It has been demonstrated that almost all polymer-clay nanocomposites show higher temperature stability than that of pure polymer, which is attributed to the active exfoliated clay nanosheet firmly adsorbed onto the po...It has been demonstrated that almost all polymer-clay nanocomposites show higher temperature stability than that of pure polymer, which is attributed to the active exfoliated clay nanosheet firmly adsorbed onto the polymer chains, due to polerization and nucleation effect, the clay nanosheets could protect the polymer chains from destroying. To prove such mechanism, the water-soluble polymer nanocomposites(AAA/SLS-MMT) were synthesized by the in-situ polymerization of 2-acrylamide-2-methyl-propane sulfonic acid, acrylamide, 4-acryloylmorpholine, and organically modified montmorillonite. The techniques of nuclear magnetic resonance, atomic force microscopy and scanning electron microscopy etc., clearly characterized the successful synthesized of sample's structure, the exfoliated MMT nanosheet adsorbed polymer chain's scale, and well-dispersed morphology, espectively. The adsorption model, X-ray photoelectron spectroscopy presented the existence of strong adsorption, while molecular simulation calculations first concluded that the strong adsorption energy was-13032.06 kcal/mol. Thermo-gravimetric-analysis proved the temperature of maximum thermal degradation of powder sample(AAA/1.0 wt% SLS-MMT) was over 298℃. After ageing at 180℃ for 4 h, the apparent viscosity of 5 g/L AAA/1.0 wt% SLS-MMT aqueous solution was 326.7 mPa,s, while that of pure polymer(AAA) was only 8.3 mPa,s. This optimized sample has the smallest FLAPIvalue at all test temperatures from 180 to 220℃ in both fresh and salt water based drilling fluid. All the evidences of high temperature resistance indicate that the strong adsorption can enhance the thickness of hydrated shell and adsorption of clay particles in drilling fluid at high temperature. Such mechanism supplied the better way to design high-temperature resistant fluid loss additives for deep and ultra-deep oil and gas formation engineering.展开更多
Exfoliated graphite (EG) is selected as a new kind of sorbent to sorb heavy oil spilled. In order to make use of EG more effectively, some basic experiments are performed to investigate its sorption properties, i.e...Exfoliated graphite (EG) is selected as a new kind of sorbent to sorb heavy oil spilled. In order to make use of EG more effectively, some basic experiments are performed to investigate its sorption properties, i.e. , specific sorption, height of saturation layer, sorption time constant. In the present experiments, A grade heavy oil is employed as a standard sorbate. It is concluded that 1) under the condition that the area of solid (filter bottom) liquid (heavy oil) interface is a constant, specific sorption usually decreases when the amount of EG filled or the apparent bulk density increase; however, the specific sorption initially increases when the apparent bulk density is too low and the amount of EG filled is too much; 2) under the condition that the apparent bulk density of EG filled is a constant, the sorption time constant tends to increase when the amount of EG filled increases; however, for a constant amount of EG filled, the sorption time constant will decrease when the apparent bulk density increases.展开更多
Ultrathin MoS2 nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron...Ultrathin MoS2 nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2 nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm-2/zm. As anode material for Li-ion batteries, the as-prepared MoS2 nanosheets electrodes exhibited a good initial capacity of 1190 mAh.g-l and excellent cyclic stability at constant current density of 50 mA.g-1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh.g-1.展开更多
The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of e...The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of energy density of LIBs is restricted by the limited capacity below 0.5 V of CG.Here,based on the supercritical CO2 exfoliation technique,the production of multi-layered graphene(MLG)is achieved from the pilot scale production line.The great merit of the exfoliated MLG anode is that the voltage plateau below 0.5 V is broadened obviously as compared to those of natural graphite and CG.Additionally,no obvious lithium dendrites are observed for MLG during the lithiation process.The large delithiation capacity under the low voltage plateau of MLG is mainly benefited from the combination of Li intercalation and boundary storage mechanism,which is further confirmed by the density functional theory calculations.The LiFePO4/MLG full cell can afford the satisfactory electrochemical property with respect to the capacity,energy density and ultralong cycling stability(90%capacity retention after 500 cycles at 2 C),significantly better than that of LiFePO4/CG.Besides,this developed technique not only dedicates to producing the high-performance anode for LIBs but also opens a door for the mass production of MLG in the industrial scale.展开更多
Intensive research effort is currently focused on the development of efficient, reliable, and environmentally safe electrochemical energy storage systems due to the ever-increasing global energy storage demand. Li ion...Intensive research effort is currently focused on the development of efficient, reliable, and environmentally safe electrochemical energy storage systems due to the ever-increasing global energy storage demand. Li ion battery systems have been used as the primary energy storage device over the last three decades. However, low abundance and uneven distribution of lithium and cobalt in the earth crust and the associated cost of these materials, have resulted in a concerted effort to develop beyond lithium electrochemical storage systems. In the case of non-Li ion rechargeable systems, the development of electrode materials is a significant challenge, considering the larger ionic size of the metal-ions and slower kinetics. Two-dimensional(2D) materials, such as graphene, transition metal dichalcogenides, MXenes and phosphorene, have garnered significant attention recently due to their multi-faceted advantageous properties: large surface areas, high electrical and thermal conductivity, mechanical strength, etc. Consequently, the study of 2D materials as negative electrodes is of notable importance as emerging non-Li battery systems continue to generate increasing attention. Among these interesting materials, graphene has already been extensively studied and reviewed, hence this report focuses on 2D materials beyond graphene for emerging non-Li systems. We provide a comparative analysis of 2D material chemistry, structure, and performance parameters as anode materials in rechargeable batteries and supercapacitors.展开更多
