Polycrystalline SnO2 fine powder consisting of nano-particles (SnO2-NP), SnO2 nano-sheets (SnO2-NS), and SnO2 containing both nano-rods and nano-particles (SnO2-NR+NP) were prepared and used for CO oxidation. S...Polycrystalline SnO2 fine powder consisting of nano-particles (SnO2-NP), SnO2 nano-sheets (SnO2-NS), and SnO2 containing both nano-rods and nano-particles (SnO2-NR+NP) were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR+NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active (110) facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.展开更多
A new biosensor platform was explored for detection of surfactant based on fluorescence changes from single strand DNA (ssDNA) and single-walled carbon nanotubes (SWNTs). Thermodynamics assay was performed to valu...A new biosensor platform was explored for detection of surfactant based on fluorescence changes from single strand DNA (ssDNA) and single-walled carbon nanotubes (SWNTs). Thermodynamics assay was performed to value the stability of probe. The affinities of SWNT to five common surfactants (SDS, DBS, Triton X-100, Tween-20 and Tween-80) were investigated by real-time fluorescence method. The effects of Mg^2+ and pH on the fluorescence intensity of self-assembled quenched sensor were performed. The fluorescent emission spectra were used to measure the responses of self-assembled quenched fluorescent of ssDNA/SWNTs to different concentration surfactant(Triton X-100). The FAM-DNA wrapped SWNTs probe was stable in a wide temperature range (5 ℃ to 80℃). The binding strength of surfactants and single-stranded DNA (ssDNA) on SWNTs surfaces was shown as follows: Triton X-100〉DBS〉Tween-20〉Tween-80〉ssDNA〉SDS, and the optimized reaction conditions included pH 7.4 and 10 mmol/L Mg2+. The fluorescence of FAM-ssDNA wrapped SWNTs was proportionally recovered as a result of adding different concentrations of Triton X- 100, which realizes the quantitative detection of Triton X- 100.展开更多
Enhanced oil recovery (EOR) via carbon dioxide (CO2) flooding has received a considerable amount of attention as an economically feasible method for carbon sequestration, with many recent studies focus- ing on dev...Enhanced oil recovery (EOR) via carbon dioxide (CO2) flooding has received a considerable amount of attention as an economically feasible method for carbon sequestration, with many recent studies focus- ing on developing enhanced CO2 foaming additives, However, the potential long-term environmental effects of these additives in the event of leakage are poorly understood and, given the amount of additives injected in a typical CO2 EOR operation, could he far-reaching, This paper presents a summary of recent developments in surfactant and surfactant/nanoparticle-hased CO2 foaming systems, with an emphasis on the possible environmental impacts of CO2 foam leakage, Most of the surfactants studied are unlikely to degrade under reservoir conditions, and their release can cause major negative impacts on wildlife, With recent advances in the use of additives (e,g,, nonionic surfactants, nanoparticles, and other chemicals) the use of harsh anionic surfactants may no longer he warranted, This paper discusses recent advances in producing foaming systems, and highlights possible strategies to develop environmentally friendly CO2 EOR methods,展开更多
A precise understanding of the redox chemistry of Nm-Mn+(like N4-Fe^(2+))systems is essential for fundamental studies and rational design of Nm-Mn+-based electrocatalysts for the oxygen reduction reaction(ORR).Herein,...A precise understanding of the redox chemistry of Nm-Mn+(like N4-Fe^(2+))systems is essential for fundamental studies and rational design of Nm-Mn+-based electrocatalysts for the oxygen reduction reaction(ORR).Herein,three different iron phthalocyanines(FePcs)adsorbed on carbon nanotubes((NH2)4FePc@CNTs,(t-Bu)4FePc@CNTs,and FePc@CNTs)were evaluated to demonstrate the effect of the electron donating power of the substituents on the Fe^(3+)/Fe^(2+)redox potential of FePc@CNTs and the role of these composites as ORR mediators in alkaline media.The Fe^(3+)/Fe^(2+)redox potential of the FePcs was found to shift towards the cathodic region upon substitution with electron-donating groups.This up-field shift in the eg-orbital leads to a lower overlap between the onset potential of the Fe^(3+)/Fe^(2+)redox couple and that of the ORR,and thus,the ORR activity decreased in the following order based on the substitution of FePc:-H>-t-Bu>-NH2.展开更多
