A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane ...A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.402 exhibited the best activity, which converted 94.52% of CH4 at 900 ℃.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
A series of copper (Ⅱ) complexes with pyridine N- oxide- 2- ylmethylidened-ithiocarbazates as ligands were synthesized and characterized by IR spectra, electronic spectra and magnetic moments measurement at room temp...A series of copper (Ⅱ) complexes with pyridine N- oxide- 2- ylmethylidened-ithiocarbazates as ligands were synthesized and characterized by IR spectra, electronic spectra and magnetic moments measurement at room temperature. Variable temperature magnetic susceptibilites (3-300K) of four complexs were measured and fitted with the Bleaney-Bowers dimer equation by considering the magnetic interaction between molecules. The fitting results show the existence of intramolecular ferromagnetic interactions and intermolecu-lar anti-ferromagnetic interactions in these copper( Ⅱ) complexes.展开更多
The crystal and molecular structure of copper(Ⅱ) dimeric complex of S-methyl-B-N-(pyridine N-oxide-2-ylmethylidene) dithiocarbazate with acetonitrile, [CuL (CH3CN)]2 (ClO4)2, was determined by X-ray diffraction. The ...The crystal and molecular structure of copper(Ⅱ) dimeric complex of S-methyl-B-N-(pyridine N-oxide-2-ylmethylidene) dithiocarbazate with acetonitrile, [CuL (CH3CN)]2 (ClO4)2, was determined by X-ray diffraction. The complex crystalizes in monoclinic system with space group P21/n, a= 7. 685(2), 6=20.160(6), c= 10. 847(5) A ,B = 107.89(3), Z=2,Dc=1.788 g/cm3, F(000) = 835. 8, u= 18. 17 cm-1(Moka,R= 0. 057.Each Cu(Ⅱ) ion in the complex is surrounded by a distorted square pyramidal. The basal plane is comprised of S, N and O atoms of one ligand together with a N atom of the solvent--acetonitrile, while the axial position is occupied by the S atom of the other ligand. The bond length of Cu-S(bridging) is 3. 038A . and Cu-Cu distance is 3. 700A.展开更多
Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10^(20)–10^(21)cm^(−3)and an excessively high lattice thermal conductivity.However,the high carri...Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10^(20)–10^(21)cm^(−3)and an excessively high lattice thermal conductivity.However,the high carrier concentration and lattice thermal conductivity observed in SnTe are not solely attributable to the presence of numerous intrinsic tin vacancies and a simple crystal structure.Additionally,the oxides formed through the oxidation of Sn and SnTe exert a partial influence on these properties.In this study,by pretreating the raw Sn material and isolating it from oxygen during preparation,we achieve a significant improvement in the thermoelectric performance of binary SnTe at high temperatures,with a peak ZT of approximately 0.83 at 800 K.This approach effectively reduces the content of SnO_(2)in the matrix,enhancing the electrical and thermal transport properties of the samples.Specifically,the high-thermal conductivity of SnO_(2)facilitates the formation of channels at grain boundaries that are more conducive to heat transfer,while its poor electrical conductivity and Seebeck coefficient diminish the intrinsic electrical transport behavior of SnTe.The removal of SnO_(2)reflects the true thermoelectric performance of SnTe,making the samples prepared by this method stand out compared to other reported binary SnTe materials.展开更多
