Sulfur-decorated nanomesh graphene （S@G） has been synthesized by a 155℃ heat treatment of a mixture of nanomesh graphene and S. The as-obtained S@G materials keep a high specific surface area, and exhibit obviously...Sulfur-decorated nanomesh graphene （S@G） has been synthesized by a 155℃ heat treatment of a mixture of nanomesh graphene and S. The as-obtained S@G materials keep a high specific surface area, and exhibit obviously enhanced conductivity and hydrophilicity as compared to the pristine graphene. X-ray photoelectron spectroscopy and thermogravimetric analysis indicate that most S atoms in the S@G samples are stably combined with nanomesh graphene via covalent bonds rather than exist as free elemental S. As an electrode material for aqueous supercapacitors, the S@G with a S content of 5 wt% delivers a specific capacitance up to 257 Fig at the current density of 0.25 A/g, which is 23.6% higher than that of the undoped graphene. Our results provide a simple approach to scalable synthesis of S-doped porous carbon materials, which have potential applications in the high-performance capacitive energy storage devices.展开更多
Basic magnesium carbonate microspheres with a red blood cell （RBC）-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the sel...Basic magnesium carbonate microspheres with a red blood cell （RBC）-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the self-assembly, sodium dodecyl benzene sulfonate served as a template for the formation of Mg（OH）2 spherical micelles and also as a reactant precursor that releases CO2 to react with Mg（OH）2. The growth of the microspheres is driven by the continuous generation of new hydrophobic centers because of the consumption of hydrophilic poles （--SO3-）. The surfactant-directed self-assembly can be applied to the synthesis of other carbonate or metallic oxide self-assemblies, indicating that it is a universal self-assembly method for amphiphilic molecules.展开更多
We have developed a one-step process for the synthesis of basic magnesium sulfate （5Mg（OH）2-MgSO4-3H20, abbreviated as 513MOS） whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process sho...We have developed a one-step process for the synthesis of basic magnesium sulfate （5Mg（OH）2-MgSO4-3H20, abbreviated as 513MOS） whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process shows potential for the low-cost mass production of controlled- structure whiskers. Their 0.3-1.0 μm diameter and 40-80 μm length correspond to an aspect ratio of 40-260. The 513MOS whisker morphology is related closely to MgSO4 concentration and reflux time. The optimized MgSO4 concentration is 1.2-1.5 mol/L with a 25-30 h reflux time. X-ray diffractometry revealed that the b-axis is the predominant growth direction of the whiskers. Their growth mechanism is by the relatively slow liquid-phase deposition of Mg2＋, OH-, and SO42-. The long reaction time and high MgSO4 concentration are conducive to the formation of 513MOS whiskers under gentle reaction conditions. Porous MgO whiskers with a fibrous structure were obtained after calcination of the 513MOS whiskers at 1020 ℃.展开更多
Although MgO has been widely used for the MgO-templated synthesis of carbon materials, little attention has been paid to MgO＇s catalytic function during carbon deposition. Here, a systematic analysis of the products ...Although MgO has been widely used for the MgO-templated synthesis of carbon materials, little attention has been paid to MgO＇s catalytic function during carbon deposition. Here, a systematic analysis of the products of slurry oil （SO） carbonization with and without MgO templates present indicates that MgO catalytically promoted the breakage of C--H bonds by immobilizing heavy oil molecules on MgO surfaces and the attractive interaction between hydrogen and MgO. Compared with the carbonization of SO alone, a notably higher H2 concentration and a lower hydrocarbon concentration was observed in the tail gas, a higher solid yield and a lower degree of graphitization of the carbon product were observed when MgO was also present. Furthermore, treatment at 900 ℃in the presence of MgO efficiently enhanced the capacitance and rate capability of the as-obtained porous carbon when tested as an electrode material for supercapacitors. These results suggest that the catalytic function of MgO could exist in all MgO-templated syntheses and in the heat treatment of porous carbons and graphene,展开更多
Nanomesh graphene （NMG） obtained by template chemical vapor deposition was used to synthesize the binder-free graphene monoliths by simple tablet pressing. The stacking manner of the NMG sheets was crucial to the co...Nanomesh graphene （NMG） obtained by template chemical vapor deposition was used to synthesize the binder-free graphene monoliths by simple tablet pressing. The stacking manner of the NMG sheets was crucial to the cohesion interaction between the graphene sheets, only the NMG materials with a loosely stacking manner could be pressed into binder-free monoliths. At the tableting pressure of 2-8 MPa, both the bulk densities and the specific surface areas of the monoliths keep nearly constant as the tableting pressure increases, indicating that the NMG monoliths have obvious elasticity and a porous structure due to the large corrugations and the mesh structures of the graphene sheets. As a result, an extraordinary methane storage capacity of 236 （v/v） at 9 MPa was obtained in the graphene monolith prepared by tabletin~ at 4 MPa.展开更多
Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular a-Fe catalyst particles. The growth mechanism of MWNTs o...Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular a-Fe catalyst particles. The growth mechanism of MWNTs on the larger catalyst particles are attributed to the interaction between the Fe nanoparticles with the surface-modified silica layer. This interaction-mediated growth mechanism is illustrated by studying the electronic, atomic and crystal properties of surface-modified catalysts and MWNTs products by characterization with X-ray diffraction (XRD), transmis-sion electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermal gravimetric analy-sis (TGA) and Raman spectra.展开更多
基金supported by the National Key Projects for Fundamental Research and Development of China(2016YFB0600903)the National Natural Science Foundation of China(91434107,21506226,21476245)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDY-SSW-JSC011)~~
基金Foundation item： Supported by the National Natural Science Foundation of China （Nos. 51077014, 21003028 and 51202043）： the Fundamental Research funds for the Central Universities, the Program for New Century Excellent Talents in University （NCET-10-0050）, and the Excellent Youth Foundation of Heilongjiang Province of China.
