The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed...The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO_(2),thus generating the Pt/10EG-TiO_(2)-10 catalyst.The best CO oxidation activity with the excellent resistance to H_(2)O and SO_(2) was obtained over the Pt/10EG-TiO_(2)-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H_(2)O and 100 ppm SO_(2) at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO_(2) of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO_(2)-10 catalyst.The 10 wt.%EG doped in TiO_(2) caused the TiO_(2) support to form a more hydrophobic surface,which reduced the adsorption of H_(2)O and SO_(2) on the catalyst,greatly inhibited deposition of the TiOSO_(4) and formation of the PtSO4 species as well as suppressed the oxidation of SO_(2),thus resulting in an improvement in the resistance to H_(2)O and SO_(2) of the Pt/10EG-TiO_(2)-10 catalyst.展开更多
In this study, a series of flame-retardant polyisocyanurate-polyurethane (PIR-PUR) foams were prepared using various concentrations (0-25% by weight) of expandable graphite (EG) and dimethyl methyl phosphonate (DMMP) ...In this study, a series of flame-retardant polyisocyanurate-polyurethane (PIR-PUR) foams were prepared using various concentrations (0-25% by weight) of expandable graphite (EG) and dimethyl methyl phosphonate (DMMP) (0-7% by weight). The effect of these additives on the properties of the PIR-PUR foams, including physico-mechanical, morphological, flame retardancy, and thermal stability, was studied. Increasing amounts of EG in the PIR-PUR foam caused a significant drop in the compression strength. However, DMMP caused the mechanical properties of PIR-PUR foam to improve compared to foam filled with EG alone. The flame retardancy of PIR-PUR foams containing both EG and DMMP was enhanced significantly compared to EG filled foams. Thermogravimetric analysis (TGA) indicated that EG enhances the thermal stability of PIR-PUR foams but that DMMP decreased it. The morphology of the residual char provided conclusive evidence for the weak thermal stability of foams filled with DMMP.展开更多
In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding s...In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding strengths,oxygen index,and fluidity of rigid polyurethane foam(RPUF).The results revealed that EG significantly increased the oxygen index of RPUF,enlarged the diameter of foam cells,and decreased the cell-closed content in foam;thus,leading to a pressure drop in RPUF.However,excessive EG was capable of reducing the fluidity of polyurethane slurry.TEA exhibited significant influence on the compressive strength of RPUF,which dropped initially,and then increased.DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF.Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP,and achieved the maximum value at DMMP dosage of 4%.DMMP could effectively reduce the diameter of RPUF cells leading to an increase in the percentage of close area in foam.DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF.Moreover,the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO_2.The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.展开更多
This work reports on the effect of commercial expandable graphite(EG)on the flammability and thermal decomposition properties of PLA-starch blend.The PLA-starch/EG composites were prepared by melt-mixing and their the...This work reports on the effect of commercial expandable graphite(EG)on the flammability and thermal decomposition properties of PLA-starch blend.The PLA-starch/EG composites were prepared by melt-mixing and their thermal stability,volatile pyrolysis products and flammability characteristics were investigated.The char residues of the composites,after combustion in a cone calorimeter,were analyzed with environmental scanning electron microscopy(ESEM).The thermal decomposition stability of the composites improved in the presence of EG.However,the char content was less than expected as per the combination of the wt%EG added into PLA-starch and the%residue of PLA-starch.The flammability performance of the PLA-starch/EG composites improved,especially at 15 wt%EG content,due to a thick and strong worm-like char structure.The peak heat release rate(PHRR)improved by 74%,the total smoke production(TSP)by 40%and the specific extinction area(SEA)by 55%.The improvements are attributed to the ability of EG to exfoliate at increased temperatures during which time three effects occurred:(i)cooling due to an endothermic exfoliation process,(ii)dilution due to release of H2O,SO2 and CO2 gases,and (iii)formation of a protective intumescent char layer.However,the CO and CO2 yields were found to be unfavorably high due to the presence of EG.展开更多