The direct coating of graphene sheets obtained by electrochemical exfoliation on commercial paper renders the preparation of highly conductive flexible paper substrate for subsequent deposition of polyaniline (PANi) n...The direct coating of graphene sheets obtained by electrochemical exfoliation on commercial paper renders the preparation of highly conductive flexible paper substrate for subsequent deposition of polyaniline (PANi) nanorods via electrochemical polymerization. The deposit ion of PANi can be well-controlled by adjusting the electrochemical polymerization time, leading to the formation of PANi coated graphene paper (PANi-GP). The as-prepared electrode exhibited high areal capacitance of 176 mF cm^-2 in three-electrode system at a current density of 0.2 mA cm^-2 which is around 10 times larger than that of pris-tine graphene paper due to the pseudocapacitive behavior of PANi. In-situ Raman test was used to determine the molecular changes during redox process of PANi. More importantly, all-solid-state symmetric capacitor assembled with two PANi-GP electrodes in a polymer electrolyte delivered an areal capacitanee of 123 mF cm^-2, corresponding to an areal energy density of 17.1 μWh cm^-2 and an areal power density of 0.25 mW cm^-2. The symmetric capacitor held a capacitive retention of 74.8% after 500 bending tests from 0 to 120°, suggesting the good flexibility and mechanical stability. These results showed the great promising application in flexible energy-storage devices.展开更多
With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent p...With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent properties,such as distinct pleated structures in layers,adjustable direct bandgap,high carrier mobility,moderate on/off ratio,large specific surface area,and various interesting in-layer anisotropies.However,the realization of these excellent properties depends on the preparation of highquality 2 D BP sheets.Electrochemical exfoliation methods are typically performed under mild conditions,thus,these methods are convenient,controllable,and can produce high-quality 2 D BP sheets.This review summarizes research progress in BP sheets preparation through anodic,cathodic,and electrolyte exfoliation in recent years.Different exfoliating methods affect the quality of 2 D BP sheets.Moreover,possible exfoliating mechanisms and the potential applications of different exfoliating methods are summarized and discussed in detail.Lastly,the shortcomings of existing research on electrochemical exfoliation are presented,and suggestions and prospects for future research on the electrochemical exfoliation of 2 D BP are proposed.展开更多
Aluminum^-graphene battery is promising for its abundant raw materials,high power density,ultralong cycle life and superior safety.However,the development of aluminum^-graphene battery is currently restricted by its i...Aluminum^-graphene battery is promising for its abundant raw materials,high power density,ultralong cycle life and superior safety.However,the development of aluminum^-graphene battery is currently restricted by its insufficient cathode capacity,calling for a newly developed working mechanism.In addition,an irregular constant increase of the cathode capacity was always observed during cycling,but cannot be explained based on the current understanding.Here,we observed an increase of specific capacity by 60%with stable Coulombic efficiency of 98%during 7000 cycles life of Al-graphene batteries employing AlCl3/ET3NHCl electrolyte.We demonstrated this growing cathode capacity is attributed to an increasing contribution of capacitive charge storage during cycling,because a gradually enlarged surface area as capacitive active sites is enabled by the exfoliation of graphitic cathode during the periodic intercalation process.Moreover,the graphene cathode was exfoliated more significantly in AlCl3/ET3NHCl than 1-ethyl-3-methylimidazolium chloride-based electrolyte,which results from the heavier stress on the graphene layers caused by the larger intercalants in AlCl3/ET3NHCl.The common intercalation of cations with AlCl4-clusters was therefore supposed to occur during charging.This new proposed mechanism can offer the new thought for future design on high-capacity cathode of Al-ion battery.展开更多
The various methods for microwave processing of materials exhibit numerous advantages,such as short processing times,high yield,expanded reaction conditions,high reproducibility,and high purity of products.Microwave-a...The various methods for microwave processing of materials exhibit numerous advantages,such as short processing times,high yield,expanded reaction conditions,high reproducibility,and high purity of products.Microwave-assisted synthesis strategies have been widely adopted for the preparation of highperformance graphene-based materials for supercapacitor electrodes.Metal oxides,mixed metal oxides,metal hydroxides,layered double hydroxides,carbon nanotubes and conducting polymers are some of the main materials which have been added to graphene derivatives for advanced composite/hybrid electrodes.This review article first provides a brief introduction and an overview of microwave heating and its advantages for processing graphene-based electrode materials.After that,a systematic survey of recently published research on microwave irradiation-assisted processing is presented,focusing on:(i)transformation of graphite/graphite oxide into graphene/graphene oxide by exfoliation and reduction;(ii)formation of graphene derivatives in various liquid and gaseous media;(iii)modification of graphene derivatives with various metal oxides/hydroxides,carbon nanotubes,and conducting polymers for use in supercapacitors.Major challenges and future perspectives for microwave-assisted processing of graphene-based materials for cutting-edge supercapacitor electrode applications are also summarized in the conclusion.展开更多
Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductilit...Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network.A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles,generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies,such as ultrasonication,high-shear mixing and ball milling.Inspired by nacre,a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol-gel-film transformation.It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers,but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.展开更多
