assay, an indirect method, and two direct methods including electron paramagnetic resonance (EPR) spectroscopy and transient absorption spectroscopy (TAS), both having qualitative and quantitative power, were employed in this work. All the experimental results obtained from the three methods demonstrated that Cu-Aβ in the biological reducing environment was not only able to catalyze the production of H 2 O 2 and •OH, but also to generate free O 2 •- . The results further indicated that O 2 •- was the precursor of H 2 O 2 and •OH. It is also important to note that the results obtained from EPR spectroscopy and TAS provided direct evidence for the presence of O 2 •- and •OH. By virtue of the direct techniques, we also found that the longest peptide fragments of Aβ 16 , Aβ 40 , and Aβ 42 produced the least radicals with a lowest rate. More interestingly, the fibrillar forms of Aβ generated less O 2 •- and •OH compared with oligomeric and monomeric forms.
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SENSORS AND ACTUATORS B-CHEMICAL
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2019
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IF 6.393
Pengcheng Ma,Xiaoyan Ma,Qi Suo,Fang Chen
Copper nanoparticles (Cu NPs) were uniformly deposited on a nickel foam substrate (Cu NPs@NiF electrode) rapidly by one-step electrochemical deposition in the aqueous solution of copper sulfate, which can be successfully applied to catalyze glucose oxidation, and act as a non-enzymatic glucose sensor. The specific structure and morphology of Cu NPs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electro-oxidation of glucose on Cu NPs@NiF catalytic oxidation of process was proved by cyclic voltammetry (CV). It is found that Cu NPs show remarkable catalytic activity to glucose, involving in multistep catalytic of Cu NPs, in which the transform from Cu (II) into Cu (III) is the key to success. The performances of electrode sensitivity were investigated by CV and chronoamperometry methods in alkaline conditions. It is found that the developed sensor had excellent glucose sensing performances, including two-section broad linear detection ranges (0.002–0.650 mM and 0.65–6.00 mM), high corresponding sensitivity (2679 μA cm −2 mM −1 and 1122 μA cm −2 mM −1 ), fast response time (<3 s) and a low detection limit (0.5 μM, S/N = 3). In short, the Cu NPs@NiF electrode developed by low-cost, efficient and simple preparation method is expected to be used for the development of non-enzymatic glucose sensors.
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Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 10
·5712-5718
·
IF 10.733
Ying Zhou,Kai Zhao,Yu Han,Zhenhe Sun,Hongtao Zhang,Lingqun Xu,Yanfeng Ma,Yongsheng Chen
The two most challenging issues for Li metal anodes are large volume change during the plating/stripping process and the growth of Li dendrites induced by uneven Li deposition. They lead to low coulombic efficiency, short cycling lifespan and serious safety issues of Li metal batteries. Here we developed a facile strategy to prepare a nitrogen-doped-carbon/ZnO (NDC/ZnO) modified Cu foam (MCuF) current collector for Li metal anodes. The MCuF shows stable Li plating/stripping behavior with the Li dendrite-mitigation feature. The resultant half cells achieve a super long lifespan of over 600 cycles at 1 mA cm−2 and over 200 cycles at a high current density 10 mA cm−2. Moreover, the full cell paired with LiFePO4 also exhibits a long lifespan of over 150 cycles at a high rate of 5C. Such high performance can be attributed to the characteristics of MCuF, including its 3D porous structure with high conductivity, enlarged surface area and uniform lithophilic NDC/ZnO sites. We believed that our work can provide a facile strategy for fabricating high-performance 3D current collectors for Li metal storage and stable Li metal batteries.
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CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2019
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IF 3.073
Juan Ma,Baiqin Zhou,Hong Zhang,Wenbo Zhang,Zhilong Wang
Tetracycline with high solubility and biodegradation-resistance has been widely detected from both surface and ground water, and has been proved negative impact on water environment and human health. Adsorption is considered as an environment-friendly and efficient approach to deal with TC contamination in wastewater treatment . In this work, KOH activating municipal wasted sludge biochar with different amounts of nanoscale Fe/Cu was prepared and used to remove TC from water with high performance. The removal efficiency of the composite was found to be significantly improved after loading Fe/Cu particles and the highest removal amount could reach to 386.93 mg/g under the optimum molar ratio of Fe:Cu = 5:3. The analytical results of isotherms, kinetics and thermodynamics suggested that the excellent removal performance of TC by the composite was involved many mechanisms, such as physical adsorption, hydrogen bonding, π–π interaction, complexation and electron transfer. The removal mechanisms of TC and the characteristics of composite were also confirmed by FTIR, XRD , XPS and BET determination. The excellently improved adsorption capacity , environmental-friendly and readily-made properties entrusted the novel sludge-based composite with great potential for TC removal from wastewater.
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ACS Catalysis
·
2019
·
IF 12.221
Yue Ma,Songqi Cheng,Xiaodong Wu,Yunzhou Shi,Li Cao,Liping Liu,Rui Ran,Zhichun Si,Jianbo Liu,Duan Weng
Solid-state ion-exchange (SSIE) is an effictive method to prepare Cu-SSZ-13, but usually requires high temperatures or assistance of NH3 for catalyst activation. Herein, an environmentally friendly low-temperature solid-state ion-exchange (LT-SSIE) method was developed. Cu salts that can decompose at temperatures lower than 300 °C (e.g., CuAc2 and Cu(NO3)2) were chosen as Cu precursors. An impregnation method was adopted to obtain high dispersion of the precursors inside the channels of SSZ-13, as confirmed by scanning transmission electron microscopy. A calcination in air at 300 °C for 30 min was found enough for catalyst activation. In situ X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetry, ultraviolet–visible spectroscopy and H2 temperature-programmed reduction were performed to monitor the activation prcoess of CuAc2-impregnated SSZ-13. The ion-exchange sites of SSZ-13 are occupied by Cu2+ ions originating from CuAc2 at 250–300 °C, revealing the nature of the LT-SSIE process between CuAc2 and SSZ-13.
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