Fixation of CO_2 by electrocatalytic reduction to synthesis of dimethyl carbonate in ionic liquid using effective silver-coated nanoporous copper composites

With high surface area,open porosity and high efficiency,a catalyst was prepared and firstly employed in electrocatalytic reduction of CO2 and electrosynthesis of dimethyl carbonate（DMC）.The electrochemical property for electrocatalytic reduction of CO2 in ionic liquid was studied by cyclic voltammogram（CV）.The effects of various reaction variables like temperature,working potential and cathode materials on the electrocatalytic performance were also investigated.80%yield of DMC was obtained under the optimal reaction conditions.

Weaving 3D highly conductive hierarchically interconnected nanoporous web by threading MOF crystals onto multi walled carbon nanotubes for high performance Li-Se battery

Lithium-selenium(Li-Se)battery has attracted growing attention.Nevertheless,its practical application is still impeded by the shuttle effect of the formed polyselenides.Herein,we report in-situ hydrothermal weaving the three-dimensional(3 D)highly conductive hierarchically interconnected nanoporous web by threading microporous metal organic framework MIL-68(Al)crystals onto multi-walled carbon nanotubes(MWCNTs).Such 3 D hierarchically nanoporous web(3 D MIL-68(Al)@MWCNTs web)with a very high surface area,a large amount of micropores,electrical conductivity and elasticity strongly traps the soluble polyselenides during the electrochemical reaction and significantly facilitates lithium ion diffusion and electron transportation.Molecular dynamic calculation confirmed the strong affinity of MIL-68(Al)for the adsorption of polyselenides,quite suitable for Li-Se battery.Their hexahedral channels(1.56 nm)are more efficient for the confinement of polyselenides and for the diffusion of electrolytes compared to their smaller triangular channels(0.63 nm).All these excellent characteristics of 3 D MIL-68(Al)@MWCNTs web with suitable confinement of a large amount of selenium and the conductive linkage between MIL-68(Al)host by MWCNTs result in a high capacity of 453 m Ah/g at 0.2 C with 99.5%coulombic efficiency after 200 cycles with significantly improved cycle stability and rate performance.The 3 D MIL-68(Al)@MWCNTs web presents a good performance in Li-Se battery in term of the specific capacity and cycling stability and also in terms of rate performance compared with all the metal-organic framework(MOF)based or MOF derived porous carbons used in Li-Se battery.

New amperometric glucose biosensor by entrapping glucose oxidase into chitosan/nanoporous ZrO_2/multiwalled carbon nanotubes nanocomposite film

A new nanocomposite material for construction of glucose biosensor was prepared. The biosensor was formed by entrapping glucose oxidase(Gox) into chitosan/nanoporous ZrO2/multiwalled carbon nanotubes nanocomposite film. In this biosensing thin film, the multiwalled carbon nanotubes can effectively catalyze hydrogen peroxide and nanoporous ZrO2 can enhance the stability of the immobilized enzyme. The resulting biosensor provides a very effective matrix for the immobilization of glucose oxidase and exhibits a wide linear response range from 8 μmol/L to 3 mmol/L with a correlation coefficient of 0.994 for the detection of glucose. And the response time and detection limit of the biosensor are determined to be 6 s and 3.5 μmol/L, respectively. Another attractive characteristic is that the biosensor is inexpensive, stable and reliable.

Nanoconfinement effect of nanoporous carbon electrodes for ionic liquid-based aluminum metal anode

Rechargeable aluminum batteries(RABs),which use earth-abundant and high-volumetric-capacity metal anodes(8040 m Ah cm-3),have great potential as next-generation power sources because they use cheaper resources to deliver higher energies,compared to current lithium ion batteries.However,the mechanism of charge delivery in the newly developed,ionic liquid-based electrolytic system for RABs differs from that in conventional organic electrolytes.Thus,targeted research efforts are required to address the large overpotentials and cycling decay encountered in the ionic liquid-based electrolytic system.In this study,a nanoporous carbon(NPC)electrode with well-developed nanopores is used to develop a high-performance aluminum anode.The negatively charged nanopores can provide quenched dynamics of electrolyte molecules in the aluminum deposition process,resulting in an increased collision rate.The fast chemical equilibrium of anionic species induced by the facilitated anionic collisions leads to more favorable reduction reactions that form aluminum metals.The nanoconfinement effect causes separated nucleation and growth of aluminum nanoparticles in the multiple confined nanopores,leading to higher coulombic efficiencies and more stable cycling performance compared with macroporous carbon black and 2D stainless steel electrodes.