A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction (MOR) without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cle...A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction (MOR) without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cleaned and pre-oxidized multiwall carbon nanotubes (MWC- NTs) from Pt salt by using CO as the reductant. MOR activity has been characterized by both cyclic voltammetry and chronoamperometry, the current density and mass specific current at the peak potential (ca. 0.9 V vs. RHE) reaches 11.6 mA/cm^2 and 860 mA/mgpt, respectively. After electro-deposition of Ru onto the Pt/MWCNTs surface, the catalysts show steady state mass specific current of 20 and 80 mA/mgpt at 0.5 and 0.6 V, respectively.展开更多
Diesel soot subjected to high exhaust temperature suffers from thermal ageing,which is difficult to be removed by regeneration process.Based on the thermogravimetric(TG)analysis and images by high resolution transmiss...Diesel soot subjected to high exhaust temperature suffers from thermal ageing,which is difficult to be removed by regeneration process.Based on the thermogravimetric(TG)analysis and images by high resolution transmission electron microscope(HRTEM),effects of thermal ageing temperature,ageing time and oxygen concentration on oxidation characteristic of soot are investigated.The activation energy of soot increases with the increase of ageing temperature and oxygen concentration.The activation energy increases rapidly when the ageing time is less than 45 min,and then it keeps in a value of 157 kJ/mol when the ageing time is between 45 and 60 min.Compared to the soot without thermal ageing,the shape of ageing soot particles presents shorter diameter and more regular circle by observing soot nanostructure.With the increase of ageing temperature,ageing time and oxygen concentration,the more stable structure of“shell and core”is shown in the basic carbon.The soot has an increased fringe length,decreased tortuosity and separation distance after thermal ageing process,which leads to the deepening of the disorder degree of soot nanostructures and reduction of soot oxidation activity.Consequently,the thermal ageing process should be avoided in order to optimize the active regeneration strategy.展开更多
Tungsten carbide and zeolite nanocomposite was prepared by combining a mechanochemical approach with a reduction and carbonization approach,using natural zeolite and ammonia metatungstate as precursors.The sample was ...Tungsten carbide and zeolite nanocomposite was prepared by combining a mechanochemical approach with a reduction and carbonization approach,using natural zeolite and ammonia metatungstate as precursors.The sample was characterized by X-ray diffraction and scanning electron microscope.The results showed that the crystal phase of the sample is composed of zeolite,monotungsten carbide and bitungsten carbide.The mass percentage and the crystallite diameter of tungsten carbide change along with the reacted time.Its electrocatalytic activity was measured with a microelectrode system with three electrodes.The results show that its electrocatalytic property is related to its crystal phase and the mass percentage of tungsten carbide,and its electrocatalytic activity is connected with the property of electrolyte,in which it is measured.Synergistic effect between tungsten carbide and zeolite is found during electrocatalysis.展开更多
Oxygen reduction reaction (ORR) is key to fuel cells and metal-air batteries which are considered as the al- ternative clean energy. Various carbon materials have been widely researched as ORR electrocatalysts. It h...Oxygen reduction reaction (ORR) is key to fuel cells and metal-air batteries which are considered as the al- ternative clean energy. Various carbon materials have been widely researched as ORR electrocatalysts. It has been ac- cepted that heteroatom doping and exposure of the edge sites can effectively improve the activity of carbon materials. In this work, we used a simple method to prepare a novel N, P-dual doped carbon-based catalyst with many holes on the surface. In addition, trace level Co doping in the carbon material forming Co-N-C active species can further enhance the ORR performance. On one hand, the doping can adjust the elec- tronic structure of carbon atoms, which would induce more active sites for ORR. And on the other hand, the holes formed on the surface of carbon nanosheets would expose more edge sites and can improve the intrinsic activity of carbon. Due to the heteroatom doping and the exposed edge sites, the pre- pared carbon materials showed highly excellent ORR perfor- mance, dose to that of commercial Pt/C.展开更多