Graphene nanosheets(GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. Th...Graphene nanosheets(GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. The results show that the GSs with pore sizes center around 4.0 nm. With an increase of thermal reduction temperature, the number of stacking layers and the structure disorder degree increase, while the oxygen-containing groups content, BET surface area,and electrical resistivity of GSs decrease. The results indicate that 673 K is the preferable thermal exfoliation temperature to acquire good supercapacitive performance. In this case, the GSs have the best supercapacitive performance(233.1 F g-1) in a 6 mol L-1KOH electrolyte. The prepared GSs at the preferable thermal exfoliation temperature have good rate performance and cycle stability.展开更多
Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate an...Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate and effective methods for fabricating Sn-based biomaterials.Herein,we explored a new approach combining cryogenic exfoliation and liquid-phase exfoliation to successfully manufacture two-dimensional(2D)Sn nanosheets(SnNSs).The obtained SnNSs exhibited a typical sheet-like structure with an average size of~100 nm and a thickness of~5.1 nm.After PEGylation,the resulting PEGylated SnNSs(SnNSs@PEG)exhibited good stability,superior biocompatibility,and excellent photothermal performance,which could serve as robust photothermal agents for multi-modal imaging(fluorescence/photoacoustic/photothermal imaging)-guided photothermal elimination of cancer.Furthermore,we also used first-principles density functional theory calculations to investigate the photothermal mechanism of SnNSs,revealing that the free electrons in upper and lower layers of SnNSs contribute to the conversion of the photo to thermal.This work not only introduces a new approach to fabricate 2D SnNSs but also establishes the SnNSs-based nanomedicines for photonic cancer theranostics.This new type of SnNSs with great potential in the field of nanomedicines may spur a wave of developing Sn-based biological materials to benefit biomedical applications.展开更多
Electrochemistry has emerged as a major route for graphene and graphene oxide synthesis from graphite.Anodic graphite oxidation is commonly used with dilute mineral acid or aqueous salt electrolytes.In this system,the...Electrochemistry has emerged as a major route for graphene and graphene oxide synthesis from graphite.Anodic graphite oxidation is commonly used with dilute mineral acid or aqueous salt electrolytes.In this system,the electrolyte acid concentration appears to be a critical parameter.However,the effect of the acid concentration,particularly at low concentrations,is still not fully understood.To address this issue,we used a packed bed electrochemical reactor to synthesize seven different electrochemical graphite oxide(EGO)products in 2–16M sulfuric acid.Detailed XRD,XPS,Raman,conductivity and optical microscopy analysis of the products was carried out.We found dilute acid(<10 M)graphite oxides were less crystalline and less oxidized than those produced in stronger acids.The oxygen evolution reaction at the graphite surface appears to affect the structural changes,oxidation mechanism,and electrochemical corrosion of the anode.EGO conductivity is also strongly affected by the electrolyte’s acidity.We show that well oxidized,yet reasonably conductive,single layer graphene oxide can be produced from 7.1M acid.These results broaden our understanding of graphite electrochemistry and will serve to inform future electrochemical graphene synthesis efforts.展开更多
MoS_(2) is a highly promising material for application in lithium-ion battery anodes due to its high theoretical capacity and low cost.However,problems with a fast capacity decay over cycling,especially at the first c...MoS_(2) is a highly promising material for application in lithium-ion battery anodes due to its high theoretical capacity and low cost.However,problems with a fast capacity decay over cycling,especially at the first cycles,and poor rate performance have deterred its practical implementation.Herein,electrodes comprised solely of few-layers 2D MoS_(2) nanosheets have been manufactured by scalable liquid-phase exfoliation and spray deposition methods.The long-standing controversy questioning the reversibility of conversion processes of MoS_(2)-based electrodes was addressed.Raman studies revealed that,in 2D MoS_(2) electrodes,conversion processes are indeed reversible,where nanostructure played a key role.Cycling of the electrodes at high current rates revealed an intriguing phenomenon consisting of a continuously increasing capacity after ca.100-200 cycles.This phenomenon was comprehensively addressed by a variety of electrochemical and microscopy methods that revealed underlying physical activation mechanisms that involved a range of profound electrode structural changes.Activation mechanisms delivered a capacitive electrode of a superior rate performance and cycling stability,as compared to the corresponding pristine electrodes,and to MoS_(2) electrodes previously reported.Herein,we have devised a methodology to overcome the problem of cycling stability of 2D MoS_(2) electrodes.Moreover,activation of electrodes constitutes a methodology that could be applied to enhance the energy storage performance of electrodes based on other 2D nanomaterials,or combinations thereof,strategically combining chemistries to engineer electrodes of superior energy storage properties.展开更多
The doping of functionalized graphene oxide(GO)in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells(HT-PEMFC).Phosphonated graphene oxide(PG...The doping of functionalized graphene oxide(GO)in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells(HT-PEMFC).Phosphonated graphene oxide(PGO)with a P/O ratio of 8.5%was quickly synthesised by one-step electrochemical exfoliation based on a three-dimensiaonal(3D)printed reactor and natural graphite flakes.Compared with the GO prepared by the two-step electrochemical exfoliation method,the PGO synthesized by the one-step electrochemical exfoliation can better improve the performance of the membrane-electrode-assembly(MEA)based on the polybenzimidazole(PBI)membrane in the HTPEMFC.The doping of 1.5 wt%GO synthesised by electrochemical exfoliation with the 2-step method or reactor method in PBI increased the peak power density by 17.4%or 35.4%compared to MEA based on pure PBI membrane at 150℃,respectively.In addition,the doping of PGO in PBI improves its durability under accelerated stress test(AST).展开更多