Nanoporous carbons as promising novel methane adsorbents for natural gas technology

Nanoporous carbons were synthesized using furfuryl alcohol and sucrose as precursors and MCM-41 and mordenite as nanoporous templates.The produced nanoporous carbons were used as adsorbent for methane storage.The average pore diameter of the samples varied from 3.9 nm to 5.9 nm and the BET surface area varied from 320m2/g to 824m2/g.The volumetric adsorption experiments revealed that MCM-41 and sucrose had better performance compared with mordenite and furfuryl alcohol,correspondingly.Also,the effect of precursor to template ratio on the structure of nanoporous carbons and their adsorption capacities was investigated.The nanoporous carbon produced from MCM-41 mesoporous molecular sieve partially filled by sucrose shows the best methane adsorption capacity among the tested samples.

Effects of nanopores and sulfur doping on hierarchically bunched carbon fibers to protect lithium metal anode

Studies on three-dimensional structured carbon templates have focused on how to guide homogeneous lithium metal nucleation and growth for lithium metal anodes(LMAs).However,there is still insufficient evidence for a key factor to achieve their high electrochemical performance.Here,the effects of nanopores and sulfur doping on carbon-based nanoporous host(CNH)electrode materials for LMAs were investigated using natural polymer-derived CNHs.Homogeneous pore-filling behaviors of lithium metal in the nanopores of the CNH electrode materials were first observed by ex situ scanning electron microscopy analysis,where the protective lithium metal nucleation and growth process led to significantly high Coulombic efficiency(CE)of~99.4%and stable 600 cycles.In addition,a comparison study of CNH and sulfurdoped CNH(S-CNH)electrodes,which differ only in the presence or absence of sulfur,revealed that sulfur doping can cause lower electrochemical series resistance,higher CE value,and better cycling stability in a wide range of current densities and number of cycles.Moreover,S-CNH-based LMAs showed high electrochemical performance in full-cell Li-S battery tests using a sulfur copolymer cathode,where a high energy density of 1370Wh kgelectrode−1 and an excellent power density of 4120Wkgelectrode−1 were obtained.

Symmetrizing cathode-anode response to speed up charging of nanoporous supercapacitors

Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,we perform constant-potential molecular dynamics simulations to reveal asymmetric features of porous supercapacitors and their effects on capacitance and charging dynamics.Our simulations show that,counterintuitively,charging dynamics can be fast in pores providing slow ion diffusion and vice versa.Unlike electrodes with singlesize pores,multi-pore electrodes show overcharging and accelerated co-ion desorption,which can be attributed to the subtle interplay between the dynamics and charging mechanisms.We find that capacitance and charging dynamics correlate with how the ions respond to an applied cell voltage in the cathode and anode.We demonstrate that symmetrizing this response can help boost power density,which may find practical applications in supercapacitor optimization.

Dynamic surface restructuring of nanoporous Cu_(2-x)Se for efficient CO_(2) electroreduction into methanol

The nanoporous Cu_(2-x)Se with Cu(Se-5%)surface catalysts were prepared through in situ dynamic restructuring strategy during the electrochemical process,which achieves highly selective electrochemical CO_(2) reduction to methanol.In situ and quasi-operando spectroscopic results provide a deep insight into the catalytic active centres of reconstructed heterogeneous catalysts for CO_(2) electroreduction.

Co-hydrothermal carbonization of polystyrene waste and maize stover combined with KOH activation to develop nanoporous carbon as catalyst support for catalytic hydrotreating of palm oil

Plastic waste is massively generated daily from households,mainly as packaging material,causing serious surrounding ecological problems.The development of plastic waste for higher value-added applications instead of landfilling and incineration has received consideration interest in bioenergy and material science research.Herein,a nanoporous carbon support of nickel phosphide catalyst for palm oil hydrotreating was developed from blended polystyrene waste and maize stover via the Co-hydrothermal carbonization(HTC)coupled with the KOH activation process.The Co-HTC parameters,such as temperature,reaction time,and PS percentage,were studied on the properties of co-hydrochar feedstocks for further activation using the Box behnken design.From the comprehensive characterization results,response surface methodology(RSM)results showed that the rising polystyrene proportion significantly exhibited the higher production yield and fixed carbon of co-hydrochar products,an essential characteristic for porous carbon manufacturing.After activation step,the final nanoporous carbon derived from the co-hydrochar(PMPC)exhibited the highest specific surface area of 1033.58 m2/g with total pore volume of 0.45 cm^(3)/g.Moreover,the PCMC-supported nickel phosphide catalysts were successfully synthesized and tested for the catalytic hydrotreating of palm oil as alternative catalyst.The NiP-PMPC catalyst represents an impressive liquid hydrocarbon yield of 74.68%with a high green diesel selectivity of 85.92%at 100%palm oil conversion.The findings of this study might help develop and utilize blended plastic waste and agricultural waste as an alternate catalytic support for various processes in biofuel and biochemical synthesis.

