ACS Applied Materials & Interfaces
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2017
·
IF 7.504
Dengfeng Wu,Wei Zhang,Daojian Cheng
The design and development of low-cost Pt-free, high-active, and durable noble-metal-free electrocatalysts for methanol electrooxidation is highly desirable but remains a challenge. Herein, unique Cu/NiCu nanowires (NWs) integrating alloy, core–shell, and one-dimensional structures are prepared by a facile one-pot strategy. It is found that the Ni–Cu surface alloying structure can effectively change the charge distribution of the atomic configuration, the core–shell structure can be optimized with the usage of Ni and Cu, and the one-dimensional structure can effectively enhance the charge transfer between the electrode surface and the active sites, making the prepared NWs promising electrocatalysts. Detailed catalytic investigations showed that the obtained Cu/NiCu NWs exhibit an enhanced electrocatalytic performance for methanol oxidation reaction (MOR). The optimized Cu/NiCu NWs in this work show a mass current density of 867.1 mA mgmetal–1 at 1.55 V (vs. RHE) for MOR, which is far higher than those of Ni-based previously reported electrocatalysts. This work opens up a new pathway for the design and engineering of noble-metal-free alloy electrocatalysts with enhanced activity and durability.
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CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Zhiqiang Zhang,Yongpeng Xu,Wenxin Shi,Wei Wang,Ruijun Zhang,Xian Bao,Bing Zhang,Li Li,Fuyi Cui
The Pd–Cu/γAl 2 O 3 catalysts were prepared by impregnation method and introduced into the cathode chamber of a divided electrochemical denitrification cell with two graphite plates as the cathode and anode, to enhance the nitrate removal efficiency and N 2 selectivity. The Pd–Cu/γAl 2 O 3 catalysts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), specific surface area measurements (BET) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). In the rationally designed electrochemical-catalytic (ECC) system, the as-prepared catalyst could significantly enhance the nitrate degradation rate to 1.08 mg/L at current density of 10 mA/cm 2 , which was approx. 2.5 times compared with the electrochemical (EC) system without catalysts adding in. Additionally, a higher nitrogen selectivity of 80.37% was obtained under the same experiment condition. The improved performances were likely due to the presence of a catalytic reduction reaction of nitrate with the appropriate amount of hydrogen generated by electrolysis as reductant. Significantly, the current efficiency was calculated and enhanced value of 20–40% (depended on current density) was obtained in the ECC process with a catalyst content of 1.0 g/L.
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JOURNAL OF NANOPARTICLE RESEARCH
·
2017
·Vol. 19
·期 2
·1-14
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IF 2.02
Liu Yuling,Wu Qingsheng
The novel BiOBr flower-nanospheres embedded by hexagonal Cu have been synthesized successfully through an ingenious design, by one-step solvothermal process with two kinds of bifunctional reagents, namely, 1-hexadecyl-3-methylimidazolium bromide [C 16 min]Br and ethylene glycol (EG). Pure BiOBr flower-sphere has been synthesized by solvothermal process. In the result of Cu-embedded BiOBr flower-nanospheres, the diameter of the flower-sphere is about 1.5 μm (±0.1) with hexagon copper about 10-nm side length in the petals of BiOBr flower-nanospheres. The Cu-embedded BiOBr composites exhibit high photocatalytic activity than pure BiOBr, which was investigated by the degradation of rhodamine B solution (RhB) and methyl orange solution (MO) under simulative visible-light irradiation. Nearly 100 and 80% of conversion can be achieved from the degradation of RhB and MO after 1.5 h, respectively. The high ability of photocatalysis may be attributed to the narrow-band-gap semiconductor BiOBr, high electron transportation of copper, and the coupling of Cu and BiOBr. It can lead to the strong absorption in the visible region and improve the separation of photogenerated electron–hole pairs.