High-quality graphene flakes have long been desirable for numerous applications including energy stor- age, printable electronics, and catalysis. In this contribution, we report a green, efficient, facile gas-driven e...High-quality graphene flakes have long been desirable for numerous applications including energy stor- age, printable electronics, and catalysis. In this contribution, we report a green, efficient, facile gas-driven exfoliation process for the preparation of high-quality graphene in large scale. The gas exfoliation process was realized by the interplay between the expansion of interlayer at high temperature and the gasifi- cation of liquid nitrogen within the interlayer. Detailed experiments demonstrated that the higher tem- perature was critical to the formation of fewer layers. The exfoliated graphene was proved to be of high quality. We further investigated the electrochemical behavior of this exfoliated graphene. As a result, this few-layered graphene demonstrated an enhanced capability as a supercapacitor, much higher than its counterpart parent material.展开更多
Two-dimensional（2D） organic nanomaterials are fascinating because of their unique properties and pentential applications in future optoelectronic devices.Polyaniline（PANI） has attracted much attention for its high...Two-dimensional（2D） organic nanomaterials are fascinating because of their unique properties and pentential applications in future optoelectronic devices.Polyaniline（PANI） has attracted much attention for its high conductivity,good environmental stability and unusual doping chemistry.We report on liquid-phase exfoliation of layered PANI films grown by electrochemical polymerization.Atomic force microscopy images demonstrate that few-or even mono-layer PANI nanosheets can be fabricated.The PANI nanosheets can be transferred onto a variety of surfaces,providing a promising route to their incorporation into a variety of devices for further studies and various applications.展开更多
We report a new facile light-induced strategy to disperse micron-sized aggregated bulk covalent organic frameworks(COFs)into isolated COFs nanoparticles.This was achieved by a series of metal-coordinated COFs,namely C...We report a new facile light-induced strategy to disperse micron-sized aggregated bulk covalent organic frameworks(COFs)into isolated COFs nanoparticles.This was achieved by a series of metal-coordinated COFs,namely COF-909-Cu,-Co or-Fe,where for the first time the diffusio-phoretic propulsion was utilized to design COF-based micro/nanomotors.The mechanism studies revealed that the metal ions decorated in the COF-909 backbone could promote the separation of electron and holes and trigger the production of sufficient ionic and reactive oxygen species under visible light irradiation.In this way,strong light-induced self-diffusiophoretic effect is achieved,resulting in good dispersion of COFs.Among them,COF-909-Fe showed the highest dispersion performance,along with a drastic decrease in particle size from 5μm to500 nm,within only 30 min light irradiation,which is inaccessible by using traditional magnetic stirring or ultrasonication methods.More importantly,benefiting from the outstanding dispersion efficiency,COF-909-Fe micro/nanomotors were demonstrated to be efficient in photocatalytic degradation of tetracycline,about 8 times faster than using traditional magnetic stirring method.This work opens up a new avenue to prepare isolated nanosized COFs in a high-fast,simple,and green manner.展开更多
Disulfide zirconium(ZrS_(2)) is a two-dimensional(2D) transition metal disulfide and has given rise to extensive attention because of its distinctive electronic structure and properties.However,mass production of high...Disulfide zirconium(ZrS_(2)) is a two-dimensional(2D) transition metal disulfide and has given rise to extensive attention because of its distinctive electronic structure and properties.However,mass production of high quality of ZrS_(2)nanosheets to realize their practical application remains a challenge.Here,we have successfully exfoliated the bulk ZrS_(2)powder with the thickness of micron into single and few-layer nanosheets through liquid-phase exfoliation in N-methylpyrrolidone(NMP) assisted via aliphatic amines as intercalators.It is found that the exfoliation yield is as high as 27.3%,which is the record value for the exfoliation of ZrS_(2)nanosheets from bulk ZrS_(2)powder,and 77.1% of ZrS_(2)nanosheets are 2-3 layers.The molecular geometric size and aliphatic amine basicity have important impact on the exfoliation.Furthermore,the ZrS_(2)nanosheets have been used as catalyst in the electrocatalytic dinitrogen reduction with the NH3yield of 57.75 μg h^(-1)mg_(cat.)^(-1),which is twice that by ZrS_(2)nanofibers reported in literature and three times that by the bulk ZrS_(2)powder.Therefore,the liquid phase exfoliation strategy reported here has great potential in mass production of ZrS_(2)nanosheets for high activity electrocatalysis.展开更多
基金financially supported by the National Major Project (No. 2017ZX05009-003,50)National Natural Science Foundation of China (No. 51974339+2 种基金51674270)Foreign Expert Project of the Belt and Road Innovation Talents Exchange (DL2022122001)the Research Institute of Petroleum Exploration Development of China National Petroleum Cooperation (HX20201095)。
文摘It has been demonstrated that almost all polymer-clay nanocomposites show higher temperature stability than that of pure polymer, which is attributed to the active exfoliated clay nanosheet firmly adsorbed onto the polymer chains, due to polerization and nucleation effect, the clay nanosheets could protect the polymer chains from destroying. To prove such mechanism, the water-soluble polymer nanocomposites(AAA/SLS-MMT) were synthesized by the in-situ polymerization of 2-acrylamide-2-methyl-propane sulfonic acid, acrylamide, 4-acryloylmorpholine, and organically modified montmorillonite. The techniques of nuclear magnetic resonance, atomic force microscopy and scanning electron microscopy etc., clearly characterized the successful synthesized of sample's structure, the exfoliated MMT nanosheet adsorbed polymer chain's scale, and well-dispersed morphology, espectively. The adsorption model, X-ray photoelectron spectroscopy presented the existence of strong adsorption, while molecular simulation calculations first concluded that the strong adsorption energy was-13032.06 kcal/mol. Thermo-gravimetric-analysis proved the temperature of maximum thermal degradation of powder sample(AAA/1.0 wt% SLS-MMT) was over 298℃. After ageing at 180℃ for 4 h, the apparent viscosity of 5 g/L AAA/1.0 wt% SLS-MMT aqueous solution was 326.7 mPa,s, while that of pure polymer(AAA) was only 8.3 mPa,s. This optimized sample has the smallest FLAPIvalue at all test temperatures from 180 to 220℃ in both fresh and salt water based drilling fluid. All the evidences of high temperature resistance indicate that the strong adsorption can enhance the thickness of hydrated shell and adsorption of clay particles in drilling fluid at high temperature. Such mechanism supplied the better way to design high-temperature resistant fluid loss additives for deep and ultra-deep oil and gas formation engineering.