The paper deals with a new method to synthesize expand-able graphite with H2O2 as oxidizer. This method causes less environ ——mental pollution than the tradi——tional method using HNO3. Some, opti-mum technical con...The paper deals with a new method to synthesize expand-able graphite with H2O2 as oxidizer. This method causes less environ ——mental pollution than the tradi——tional method using HNO3. Some, opti-mum technical conditions have been given here. It is shorvn that traditional method for manufacturing expandable graphite with HNO3 as oxidizer can be replaced completely with H2O2 as an oxidizer. Expandable graphite made, in this way has the same characteristics as that made in traditional way, but the pollution of NO2 to air decreases greatly.展开更多
In this paper,we introduced a novel method to prepare the few-layer nitrogen-doped graphene(FNG)from expandable graphite with melamine.The super-capacitive properties of FNG were thoroughly characterized by a three-el...In this paper,we introduced a novel method to prepare the few-layer nitrogen-doped graphene(FNG)from expandable graphite with melamine.The super-capacitive properties of FNG were thoroughly characterized by a three-electrode system,and the results showed the FNG electrode achieved a specific capacitance as high as 83.8 mF/cm2 together with excellent cycling stability.This method could be a novel approach to combine the pseudo-capacitors and electric double layer capacitors.展开更多
Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental frien...Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental friendliness.However,its intrinsic low conductivity and sluggish Na^(+)diffusion restricted the fast-charge and low-temperature sodium storage.Herein,an NFPP composite encapsulated by in-situ pyrolytic carbon and coupled with expanded graphite(NFPP@C/EG)was constructed via a sol-gel method followed by a ballmill procedure.Due to the dual-carbon modified strategy,this NFPP@C/EG only enhanced the electronic conductivity,but also endowed more channels for Na^(+)diffusion.As cathode for SIBs,the optimized NFPP(M-NFPP@C/EG)delivers excellent rate capability(capacity of~80.5 mAh/g at 50 C)and outstanding cycling stability(11000 cycles at 50 C with capacity retention of 89.85%).Additionally,cyclic voltammetry(CV)confirmed that its sodium storage behavior is pseudocapacitance-controlled,with in-situ electrochemical impedance spectroscopy(EIS)further elucidating improvements in electrode reaction kinetics.At lower temperatures(0℃),M-NFPP@C/EG demonstrated exceptional cycling performance(8800 cycles at 10 C with capacity retention of 95.81%).Moreover,pouch cells also exhibited excellent stability.This research demonstrates the feasibility of a dual carbon modification strategy in enhancing NFPP and proposes a low-cost,high-rate,and ultra-stable cathode material for SIBs.展开更多
基金supported by the National Key R&D Program of China (No.2017YFC0210303).
文摘The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO_(2),thus generating the Pt/10EG-TiO_(2)-10 catalyst.The best CO oxidation activity with the excellent resistance to H_(2)O and SO_(2) was obtained over the Pt/10EG-TiO_(2)-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H_(2)O and 100 ppm SO_(2) at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO_(2) of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO_(2)-10 catalyst.The 10 wt.%EG doped in TiO_(2) caused the TiO_(2) support to form a more hydrophobic surface,which reduced the adsorption of H_(2)O and SO_(2) on the catalyst,greatly inhibited deposition of the TiOSO_(4) and formation of the PtSO4 species as well as suppressed the oxidation of SO_(2),thus resulting in an improvement in the resistance to H_(2)O and SO_(2) of the Pt/10EG-TiO_(2)-10 catalyst.
基金supported by the State Key Program of Coal Joint Funds of National Natural Science Foundation of China (No.51134020)the Natural Science Foundation of Shandong Province(No. ZR2011EL036)the High School Science & Technology Fund Planning Project of Shandong Province (No. JIILD53)
文摘In this study, a series of flame-retardant polyisocyanurate-polyurethane (PIR-PUR) foams were prepared using various concentrations (0-25% by weight) of expandable graphite (EG) and dimethyl methyl phosphonate (DMMP) (0-7% by weight). The effect of these additives on the properties of the PIR-PUR foams, including physico-mechanical, morphological, flame retardancy, and thermal stability, was studied. Increasing amounts of EG in the PIR-PUR foam caused a significant drop in the compression strength. However, DMMP caused the mechanical properties of PIR-PUR foam to improve compared to foam filled with EG alone. The flame retardancy of PIR-PUR foams containing both EG and DMMP was enhanced significantly compared to EG filled foams. Thermogravimetric analysis (TGA) indicated that EG enhances the thermal stability of PIR-PUR foams but that DMMP decreased it. The morphology of the residual char provided conclusive evidence for the weak thermal stability of foams filled with DMMP.