Ionic Group Derivitized Nano Porous Carbon Electrodes for Capacitive Deionization

Capacitance for electrostatic adsorption forms primarily within a Debye length of the electrode surface. Capacitive carbon electrodes were derivatized with ionic groups by means of adsorbing a surfactant in order to test the theory that attached ionic groups would exclude co-ions and increase coulombic efficiency without the need for an added charge barrier membrane. It has been discovered that capacitive electrodes surface derivatized with ionic groups become polarized and intrinsically more coulombically efficient.

Effects of cosolvents on CO_(2) displacement of shale oil and carbon storage

Molecular dynamics method was used to establish composite wall/inorganic nanopores of three pore sizes, three shale oil systems, five CO_(2)-cosolvent systems, and pure CO_(2) system. The process of CO_(2)-cosolvent displacement of crude oil in shale nanopores and carbon storage was simulated and the influencing factors of displacement and storage were analyzed. It is shown that the attraction of the quartz wall to shale oil increases with the degree of hydroxylation. The higher the degree of quartz hydroxylation, the more difficult it is to extract the polar components of shale oil. Nanopore size also has a great impact on shale oil displacement efficiency. The larger the pore size, the higher the shale oil displacement efficiency. The closer the cosolvent molecules are to the polarity of the shale oil, the higher the mutual solubility of CO_(2) and shale oil. The more the non-polar components of shale oil, the lower the mutual solubility of CO_(2) and shale oil with highly polar cosolvent. Ethyl acetate is more effective in stripping relatively high polar shale oil, while dimethyl ether is more effective in stripping relatively low polar shale oil. Kerogen is highly adsorptive, especially to CO_(2). The CO_(2) inside the kerogen is not easy to diffuse and leak, thus allowing for a stable carbon storage. The highest CO_(2) storage rate is observed when dimethyl ether is used as a cosolvent, and the best storage stability is observed when ethyl acetate is used as a cosolvent.

微纳米孔隙内气体流动特性与LBM数值模拟研究

目的研究瓦斯气体在煤层中的流动特性对于揭示煤层瓦斯赋存机理和扩散运移特性具有重要意义。煤中微纳米级孔隙结构十分复杂,为研究煤层瓦斯气体在微纳米孔隙中的流动特性,方法以均质纳米多孔炭薄膜为测试对象,采用扫描电镜实验对其孔隙大小和孔隙率进行定性定量分析;利用纳米尺度气体流动特征实验装置开展微纳米孔隙的气体流动实验研究,通过对比分析传统达西渗流模型和适用于微尺度下气体流动模型,结果得到更为详细的微纳米孔隙内气体流动特性:纳米多孔炭薄膜的视渗透率随着进气口压力的升高而下降,二者呈负相关的线性变化规律;视渗透率随着努森数降低而降低,二者呈正相关的线性变化规律,表明气体在微纳米尺度下的流动不符合传统的达西定律,滑脱效应和气体扩散不可忽视。采用格子Boltzmann方法(lattice boltzmann method,LBM)模拟不同进气口压力下的气体流动,得到不同气体压力下出口的气体流量,与实验结果进行对比,LBM模拟的平均误差为8.25%,整体吻合性较好,表明LBM数值模拟可有效揭示气体在微纳米尺度下的流动特性。结论研究结果可为今后分析煤层中的瓦斯流动机制和流动规律提供理论借鉴。

纳米多孔碳孔径对SrBr_(2)化学蓄放热性能的影响

溴化锶(SrBr_(2))被认为是化学蓄热领域最有前景的材料之一。为探究载体孔径大小对SrBr_(2)蓄放热性能的影响,分别以孔径为10、30、50和100 nm的纳米多孔碳(NCP)为载体,采用浸渍法制备多孔碳基SrBr_(2)复合材料。通过XRD、SEM和BET对复合材料的微观形貌结构进行表征,并通过水合实验和同步热分析对其蓄放热性能进行测试。结果表明,复合材料的吸水量和蓄热密度随孔径先增大后减小,存在最优载体孔径。其中,NCP50-SrBr_(2)具有最优的平衡吸水量和蓄热密度,分别为0.703 g/g和1198.62 kJ/kg。NCP50-SrBr_(2)表现出更快的反应速率,在水合反应30min后蓄热密度可达945.34kJ/kg。研究结果可为纳米尺度定向调控化学蓄热材料性能提供理论依据。