基金theNewEnergyandIndustrialTechnologyDevelopmentOrganizationofJapan(NEDO No .98E 1 2 0 0 2 )
文摘Exfoliated graphite (EG) is selected as a new kind of sorbent to sorb heavy oil spilled. In order to make use of EG more effectively, some basic experiments are performed to investigate its sorption properties, i.e. , specific sorption, height of saturation layer, sorption time constant. In the present experiments, A grade heavy oil is employed as a standard sorbate. It is concluded that 1) under the condition that the area of solid (filter bottom) liquid (heavy oil) interface is a constant, specific sorption usually decreases when the amount of EG filled or the apparent bulk density increase; however, the specific sorption initially increases when the apparent bulk density is too low and the amount of EG filled is too much; 2) under the condition that the apparent bulk density of EG filled is a constant, the sorption time constant tends to increase when the amount of EG filled increases; however, for a constant amount of EG filled, the sorption time constant will decrease when the apparent bulk density increases.
基金supported by the Grants from National Natural Science Foundation of China(No.51172191,51002129 and 11074211)the National Basic Research Program of China(2012CB921303)the Hunan Provincial Innovation Foundation for Graduate(No.CX2012B265)
文摘Ultrathin MoS2 nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2 nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm-2/zm. As anode material for Li-ion batteries, the as-prepared MoS2 nanosheets electrodes exhibited a good initial capacity of 1190 mAh.g-l and excellent cyclic stability at constant current density of 50 mA.g-1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh.g-1.
基金supported by the National Natural Science Foundation of China(Nos.21706283 and 21776308)Beijing Talents Foundation(No.2017000020124G010)+1 种基金Science Foundation of China University of Petroleum,Beijing(No.2462017YJRC003)the Joint Open Fund of Jiangsu Collaborative Innovation Center for Ecological Building Material and Environmental Protection Equipment and Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province(No.JH201812)。
文摘The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of energy density of LIBs is restricted by the limited capacity below 0.5 V of CG.Here,based on the supercritical CO2 exfoliation technique,the production of multi-layered graphene(MLG)is achieved from the pilot scale production line.The great merit of the exfoliated MLG anode is that the voltage plateau below 0.5 V is broadened obviously as compared to those of natural graphite and CG.Additionally,no obvious lithium dendrites are observed for MLG during the lithiation process.The large delithiation capacity under the low voltage plateau of MLG is mainly benefited from the combination of Li intercalation and boundary storage mechanism,which is further confirmed by the density functional theory calculations.The LiFePO4/MLG full cell can afford the satisfactory electrochemical property with respect to the capacity,energy density and ultralong cycling stability(90%capacity retention after 500 cycles at 2 C),significantly better than that of LiFePO4/CG.Besides,this developed technique not only dedicates to producing the high-performance anode for LIBs but also opens a door for the mass production of MLG in the industrial scale.
基金supported by the National Science Foundation Grant Number 1454151
文摘Intensive research effort is currently focused on the development of efficient, reliable, and environmentally safe electrochemical energy storage systems due to the ever-increasing global energy storage demand. Li ion battery systems have been used as the primary energy storage device over the last three decades. However, low abundance and uneven distribution of lithium and cobalt in the earth crust and the associated cost of these materials, have resulted in a concerted effort to develop beyond lithium electrochemical storage systems. In the case of non-Li ion rechargeable systems, the development of electrode materials is a significant challenge, considering the larger ionic size of the metal-ions and slower kinetics. Two-dimensional(2D) materials, such as graphene, transition metal dichalcogenides, MXenes and phosphorene, have garnered significant attention recently due to their multi-faceted advantageous properties: large surface areas, high electrical and thermal conductivity, mechanical strength, etc. Consequently, the study of 2D materials as negative electrodes is of notable importance as emerging non-Li battery systems continue to generate increasing attention. Among these interesting materials, graphene has already been extensively studied and reviewed, hence this report focuses on 2D materials beyond graphene for emerging non-Li systems. We provide a comparative analysis of 2D material chemistry, structure, and performance parameters as anode materials in rechargeable batteries and supercapacitors.