A new protocol for the synthesis of nearly monodisperse gold nanoparticles with controllable size is described. The pathway is based on the reduction of AuCl4 by ammonium bicarbonate in the presence of sodium stearate...A new protocol for the synthesis of nearly monodisperse gold nanoparticles with controllable size is described. The pathway is based on the reduction of AuCl4 by ammonium bicarbonate in the presence of sodium stearate under hydrothermal conditions. The particle sizes could be easily tuned by regulating the reaction conditions including precursor concentration, reaction temperature and growth time. A tentative explanation for the reduction and growth mechanism of uniform gold nanoparticles has been proposed. The as-prepared gold particles showed good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4, and a surface-enhanced Raman scattering (SERS) study suggested that the gold nanoparticles exhibited a high SERS effect on the probe molecule Rhodamine 6G.展开更多
Owing to the excellent redox reversibility and structural diversity,polytriphenylamine(PTPAn)has been regarded as one of the promising cathode candidates for sodium-ion batteries.However,it still suffers from the bulk...Owing to the excellent redox reversibility and structural diversity,polytriphenylamine(PTPAn)has been regarded as one of the promising cathode candidates for sodium-ion batteries.However,it still suffers from the bulk aggregation and low operating capacity in practical applications.Assisted by the in-situ polymerization,leaf-like PTPAn nanosheets are uniformly introduced on the surface of carbon nanofibers(CNFs)to form the free-standing CNF@PTPAn composite electrodes.Interestingly,the formation mechanism of the leaf-on-branch structure of CNF@PTPAn composites is systematically explored,confirming that the controlling of oxidation rate and growth degree plays crucial roles in tuning the morphology and active material content of the composite electrodes.Supported by the capacity-cutting analysis,the effective coupling between the active PTPAn and conductive CNFs can provide fast electron/ion-shuttling channels and deepen the electrochemical reaction process.At 50mAg^(-1),the capacity of the optimized CNF@PTPAn composite can reach 105mAh g^(-1),with a stable rate capability of 78mAh g^(-1)even at 400mAg^(-1)after 500 cycles in a half cell.The detailed kinetic analysis confirms that the ion-storage behaviors in the lowvoltage region can be tailored for the improved capacitive contribution and diffusion coefficients.Meanwhile,the flexible CNF-based full cell with CNF@PTPAn as the cathode and CNFs as the anode exhibits a high energy density of 60Wh kg^(-1)at 938Wkg^(-1).Based on this,the rational design is expected to provide more possibilities to obtain advanced freestanding electrode systems.展开更多
基金supported by the National Natural Science Foundation of China (21263015)the Education Department of Jiangxi Province (KJLD14005)the Natural Science Foundation of Jiangxi Province(20151BBE50006,20122BAB203009)~~
文摘Polycrystalline SnO2 fine powder consisting of nano-particles (SnO2-NP), SnO2 nano-sheets (SnO2-NS), and SnO2 containing both nano-rods and nano-particles (SnO2-NR+NP) were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR+NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active (110) facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.
基金Projects (21075032, 21005026, 21135001) supported by the National Natural Science Foundation of ChinaProject (llJJ5012) supported by Hunan Provincial Natural Science Foundation, China
文摘A new biosensor platform was explored for detection of surfactant based on fluorescence changes from single strand DNA (ssDNA) and single-walled carbon nanotubes (SWNTs). Thermodynamics assay was performed to value the stability of probe. The affinities of SWNT to five common surfactants (SDS, DBS, Triton X-100, Tween-20 and Tween-80) were investigated by real-time fluorescence method. The effects of Mg^2+ and pH on the fluorescence intensity of self-assembled quenched sensor were performed. The fluorescent emission spectra were used to measure the responses of self-assembled quenched fluorescent of ssDNA/SWNTs to different concentration surfactant(Triton X-100). The FAM-DNA wrapped SWNTs probe was stable in a wide temperature range (5 ℃ to 80℃). The binding strength of surfactants and single-stranded DNA (ssDNA) on SWNTs surfaces was shown as follows: Triton X-100〉DBS〉Tween-20〉Tween-80〉ssDNA〉SDS, and the optimized reaction conditions included pH 7.4 and 10 mmol/L Mg2+. The fluorescence of FAM-ssDNA wrapped SWNTs was proportionally recovered as a result of adding different concentrations of Triton X- 100, which realizes the quantitative detection of Triton X- 100.
