RSC Advances
·
2022
·Vol. 12
·期 36
·23183-23192
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IF 4.036
Xiaoyan Cao,Lingxin Kong,Zhenggui Gu,Xiao Xu
The application of recyclable heterogeneous catalysts in the production of polypropylene glycol monomethyl ether (MPPG) is of great significance to the green chemical industry. In this study, the CeO2/MgAl-LDH(P123) composite was prepared using a nucleation/crystallization isolation method and aqueous reconstruction method, and CeO2/MgAl-LDO(P123) solid base catalyst was prepared by calcination with it as precursor. Thereafter, the morphology, crystal structure, functional group, and thermal stability of the catalyst were characterized using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, temperature-programmed desorption of carbon dioxide, thermogravimetry, and X-ray photoelectron spectroscopy. The results showed that the catalyst had a larger specific surface area, pore size and pore volume and more basic sites, providing sufficient catalytic activity for the polymerization process. The experimental results for the fabrication of MPPG using CeO2/MgAl-LDO(P123) as catalyst and methanol and propylene oxide as reaction raw materials showed that the conversion of propylene oxide reached 92.04% and the molecular weight of MPPG was 405 under the optimal reaction conditions. Moreover, the conversion of propylene oxide was maintained above 83.69% after the catalyst was reused six times. This study offers a new prospect for the green synthesis of MPPG products.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Shanshan Wang,Yi Liu,Xiaolong Deng,Jiafeng Cao,Yufeng Han,Jinzhao Huang,Yibing Li
In this study, unique Co 3 S 4 /Fe 3 S 4 heterostructures (denoted as CoFe-HM-T) were synthesized from CoFe layered double hydroxides (LDHs) by a two-step hydrothermal process (hydrazine monohydrate and thiourea treatment). The effect of Co 3 S 4 /Fe 3 S 4 heterostructures on the electrocatalytic water splitting was investigated in alkaline solution. The CoFe-HM-T electrode exhibited excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic activity with overpotentials of 320 mV and 200 mV at the current density of 100 mA cm −2 , respectively. CoFe-HM-T also possessed the smallest Tafel slope among the prepared samples, which was estimated to be 38.1 mV dec −1 and 144.9 mV dec −1 for OER and HER, respectively. Serving as bifunctional catalysts, the CoFe-HM-T electrode reached the state-of-art current density of 10 mA cm −2 at a cell voltage of 1.70 V with excellent stability. The enhanced electrocatalytic activity was ascribed to the interconnected structure facilitating the mass transport, the heterojunction accelerating the charge transfer, and the synergistic effect between them. This study offered a new strategy for in situ synthesizing the heterojunction electrocatalysts with unique interface by readily tuning the metal components in transition-metal LDHs.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2022
·
IF 7.139
Yuan Chen,Hao Guo,Fan Yang,Ning Wu,Junye Zhang,Liping Peng,Bingqing Liu,Zhilan Pan,Wu Yang
A metal porous carbon (Ni@NC) supported nickel/cobalt layered double hydroxide (NiCo-LDH) (Ni@NC@NiCo-LDH) with a cauliflower morphology was synthesized by a successive double template method . At first a nickel metal-organic framework (Ni-MOF) was prepared and used as a sacrifice template to produce metal porous carbon (Ni@NC). Then the prepared conductive porous carbon material was exploited as a substrate for in-situ growing of ZIF-67 on its surface. Lastly the obtained Ni@NC@ZIF-67 was further used as a sacrifice template to prepare the final electrode material Ni@NC@NiCo-LDH by Ni 2+ etching and co-precipitation. The cooperation of Ni@NC with excellent conductivity and NiCo-LDH with superior pseudocapacitive property yielded a synergistic effect , which effectively improved the electrochemical performance of the resulted electrode material. And the special flower morphology exposed more redox active sites and provided proper charge transport path for enhanced electrochemical performance. The prepared Ni@NC@NiCo-LDH exhibited a high specific capacitance of 1761.8 F·g −1 at the current density of 1 A·g −1 . The assembled Ni@NC@NiCo-LDH//AC asymmetric supercapacitor also displayed an acceptable energy density (39.27 Wh·kg −1 at the power density of 757.21 W·kg −1 ) and ultrahigh cycling stability (94.74% capacitance retention after 25000 cycles at 10 A g −1 ).