In this study,the Ti/SnO_(2)-RuO_(2) electrodes with different Yb contents were prepared by sol-gel method and thermal decomposition method,and the surface morphology and crystal structure of the electrodes were chara...In this study,the Ti/SnO_(2)-RuO_(2) electrodes with different Yb contents were prepared by sol-gel method and thermal decomposition method,and the surface morphology and crystal structure of the electrodes were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM) and X-ray diffraction(XRD),the electrochemical properties of the electrodes were tested by linear sweep voltammetry(LSV) and cyclic voltammetry(CV).The electrochemical oxidation device was constructed with Yb-doped Ti/SnO_(2)-RuO_(2) electrode as the anode and titanium plate as the cathode,and the electrochemical oxidation effect and product changes of the anode on co king wastewater were investigated.The results show that the surface of the electrode is flat with high crystallinity of SnO_(2) and RuO_(2) crystals at1.5% Yb doping,and the LSV and CV curves indicate that the Yb doping of 1.5% increases the oxygen precipitation potential and electrocatalytic oxidation activity of the electrode.When the electrode with Yb doping of 1.5% is the anode with current density of 10 mA/cm^(2) electrochemical oxidation time of 30 min,the electrode can remove chemical oxygen demand(COD) up to 85.06%,total organic carbon(TOC) up to 60.59% and UV_(254) from 1.594 to 0.507 for coking wastewater.Gas chromatography(GC-MS),UV-vis and three-dimensional fluorescence results of coking wastewater before and after treatment show that large toxic substances in coking wastewater are degraded to low toxic organic substances,and most soluble organic substances are degraded and transformed.This study provides the possibility of basic research for the engineering practice of electrochemical oxidation for the treatment of coking wastewater.展开更多
Nanostructure K2NiF4 type oxides La2-xKxCuO4 complex oxides were prepared using the Sol-Gel method, characterized by X-Ray Diffraction （XRD）, Fourier Transform Infrared （FT-IR）, and Scanning Electron Microscopy （...Nanostructure K2NiF4 type oxides La2-xKxCuO4 complex oxides were prepared using the Sol-Gel method, characterized by X-Ray Diffraction （XRD）, Fourier Transform Infrared （FT-IR）, and Scanning Electron Microscopy （SEM）. The catalytic activity for soot combustion was evaluated by the Temperature-Programmed Reaction （TPO） technique. The results demonstrated that the substitution quality of K^＋ for La^3＋ at the A-site would increase the catalytic activities of La2-xKxCuO4 for soot combustion greatly; the substitution quality affected the structure and catalytic activity obviously. The La1.8K0.2CuO4 complex oxides with tetrahedral structures had the best catalytic activity for soot combustion, and the ignition temperature of soot combustion was lowered from 490 to 320 ℃.展开更多
Being abundant and active,Fe_(2)O_(3) is suitable for selective oxidation of H_(2)S.However,its practical application is limited due to the poor sulfur selectivity and rapid deactivation.Herein,we report a facile temp...Being abundant and active,Fe_(2)O_(3) is suitable for selective oxidation of H_(2)S.However,its practical application is limited due to the poor sulfur selectivity and rapid deactivation.Herein,we report a facile template-free hydrothermal method to fabricate porousα-Fe_(2)O_(3)/SnO_(2) composites with hierarchical nanoflower that can obviously improve the catalytic performance of Fe_(2)O_(3).It was disclosed that the synergistic effect betweenα-Fe_(2)O_(3) and SnO_(2) promotes the physico-chemical properties ofα-Fe_(2)O_(3)/SnO_(2) composites.Specifically,the electron transfer between the Fe^(2+)/Fe^(3+)and Sn^(2+)/Sn^(4+)redox couples enhances the reducibility ofα-Fe_(2)O_(3)/SnO_(2) composites.The number of oxygen vacancies is improved when the Fe cations incorporate into SnO_(2) structure,which facilitates the adsorption and activation of oxygen species.Additionally,the porous structure improves the accessibility of H_(2) S to active sites.Among the composites,Fe1 Sn1 exhibits complete H_(2) S conversion with 100%sulfur selectivity at 220℃,better than those of pureα-Fe_(2)O_(3) and SnO2.Moreover,Fe1 Sn1 catalyst shows high stability and water resistance.展开更多
