Graphene-based heterostructure is one of the most attractive topics in physics and material sciences due to its intriguing properties and applications. We report the one-step fabrication of a novel graphene/Mo2C heter...Graphene-based heterostructure is one of the most attractive topics in physics and material sciences due to its intriguing properties and applications. We report the one-step fabrication of a novel graphene/Mo2C heterostructure by using chemical vapor deposition（CVD）. The composition and structure of the heterostructure are characterized through energydispersive spectrometer, transmission electron microscope, and Raman spectrum. The growth rule analysis of the results shows the flow rate of methane is a main factor in preparing the graphene/Mo2C heterostructure. A schematic diagram of the growth process is also established. Transport measurements are performed to study the superconductivity of the heterostructure which has potential applications in superconducting devices.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
In this contribution, a novel high-temperature CO_2 adsorbent consisting of Mg-Al layered double hydroxide （LDH） and graphene oxide （GO） nanosheets was prepared and evaluated. The nanocomposite-type adsorbent was ...In this contribution, a novel high-temperature CO_2 adsorbent consisting of Mg-Al layered double hydroxide （LDH） and graphene oxide （GO） nanosheets was prepared and evaluated. The nanocomposite-type adsorbent was synthesized based on the electrostatically driven self-assembly between positively charged Mg-Al LDH single sheet and negatively charged GO monolayer. The characteristics of this novel adsorbent were investigated using XRD, FE-SEM, HRTEM, FT-IR, BET and TGA. The results showed that both the CO_2 adsorption capacity and the multi- cycle stability of LDH were increased with the addition of GO owing to the enhanced particle dispersion and stabilization. In particular, the absolute CO_2 capture capacity of LDH was increased by more than twice by adding 6.54 wt% GO as support. GO appeared to be especially effective for supporting LDH sheets. Moreover, the CO_2 capture capacity of the adsorbent could be further increased by doping with 15 wt% K_2CO_3. This work demonstrated a new approach for the preparation of LDH-based hybrid-type adsorbents for CO2 capture.展开更多
Graphene oxide(GO)nanosheets were dispersed into premixed powders(Cu-0.4 wt%Al/35W5Cr)by wet grinding and vacuum freeze-drying process.The 0.3 wt%GO/Al2O3-Cu/35W5Cr and 0.5 wt%GO/Al2O3-Cu/35W5Cr composites,used for el...Graphene oxide(GO)nanosheets were dispersed into premixed powders(Cu-0.4 wt%Al/35W5Cr)by wet grinding and vacuum freeze-drying process.The 0.3 wt%GO/Al2O3-Cu/35W5Cr and 0.5 wt%GO/Al2O3-Cu/35W5Cr composites,used for electrical contacts,were fabricated by vacuum hot-pressing sintering.The microstructure was analyzed by field emission scanning electron and transmission electron microscopy.In addition,the Raman spectroscopy and X-ray photoelectron spectroscopy were used to investigate the structural changes of GO before and after sintering.The arc erosion behavior was investigated by the JF04 C electrical contact testing apparatus.Consequently,the Al2O3 nanoparticles were evenly dispersed in the matrix,causing dislocation tangles.GO was converted to reduced graphene oxide after sintering.A group of carbon atoms combined with Cr forming Cr3C2 in situ during sintering,which enhanced the interface bonding.Compared with the Al2O3-Cu/35W5Cr composite,the tensile strength of the two contact materials containing 0.3 wt%GO and 0.5 wt%GO was increased by 45%and 34%,respectively.Finally,pips and craters were present on the anode and cathode surfaces,respectively.Tungsten has undergone re-sintering during arcing and formed needle-like structures.Compared with Al2O3-Cu/35W5Cr,the GO/Al2O3-Cu35W5Cr composites have better welding resistance.The final mass transfer direction of the two composites was from the cathode to anode.展开更多
Unique nanofoams consisting of interweaved ultrathin graphene confining Zn–N–C dipoles (ZnNG) are constructed via calcination of Zn-coordinated precursor.Due to the introduction of local polar Zn–N–C configuration...Unique nanofoams consisting of interweaved ultrathin graphene confining Zn–N–C dipoles (ZnNG) are constructed via calcination of Zn-coordinated precursor.Due to the introduction of local polar Zn–N–C configurations,with hypersensitivity for mechanical stress,the piezoelectricity is created on the nonpiezoelectric graphene,and the hierarchical ZnNG exhibits obvious piezocatalytic activity of water splitting for H_(2) production even under mild agitation.The corresponding rate of H_(2) production is about 14.65 μmol g^(-1)h^(-1).It triggers a breakthrough in piezocatalytic H_(2) evolution under low-frequency vibration,and takes a significant step forward for piezocatalysis towards practical applications.Furthermore,the presented concept of confining atomic polar configuration for engineering piezoelectricity would open up new horizon for constructing new-type piezoelectrics based on both piezoelectric and nonpiezoelectric materials.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.1402342,11574338,and 11274333)the Hundred Talents Program of Chinese Academy of Sciences,the International Collaboration and Innovation Program on High Mobility Materials Engineering,Chinese Academy of Sciences(Grant No.KGZD-EW-303)the“Strategic Priority Research Program(B)”of the Chinese Academy of Sciences(Grant No.XDB04040300)
文摘Graphene-based heterostructure is one of the most attractive topics in physics and material sciences due to its intriguing properties and applications. We report the one-step fabrication of a novel graphene/Mo2C heterostructure by using chemical vapor deposition（CVD）. The composition and structure of the heterostructure are characterized through energydispersive spectrometer, transmission electron microscope, and Raman spectrum. The growth rule analysis of the results shows the flow rate of methane is a main factor in preparing the graphene/Mo2C heterostructure. A schematic diagram of the growth process is also established. Transport measurements are performed to study the superconductivity of the heterostructure which has potential applications in superconducting devices.