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ChemCatChem
·
2021
·Vol. 13
·期 23
·4937-4947
·
IF 5.686
Chenglin Miao,Fengyu Zhang,Luoyu Cai,Tianli Hui,Junting Feng,Dianqing Li
Graphical Two kinds of electron-rich interface sites are clearly identified in ultrathin Pt/CoAl-LDH catalyst. A series of technologies found that the Pt−V O −Co δ+ interface site can change the adsorption mode of C=O bond, and the Pt−V Co −OH δ− interface site facilitates the mobility of active hydrogen. Therefore, the ultrathin catalyst exhibits enhanced COL yield under the synergistic effect of the dual interface sites. Focusing on the simultaneous enhancement of activity and selectivity in α, β-unsaturated aldehyde hydrogenation, we designed and prepared an ultrathin CoAl-LDH supported Pt catalyst. A series of technologies revealed the ultrathin CoAl-LDH support possesses the characteristic of dual defects, oxygen vacancy (V O ) and cobalt vacancy (V Co ). Then, two kinds of vacancy related interface sites were identified, namely Pt−V O −Co δ+ and Pt−V Co −OH δ− . Compared with the bulk catalyst, the ultrathin catalyst exhibits both enhanced intrinsic activity and C=O bond selectivity under the synergistic effect of the dual interface sites. Specifically, the Pt−V O −Co δ+ interface site changes the adsorption mode of cinnamaldehyde and promotes the activation of C=O bonds, thus leading to the improved cinnamyl alcohol selectivity. The H atoms of the Pt−V Co −OH δ− interface site participate in the hydrogenation process, which facilitates the mobility of active hydrogen and therefore promotes the intrinsic activity. More importantly, the ultrathin catalyst shows good reusability.
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CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Yue Su,Shihui Qiu,Jiayu Wei,Xiaobo Zhu,Haichao Zhao,Qunji Xue
The strong barrier of well dispersed graphene provides excellent labyrinth effect in organic coating. However, the high conductive graphene sheets are prone to forming conductive path in coating matrix with corrosive medium, resulting in serious micro current corrosion. Although a large number of methods to reduce the conductivity of graphene have been reported, how to balance the conductivity of graphene, the affinity between filler and resin, and the self-healing property of coating are major issues for researchers to consider. Here, we have developed a strategy for insulating graphene with layered double hydroxides via sulfonated polyaniline mediated self-assembly approach. Graphene sheets were stripped by sulfonated polyaniline to improve the interlayer spacing of graphene followed by covered with layered double metal hydroxide (LDH) via ionic crosslinking, which reduced the conductivity of graphene and improve the interfacial compatibility between the fillers and the resin. At the same time, the electroactive polyanilines between the graphene layers afford the coating with self-healing effect. The novel graphene-LDH nanohybrid material was incorporated into the waterborne epoxy resin to prepare corrosion resistant coatings with a thickness of about 70 ± 5 μm. The electrochemical and self-healing properties of the prepared composite coating were characterized by EIS, Tafel and LEIS techniques. This novel sulfonated polyaniline crosslinked graphene-LDH nanohybrid expands in the research and development of graphene based high performance anticorrosive coatings.
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Journal of Cleaner Production
·
2021
·
IF 9.297
Xiuling Guo,Yang Ruan,Zenghui Diao,Kaimin Shih,Minhua Su,Gang Song,Diyun Chen,Shuao Wang,Lingjun Kong
With the wide application of nuclear energy and the rapid development of mining, a great quantity of uranium (U(VI)) containing wastewater is inevitably generated. In this work, a facile environmental-friendly coprecipitation method was proposed for the green synthesis of binary layered double hydroxides (Ni–Co LDH W -7), which could be used to efficiently adsorb U(VI) from wastewater. Pseudo-second-order kinetic model and Dubinin-Radushkevich model fitted well with the adsorption of U(VI) on Ni–Co LDH W -7, the maximum adsorption capacity of U(VI) on Ni–Co LDH W -7 was 201.09 mg/g calculated by the Langmuir model. Adsorption equilibrium reached after 30 min, which is a spontaneous and endothermic process . Fourier Transform Infrared Spectrometer (FTIR) and X-ray Photoelectron Spectroscopy (XPS) measurements manifested that the favorable U(VI) extraction on Ni–Co LDH W -7 is mainly ascribed to inner-layer surface electrostatic interaction and complexation, which is dominated by abundant oxygen-containing M-OH and interlayer OH − ions. Briefly, this work provides a facial and environmental-friendly Ni–Co LDH W -7 for removing U(VI) in actual uranium-containing wastewater.