The K2NiF4 type oxides, La2-x KxCuO4 complex oxides with nanometric size were prepared by sol-gel method. The characters of these samples were analyzed by H2-TPR, XRD, FT-IR and SEM. The catalytic activity for soot co...The K2NiF4 type oxides, La2-x KxCuO4 complex oxides with nanometric size were prepared by sol-gel method. The characters of these samples were analyzed by H2-TPR, XRD, FT-IR and SEM. The catalytic activity for soot combustion was evaluated by temperature-programmed reaction （TPO） technique. The results demonstrate that the substitution of K^＋ for La^3＋ at A-site will increase the catalytic activities of La2-xKxCuO4 to soot combustion greatly, and the substitution quantity affects the structure and catalytic activity obviously. The La1.8 K0.2 CuO4 complex oxides with tetrahedral structure has the best catalytic activity for soot removal reaction, the ignition temperature of soot combustion is decreased from 490 to 320℃.展开更多
Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and al...Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and alcohols with the conversion of 15.00％～34.58％ containing of 97.60％～99.80％ ketones and alcohols. The turnover numbers of these catalysts are over 3500 mol-cat. ^(-1)for 3.5 h.展开更多
Electrochemical oxidation is an effective method to degrade persistent organic pollutants.However,due to the limited catalytic activity of traditional thin film electrodes,the anodic oxidation process is slow and usua...Electrochemical oxidation is an effective method to degrade persistent organic pollutants.However,due to the limited catalytic activity of traditional thin film electrodes,the anodic oxidation process is slow and usually requires high energy consumption.Herein,Ti/SnO_(2)-Sb electrode with regulated surface structure was reported to enhance the performance for electrochemical oxidation of persistent organic pollutants.The electrode deposited with SnO_(2)-Sb nanoneedles(Ti/N-SnO_(2)-Sb)showed higher oxidation activity.Its kinetic constant for perfluorooctanoic acid(PFOA)oxidation was 2.0 h^(-1)and the total organic carbon removal rate was 81.7%(4 h)at a relatively low current density of 6 mA/cm^2.Compared with Ti/SnO_(2)-Sb thin film and nanoparticles,Ti/N-SnO_(2)-Sb significantly improved the electrochemical active area and·OH yield,and simultaneously reduced the electron transfer resistance,which enabled it to oxidize PFOA more rapidly even at a lower potential.This work provides a new strategy for promoting the electrochemical oxidation performance.展开更多
基金the National Natural Science Foundation of China (50574046)National Natural Science Foundation of Major Research Projects (90610035)+1 种基金Natural Science Foundation of Yunnan Province (2004E0058Q)High School Doctoral Subject Special Science and Re- search Foundation of Ministry of Education (20040674005)
文摘A series of Ce1-xFexO2 （x=0, 0.2, 0.4, 0.6, 0.8, 1） complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.402 exhibited the best activity, which converted 94.52% of CH4 at 900 ℃.
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A series of copper (Ⅱ) complexes with pyridine N- oxide- 2- ylmethylidened-ithiocarbazates as ligands were synthesized and characterized by IR spectra, electronic spectra and magnetic moments measurement at room temperature. Variable temperature magnetic susceptibilites (3-300K) of four complexs were measured and fitted with the Bleaney-Bowers dimer equation by considering the magnetic interaction between molecules. The fitting results show the existence of intramolecular ferromagnetic interactions and intermolecu-lar anti-ferromagnetic interactions in these copper( Ⅱ) complexes.
文摘The crystal and molecular structure of copper(Ⅱ) dimeric complex of S-methyl-B-N-(pyridine N-oxide-2-ylmethylidene) dithiocarbazate with acetonitrile, [CuL (CH3CN)]2 (ClO4)2, was determined by X-ray diffraction. The complex crystalizes in monoclinic system with space group P21/n, a= 7. 685(2), 6=20.160(6), c= 10. 847(5) A ,B = 107.89(3), Z=2,Dc=1.788 g/cm3, F(000) = 835. 8, u= 18. 17 cm-1(Moka,R= 0. 057.Each Cu(Ⅱ) ion in the complex is surrounded by a distorted square pyramidal. The basal plane is comprised of S, N and O atoms of one ligand together with a N atom of the solvent--acetonitrile, while the axial position is occupied by the S atom of the other ligand. The bond length of Cu-S(bridging) is 3. 038A . and Cu-Cu distance is 3. 700A.
