Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology r...Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.展开更多
For the application of carbon capture by membrane process,it is crucial to develop a highly permeable CO_(2)-selective membrane.In this work,we reported an ultra-thin polyether-block-amide(Pebax)mixedmatrix membranes(...For the application of carbon capture by membrane process,it is crucial to develop a highly permeable CO_(2)-selective membrane.In this work,we reported an ultra-thin polyether-block-amide(Pebax)mixedmatrix membranes(MMMs)incorporated by graphene oxide(GO),in which the interlayer channels were regulated to optimize the CO_(2)/N_(2) separation performance.Various membrane preparation conditions were systematically investigated on the influence of the membrane structure and separation performance,including the lateral size of GO nanosheets,GO loading,thermal reduction temperature,and time.The results demonstrated that the precisely regulated interlayer channel of GO nanosheets can rapidly provide CO_(2)-selective transport channels due to the synergetic effects of size sieving and preferential adsorption.The GO/Pebax ultra-thin MMMs exhibited CO_(2)/N_(2) selectivity of 72 and CO_(2) permeance of 400 GPU(1 GPU=106 cm^(3)(STP)·cm^(2)·s^(-1)·cmHg^(-1)),providing a promising candidate for CO_(2) capture.展开更多
Manganese ferrite(MnFe_(2)O_(4))has the advantages of simple preparation,high resistivity,and high crystal symmetry.Herein,we have developed an electrochemical sensor utilizing graphene and MnFe_(2)O_(4) nanocomposite...Manganese ferrite(MnFe_(2)O_(4))has the advantages of simple preparation,high resistivity,and high crystal symmetry.Herein,we have developed an electrochemical sensor utilizing graphene and MnFe_(2)O_(4) nanocomposites modified glassy carbon electrode(GCE),which is very efficient and sensitive to detect bisphenol A(BPA).MnFe_(2)O_(4)/graphene(GR)was synthesized by immobilizing the MnFe_(2)O_(4) microspheres on the graphene nanosheets via a simple one-pot solvothermal method.The morphology and structure of the MnFe_(2)O_(4)/GR nanocomposite have been characterized through scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).In addition,electrochemical properties of the modified materials are comparably explored by means of cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential pulse voltammetry(DPV).Under the optimal conditions,the proposed electrochemical sensor for the detection of BPA has a linear range of 0.8-400μmol/L and a detection limit of 0.0235μmol/L(S/N=3)with high sensitivity,good selectivity and high stability.In addition,the proposed sensor was used to measure the content of BPA in real water samples with a recovery rate of 97.94%-104.56%.At present,the synthesis of MnFe_(2)O_(4)/GR provides more opportunities for the electrochemical detection of BPA in practical applications.展开更多
We have prepared the graphene∕MoS2 heterostructure by a hydrothermal method, and presented its nonlinear absorption parameters and application as a nonlinear optical modulator in the mid-infrared region.Using the non...We have prepared the graphene∕MoS2 heterostructure by a hydrothermal method, and presented its nonlinear absorption parameters and application as a nonlinear optical modulator in the mid-infrared region.Using the nonlinear optical modulator, stable passively Q-switched operation of an Er^(3+)-doped ZrF4-BaF2-LaF3-AlF3-NaF(ZBLAN) fiber laser at ~2.8 μm can be obtained. The Q-switched Er^(3+)-doped ZBLAN fiber laser can yield per-pulse energy up to 2.2 μJ with the corresponding pulse width and pulse repetition rate of 1.9 μs and 45 kHz, respectively. Our results indicate that the graphene∕MoS2 heterostructure can be a robust optical modulator for pulsed lasers in the mid-infrared spectral range.展开更多