Effective adsorption of sulfamethoxazole, bisphenol A and methyl orange on nanoporous carbon derived from metal-organic frameworks

Nanoporous carbons（NPCs） derived from metal–organic frameworks（MOFs） are attracting increasing attention in many areas by virtue of their high specific surface area, large pore volume and unique porosity. The present work reports the preparation of an NPC with high surface area（1731 m^2/g） and pore volume（1.68 cm^3/g） by direct carbonization of MOF-5. We examined the adsorption of three typical contaminants from aqueous solutions, i.e., sulfamethoxazole（SMX）,bisphenol A（BPA） and methyl orange（MO）, by using the as-prepared NPC. The results demonstrated that NPC could adsorb the contaminants effectively, with adsorption capacity（qm） of 625 mg/g（SMX）, 757 mg/g（BPA） and 872 mg/g（MO）, respectively. These values were approximately 1.0-3.2 times higher than those obtained for single-walled carbon nanotubes（SWCNTs） and commercial powder active carbon（PAC） under the same conditions. With its high surface area and unique meso/macropore structure, the enhanced adsorption of NPC most likely originates from the cooperative interaction of a pore-filling mechanism, electrostatic interaction,and hydrogen bonding. In particular, the p H value has a crucial impact on adsorption, suggesting the significant contribution of electrostatic interaction between NPC and the contaminants. This study provides a proof-of-concept demonstration of MOF-derived nanoporous carbons as effective adsorbents of contaminants for water treatment.

Nanopore design of sulfur doped hollow carbon nanospheres for superior potassium-ion battery anodes

Sulfur doped carbonaceous materials are promising anodes for potassium-ion batteries because of their ability to bridge active sites and induce C/S electron coupling,resulting in increased ion storage capacitance However,the large potassium ions could cause significant volume expansion and structure collapse during operation in sulfur doped carbonaceous anodes,which lead to rapidly capacity sacrifice during long-term cycling.Nanopore design for anchoring sulfur atom in carbon skeleton is a novel way to alleviate the structure collapse and maintain the cycling stability.Therefore,this study developed a controlled nanopore and sulfur doped carbon sphere structure(S-NPHCSs).In potassium-ion batteries S-NPHCSs anode demonstrated exceptional performance with a high reversible capacity of 247 mAh·g^(–1)after 50 cycles at 0.2 A·g^(–1)and delivered a long cycle stability of 600 cycles at a high current density of 1.0 A·g^(–1).Interconnected nanopores and doped sulfur structure not only expand the accumulation space and offer ample active sites for diffusion and adsorption of potassium ions,but also build stable channels through nanopore structure to ensure the cyclic stability.This finding provides a fundamental theory for designing nanopore structures and introducing sulfur doped carbonaceous materials to enhance capacitive potassium storage and long cycle stability.

Capacitive humidity sensing properties of carbon nanotubes grown on silicon nanoporous pillar array

Multi-walled carbon nanotubes (CNTs) were grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition method, and the structural and capacitive humidity sensing properties of CNT/Si-NPA were studied. It was found that with the relative humidity (RH) changing from 11% to 95%, a device re-sponse of ~480% was achieved at the frequency of 50000 Hz, and a linear device response curve could be obtained by adopting longitudinal logarithmic coordinate. The response/recovery times were measured to be ~20 s and ~10 s, respectively, which indicated a rather fast response/recovery rate. The adsorption-desorption dynamic cycle experiments demonstrated the high measurement reproducibility of CNT/Si-NPA sensors. These excellent performances were attributed to the unique surface structure, morphology and chemical inertness of CNT/Si-NPA.

Metal-organic framework derived magnetic nanoporous carbon as an adsorbent for the magnetic solid-phase extraction of chlorophenols from mushroom sample

In this work, a metal-organic framework derived nanoporous carbon （MOF-5-C） was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon （Fe304@MOF-5-C） was then used for the magnetic solid-phase extraction of chlorophenols （CPs） from mushroom samples prior to high performance liquid chromatography-ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 mL, desorption solvent as 0.4 mL （0.2 mL × 2） of alkaline methanol, and sample pH as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8-100.0 ng g 1 with the correlation coefficients between 0.9923 and 0.9963. The limits of detection （SIN= 3） were in the range of 0.25-0.30 ng g-1, and the relative standard deviations were below 6.8%. The result showed that the Fe304@MOF-5-C has an excellent adsorption capacity for the analytes.