基金supported by the National Natural Science Foundation of China(Grant No.52371235)the National Natural Science Foundation of China(Grant No.52171221).
文摘Previous studies on SnTe have indicated that its low ZT value is associated with a high carrier concentration of up to 10^(20)–10^(21)cm^(−3)and an excessively high lattice thermal conductivity.However,the high carrier concentration and lattice thermal conductivity observed in SnTe are not solely attributable to the presence of numerous intrinsic tin vacancies and a simple crystal structure.Additionally,the oxides formed through the oxidation of Sn and SnTe exert a partial influence on these properties.In this study,by pretreating the raw Sn material and isolating it from oxygen during preparation,we achieve a significant improvement in the thermoelectric performance of binary SnTe at high temperatures,with a peak ZT of approximately 0.83 at 800 K.This approach effectively reduces the content of SnO_(2)in the matrix,enhancing the electrical and thermal transport properties of the samples.Specifically,the high-thermal conductivity of SnO_(2)facilitates the formation of channels at grain boundaries that are more conducive to heat transfer,while its poor electrical conductivity and Seebeck coefficient diminish the intrinsic electrical transport behavior of SnTe.The removal of SnO_(2)reflects the true thermoelectric performance of SnTe,making the samples prepared by this method stand out compared to other reported binary SnTe materials.
基金Project supported by Natural Science Foundation of Inner Mongolia(2018LH04003,2020MS05047)Inner Mongolia Autonomous Region Science Technology Plan Project(201702100)+1 种基金Inner Mongolia Autonomous Region Results Transfer Project(2019CG075)。
文摘In this study,the Ti/SnO_(2)-RuO_(2) electrodes with different Yb contents were prepared by sol-gel method and thermal decomposition method,and the surface morphology and crystal structure of the electrodes were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM) and X-ray diffraction(XRD),the electrochemical properties of the electrodes were tested by linear sweep voltammetry(LSV) and cyclic voltammetry(CV).The electrochemical oxidation device was constructed with Yb-doped Ti/SnO_(2)-RuO_(2) electrode as the anode and titanium plate as the cathode,and the electrochemical oxidation effect and product changes of the anode on co king wastewater were investigated.The results show that the surface of the electrode is flat with high crystallinity of SnO_(2) and RuO_(2) crystals at1.5% Yb doping,and the LSV and CV curves indicate that the Yb doping of 1.5% increases the oxygen precipitation potential and electrocatalytic oxidation activity of the electrode.When the electrode with Yb doping of 1.5% is the anode with current density of 10 mA/cm^(2) electrochemical oxidation time of 30 min,the electrode can remove chemical oxygen demand(COD) up to 85.06%,total organic carbon(TOC) up to 60.59% and UV_(254) from 1.594 to 0.507 for coking wastewater.Gas chromatography(GC-MS),UV-vis and three-dimensional fluorescence results of coking wastewater before and after treatment show that large toxic substances in coking wastewater are degraded to low toxic organic substances,and most soluble organic substances are degraded and transformed.This study provides the possibility of basic research for the engineering practice of electrochemical oxidation for the treatment of coking wastewater.
