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.

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.

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.

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.

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。

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.

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.

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.

基于碳纳米材料构建传感器用于抗坏血酸、尿酸和多巴胺检测的研究进展

对应用于抗坏血酸、尿酸和多巴胺同时检测的碳纳米材料和电化学方法进行了简单阐述,重点从不同碳纳米材料的物理化学特性介绍了其在电化学传感器构建中发挥材料自身优势促进生物分子在传感器表面被灵敏准确识别的传感方法。总结了近年来基于石墨烯、碳纳米管、碳纳米纤维、纳米多孔碳和氮掺杂碳纳米材料等碳纳米材料构建传感器应用于三种生物分子同时检测的研究进展;分析了当前电化学传感器构建的不足及面临的挑战,并对今后电化学领域应用于生物活性分子快速检测的研究方向进行了展望。

助溶剂对二氧化碳置换页岩油及碳封存的影响

利用分子动力学方法建立了3种孔隙尺寸的复合壁面纳米孔隙/无机纳米孔隙、3种页岩油体系、5种CO_(2)+助溶剂复合体系及纯CO_(2)体系,模拟了页岩纳米孔隙中CO_(2)+助溶剂对页岩油的置换及封存过程,分析了置换与封存的影响因素。研究表明:石英壁面对页岩油的吸引作用随羟基化程度增大而增强,石英羟基化程度越高,页岩油中极性组分的开采难度越大。纳米孔隙孔径对页岩油置换效率也有较大影响,孔径越大,页岩油置换效率越高。助溶剂分子与页岩油极性越接近,越有利于CO_(2)与页岩油互溶,加入强极性助溶剂时页岩油中非极性组分越多,越不利于CO_(2)与页岩油互溶。乙酸乙酯对极性相对较强的页岩油剥离效果较好,二甲醚则对极性相对较弱的页岩油剥离效果较好。干酪根具有较强的吸附性能,对CO_(2)具有更强的吸附能力,CO_(2)进入干酪根后不易发生扩散泄漏,碳封存稳定性好。二甲醚作为助溶剂时,CO_(2)的封存率最高,乙酸乙酯作为助溶剂时,封存稳定性最好。

宽温域纳米多孔硅/碳复合负极的制备及储锂性能研究

基于商用铸造Mg-Si合金,采用化学腐蚀和碳包覆技术相结合,制备出纳米多孔硅/碳复合负极。通过SEM、XRD和EDS技术表征了该负极的物相构成、化学成分和微观结构,并对其电化学性能进行了研究。结果表明,该负极具有典型的三维双连通纳米多孔结构,且碳层均匀包覆在多孔硅表面。0.1 C电流密度下,该负极首次充/放电比容量为724.44/1404.49 m A·h/g,循环寿命800次以上,且在-30~50℃的温度范围内可正常使用。

钠离子电池硬炭负极研究进展

无定形结构的硬炭以其不同于石墨有序结构的结构优势,以及低成本和原材料来源广,被认为是钠离子电池(SIBs)最有前途的碳基负极材料,其复杂的微观结构与钠储存有着密切的关系。在硬炭微观结构中缺陷,层间和纳米孔隙是硬炭储钠的三个关键特征结构,深入研究这些特征结构有利于实现高容量钠离子电池碳基负极的有效构造,并有利于推进钠离子电池产业化进程。最后对高性能钠离子电池负极的结构设计进行了展望。

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.

Single-Molecule Measurement of Carbonic Anhydrase in Cation Coordinated Environment Using MspA Nanopore

Carbonic anhydrase accounts for catalytic reaction of CO_(2)/HCO_(3)^(–) transformation, thus resulting in neutralization and acidification of the cellular environment, thereby favoring tumor development. Hence, it is a classical protein model of greatly biocatalytic significance as well as a highly expressed biomarker with renal tumor. We herein proposed a single-molecule measurement on carbonic anhydrase using MspA nanopore, in [BMIM+] and asymmetric K^(+)/Ca^(2+) cationic coordinated environment, instead of usual symmetric KCl/NaCl electrolyte. Significantly, our empirical analysis showed that asymmetric K^(+)/Ca^(2+) cationic environment contributes to distinguishable current modulations, thus yielding better resolution for carbonic anhydrase measurement, which is independent of applied voltage and more importantly, is stable enough at varied pH conditions and for very low concentration test in urine sample. Our results provide a classical model for nanopore protein analysis, and may also permit biocatalytic measurement at single-molecule level.