本研究以氧化石墨烯为前驱体,利用钼酸钠和硫脲通过水热法在不同阳离子表面活性剂(C14TAB,C16TAB,C18TAB)的辅助下合成得到MoS_2/GF复合结构。XRD和SEM分析表明,MoS_2/GF复合材料因阳离子表面活性剂的不同而呈现不同的结构和表面形貌;...本研究以氧化石墨烯为前驱体,利用钼酸钠和硫脲通过水热法在不同阳离子表面活性剂(C14TAB,C16TAB,C18TAB)的辅助下合成得到MoS_2/GF复合结构。XRD和SEM分析表明,MoS_2/GF复合材料因阳离子表面活性剂的不同而呈现不同的结构和表面形貌;电化学性能测试表明其结构和表面形貌对电极的容量、循环稳定性和倍率性能都有较大影响。相比于C16TAB和C18TAB,C14TAB辅助合成的MoS_2/GF复合结构具有最高的首次放电容量(955 m Ah/g),50次循环后仍保持751 m Ah/g的可逆容量,而且倍率性能更好。本研究揭示MoS_2/GF复合材料电化学性能的提升可归因于其独特的praticle-on-sheet结构以及MoS_2与石墨烯之间的协同作用。展开更多
The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clu...The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.展开更多
Reduced graphene oxide(rGO)aerogels are emerging as very attractive scaffolds for high-performance electromagnetic wave absorption materials(EWAMs)due to their intrinsic conductive networks and intricate interior micr...Reduced graphene oxide(rGO)aerogels are emerging as very attractive scaffolds for high-performance electromagnetic wave absorption materials(EWAMs)due to their intrinsic conductive networks and intricate interior microstructure,as well as good compatibility with other electromagnetic(EM)components.Herein,we realized the decoration of rGO aerogel with Mo_(2)C nanoparticles by sequential hydrothermal assembly,freeze-drying,and high-temperature pyrolysis.Results show that Mo_(2)C nanoparticle loading can be easily controlled by the ammonium molybdate to glucose molar ratio.The hydrophobicity and thermal insulation of the rGO aerogel are effectively improved upon the introduction of Mo_(2)C nanoparticles,and more importantly,these nanoparticles regulate the EM properties of the rGO aerogel to a large extent.Although more Mo_(2)C nanoparticles may decrease the overall attenuation ability of the rGO aerogel,they bring much better impedance matching.At a molar ratio of 1:1,a desirable balance between attenuation ability and impedance matching is observed.In this context,the Mo_(2)C/r GO aerogel displays strong reflection loss and broad response bandwidth,even with a small applied thickness(1.7 mm)and low filler loading(9.0wt%).The positive effects of Mo_(2)C nanoparticles on multifunctional properties may render Mo_(2)C/r GO aerogels promising candidates for high-performance EWAMs under harsh conditions.展开更多
The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed a...The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.展开更多
The electrochemical reduction of CO_(2)(CO_(2)ER)into the renewable and sustainable green fuels,such as low-carbon alcohols,is one of several workable strategies.CO_(2)ER can be combined with renewable electricity to ...The electrochemical reduction of CO_(2)(CO_(2)ER)into the renewable and sustainable green fuels,such as low-carbon alcohols,is one of several workable strategies.CO_(2)ER can be combined with renewable electricity to transform intermittent energy sources(such as wind,hydro,and solar)into a fuel that can be stored until it is ready to be used.The intrinsic characteristics of the employed catalyst have a significant and substantial effect on the efficiency of CO_(2)ER and the ensuing economic viability.The paradigmatic multicarbon alcohol catalysts should increase the concentration of*CO in the reaction environment,stabilize the key intermediate products during the reaction,and facilitate the C-C coupling interaction.Since graphene has a large surface area and exceptional conductivity,it has been used as a support for active phases(nanoparticles or nanosheets).It is possible for graphene to enhance charge transport and accelerate CO_(2)conversion through its electronic and structural coupling effects.At the interface,a synergy can be produced that improves CO_(2)ER by increasing*CO adsorption,intermediate binding,and stability.This article focuses on recent advancements in graphene-based catalysts that promote CO_(2)ER to alcohols.Likewise,this paper also describes and discusses the key role graphene plays in catalyzing CO_(2)ER into alcohols.Finally,we hope to provide future ideas for the design of graphene-based electrocatalysts.展开更多