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ELECTROCHIMICA ACTA
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2017
·
IF 4.798
Wei Meng,Shuang Xu,Lei Dai,Yuehua Li,Jing Zhu,Ling Wang
As a large class of highly crystalline hybrid materials, metal-organic frameworks (MOFs) have the potentials to act as electrochemical sensors due to their active metal sites and diverse structures. However, the poor electron-conductive property limits their application as electrocatalyst. An effective strategy is to introduce conductive phases to the MOFs. In this paper, a novel Cu metal–organic framework {[Cu 2 (bep)(ada) 2 ]·H 2 O} n (Cu-MOF) (beb = 1,4-bis(2-ethylbenzimidazol-1-ylmethyl) benzene, H 2 ada = 1,3-adamantanediacetic acid) was synthesized under hydrothermal condition. Single-crystal X-ray analysis revealed that the Cu-MOF was a three-dimensional pillar-layered framework with two kinds of paddle-wheel secondary building units. Subsequently, the Cu-MOF modified glassy carbon electrode (GCE) was applied in the H 2 O 2 detection in alkaline solution, and it exhibited the good electrocatalytic activity towards H 2 O 2 reduction. When acetylene black (AB) was added to the Cu-MOF, the electrocatalytic performance of the Cu-MOF modified electrode was greatly improved. The results of amperometric response to H 2 O 2 with different AB addition showed that the Cu-MOF/AB-2%/GCE exhibited a wide linear relationship in the H 2 O 2 concentration range of 0.05–3 μM with a rather high sensitivity of 5.56 μA μM −1 cm −2 , a low detection limit of 0.014 μM as well as a fast response time of 4 s. The Cu-MOF/AB-2%/GCE also exhibited the good selectivity towards H 2 O 2 reduction, and had no response to its normal co-existences of glucose, glycerin, alcohol and lactose. In addition, the modified electrode showed a good stability in the test period.
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Inorganic Chemistry Frontiers
·
2017
·Vol. 5
·期 1
·258-265
·
IF 4.036
Lili Tan,Yanhong Liu,Baodong Mao,Bifu Luo,Guan Gong,Yuanzhi Hong,Biyi Chen,Weidong Shi
The development of single-component photocatalysts with narrow bandgaps (2.0–3.0 eV) has been one of the most important goals for photocatalytic H2 production, for which I–III–VI multinary sulfides play an important role due to their widely tunable composition-dependent bandgap. However, simultaneous bandgap narrowing and photocatalytic activity enhancement in the I–III–VI sulfides are often difficult to achieve due to increased defect states. Here, a series of Cu–In–Zn–S quantum dots (QDs) were synthesized by a facile hydrothermal method focusing on a more profound understanding of bandgap tuning and the subsequent effect on the photocatalytic process by controlling the Cu content. The bandgap of the QDs can be effectively tuned from 2.90 eV to 1.98 eV with an increasing Cu : In ratio from 0.05 : 10 to 2.5 : 10 and a color change from light yellow to dark red. The QDs show photocatalytic H2 production activity even without any cocatalyst, but it quickly starts to decrease with the Cu/In ratio over 0.1 : 10 (bandgap of 2.59 eV), which highly limits the potential for visible light photocatalysis. Interestingly, Pt-loading effectively enhanced not only the tolerance of Cu incorporation, but also enabled a high H2 production activity even with further bandgap narrowing down to ∼2 eV. The best photocatalytic performance of 456.4 μmol h−1 g−1 was achieved for the Cu : In : Zn ratio of 1 : 10 : 5 with a bandgap of 2.27 eV. This increased tolerance of Cu content may result from a combined effect of charge separation by Pt as the cocatalyst that alleviated the Cu-induced charge recombination. The enhanced charge separation was proved by the photoluminescence quenching of the QDs with the cocatalyst. Electrochemical impedance spectroscopy was further used to study the charge separation properties of this photocatalytic system. This is the first observation of the cocatalyst-enhanced tolerance of Cu resulting from the competition of cocatalyst-induced charge separation and defect-induced charge recombination in multinary sulfides, which provides an interesting view and design guideline for the development of narrow bandgap photocatalysts.
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APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Lifang Zhang,Peng Dou,Wenjing Wang,Jiao Zheng,Xinhua Xu
The novel Sn-Cu nanotubes enveloped in three-dimensional (3D) hierarchical polyaniline (PANI) hydrogel (Sn-Cu/PANI) were successfully prepared as a high performance anode for lithium-ion battery. The binder-free electrode exhibits reversible capacity of 548 mA h g −1 after 500 cycles and admirable rate capacity even up to 5000 mA g −1 . The exceptional electrochemical performance of Sn-Cu/PANI hydrogel could be attributed to the unique structure: (1) The inactive Cu matrix in binary Sn-Cu compounds and the tubular construction conduce to relieve the volume swing; The high porosity originated from galvanic replacement reaction accelerates ions transmission, which contributes to rapid charging and discharging. (2) The 3D porous PANI framework offers a continuous electron and lithium ions transport network among the whole electrode; the hierarchical PANI serves as mechanical support to accommodate the stress related to the large volume change of Sn-Cu nanotubes, thus reducing the risk of electrode pulverization.