基金support from the American Chemical Society Petroleum Research Fund (ACS-PRF) (55801-DNI6)
文摘Enhanced oil recovery (EOR) via carbon dioxide (CO2) flooding has received a considerable amount of attention as an economically feasible method for carbon sequestration, with many recent studies focus- ing on developing enhanced CO2 foaming additives, However, the potential long-term environmental effects of these additives in the event of leakage are poorly understood and, given the amount of additives injected in a typical CO2 EOR operation, could he far-reaching, This paper presents a summary of recent developments in surfactant and surfactant/nanoparticle-hased CO2 foaming systems, with an emphasis on the possible environmental impacts of CO2 foam leakage, Most of the surfactants studied are unlikely to degrade under reservoir conditions, and their release can cause major negative impacts on wildlife, With recent advances in the use of additives (e,g,, nonionic surfactants, nanoparticles, and other chemicals) the use of harsh anionic surfactants may no longer he warranted, This paper discusses recent advances in producing foaming systems, and highlights possible strategies to develop environmentally friendly CO2 EOR methods,
文摘A precise understanding of the redox chemistry of Nm-Mn+(like N4-Fe^(2+))systems is essential for fundamental studies and rational design of Nm-Mn+-based electrocatalysts for the oxygen reduction reaction(ORR).Herein,three different iron phthalocyanines(FePcs)adsorbed on carbon nanotubes((NH2)4FePc@CNTs,(t-Bu)4FePc@CNTs,and FePc@CNTs)were evaluated to demonstrate the effect of the electron donating power of the substituents on the Fe^(3+)/Fe^(2+)redox potential of FePc@CNTs and the role of these composites as ORR mediators in alkaline media.The Fe^(3+)/Fe^(2+)redox potential of the FePcs was found to shift towards the cathodic region upon substitution with electron-donating groups.This up-field shift in the eg-orbital leads to a lower overlap between the onset potential of the Fe^(3+)/Fe^(2+)redox couple and that of the ORR,and thus,the ORR activity decreased in the following order based on the substitution of FePc:-H>-t-Bu>-NH2.
基金ACKNOWLEDGEMENTS This work was supported by the National Natural Science Foundation of China (No.21273215), National Instrumentation Program (No.2011YQ03012416), and 973 Program from the Ministry of Science and Technology of China (No.2010CB923302).
文摘A simple and green approach to synthesize highly active electro-catalysts for methanol oxi- dation reaction (MOR) without using any organic agents is described. Pt nanoparticles are directly deposited on the pre-cleaned and pre-oxidized multiwall carbon nanotubes (MWC- NTs) from Pt salt by using CO as the reductant. MOR activity has been characterized by both cyclic voltammetry and chronoamperometry, the current density and mass specific current at the peak potential (ca. 0.9 V vs. RHE) reaches 11.6 mA/cm^2 and 860 mA/mgpt, respectively. After electro-deposition of Ru onto the Pt/MWCNTs surface, the catalysts show steady state mass specific current of 20 and 80 mA/mgpt at 0.5 and 0.6 V, respectively.
基金Project(51676167)supported by the National Natural Science Foundation of ChinaProject(17TD0035)supported by the Sichuan Provincial Scientific Research Innovation Team Program,ChinaProjects(2017TD0026,2015TD0021)supported by Science&Technology Department of Sichuan Province,China。
文摘Diesel soot subjected to high exhaust temperature suffers from thermal ageing,which is difficult to be removed by regeneration process.Based on the thermogravimetric(TG)analysis and images by high resolution transmission electron microscope(HRTEM),effects of thermal ageing temperature,ageing time and oxygen concentration on oxidation characteristic of soot are investigated.The activation energy of soot increases with the increase of ageing temperature and oxygen concentration.The activation energy increases rapidly when the ageing time is less than 45 min,and then it keeps in a value of 157 kJ/mol when the ageing time is between 45 and 60 min.Compared to the soot without thermal ageing,the shape of ageing soot particles presents shorter diameter and more regular circle by observing soot nanostructure.With the increase of ageing temperature,ageing time and oxygen concentration,the more stable structure of“shell and core”is shown in the basic carbon.The soot has an increased fringe length,decreased tortuosity and separation distance after thermal ageing process,which leads to the deepening of the disorder degree of soot nanostructures and reduction of soot oxidation activity.Consequently,the thermal ageing process should be avoided in order to optimize the active regeneration strategy.
基金Supported by the National Natural Science Foundation of China (21173193)the Natural Science Foundation of Zhejiang Province (Y4080209, Y406094)the Science Plan of Zhejiang Province (2007F70039)
文摘Tungsten carbide and zeolite nanocomposite was prepared by combining a mechanochemical approach with a reduction and carbonization approach,using natural zeolite and ammonia metatungstate as precursors.The sample was characterized by X-ray diffraction and scanning electron microscope.The results showed that the crystal phase of the sample is composed of zeolite,monotungsten carbide and bitungsten carbide.The mass percentage and the crystallite diameter of tungsten carbide change along with the reacted time.Its electrocatalytic activity was measured with a microelectrode system with three electrodes.The results show that its electrocatalytic property is related to its crystal phase and the mass percentage of tungsten carbide,and its electrocatalytic activity is connected with the property of electrolyte,in which it is measured.Synergistic effect between tungsten carbide and zeolite is found during electrocatalysis.