基金financially supported by the National Natural Science Foundation of China(No.21503116)The Taishan Scholars Program of Shandong Province(No.tsqn20161004)the Youth1000 Talent Program of China
文摘The direct coating of graphene sheets obtained by electrochemical exfoliation on commercial paper renders the preparation of highly conductive flexible paper substrate for subsequent deposition of polyaniline (PANi) nanorods via electrochemical polymerization. The deposit ion of PANi can be well-controlled by adjusting the electrochemical polymerization time, leading to the formation of PANi coated graphene paper (PANi-GP). The as-prepared electrode exhibited high areal capacitance of 176 mF cm^-2 in three-electrode system at a current density of 0.2 mA cm^-2 which is around 10 times larger than that of pris-tine graphene paper due to the pseudocapacitive behavior of PANi. In-situ Raman test was used to determine the molecular changes during redox process of PANi. More importantly, all-solid-state symmetric capacitor assembled with two PANi-GP electrodes in a polymer electrolyte delivered an areal capacitanee of 123 mF cm^-2, corresponding to an areal energy density of 17.1 μWh cm^-2 and an areal power density of 0.25 mW cm^-2. The symmetric capacitor held a capacitive retention of 74.8% after 500 bending tests from 0 to 120°, suggesting the good flexibility and mechanical stability. These results showed the great promising application in flexible energy-storage devices.
基金financially supported by the Youth talent support program of science and technology association of colleges of Shaanxi Province(Grant No.20190609)the Special scientific research plan of education department of Shaanxi province(Grant No.19JK0190 and 19JK0186)+3 种基金the Natural Science Foundation of Shaanxi Province(Grant No.2019JM508)the Open project of Key laboratory of catalytic foundation and application of Shaanxi province(Grant No.SLGPT2019KF01-23)the Opening Foundation of Shaanxi Key Laboratory of Industrial Automation(No.SLGPT2019KF01-10)the School-level project of Shaanxi University of Technology(Grant No.SLGRC03,SLGRC02)。
文摘With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent properties,such as distinct pleated structures in layers,adjustable direct bandgap,high carrier mobility,moderate on/off ratio,large specific surface area,and various interesting in-layer anisotropies.However,the realization of these excellent properties depends on the preparation of highquality 2 D BP sheets.Electrochemical exfoliation methods are typically performed under mild conditions,thus,these methods are convenient,controllable,and can produce high-quality 2 D BP sheets.This review summarizes research progress in BP sheets preparation through anodic,cathodic,and electrolyte exfoliation in recent years.Different exfoliating methods affect the quality of 2 D BP sheets.Moreover,possible exfoliating mechanisms and the potential applications of different exfoliating methods are summarized and discussed in detail.Lastly,the shortcomings of existing research on electrochemical exfoliation are presented,and suggestions and prospects for future research on the electrochemical exfoliation of 2 D BP are proposed.
基金supported by the National Natural Science Foundation of China(No.51533008)National Key R&D Program of China(No.2016YFA0200200)+1 种基金Key Research and Development Plan of Zhejiang Province(2018C01049)Fujian Provincial Science and Technology Major Projects(No.2018HZ0001-2)。
文摘Aluminum^-graphene battery is promising for its abundant raw materials,high power density,ultralong cycle life and superior safety.However,the development of aluminum^-graphene battery is currently restricted by its insufficient cathode capacity,calling for a newly developed working mechanism.In addition,an irregular constant increase of the cathode capacity was always observed during cycling,but cannot be explained based on the current understanding.Here,we observed an increase of specific capacity by 60%with stable Coulombic efficiency of 98%during 7000 cycles life of Al-graphene batteries employing AlCl3/ET3NHCl electrolyte.We demonstrated this growing cathode capacity is attributed to an increasing contribution of capacitive charge storage during cycling,because a gradually enlarged surface area as capacitive active sites is enabled by the exfoliation of graphitic cathode during the periodic intercalation process.Moreover,the graphene cathode was exfoliated more significantly in AlCl3/ET3NHCl than 1-ethyl-3-methylimidazolium chloride-based electrolyte,which results from the heavier stress on the graphene layers caused by the larger intercalants in AlCl3/ET3NHCl.The common intercalation of cations with AlCl4-clusters was therefore supposed to occur during charging.This new proposed mechanism can offer the new thought for future design on high-capacity cathode of Al-ion battery.
基金Science and Engineering Research Board(SERB),Department of Science&Technology(DST),New Delhi,India for providing research fund under Ramanujan Fellowship/Award(SB/S2/RJN-159/2017)。
文摘The various methods for microwave processing of materials exhibit numerous advantages,such as short processing times,high yield,expanded reaction conditions,high reproducibility,and high purity of products.Microwave-assisted synthesis strategies have been widely adopted for the preparation of highperformance graphene-based materials for supercapacitor electrodes.Metal oxides,mixed metal oxides,metal hydroxides,layered double hydroxides,carbon nanotubes and conducting polymers are some of the main materials which have been added to graphene derivatives for advanced composite/hybrid electrodes.This review article first provides a brief introduction and an overview of microwave heating and its advantages for processing graphene-based electrode materials.After that,a systematic survey of recently published research on microwave irradiation-assisted processing is presented,focusing on:(i)transformation of graphite/graphite oxide into graphene/graphene oxide by exfoliation and reduction;(ii)formation of graphene derivatives in various liquid and gaseous media;(iii)modification of graphene derivatives with various metal oxides/hydroxides,carbon nanotubes,and conducting polymers for use in supercapacitors.Major challenges and future perspectives for microwave-assisted processing of graphene-based materials for cutting-edge supercapacitor electrode applications are also summarized in the conclusion.
基金support from the National Natural Science Foundation of China(51973054)Young Talents Program in Hunan Province(2020RC3024)+2 种基金Natural Science Funds of Hunan Province for Distinguished Young Scholar(2021JJ10018)Science Research Project of Hunan Provincial Education Department(21B0027)High-level Innovative Talent Project in Hunan Province(2018RS3055).
文摘Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices.Herein,we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network.A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles,generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies,such as ultrasonication,high-shear mixing and ball milling.Inspired by nacre,a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol-gel-film transformation.It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers,but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.