As a layered inorganic material,MoS2 has recently attracted intensive attention as anode for sodium ion batteries(SIBs).However,this anode is plagued with low electronic conductivity,serious volume expansion and slugg...As a layered inorganic material,MoS2 has recently attracted intensive attention as anode for sodium ion batteries(SIBs).However,this anode is plagued with low electronic conductivity,serious volume expansion and sluggish kinetics,resulting in capacity fading and poor rate performance.Herein,we develop an interface engineering strategy to substantially enhance the sodium storage performance of MoS2 by incorporating layered MoS2 into three dimensional N-doped graphene scaffold.The strong coupling-interface between MoS2 and N-doped graphene scaffold can not only stabilize the MoS2 structure during sodium insertion/extraction processes,but also provide plenty of anchor sites for additional surface sodium storage.The 3D MoS2@N-doped graphene composite as anode for SIBs performs an outstanding specific capacity of 667.3 mA h g^-1 at 0.2 A g^-1,a prolonged stability with a capacity retention of 94.4%after 140cycles and excellent rate capability of 445 mA h g^-1 even at a high rate of 10 A g^-1.We combined experiment and theoretical simulation to further disclose the interaction between MoS2 and N-doped graphene,adsorption and diffusion of sodium on the composite and the corresponding sodium storage mechanism.This study opens a new door to develop high performance SIBs by introducing the interface engineering technique.展开更多
The substrate treatment with seeding promoter can promote the two-dimensional material lateral growth in chemical vapor deposition (CVD) process. Herein, graphene quantum dots (GQDs) as a novel seeding promoter w...The substrate treatment with seeding promoter can promote the two-dimensional material lateral growth in chemical vapor deposition (CVD) process. Herein, graphene quantum dots (GQDs) as a novel seeding promoter were used to obtain uniform large-area MoS2 monolayer. The obtained monolayer MoS2 films were confirmed by optical microscope, scanning electron microscope, Raman and photoluminescence spectra. Raman mapping revealed that the MoS2 monolayer was largely homogeneous.展开更多
Two-dimensional(2D)moirématerials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties.Although great progress has been achieved,the inability...Two-dimensional(2D)moirématerials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties.Although great progress has been achieved,the inability to precisely and reproducibly manipulate the twist angle hinders the further development of twistronics.Here,we demonstrated an atomic force microscope(AFM)tip manipulation method to control the interlayer twist angle of epitaxial MoS_(2)/graphene heterostructure with an ultra-high accuracy better than 0.1°.Furthermore,conductive AFM and spectroscopic characterizations were conducted to show the effects of the twist angle on moirépattern wavelength,phonons and excitons.Our work provides a technique to precisely control the twist angle of 2D moirématerials,enabling the possibility to establish the phase diagrams of moiréphysics with twist angle.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.U2002212,52102058,52204414,52204413,and 52204412)the National Key R&D Program of China (Nos.2021YFC1910504,2019YFC1907101,2019YFC1907103,and 2017YFB0702304)+7 种基金the Key R&D Program of Ningxia Hui Autonomous Region,China (Nos.2021BEG01003 and2020BCE01001)the Xijiang Innovation and Entrepreneurship Team,China (No.2017A0109004)the Macao Young Scholars Program (No.AM2022024),Chinathe Beijing Natural Science Foundation (Nos.L212020 and 2214073),Chinathe Guangdong Basic and Applied Basic Research Foundation,China (Nos.2021A1515110998 and 2020A1515110408)the China Postdoctoral Science Foundation (No.2022M710349)the Fundamental Research Funds for the Central Universities,China (Nos.FRF-BD-20-24A,FRF-TP-20-031A1,FRF-IC-19-017Z,and 06500141)the Integration of Green Key Process Systems MIIT and Scientific and Technological Innovation Foundation of Foshan,China(Nos.BK22BE001 and BK21BE002)。
文摘Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.