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Nano Energy
·
2016
·
IF 11.553
Zongwei Mei,Bingkai Zhang,Jiaxin Zheng,Sheng Yuan,Zengqing Zhuo,Xianguang Meng,Zonghai Chen,Khalil Amine,Wanli Yang,Lin.-Wang Wang,Wei Wang,Shufeng Wang,Qihuang Gong,Jun Li,Fu.-Sheng Liu,Feng Pan
Cu-doping into Zn 1−x Cd x S can greatly enhance the photocatalytic H 2 evolution from water splitting under visible-light irradiation. However, it is still controversial for how the Cu-dopant improves this performance. Here, we report that appropriate Cu-doped Zn 0.5 Cd 0.5 S nanocrystals reach 21.4 mmol/h/g of H 2 evolution rate without cocatalyst in the visible-light region, which is also 2.8 times as high as that of the undoped counterpart, and the corresponding apparent quantum efficiency is 18.8% at 428 nm. It is firstly confirmed that the Cu 2+ changes into Cu + after being doped by soft X-ray absorption spectroscopy (sXAS). We theoretically propose that the transformation of 2Cu 2+ to 2Cu + results in one adjacent S 2 − vacancy (V S ) in host during the doping process, while the Cu + -dopant and V S attract the photoexcited holes and electrons, respectively. Accordingly, the photocatalytic activity is improved due to the enhanced separation of photoexcited carriers accompanied with the enhanced light absorption resulting from the Cu + -dopant and 2Cu + /V S complex as possible active site for photocatalytic H 2 evolution.
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ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Yuan Pan,Yunqi Liu,Yan Lin,Chenguang Liu
The enhancement of catalytic performance of cobalt phosphide-based catalysts for the hydrogen evolution reaction (HER) is still challenging. In this work, the doping effect of some transition metal (M = Fe, Ni, Cu) on the electrocatalytic performance of the M–Co2P/NCNTs (NCNTs, nitrogen-doped carbon nanotubes) hybrid catalysts for the HER was studied systematically. The M–Co2P/NCNTs hybrid catalysts were synthesized via a simple in situ thermal decomposition process. A series of techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, transmission electron microscopy, and N2 sorption were used to characterize the as-synthesized M–Co2P/NCNTs hybrid catalysts. Electrochemical measurements showed the catalytic performance according to the following order of Fe–Co2P/NCNTs > Ni–Co2P/NCNTs > Cu–Co2P/NCNTs, which can be ascribed to the difference of structure, morphology, and electronic property after doping. The doping of Fe atoms promote the growth of the [111] crystal plane, resulting in a large specific area and exposing more catalytic active sites. Meanwhile, the Feδ+ has the highest positive charge among all the M–Co2P/NCNTs hybrid catalysts after doping. All these changes can be used to contribute the highest electrocatalytic activity of the Fe–Co2P/NCNTs hybrid catalyst for HER. Furthermore, an optimal HER electrocatalytic activity was obtained by adjusting the doping ratio of Fe atoms. Our current research indicates that the doping of metal is also an important strategy to improve the electrocatalytic activity for the HER.
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Energy & Environmental Science
·
2016
·Vol. 9
·期 12
·3736-3745
·
IF 25.427
Haihua Wu,Haobo Li,Xinfei Zhao,Qingfei Liu,Jing Wang,Jianping Xiao,Songhai Xie,Rui Si,Fan Yang,Shu Miao,Xiaoguang Guo,Guoxiong Wang,Xinhe Bao
A coordinatively unsaturated copper–nitrogen architecture in copper metalloenzymes is essential for its capability to catalyze the oxygen reduction reaction (ORR). However, the stabilization of analogous active sites in realistic catalysts remains a key challenge. Herein, we report a facile route to synthesize highly doped and exposed copper(I)–nitrogen (Cu(I)–N) active sites within graphene (Cu–N©C) by pyrolysis of coordinatively saturated copper phthalocyanine, which is inert for the ORR, together with dicyandiamide. Cu(I)–N is identified as the active site for catalyzing the ORR by combining physicochemical and electrochemical studies, as well as density function theory calculations. The graphene matrix could stabilize the high density of Cu(I)–N active sites with a copper loading higher than 8.5 wt%, while acting as the electron-conducting path. The ORR activity increases with the specific surface area of the Cu–N©C catalysts due to more exposed Cu(I)–N active sites. The optimum Cu–N©C catalyst demonstrates a high ORR activity and stability, as well as an excellent performance and stability in zinc–air batteries with ultralow catalyst loading.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2016
·
IF 3.014
Silin Li,Hengyong Tu,Feng Li,Muhammad Tuoqeer Anwar,Lijun Yu
In order to improve the performance of intermediate temperature solid oxide fuel cells (IT-SOFCs), the effect of partial substitution of the transition metal M = Co, Cu, Fe and Mn for Ni in Nd 2 NiO 4+δ on the crystal chemistry, electrical conductivity , thermal stability, chemical reactivity with YSZ electrolyte and electrochemical performance has been systematically investigated. The electrochemical performances of the cathode materials are tested on planar NiO-YSZ anode-supported cells fabricated with YSZ as electrolyte in size of 50 mm × 50 mm. Compared to Nd 2 NiO 4+δ , each Nd 2 Ni 0.9 M 0.1 O 4+δ material shows a decrease in electrical conductivity and an increase in lattice volume, oxygen vacancy concentration and chemical reactivity with YSZ electrolyte. The cell with Nd 2 Ni 0.9 Co 0.1 O 4+δ cathode achieves the maximum power density of 530 mW cm −2 at 0.7 V at 800 °C. The cell with Nd 2 Ni 0.9 Cu 0.1 O 4+δ cathode is the most stable in short-term test. A small amount of B-site doping in Nd 2 NiO 4+δ does not cause any change in the cathode microstructure. The study demonstrates that a tradeoff between oxygen transport properties and electrical conductivity can be accomplished by appropriate selection of transition metal and level of cation B-site doping in Nd2NiO4+δ. Nd2Ni0.9M0.1O4+δ (M = Co, Cu) can be considered to be potential cathode materials in IT-SOFCs.