基金supported by the National Natural Science Foundation of China (Grant No. 41272051)the Doctor Foundation of Southwest University of Science and Technology (Grant No. 11ZX7135)
文摘Graphene nanosheets(GSs) were prepared from graphite oxide by thermal exfoliation method. The effect of thermal exfoliation temperature on the structure and supercapacitive performance of GSs has been investigated. The results show that the GSs with pore sizes center around 4.0 nm. With an increase of thermal reduction temperature, the number of stacking layers and the structure disorder degree increase, while the oxygen-containing groups content, BET surface area,and electrical resistivity of GSs decrease. The results indicate that 673 K is the preferable thermal exfoliation temperature to acquire good supercapacitive performance. In this case, the GSs have the best supercapacitive performance(233.1 F g-1) in a 6 mol L-1KOH electrolyte. The prepared GSs at the preferable thermal exfoliation temperature have good rate performance and cycle stability.
基金the US METAvivor Early Career Investigator Award(W.T.)and Harvard Medical School/Brigham and Women’s Hospital Department of Anesthesiology-Basic Scientist Grant(W.T.)National Natural Science Foundation of China(Nos.21877049,21807117)+2 种基金Major Program for Tackling Key Problems of Industrial Technology in Guangzhou(201902020013)Dedicated Fund for Promoting High-Quality Marine Economic Development in Guangdong Province(GDOE-2019-A31,2020-035)Dr J.Ouyang was supported by the China Postdoctoral Science Foundation(No.2020M683173).
文摘Stanene(Sn)-based materials have been extensively applied in industrial production and daily life,but their potential biomedical application remains largely unexplored,which is due to the absence of the appropriate and effective methods for fabricating Sn-based biomaterials.Herein,we explored a new approach combining cryogenic exfoliation and liquid-phase exfoliation to successfully manufacture two-dimensional(2D)Sn nanosheets(SnNSs).The obtained SnNSs exhibited a typical sheet-like structure with an average size of~100 nm and a thickness of~5.1 nm.After PEGylation,the resulting PEGylated SnNSs(SnNSs@PEG)exhibited good stability,superior biocompatibility,and excellent photothermal performance,which could serve as robust photothermal agents for multi-modal imaging(fluorescence/photoacoustic/photothermal imaging)-guided photothermal elimination of cancer.Furthermore,we also used first-principles density functional theory calculations to investigate the photothermal mechanism of SnNSs,revealing that the free electrons in upper and lower layers of SnNSs contribute to the conversion of the photo to thermal.This work not only introduces a new approach to fabricate 2D SnNSs but also establishes the SnNSs-based nanomedicines for photonic cancer theranostics.This new type of SnNSs with great potential in the field of nanomedicines may spur a wave of developing Sn-based biological materials to benefit biomedical applications.
基金support from the Australian Research Council (LP160101521 and DP190100120)
文摘Electrochemistry has emerged as a major route for graphene and graphene oxide synthesis from graphite.Anodic graphite oxidation is commonly used with dilute mineral acid or aqueous salt electrolytes.In this system,the electrolyte acid concentration appears to be a critical parameter.However,the effect of the acid concentration,particularly at low concentrations,is still not fully understood.To address this issue,we used a packed bed electrochemical reactor to synthesize seven different electrochemical graphite oxide(EGO)products in 2–16M sulfuric acid.Detailed XRD,XPS,Raman,conductivity and optical microscopy analysis of the products was carried out.We found dilute acid(<10 M)graphite oxides were less crystalline and less oxidized than those produced in stronger acids.The oxygen evolution reaction at the graphite surface appears to affect the structural changes,oxidation mechanism,and electrochemical corrosion of the anode.EGO conductivity is also strongly affected by the electrolyte’s acidity.We show that well oxidized,yet reasonably conductive,single layer graphene oxide can be produced from 7.1M acid.These results broaden our understanding of graphite electrochemistry and will serve to inform future electrochemical graphene synthesis efforts.
基金financial support from the China Scholarship Council(CSC grant.201808330389)。
文摘MoS_(2) is a highly promising material for application in lithium-ion battery anodes due to its high theoretical capacity and low cost.However,problems with a fast capacity decay over cycling,especially at the first cycles,and poor rate performance have deterred its practical implementation.Herein,electrodes comprised solely of few-layers 2D MoS_(2) nanosheets have been manufactured by scalable liquid-phase exfoliation and spray deposition methods.The long-standing controversy questioning the reversibility of conversion processes of MoS_(2)-based electrodes was addressed.Raman studies revealed that,in 2D MoS_(2) electrodes,conversion processes are indeed reversible,where nanostructure played a key role.Cycling of the electrodes at high current rates revealed an intriguing phenomenon consisting of a continuously increasing capacity after ca.100-200 cycles.This phenomenon was comprehensively addressed by a variety of electrochemical and microscopy methods that revealed underlying physical activation mechanisms that involved a range of profound electrode structural changes.Activation mechanisms delivered a capacitive electrode of a superior rate performance and cycling stability,as compared to the corresponding pristine electrodes,and to MoS_(2) electrodes previously reported.Herein,we have devised a methodology to overcome the problem of cycling stability of 2D MoS_(2) electrodes.Moreover,activation of electrodes constitutes a methodology that could be applied to enhance the energy storage performance of electrodes based on other 2D nanomaterials,or combinations thereof,strategically combining chemistries to engineer electrodes of superior energy storage properties.