基金supported by the National Natural Science Foundation of China(No.51304027)China Postdoctoral Science Foundation(2014M560567 and 2015T80730)+4 种基金Shandong Province Science and Technology Development Plan(2014GSF120012)the State Key Program of Coal Joint Funds of National Natural Science Foundation of China(Nos.51134020 and U1261205)Shandong Province Natural Science Foundation(No.ZR2011EL036)the Doctoral Scientific Research Foundation of Binzhou University(No.2013Y06)the Key Technology Projects for Preventing Major Accident of National Security State Administration of Work Safety
文摘In this study,orthogonal experiments were conducted to investigate the influence of expandable graphite(EG),dimethyl methylphosphonate(DMMP),triethanolamine(TEA),and isocyanate content on the compressive and bonding strengths,oxygen index,and fluidity of rigid polyurethane foam(RPUF).The results revealed that EG significantly increased the oxygen index of RPUF,enlarged the diameter of foam cells,and decreased the cell-closed content in foam;thus,leading to a pressure drop in RPUF.However,excessive EG was capable of reducing the fluidity of polyurethane slurry.TEA exhibited significant influence on the compressive strength of RPUF,which dropped initially,and then increased.DMMP had a remarkable effect on the flame retardant property and compressive strength of RPUF.Compressive strength of RPUF initially displayed an increase followed by a decrease with increasing dosage of DMMP,and achieved the maximum value at DMMP dosage of 4%.DMMP could effectively reduce the diameter of RPUF cells leading to an increase in the percentage of close area in foam.DMMP displayed the flame-retardation effects mainly in the gas phase leading to a significant enhancement in the oxygen index of RPUF.Moreover,the compressive strength and bonding strength of RPUF decrease significantly with the increase of isocyanate content due to the increased blowing efficiency by the CO_2.The oxygen index and flowing length of foam increased with the increase in isocyanate dosage.
文摘This work reports on the effect of commercial expandable graphite(EG)on the flammability and thermal decomposition properties of PLA-starch blend.The PLA-starch/EG composites were prepared by melt-mixing and their thermal stability,volatile pyrolysis products and flammability characteristics were investigated.The char residues of the composites,after combustion in a cone calorimeter,were analyzed with environmental scanning electron microscopy(ESEM).The thermal decomposition stability of the composites improved in the presence of EG.However,the char content was less than expected as per the combination of the wt%EG added into PLA-starch and the%residue of PLA-starch.The flammability performance of the PLA-starch/EG composites improved,especially at 15 wt%EG content,due to a thick and strong worm-like char structure.The peak heat release rate(PHRR)improved by 74%,the total smoke production(TSP)by 40%and the specific extinction area(SEA)by 55%.The improvements are attributed to the ability of EG to exfoliate at increased temperatures during which time three effects occurred:(i)cooling due to an endothermic exfoliation process,(ii)dilution due to release of H2O,SO2 and CO2 gases,and (iii)formation of a protective intumescent char layer.However,the CO and CO2 yields were found to be unfavorably high due to the presence of EG.
文摘The paper deals with a new method to synthesize expand-able graphite with H2O2 as oxidizer. This method causes less environ ——mental pollution than the tradi——tional method using HNO3. Some, opti-mum technical conditions have been given here. It is shorvn that traditional method for manufacturing expandable graphite with HNO3 as oxidizer can be replaced completely with H2O2 as an oxidizer. Expandable graphite made, in this way has the same characteristics as that made in traditional way, but the pollution of NO2 to air decreases greatly.
基金supported by the National Natural Science Foundation of China(Nos.21271082 and 21371068)。
文摘In this paper,we introduced a novel method to prepare the few-layer nitrogen-doped graphene(FNG)from expandable graphite with melamine.The super-capacitive properties of FNG were thoroughly characterized by a three-electrode system,and the results showed the FNG electrode achieved a specific capacitance as high as 83.8 mF/cm2 together with excellent cycling stability.This method could be a novel approach to combine the pseudo-capacitors and electric double layer capacitors.
基金supported by the National Key Research and Development Program of China(No.2022YFB2502000)the National Natural Science Foundation of China(Nos.U21A20332,51771076,U21A200970,52301266)the Science and Technology Planning Project of Guangzhou(No.2024A04J3332)。
文摘Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental friendliness.However,its intrinsic low conductivity and sluggish Na^(+)diffusion restricted the fast-charge and low-temperature sodium storage.Herein,an NFPP composite encapsulated by in-situ pyrolytic carbon and coupled with expanded graphite(NFPP@C/EG)was constructed via a sol-gel method followed by a ballmill procedure.Due to the dual-carbon modified strategy,this NFPP@C/EG only enhanced the electronic conductivity,but also endowed more channels for Na^(+)diffusion.As cathode for SIBs,the optimized NFPP(M-NFPP@C/EG)delivers excellent rate capability(capacity of~80.5 mAh/g at 50 C)and outstanding cycling stability(11000 cycles at 50 C with capacity retention of 89.85%).Additionally,cyclic voltammetry(CV)confirmed that its sodium storage behavior is pseudocapacitance-controlled,with in-situ electrochemical impedance spectroscopy(EIS)further elucidating improvements in electrode reaction kinetics.At lower temperatures(0℃),M-NFPP@C/EG demonstrated exceptional cycling performance(8800 cycles at 10 C with capacity retention of 95.81%).Moreover,pouch cells also exhibited excellent stability.This research demonstrates the feasibility of a dual carbon modification strategy in enhancing NFPP and proposes a low-cost,high-rate,and ultra-stable cathode material for SIBs.