基金financially supported by The Natural Science Foundation of the Jiangsu Higher Education Institutions of China(22KJB530007,22KJA530001)National Natural Science Foundation of China(22208151)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20220002)the State Key Laboratory of MaterialsOriented Chemical Engineering(SKL-MCE-22B07).
文摘For the application of carbon capture by membrane process,it is crucial to develop a highly permeable CO_(2)-selective membrane.In this work,we reported an ultra-thin polyether-block-amide(Pebax)mixedmatrix membranes(MMMs)incorporated by graphene oxide(GO),in which the interlayer channels were regulated to optimize the CO_(2)/N_(2) separation performance.Various membrane preparation conditions were systematically investigated on the influence of the membrane structure and separation performance,including the lateral size of GO nanosheets,GO loading,thermal reduction temperature,and time.The results demonstrated that the precisely regulated interlayer channel of GO nanosheets can rapidly provide CO_(2)-selective transport channels due to the synergetic effects of size sieving and preferential adsorption.The GO/Pebax ultra-thin MMMs exhibited CO_(2)/N_(2) selectivity of 72 and CO_(2) permeance of 400 GPU(1 GPU=106 cm^(3)(STP)·cm^(2)·s^(-1)·cmHg^(-1)),providing a promising candidate for CO_(2) capture.
基金Project(2108085ME184)supported by the Natural Science Foundation of Anhui Province,ChinaProject(2022AH010019)supported by the Innovation Team Project of Anhui Provincial Department of Education,China+1 种基金Project(GXXT-2021-057)supported by the Collaborative Innovation Project of Anhui Provincial Department of Education,ChinaProject(2020QDZ36)supported by the Doctoral Scientific Research Startup Foundation of Anhui Jianzhu University,China。
文摘Manganese ferrite(MnFe_(2)O_(4))has the advantages of simple preparation,high resistivity,and high crystal symmetry.Herein,we have developed an electrochemical sensor utilizing graphene and MnFe_(2)O_(4) nanocomposites modified glassy carbon electrode(GCE),which is very efficient and sensitive to detect bisphenol A(BPA).MnFe_(2)O_(4)/graphene(GR)was synthesized by immobilizing the MnFe_(2)O_(4) microspheres on the graphene nanosheets via a simple one-pot solvothermal method.The morphology and structure of the MnFe_(2)O_(4)/GR nanocomposite have been characterized through scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).In addition,electrochemical properties of the modified materials are comparably explored by means of cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential pulse voltammetry(DPV).Under the optimal conditions,the proposed electrochemical sensor for the detection of BPA has a linear range of 0.8-400μmol/L and a detection limit of 0.0235μmol/L(S/N=3)with high sensitivity,good selectivity and high stability.In addition,the proposed sensor was used to measure the content of BPA in real water samples with a recovery rate of 97.94%-104.56%.At present,the synthesis of MnFe_(2)O_(4)/GR provides more opportunities for the electrochemical detection of BPA in practical applications.
基金supported by the China Postdoctoral Science Foundation(No.2017M620349)the National Natural Science Foundation of China(Nos.61605166,11374251,and 61505124)+1 种基金the Research Foundation of Education Bureau of Hunan Province,China(No.17C1519)the Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT 17R91)
文摘We have prepared the graphene∕MoS2 heterostructure by a hydrothermal method, and presented its nonlinear absorption parameters and application as a nonlinear optical modulator in the mid-infrared region.Using the nonlinear optical modulator, stable passively Q-switched operation of an Er^(3+)-doped ZrF4-BaF2-LaF3-AlF3-NaF(ZBLAN) fiber laser at ~2.8 μm can be obtained. The Q-switched Er^(3+)-doped ZBLAN fiber laser can yield per-pulse energy up to 2.2 μJ with the corresponding pulse width and pulse repetition rate of 1.9 μs and 45 kHz, respectively. Our results indicate that the graphene∕MoS2 heterostructure can be a robust optical modulator for pulsed lasers in the mid-infrared spectral range.