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CHINESE JOURNAL OF CATALYSIS
·
2021
·
IF 8.271
Han Zhang,Guoqiang Shen,Xinying Liu,Bo Ning,Chengxiang Shi,Lun Pan,Xiangwen Zhang,Zhen-Feng Huang,Ji-Jun Zou
Developing effective and practical electrocatalyst under industrial electrolysis conditions is critical for renewable hydrogen production . Herein, we report the self-supporting NiFe LDH-MoS x integrated electrode for water oxidation under normal alkaline test condition (1 M KOH at 25 °C) and simulated industrial electrolysis conditions (5 M KOH at 65 °C). Such optimized electrode exhibits excellent oxygen evolution reaction (OER) performance with overpotential of 195 and 290 mV at current density of 100 and 400 mA·cm −2 under normal alkaline test condition. Notably, only overpotential of 156 and 201 mV were required to achieve the current density of 100 and 400 mA·cm −2 under simulated industrial electrolysis conditions. No significant degradations were observed after long-term durability tests for both conditions. When using in two-electrode system, the operational voltages of 1.44 and 1.72 V were required to achieve a current density of 10 and 100 mA·cm −2 for the overall water splitting test (NiFe LDH-MoS x /INF || 20% Pt/C). Additionally, the operational voltage of employing NiFe LDH-MoS x /INF as both cathode and anode merely require 1.52 V at 50 mA·cm −2 at simulated industrial electrolysis conditions. Notably, a membrane electrode assembly (MEA) for anion exchange membrane water electrolysis (AEMWEs) using NiFe LDH-MoS x /INF as an anode catalyst exhibited an energy conversion efficiency of 71.8% at current density of 400 mA·cm −2 in 1 M KOH at 60 °C. Further experimental results reveal that sulfurized substrate not only improved the conductivity of NiFe LDH, but also regulated its electronic configurations and atomic composition, leading to the excellent activity. The easy-obtained and cost-effective integrated electrodes are expected to meet the large-scale application of industrial water electrolysis.
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CELLULOSE
·
2020
·Vol. 28
·期 1
·301-316
·
IF 4.21
Yang Cong,Yuan Jun,Guo Yi,Luo Xiaogang
In this work, Mg/Al layered double hydroxides embedded phosphorylated cellulose microspheres (Mg/Al LDH@PCMs) were prepared first with solid-phase phosphorylation on CMs then in situ nano-assembly between Mg 2+ , Al 3+ and phosphate groups. Hence the synthesis degree of Mg/Al LDH was enhanced. The obtained Mg/Al LDH@PCMs were characterized by scanning electron microscopy (SEM), specific surface area test (BET), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ζ potential, X-ray electron energy (XPS). The novel in situ nano-assembly method provided improved Mg/Al LDH load without compromising the porous structure of CMs, making Mg/Al LDH@PCMs suitable for water treatment. The Mg/Al LDH@PCMs adsorbed tetracycline hydrochloride (TC) with a kinetic pattern of pseudo second-order kinetic model, while isothermally fitted with the Freundlich isotherm model. The maximum theory adsorption capacity of Mg/Al LDH@PCMs q m was 25.107 mg g −1 with the Gibbs free energy ∆G = 7.523 kJ mol −1 under 298 K. The TC removal mechanism was deeply investigated via characterization results and also the batch experimental results, it was inferred that electrostatic attraction between LDH particles and the anion species mainly dominated the adsorption process. These properties make Mg/Al LDH@PCMs have a wide application prospect in the water purification field.