基金supported by the National Natural Science Foundation of China (21701043, 21573066, and 51402100)the Provincial Natural Science Foundation of Hunan (2016JJ1006 and 2016TP1009)the Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province and Shenzhen Science and Technology Program (JCYJ20170306141659388)
文摘Oxygen reduction reaction (ORR) is key to fuel cells and metal-air batteries which are considered as the al- ternative clean energy. Various carbon materials have been widely researched as ORR electrocatalysts. It has been ac- cepted that heteroatom doping and exposure of the edge sites can effectively improve the activity of carbon materials. In this work, we used a simple method to prepare a novel N, P-dual doped carbon-based catalyst with many holes on the surface. In addition, trace level Co doping in the carbon material forming Co-N-C active species can further enhance the ORR performance. On one hand, the doping can adjust the elec- tronic structure of carbon atoms, which would induce more active sites for ORR. And on the other hand, the holes formed on the surface of carbon nanosheets would expose more edge sites and can improve the intrinsic activity of carbon. Due to the heteroatom doping and the exposed edge sites, the pre- pared carbon materials showed highly excellent ORR perfor- mance, dose to that of commercial Pt/C.
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China (No. 21071136), the National Basic Research Program of China (No. 2010CB934700), the Program for New Century Excellent Talents in Universities from the Chinese Ministry of Education (No. NCET2006-0552), and the Foundation of Anhui Provincial Education Department (No. KJ2008A071).
文摘A new protocol for the synthesis of nearly monodisperse gold nanoparticles with controllable size is described. The pathway is based on the reduction of AuCl4 by ammonium bicarbonate in the presence of sodium stearate under hydrothermal conditions. The particle sizes could be easily tuned by regulating the reaction conditions including precursor concentration, reaction temperature and growth time. A tentative explanation for the reduction and growth mechanism of uniform gold nanoparticles has been proposed. The as-prepared gold particles showed good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4, and a surface-enhanced Raman scattering (SERS) study suggested that the gold nanoparticles exhibited a high SERS effect on the probe molecule Rhodamine 6G.
基金financially supported by the National Natural Science Foundation of China(22075042)the Natural Science Foundation of Shanghai(20ZR1401400 and 18ZR1401600)+1 种基金the Shanghai Scientific and Technological Innovation Project(18JC1410600)the Fundamental Research Funds for the Central Universities and DHU Distinguished Young Professor Program(LZB2021002).
文摘Owing to the excellent redox reversibility and structural diversity,polytriphenylamine(PTPAn)has been regarded as one of the promising cathode candidates for sodium-ion batteries.However,it still suffers from the bulk aggregation and low operating capacity in practical applications.Assisted by the in-situ polymerization,leaf-like PTPAn nanosheets are uniformly introduced on the surface of carbon nanofibers(CNFs)to form the free-standing CNF@PTPAn composite electrodes.Interestingly,the formation mechanism of the leaf-on-branch structure of CNF@PTPAn composites is systematically explored,confirming that the controlling of oxidation rate and growth degree plays crucial roles in tuning the morphology and active material content of the composite electrodes.Supported by the capacity-cutting analysis,the effective coupling between the active PTPAn and conductive CNFs can provide fast electron/ion-shuttling channels and deepen the electrochemical reaction process.At 50mAg^(-1),the capacity of the optimized CNF@PTPAn composite can reach 105mAh g^(-1),with a stable rate capability of 78mAh g^(-1)even at 400mAg^(-1)after 500 cycles in a half cell.The detailed kinetic analysis confirms that the ion-storage behaviors in the lowvoltage region can be tailored for the improved capacitive contribution and diffusion coefficients.Meanwhile,the flexible CNF-based full cell with CNF@PTPAn as the cathode and CNFs as the anode exhibits a high energy density of 60Wh kg^(-1)at 938Wkg^(-1).Based on this,the rational design is expected to provide more possibilities to obtain advanced freestanding electrode systems.