文摘本研究以氧化石墨烯为前驱体,利用钼酸钠和硫脲通过水热法在不同阳离子表面活性剂(C14TAB,C16TAB,C18TAB)的辅助下合成得到MoS_2/GF复合结构。XRD和SEM分析表明,MoS_2/GF复合材料因阳离子表面活性剂的不同而呈现不同的结构和表面形貌;电化学性能测试表明其结构和表面形貌对电极的容量、循环稳定性和倍率性能都有较大影响。相比于C16TAB和C18TAB,C14TAB辅助合成的MoS_2/GF复合结构具有最高的首次放电容量(955 m Ah/g),50次循环后仍保持751 m Ah/g的可逆容量,而且倍率性能更好。本研究揭示MoS_2/GF复合材料电化学性能的提升可归因于其独特的praticle-on-sheet结构以及MoS_2与石墨烯之间的协同作用。
基金supported by the National Natural Science Foundation of China(22205209,52202373 and U21A200972)China Postdoctoral Science Foundation(2022M722867)Key Research Project of Higher Education Institutions in Henan Province(23A530001)。
文摘The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials.
基金supported by the China Postdoctoral Science Foundation(No.2021MD703944)the Fund of Science and Technology on Near-Surface Detection Laboratory(No.6142414211808)+1 种基金the Director Fund of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2021ZR06)the National Natural Science Foundation of China(No.21776053)。
文摘Reduced graphene oxide(rGO)aerogels are emerging as very attractive scaffolds for high-performance electromagnetic wave absorption materials(EWAMs)due to their intrinsic conductive networks and intricate interior microstructure,as well as good compatibility with other electromagnetic(EM)components.Herein,we realized the decoration of rGO aerogel with Mo_(2)C nanoparticles by sequential hydrothermal assembly,freeze-drying,and high-temperature pyrolysis.Results show that Mo_(2)C nanoparticle loading can be easily controlled by the ammonium molybdate to glucose molar ratio.The hydrophobicity and thermal insulation of the rGO aerogel are effectively improved upon the introduction of Mo_(2)C nanoparticles,and more importantly,these nanoparticles regulate the EM properties of the rGO aerogel to a large extent.Although more Mo_(2)C nanoparticles may decrease the overall attenuation ability of the rGO aerogel,they bring much better impedance matching.At a molar ratio of 1:1,a desirable balance between attenuation ability and impedance matching is observed.In this context,the Mo_(2)C/r GO aerogel displays strong reflection loss and broad response bandwidth,even with a small applied thickness(1.7 mm)and low filler loading(9.0wt%).The positive effects of Mo_(2)C nanoparticles on multifunctional properties may render Mo_(2)C/r GO aerogels promising candidates for high-performance EWAMs under harsh conditions.
基金funded by the Zhengzhou Materials Genome Institute,the National Talents Program of China,and Key Innovation Projects of the Zhengzhou Municipal City of China.
文摘The main bottleneck against industrial utilization of sodium ion batteries(SIBs)is the lack of high-capacity electrodes to rival those of the benchmark lithium ion batteries(LIBs).Here in this work,we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few-layer graphene sheets loaded with ultrafine SnO_(2)nanocrystals,using short exposure of microwave to xerogel of graphene oxide(GO)and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO(RGO).The resultant nanocomposites(SnO_(2)@MWG)enabled significantly quickened redox processes as SIB anode,which led to remarkable full anode-specific capacity reaching 538 mAh g^(−1)at 0.05 A g^(−1)(about 1.45 times of the theoretical capacity of graphite for the LIB),in addition to outstanding rate performance over prolonged charge–discharge cycling.Anodes based on the optimized SnO_(2)@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g^(−1),and capacity retention of over 70.4%was maintained at a high areal loading of 3.4 mg cm^(−2),highly desirable for high energy density SIBs to rival the current benchmark LIBs.