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JOURNAL OF CATALYSIS
·
2020
·
IF 7.888
Chenyuan Guo,Shuguang Shen,Meina Li,Ying Wang,Jing Li,Yuanquan Xing,Cui Wang,Huajie Pan
A rapid and efficient synthesis strategy of MgAl-LDH was proposed. MgAl-LDH with high specific surface area was synthesized in situ by using η -Al 2 O 3 as carrier, and the synthesis time was greatly shortened by both increasing temperature and introducing ethanol as co-solvent. Besides, the growth process of MgAl-LDH on the surface of η -Al 2 O 3 is also revealed. Under optimized conditions, the specific surface area of the MgAl-LDH is as high as 172.4 m 2 /g, the crystalline size is as small as 12.82 nm, and the basicity can reach 1.795 mmol/g. The urea wastewater was degraded from 8000 mg/L to 6.85 mg/L over the catalyst synthesized by the rapid method, and the catalyst still maintains high activity after four uses. Also, it was found that there is a good linear relationship between the urea removal rate and the basicity of MgAl-LDH.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2020
·
IF 5.774
Jia Deng,Liwen Xiao,Shoujun Yuan,Wei Wang,Xinmin Zhan,Zhen-Hu Hu
Layered double hydroxide (LDH) was a kind of layer materials with multi-metal elements and good catalytic performance, but the metals can be dissolved during catalysis. Graphene oxide (GO) was a two-dimensional structure with abundant anionic groups with the potential of immobilizing metals. However, LDH combined with GO (LDH/GO) was few reported in the treatment of pharmaceuticals and personal care products (PPCPs). In this work, CoFeNi LDH/GO composites were designed and synthesized for activating peroxymonosulfate (PMS). Meanwhile, gatifloxacin (GAT), a typical antibiotic, was used to assess the performance of LDH/GO + PMS system. The characterization of LDH/GO using various measures showed that the adding GO was inserted the layer structure of LDH and the surface functional group of GO was immobilized in LDH well. GAT could be degraded completely after 45 min under the reaction conditions of pH 7.0, 38 mg L −1 GAT, 40 mg L −1 LDH/GO and 400 mg L −1 PMS. The removal of total organic carbon and defluorination reached 55.5% and 78.0% after 5 h reaction, respectively. Quenching tests suggested that the main radicals responsible for GAT degradation and mineralization was sulfate radical (SO 4 − ). The redox cycle made the catalysis of the LDH/GO composites work continuously. Compared with LDH + PMS system, the concentration of dissolved metals decreased 60.6%-74.3% at pH 3.0–11.0 in LDH/GO + PMS system. The reusability test indicates that LDH/GO has stable catalytic performance in removing PPCPs from wastewater.
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Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 35
·18106-18116
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IF 11.301
Tuo Wang,Huimin Wu,Chuanqi Feng,Lei Zhang,Jiujun Zhang
Water electrolysis is an important way to produce hydrogen at the cathode, but the oxygen evolution reaction (OER) at the anode has a high overpotential. Using the urea oxidation reaction (UOR) to replace OER has been an energy-saving approach for its lower electrode potential, and also a potential approach for wastewater treatment. In this paper, novel materials of MoP@NiCo-LDH/NF-x (x = 10, 20, 30 minutes) are synthesized and explored as bifunctional catalysts for both the hydrogen evolution reaction (HER) at the cathode and the urea oxidation reaction (UOR) or the oxygen evolution reaction (OER) at the anodes of urea–water or water electrolysis. The morphologies and compositions of such catalyst materials are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalytic activity and stability are measured by linear sweep voltammetry, electrochemical impedance spectroscopy, chronoamperometry, etc. The results indicate that MoP@NiCo-LDH/NF-20 has better catalytic performance, and can be used as a bifunctional catalyst for both HER and OER/UOR in the electrolysis. A two-electrode electrolyser (MoP@NiCo-LDH/NF-20‖MoP@NiCo-LDH/NF-20) is constructed. At 100 mA cm−2, the two-electrode electrolyser needs only 1.405 V, while the precious metal electrolyser Pt/C/NF‖IrO2/NF needs 1.697 V at the same current density, indicating that MoP@NiCo-LDH/NF-20 could be a promising bifunctional electrocatalyst in water and urea–water electrolysis for the treatment of urea wastewater and hydrogen production.
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SENSORS
·
2020
·Vol. 20
·期 15
·4146
·
IF 3.275
Chuxuan Zhang,Xinqiang Liang,Yuanyuan Lu,Hua Li,Xiangyang Xu
Glyphosate, which has been widely reported to be a toxic pollutant, is often present at trace amounts in the environment. In this study, a novel copper-aluminum metal hydroxide doped graphene nanoprobe (labeled as CuAl–LDH/Gr NC) was first developed to construct a non-enzymatic electrochemical sensor for detection trace glyphosate. The characterization results showed that the synthesized CuAl–LDH had a high-crystallinity flowered structure, abundant metallic bands and an intercalated functional group. After mixed with Gr, the nanocomposites provided a larger surface area and better conductivity. The as-prepared CuAl–LDH/Gr NC dramatically improved the enrichment capability for glyphosate to realize the stripping voltammetry detection. The logarithmic linear detection range of the sensor was found to be 2.96 × 10−9–1.18 × 10−6mol L−1with the detection limit of 1 × 10−9mol L−1with excellent repeatability, good stability and anti-interference ability. Further, the sensor achieved satisfactory recovery rates in spiked surface water, ranging from 97.64% to 108.08%, demonstrating great accuracy and practicality.Keywords:electrochemical detection;glyphosate;layer double hydroxides;sensor
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