基金financially supported by the UK Research Council EPSRC EP/009050/1。
文摘The doping of functionalized graphene oxide(GO)in the membranes becomes a promising method for improving the performance of high-temperature proton exchange membrane fuel cells(HT-PEMFC).Phosphonated graphene oxide(PGO)with a P/O ratio of 8.5%was quickly synthesised by one-step electrochemical exfoliation based on a three-dimensiaonal(3D)printed reactor and natural graphite flakes.Compared with the GO prepared by the two-step electrochemical exfoliation method,the PGO synthesized by the one-step electrochemical exfoliation can better improve the performance of the membrane-electrode-assembly(MEA)based on the polybenzimidazole(PBI)membrane in the HTPEMFC.The doping of 1.5 wt%GO synthesised by electrochemical exfoliation with the 2-step method or reactor method in PBI increased the peak power density by 17.4%or 35.4%compared to MEA based on pure PBI membrane at 150℃,respectively.In addition,the doping of PGO in PBI improves its durability under accelerated stress test(AST).
基金the China National Natural Science Foundation of China (Nos. 21722604, 21576122, 21376111)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)+1 种基金a scholarship from the China Scholarship Council (CSC)the Postgraduate Innovation Project of Jiangsu Province (NO. KYLX15_1067)
文摘High-quality graphene flakes have long been desirable for numerous applications including energy stor- age, printable electronics, and catalysis. In this contribution, we report a green, efficient, facile gas-driven exfoliation process for the preparation of high-quality graphene in large scale. The gas exfoliation process was realized by the interplay between the expansion of interlayer at high temperature and the gasifi- cation of liquid nitrogen within the interlayer. Detailed experiments demonstrated that the higher tem- perature was critical to the formation of fewer layers. The exfoliated graphene was proved to be of high quality. We further investigated the electrochemical behavior of this exfoliated graphene. As a result, this few-layered graphene demonstrated an enhanced capability as a supercapacitor, much higher than its counterpart parent material.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574382,51372095,and 91323304)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDJ-SSW-SYS014)
文摘Two-dimensional（2D） organic nanomaterials are fascinating because of their unique properties and pentential applications in future optoelectronic devices.Polyaniline（PANI） has attracted much attention for its high conductivity,good environmental stability and unusual doping chemistry.We report on liquid-phase exfoliation of layered PANI films grown by electrochemical polymerization.Atomic force microscopy images demonstrate that few-or even mono-layer PANI nanosheets can be fabricated.The PANI nanosheets can be transferred onto a variety of surfaces,providing a promising route to their incorporation into a variety of devices for further studies and various applications.
基金supported by Huazhong University of Science and Technology(No.2021XXJS036,3004013134)National Natural Science Foundation of China(No.51903099,82002879,22102059)+2 种基金the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(No.B21003)China Postdoctoral Science Foundation(2021M692475,2021T140524,XJ2021037)support from the 100 Talents Program of the Hubei Provincial Government。
文摘We report a new facile light-induced strategy to disperse micron-sized aggregated bulk covalent organic frameworks(COFs)into isolated COFs nanoparticles.This was achieved by a series of metal-coordinated COFs,namely COF-909-Cu,-Co or-Fe,where for the first time the diffusio-phoretic propulsion was utilized to design COF-based micro/nanomotors.The mechanism studies revealed that the metal ions decorated in the COF-909 backbone could promote the separation of electron and holes and trigger the production of sufficient ionic and reactive oxygen species under visible light irradiation.In this way,strong light-induced self-diffusiophoretic effect is achieved,resulting in good dispersion of COFs.Among them,COF-909-Fe showed the highest dispersion performance,along with a drastic decrease in particle size from 5μm to500 nm,within only 30 min light irradiation,which is inaccessible by using traditional magnetic stirring or ultrasonication methods.More importantly,benefiting from the outstanding dispersion efficiency,COF-909-Fe micro/nanomotors were demonstrated to be efficient in photocatalytic degradation of tetracycline,about 8 times faster than using traditional magnetic stirring method.This work opens up a new avenue to prepare isolated nanosized COFs in a high-fast,simple,and green manner.
基金the financial supports from the National Natural Science Foundation of China (No.U1704251 and 21733011)the National Key Research and Development Program of China (2017YFA0403101)+1 种基金Natural Science Foundation of Henan province (No.202300410220)the 111 Project (No.D17007)。
文摘Disulfide zirconium(ZrS_(2)) is a two-dimensional(2D) transition metal disulfide and has given rise to extensive attention because of its distinctive electronic structure and properties.However,mass production of high quality of ZrS_(2)nanosheets to realize their practical application remains a challenge.Here,we have successfully exfoliated the bulk ZrS_(2)powder with the thickness of micron into single and few-layer nanosheets through liquid-phase exfoliation in N-methylpyrrolidone(NMP) assisted via aliphatic amines as intercalators.It is found that the exfoliation yield is as high as 27.3%,which is the record value for the exfoliation of ZrS_(2)nanosheets from bulk ZrS_(2)powder,and 77.1% of ZrS_(2)nanosheets are 2-3 layers.The molecular geometric size and aliphatic amine basicity have important impact on the exfoliation.Furthermore,the ZrS_(2)nanosheets have been used as catalyst in the electrocatalytic dinitrogen reduction with the NH3yield of 57.75 μg h^(-1)mg_(cat.)^(-1),which is twice that by ZrS_(2)nanofibers reported in literature and three times that by the bulk ZrS_(2)powder.Therefore,the liquid phase exfoliation strategy reported here has great potential in mass production of ZrS_(2)nanosheets for high activity electrocatalysis.