基金Beijing Municipal Education Committee Program (KM200710017006)
文摘Nanostructure K2NiF4 type oxides La2-xKxCuO4 complex oxides were prepared using the Sol-Gel method, characterized by X-Ray Diffraction （XRD）, Fourier Transform Infrared （FT-IR）, and Scanning Electron Microscopy （SEM）. The catalytic activity for soot combustion was evaluated by the Temperature-Programmed Reaction （TPO） technique. The results demonstrated that the substitution quality of K^＋ for La^3＋ at the A-site would increase the catalytic activities of La2-xKxCuO4 for soot combustion greatly; the substitution quality affected the structure and catalytic activity obviously. The La1.8K0.2CuO4 complex oxides with tetrahedral structures had the best catalytic activity for soot combustion, and the ignition temperature of soot combustion was lowered from 490 to 320 ℃.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.21825801)National Natural Science Foundation of China(Nos.21677036,21878052 and 21773030)。
文摘Being abundant and active,Fe_(2)O_(3) is suitable for selective oxidation of H_(2)S.However,its practical application is limited due to the poor sulfur selectivity and rapid deactivation.Herein,we report a facile template-free hydrothermal method to fabricate porousα-Fe_(2)O_(3)/SnO_(2) composites with hierarchical nanoflower that can obviously improve the catalytic performance of Fe_(2)O_(3).It was disclosed that the synergistic effect betweenα-Fe_(2)O_(3) and SnO_(2) promotes the physico-chemical properties ofα-Fe_(2)O_(3)/SnO_(2) composites.Specifically,the electron transfer between the Fe^(2+)/Fe^(3+)and Sn^(2+)/Sn^(4+)redox couples enhances the reducibility ofα-Fe_(2)O_(3)/SnO_(2) composites.The number of oxygen vacancies is improved when the Fe cations incorporate into SnO_(2) structure,which facilitates the adsorption and activation of oxygen species.Additionally,the porous structure improves the accessibility of H_(2) S to active sites.Among the composites,Fe1 Sn1 exhibits complete H_(2) S conversion with 100%sulfur selectivity at 220℃,better than those of pureα-Fe_(2)O_(3) and SnO2.Moreover,Fe1 Sn1 catalyst shows high stability and water resistance.
文摘The K2NiF4 type oxides, La2-x KxCuO4 complex oxides with nanometric size were prepared by sol-gel method. The characters of these samples were analyzed by H2-TPR, XRD, FT-IR and SEM. The catalytic activity for soot combustion was evaluated by temperature-programmed reaction （TPO） technique. The results demonstrate that the substitution of K^＋ for La^3＋ at A-site will increase the catalytic activities of La2-xKxCuO4 to soot combustion greatly, and the substitution quantity affects the structure and catalytic activity obviously. The La1.8 K0.2 CuO4 complex oxides with tetrahedral structure has the best catalytic activity for soot removal reaction, the ignition temperature of soot combustion is decreased from 490 to 320℃.
文摘Oxidation of alkybenzenes PhCH_2R(R=H, CH_3, C_2H_5 and n-C_3H_7) under 1 atm. of O_2 or air catalyzed by iron(Ⅱ, Ⅲ)-2,2'-bipyridine and 1,10-phenanthroline complexes, affords the aryl-substituted ketones and alcohols with the conversion of 15.00％～34.58％ containing of 97.60％～99.80％ ketones and alcohols. The turnover numbers of these catalysts are over 3500 mol-cat. ^(-1)for 3.5 h.
基金supported by Liaoning Revitalization Talents Program(No.XLYC2007069)the National Natural Science Foundation of China(Nos.22076019 and 22222601)open project of State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.HC201705)。
文摘Electrochemical oxidation is an effective method to degrade persistent organic pollutants.However,due to the limited catalytic activity of traditional thin film electrodes,the anodic oxidation process is slow and usually requires high energy consumption.Herein,Ti/SnO_(2)-Sb electrode with regulated surface structure was reported to enhance the performance for electrochemical oxidation of persistent organic pollutants.The electrode deposited with SnO_(2)-Sb nanoneedles(Ti/N-SnO_(2)-Sb)showed higher oxidation activity.Its kinetic constant for perfluorooctanoic acid(PFOA)oxidation was 2.0 h^(-1)and the total organic carbon removal rate was 81.7%(4 h)at a relatively low current density of 6 mA/cm^2.Compared with Ti/SnO_(2)-Sb thin film and nanoparticles,Ti/N-SnO_(2)-Sb significantly improved the electrochemical active area and·OH yield,and simultaneously reduced the electron transfer resistance,which enabled it to oxidize PFOA more rapidly even at a lower potential.This work provides a new strategy for promoting the electrochemical oxidation performance.