基金supported by the National Natural Science Foundation of China(No.21776309)
文摘Sulfur-decorated nanomesh graphene （S@G） has been synthesized by a 155℃ heat treatment of a mixture of nanomesh graphene and S. The as-obtained S@G materials keep a high specific surface area, and exhibit obviously enhanced conductivity and hydrophilicity as compared to the pristine graphene. X-ray photoelectron spectroscopy and thermogravimetric analysis indicate that most S atoms in the S@G samples are stably combined with nanomesh graphene via covalent bonds rather than exist as free elemental S. As an electrode material for aqueous supercapacitors, the S@G with a S content of 5 wt% delivers a specific capacitance up to 257 Fig at the current density of 0.25 A/g, which is 23.6% higher than that of the undoped graphene. Our results provide a simple approach to scalable synthesis of S-doped porous carbon materials, which have potential applications in the high-performance capacitive energy storage devices.
基金supported by the National Natural Science Foundation of China(No.21206191)the Science Foundation of China University of Petroleum,Beijing(No.2462013YXBS007)
文摘Basic magnesium carbonate microspheres with a red blood cell （RBC）-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the self-assembly, sodium dodecyl benzene sulfonate served as a template for the formation of Mg（OH）2 spherical micelles and also as a reactant precursor that releases CO2 to react with Mg（OH）2. The growth of the microspheres is driven by the continuous generation of new hydrophobic centers because of the consumption of hydrophilic poles （--SO3-）. The surfactant-directed self-assembly can be applied to the synthesis of other carbonate or metallic oxide self-assemblies, indicating that it is a universal self-assembly method for amphiphilic molecules.
文摘We have developed a one-step process for the synthesis of basic magnesium sulfate （5Mg（OH）2-MgSO4-3H20, abbreviated as 513MOS） whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process shows potential for the low-cost mass production of controlled- structure whiskers. Their 0.3-1.0 μm diameter and 40-80 μm length correspond to an aspect ratio of 40-260. The 513MOS whisker morphology is related closely to MgSO4 concentration and reflux time. The optimized MgSO4 concentration is 1.2-1.5 mol/L with a 25-30 h reflux time. X-ray diffractometry revealed that the b-axis is the predominant growth direction of the whiskers. Their growth mechanism is by the relatively slow liquid-phase deposition of Mg2＋, OH-, and SO42-. The long reaction time and high MgSO4 concentration are conducive to the formation of 513MOS whiskers under gentle reaction conditions. Porous MgO whiskers with a fibrous structure were obtained after calcination of the 513MOS whiskers at 1020 ℃.
基金The work was supported by the National Natural Science Foundation of China （21776309）, and the Science Foundation of China University of Petroleum, Beijing （2462015YQ0314, C201603）.
文摘Although MgO has been widely used for the MgO-templated synthesis of carbon materials, little attention has been paid to MgO＇s catalytic function during carbon deposition. Here, a systematic analysis of the products of slurry oil （SO） carbonization with and without MgO templates present indicates that MgO catalytically promoted the breakage of C--H bonds by immobilizing heavy oil molecules on MgO surfaces and the attractive interaction between hydrogen and MgO. Compared with the carbonization of SO alone, a notably higher H2 concentration and a lower hydrocarbon concentration was observed in the tail gas, a higher solid yield and a lower degree of graphitization of the carbon product were observed when MgO was also present. Furthermore, treatment at 900 ℃in the presence of MgO efficiently enhanced the capacitance and rate capability of the as-obtained porous carbon when tested as an electrode material for supercapacitors. These results suggest that the catalytic function of MgO could exist in all MgO-templated syntheses and in the heat treatment of porous carbons and graphene,
基金supported by Science Foundation of China University of Petroleum,Beijing(QD-2010-03)
文摘Nanomesh graphene （NMG） obtained by template chemical vapor deposition was used to synthesize the binder-free graphene monoliths by simple tablet pressing. The stacking manner of the NMG sheets was crucial to the cohesion interaction between the graphene sheets, only the NMG materials with a loosely stacking manner could be pressed into binder-free monoliths. At the tableting pressure of 2-8 MPa, both the bulk densities and the specific surface areas of the monoliths keep nearly constant as the tableting pressure increases, indicating that the NMG monoliths have obvious elasticity and a porous structure due to the large corrugations and the mesh structures of the graphene sheets. As a result, an extraordinary methane storage capacity of 236 （v/v） at 9 MPa was obtained in the graphene monolith prepared by tabletin~ at 4 MPa.
基金support of the National Natural Science Foundation of China(No.50071057,No.20236020)the National High Technology Research and Development Program(863 Program)(No.2003AA302630)
文摘Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular a-Fe catalyst particles. The growth mechanism of MWNTs on the larger catalyst particles are attributed to the interaction between the Fe nanoparticles with the surface-modified silica layer. This interaction-mediated growth mechanism is illustrated by studying the electronic, atomic and crystal properties of surface-modified catalysts and MWNTs products by characterization with X-ray diffraction (XRD), transmis-sion electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermal gravimetric analy-sis (TGA) and Raman spectra.