Synthesis ofγ-MnS/nanoporous carbon/reduced graphene oxide composites for high-performance supercapacitor

In the present work,nanoporous carbon(NPC)was prepared from a metal-organic framework(zeolite imidazolate framework 8,ZIF-8).Different concentrations of graphene oxide(GO)were used to make NPC/reduced graphene oxide(NPC/rGO-x,x=0.5,1.0,1.5,and 2.0)composites,and thenγ-MnS/NPC/rGO-1 composite was synthesized via a simple hydrothermal technique.The electrochemical characteristics of porous carbon composites(NPC/rGO-x)andγ-MnS/NPC/rGO-1 electrodes were investigated by galvanostatic charge and discharge,cyclic voltammetry,and electrochemical impedance spectroscopy.NPC/rGO-1 showed the highest specific capacitance of 207 F/g at 0.5 A/g.Also,theγ-MnS/NPC/rGO-1 electrode demonstrates exceptional electrochemical performance with a high specific capacitance of 300 F/g at 0.5 A/g and impressive cyclic stability of 70%capacitance retention after 10,000 cycles at 1 A/g.As a result,this study demonstrates thatγ-MnS/NPC/rGO-1 electrode can be considered a promising candidate for high-performance supercapacitors.

Template sacrificial controlled synthesis of hierarchical nanoporous carbon@NiCo_(2)S_(4)microspheres for high-performance hybrid supercapacitors

Binary transition metal sulfides are hotly investigated in advanced energy storage devices because of their ultra-high reversible capacity.Nevertheless,the unsatisfied rate capability and cycling stability still hinder their practical application.Herein,hierarchical nanoporous carbon@NiCo_(2)S_(4)(HNCMs@NCS)composites with coreshell flower-like structures were prepared by in situ growing of NiCo_(2)S_(4) nanosheets on HNCMs through a hydro thermal-as sis ted template sacrificial method.Benefiting from a synergistic effect between the NiCo_(2)S_(4)shell with high specific capacity and the HNCMs with unique porous structure,the synthesized flower-like HNCMs@NCS composites exhibit extraordinary electrochemical performances,including a high capacity of 346.9 mAh·g^(-1)at 1 A·g^(-1),superb rate property with86.4%initial capacity at 30 A·g^(-1)and predominant cycle stability with 81.2%capacity retention after 5000 cycles.Furthermore,the resulting HNCMs@NCS cathode was coupled with the chemical-activated HNCMs(AHNCMs)anode to construct a hybrid supercapacitor device.The asfabricated device exhibits superior energy density(49.9 Wh·kg^(-1)at 802 W·kg^(-1))and ultra-high power density(24 kW·kg^(-1)at 29.5 Wh·kg^(-1)).This fascinating result further demonstrates the tremendous prospect of the synthesized HNCMs@NCS composites as high-performance supercapacitor electrode materials.

羧基化纳米多孔碳电化学适配体传感器的构建及其在维生素C检测中的应用

目的建立一种简单、灵敏度高、选择性好的电化学适配体传感器用于维生素C(vitamin C,VC)的快速检测。方法将羧基化纳米多孔碳材料(carboxylated nanoporous carbon powder,NCP-COOH)修饰在丝网印刷电极(screen printed electrode,SPCE)表面,为结合氨基修饰的适配体提供大量的活性位点,构建新型适配体传感器。当VC存在时,传感器表面的适配体与VC特异性结合导致差分脉冲伏安(differential pulse voltammetry,DPV)响应信号下降,根据信号的变化实现对VC的定量检测。采用循环伏安法和交流阻抗法对传感器的构建过程及电化学性能进行考察,并通过对NCP-COOH材料浓度、适配体浓度、缓冲液pH、孵育时间等条件的优化,确定传感器对VC的最佳检测条件。结果NCP-COOH具有大的比表面积,良好的导电性和生物相容性,能显著提高传感器的电化学性能。在最佳的实验条件下,传感器在0.1~1000.0μg/L范围内对VC有良好的响应,检出限为0.01μg/L,用于实际样品的测定时回收率为92.5%~100.5%,测定结果与GB5009.86—2016《食品安全国家标准食品中抗坏血酸的测定》相符。结论该方法方便快捷、灵敏度高、选择性好,能够应用于蔬菜样品中VC的准确测定,为农产品中VC的快速检测提供了一种新方法。