文摘The electrochemical reduction of CO_(2)(CO_(2)ER)into the renewable and sustainable green fuels,such as low-carbon alcohols,is one of several workable strategies.CO_(2)ER can be combined with renewable electricity to transform intermittent energy sources(such as wind,hydro,and solar)into a fuel that can be stored until it is ready to be used.The intrinsic characteristics of the employed catalyst have a significant and substantial effect on the efficiency of CO_(2)ER and the ensuing economic viability.The paradigmatic multicarbon alcohol catalysts should increase the concentration of*CO in the reaction environment,stabilize the key intermediate products during the reaction,and facilitate the C-C coupling interaction.Since graphene has a large surface area and exceptional conductivity,it has been used as a support for active phases(nanoparticles or nanosheets).It is possible for graphene to enhance charge transport and accelerate CO_(2)conversion through its electronic and structural coupling effects.At the interface,a synergy can be produced that improves CO_(2)ER by increasing*CO adsorption,intermediate binding,and stability.This article focuses on recent advancements in graphene-based catalysts that promote CO_(2)ER to alcohols.Likewise,this paper also describes and discusses the key role graphene plays in catalyzing CO_(2)ER into alcohols.Finally,we hope to provide future ideas for the design of graphene-based electrocatalysts.
基金supported by the National Natural Science Foundation of China(Grant No.U1904187 and 21501049)the Fund of Key Scientific and Technological Project of Henan Province(No.182102410081)the High Performance Computing Center of Henan Normal University。
文摘As a layered inorganic material,MoS2 has recently attracted intensive attention as anode for sodium ion batteries(SIBs).However,this anode is plagued with low electronic conductivity,serious volume expansion and sluggish kinetics,resulting in capacity fading and poor rate performance.Herein,we develop an interface engineering strategy to substantially enhance the sodium storage performance of MoS2 by incorporating layered MoS2 into three dimensional N-doped graphene scaffold.The strong coupling-interface between MoS2 and N-doped graphene scaffold can not only stabilize the MoS2 structure during sodium insertion/extraction processes,but also provide plenty of anchor sites for additional surface sodium storage.The 3D MoS2@N-doped graphene composite as anode for SIBs performs an outstanding specific capacity of 667.3 mA h g^-1 at 0.2 A g^-1,a prolonged stability with a capacity retention of 94.4%after 140cycles and excellent rate capability of 445 mA h g^-1 even at a high rate of 10 A g^-1.We combined experiment and theoretical simulation to further disclose the interaction between MoS2 and N-doped graphene,adsorption and diffusion of sodium on the composite and the corresponding sodium storage mechanism.This study opens a new door to develop high performance SIBs by introducing the interface engineering technique.
基金Project supported by the National Basic Research Program of China(Grant Nos.2016YFA0202300 and 2016YFA0202302)the National Natural Science Foundation of China(Grant Nos.61527817,61335006,and 61378073)the Overseas Expertise Introduction Center for Discipline Innovation,111 Center,China
文摘The substrate treatment with seeding promoter can promote the two-dimensional material lateral growth in chemical vapor deposition (CVD) process. Herein, graphene quantum dots (GQDs) as a novel seeding promoter were used to obtain uniform large-area MoS2 monolayer. The obtained monolayer MoS2 films were confirmed by optical microscope, scanning electron microscope, Raman and photoluminescence spectra. Raman mapping revealed that the MoS2 monolayer was largely homogeneous.
基金Project supported by the Natioanl Natural Science Foundation of China(Grant Nos.62122084,12074412,61888102,and 11834017)。
文摘Two-dimensional(2D)moirématerials have attracted a lot of attention and opened a new research frontier of twistronics due to their novel physical properties.Although great progress has been achieved,the inability to precisely and reproducibly manipulate the twist angle hinders the further development of twistronics.Here,we demonstrated an atomic force microscope(AFM)tip manipulation method to control the interlayer twist angle of epitaxial MoS_(2)/graphene heterostructure with an ultra-high accuracy better than 0.1°.Furthermore,conductive AFM and spectroscopic characterizations were conducted to show the effects of the twist angle on moirépattern wavelength,phonons and excitons.Our work provides a technique to precisely control the twist angle of 2D moirématerials,enabling the possibility to establish the phase diagrams of moiréphysics with twist angle.