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China Postdoctoral Science Foundation(2015M570794,2017M623054)Sichuan Provincial Department of Education Funded Scientific Research and Innovation Team Program(14TD0033)
基金supported by the Fundamental Research Funds for the Central Universities(BLYJ201509)the Fundamental Research Funds for the Central Universities(TD-JC-2013-3)+4 种基金the Program for New Century Excellent Talents in University(NCET-12-0787)Beijing Nova Programme(Z131109000413013)the National Natural Science Foundation of China(51308045)the Foundation of State Key Laboratory of Coal Conversion(Grant No.J14-15-309)Institute of Coal Chemistry,Chinese Academy of Sciences
文摘In this contribution, a novel high-temperature CO_2 adsorbent consisting of Mg-Al layered double hydroxide （LDH） and graphene oxide （GO） nanosheets was prepared and evaluated. The nanocomposite-type adsorbent was synthesized based on the electrostatically driven self-assembly between positively charged Mg-Al LDH single sheet and negatively charged GO monolayer. The characteristics of this novel adsorbent were investigated using XRD, FE-SEM, HRTEM, FT-IR, BET and TGA. The results showed that both the CO_2 adsorption capacity and the multi- cycle stability of LDH were increased with the addition of GO owing to the enhanced particle dispersion and stabilization. In particular, the absolute CO_2 capture capacity of LDH was increased by more than twice by adding 6.54 wt% GO as support. GO appeared to be especially effective for supporting LDH sheets. Moreover, the CO_2 capture capacity of the adsorbent could be further increased by doping with 15 wt% K_2CO_3. This work demonstrated a new approach for the preparation of LDH-based hybrid-type adsorbents for CO2 capture.
基金supported financially by the Open Cooperation Project of Science and Technology of the Henan Province(No.182106000018)the Henan University Scientific and Technological Innovation Talent Support Program(No.18HASTIT024)+1 种基金the National Natural Science Foundation of China(U1704143)the National Science Foundation(No.IRES1358088).
文摘Graphene oxide(GO)nanosheets were dispersed into premixed powders(Cu-0.4 wt%Al/35W5Cr)by wet grinding and vacuum freeze-drying process.The 0.3 wt%GO/Al2O3-Cu/35W5Cr and 0.5 wt%GO/Al2O3-Cu/35W5Cr composites,used for electrical contacts,were fabricated by vacuum hot-pressing sintering.The microstructure was analyzed by field emission scanning electron and transmission electron microscopy.In addition,the Raman spectroscopy and X-ray photoelectron spectroscopy were used to investigate the structural changes of GO before and after sintering.The arc erosion behavior was investigated by the JF04 C electrical contact testing apparatus.Consequently,the Al2O3 nanoparticles were evenly dispersed in the matrix,causing dislocation tangles.GO was converted to reduced graphene oxide after sintering.A group of carbon atoms combined with Cr forming Cr3C2 in situ during sintering,which enhanced the interface bonding.Compared with the Al2O3-Cu/35W5Cr composite,the tensile strength of the two contact materials containing 0.3 wt%GO and 0.5 wt%GO was increased by 45%and 34%,respectively.Finally,pips and craters were present on the anode and cathode surfaces,respectively.Tungsten has undergone re-sintering during arcing and formed needle-like structures.Compared with Al2O3-Cu/35W5Cr,the GO/Al2O3-Cu35W5Cr composites have better welding resistance.The final mass transfer direction of the two composites was from the cathode to anode.
基金supported by the National Natural Science Foundation of China (21802007)the Natural Science Foundation of Hunan Province (2020JJ5615)+1 种基金the Scientific Research Project of Hunan Provincial Department of Education (20B066)the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment (SKLPEE-202001), Fuzhou University。
文摘Unique nanofoams consisting of interweaved ultrathin graphene confining Zn–N–C dipoles (ZnNG) are constructed via calcination of Zn-coordinated precursor.Due to the introduction of local polar Zn–N–C configurations,with hypersensitivity for mechanical stress,the piezoelectricity is created on the nonpiezoelectric graphene,and the hierarchical ZnNG exhibits obvious piezocatalytic activity of water splitting for H_(2) production even under mild agitation.The corresponding rate of H_(2) production is about 14.65 μmol g^(-1)h^(-1).It triggers a breakthrough in piezocatalytic H_(2) evolution under low-frequency vibration,and takes a significant step forward for piezocatalysis towards practical applications.Furthermore,the presented concept of confining atomic polar configuration for engineering piezoelectricity would open up new horizon for constructing new-type piezoelectrics based on both piezoelectric and nonpiezoelectric materials.