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ENERGY & FUELS
·
2017
·
IF 3.091
Rong Deng,Yongli Sun,Hanrong Bi,Haozhen Dou,Huawei Yang,Baoyu Wang,Wenjun Tao,Bin Jiang
In the petrochemical industry, it is critical to separate the light olefins/paraffins mixtures via an efficient and economic method. In this work, a series of deep eutectic solvents (DESs) (choline chloride (ChCl)-glycerol (G), ChCl-ethylene glycol (EG), 1-butyl-3-methylimidazolium chloride ([Bmim][Cl])-G, and [Bmim][Cl]-EG) dissolving CuCl were used as novel membrane liquids to fabricate supported liquid membranes (SLMs) for the C2H4/C2H6 mixture separation. Interactions based on a hydrogen bond network in different DESs were characterized by time-of-flight mass spectroscopy (TOF-MS), nuclear magnetic resonance (1H NMR), and Fourier transform infrared (FT-IR) spectroscopy. Moreover, by absorption experiments, the Cu+ activity was quantitatively described based on a first-order equilibrium model. The effects of DESs species, CuCl concentration, transmembrane pressure, temperature, and time on separation performances were investigated by C2H4/C2H6 mixture permeation experiments. CuCl/ChCl-EG-based SLMs possessed good permeability and comparable permslectivity, as well as good long-term stability, surpassing the reported polymeric membrane upper bound. Systemic study demonstrated that the strength of the hydrogen bond networks in DESs could be tailored by optimizing the combinations of the HBAs and HBDs, and eventually improved the separation performances of the CuCl/DES-based SLMs.
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DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 19
·6425-6432
·
IF 4.029
Yuling Liu,Qingsheng Wu,Yaping Zhao
1D Ag3PO4-NPs/Cu-NWs have been constructed to enhance visible-light-driven photocatalytic activity via biomimetic synthesis. Cu nanowires (NWs) were synthesized by a facile hydrothermal method. During the process of biomimetic synthesis, the porous PTFE film, which can mimic the transport process of cell membranes, plays an important role in controlling the transport speed of silver ions (Ag+) to decrease the reaction speed. Thus inhibition of the replacement reaction of Ag+/Cu and the uniform growth of Ag3PO4 nanoparticles (NPs) with a diameter of about 10 nm on Cu-NWs can be realized simultaneously. The diameter of Ag3PO4-NPs/Cu-NW is about 70 nm. Owing to the high electron transport of single crystal Cu-NWs, the free electrons in Ag3PO4 are transferred out to promote photogenerated electron–hole pair separation. The stability of Ag3PO4 NPs of the Ag3PO4-NPs/Cu-NWs was improved and the photodecomposition no longer occurred. Meanwhile, the band-gap of Ag3PO4 decreased to 2.07 eV after being coated on Cu-NWs and expanded the absorption scope of visible-light. In addition, the active species-trapping experiments indicated that the holes and ˙O2− play important roles in the photocatalytic reactions. The novel Ag3PO4-NPs/Cu-NWs were used for the degradation of ciprofloxacin (CPFX) for the first time and showed high photocatalytic degradation performance. After visible-light irradiation for 15 min, the degradation rates of CPFX with pure Ag3PO4 NPs and AC0.3 as catalysts were about 27% and 53%. In the end, the degradation efficiency of Ag3PO4-NPs/Cu-NWs was 6.07 times that of the pure Ag3PO4 NPs.
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