Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoret...Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide （P-Si/rGO） core-shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh-g-1 at a current density of 1,000 mA-g-1, 1,600 mAh.g-1 at 2,000 mA-g-1, 1,500 mAh-g 1 at 3,000 mA-g-1, 1,200 mAh-g-1 at 4,000 mA.g-1, and 950 mAh.g~ at 5,000 mA.g-~, and maintain a value of 1,258 mAh.g-~ after 300 cycles at a current density of 1,000 mA-g 1. Their excellent rate performance and cycling stability can be attributed to the unique structural design： 1） The graphene shell dramatically improves the conductivity and stabilizes the solid- electrolyte interface layers; 2） the inner porous structure supplies sufficient space for silicon expansion; 3） the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.展开更多
The strategy of combining highly conductive frameworks with abundant active sites is desirable in the preparation of alternative catalysts to commercial Pt/C for the oxygen reduction reaction （ORR）. In this study, N...The strategy of combining highly conductive frameworks with abundant active sites is desirable in the preparation of alternative catalysts to commercial Pt/C for the oxygen reduction reaction （ORR）. In this study, N-doped graphene （NG） and carbon nanotubes （CNT） were grown in-situ on Co-containing carbon nanofibers （CNF） to form three-dimensional （3D） interconnected networks. The NG and CNT bound the interlaced CNF together, facilitating electron transfer and providing additional active sites. The 3D interconnected fiber networks exhibited excellent ORR catalytic behavior with an onset potential of 0.924 V （vs. reversible hydrogen electrode） and a higher current density than Pt/C beyond 0.720 V. In addition, the hybrid system exhibited superior stability and methanol tolerance to Pt/C in alkaline media. This method can be extended to the design of other 3D interconnected network architectures for energy storage and conversion applications.展开更多
Propane dehydrogenation(PDH), employing Pt-or Cr-based catalysts, represents an emerging industrial route for propylene production. Due to the scarcity of platinum and the toxicity of chromium, alternative PDH catalys...Propane dehydrogenation(PDH), employing Pt-or Cr-based catalysts, represents an emerging industrial route for propylene production. Due to the scarcity of platinum and the toxicity of chromium, alternative PDH catalysts are being pursued. Herein, we report the construction of Zn-containing zeolite catalysts,namely Zn@S-1, for PDH reaction. Well-isolated zinc cations are successfully trapped and stabilized by the Si-OH groups in S-1 zeolites via in-situ hydrothermal synthesis. The as-prepared Zn@S-1 catalysts exhibit good dehydrogenation activity, high propylene selectivity, and regeneration capability in PDH reaction under employed conditions. The in-situ partial reduction of zinc species is observed and the partially reduced zinc cations are definitely identified as the active sites for PDH reaction.展开更多
Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an ...Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an urgent challenge.Herein,a simple pyrolysis of Fe3+-loaded mesoporous phenolic resin(mPF)-melamine precursor is used to prepare the single atom iron-anchored N-doped mesoporous graphitic carbon nanospheres(Fe/N-MGN).Investigation of the synthesis reveals the appropriate Fe-assisted catalysis effect and mPF template effect,which not only spurs the highly graphitic porous framework of Fe/N-MGN with plentiful pyridinic N/graphitic N,but also assures the dispersed single atom Fe anchoring without elaborated procedures.As a result,the as-synthesized Fe/N-MGN demonstrates high catalytic activity,good durability and excellent methanol tolerance for ORR.This work promises a facile method to regulate the graphitic carbon growth and single atom Fe loading for the highly efficient electrocatalysis.展开更多
Biofilm is an effective simultaneous denitrification and in situ sludge reduction system,and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction...Biofilm is an effective simultaneous denitrification and in situ sludge reduction system,and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction.In this study,the performance and mechanism of in situ sludge reduction were compared between FSC-SBBR and SC-SBBR with constructed by composite floating spherical carriers(FSC)and multi-faceted polyethylene suspension carriers(SC),respectively.The variation of EPS concentration indicated that the biofilm formation of FSC was faster than SC.Compared with SCSBBR,the FSC-SBBR yielded 0.16 g MLSS/g COD,almost 27.27%less sludge.The average removal rates of COD and NH_(4)^(+)-N were 93.39% and 96.66%,respectively,which were 5.21% and 1.43% higher than the average removal rate of SC-SBBR.Investigation of the mechanisms of sludge reduction revealed that,energy uncoupling metabolism and sludge decay were the main factors for sludge reduction inducing 43.13%and 49.65%less sludge,respectively,in FSC-SBBR.EEM fluorescence spectroscopy and SUVA analysis showed that the hydrolytic capacity of biofilm attached in FSC was stronger than those of SC,and the hydrolysis of EPS released more DOM contributed to lysis-cryptic growth metabolism.In additional,Bacteroidetes and Mizugakiibacter associated with sludge reduction were the dominant phylum and genus in FCS-SBBR.Thus,the effect of simultaneous in situ sludge reduction and pollutant removal in FSC-SBBR was better.展开更多
Linear or cross linked aqueous polyurethane dispersions with carboxyl Ag salt were prepared. TEM photos show that Ag + was homogeneously distributed in the microspheres. The Ag + was reduced in situ by photochemical m...Linear or cross linked aqueous polyurethane dispersions with carboxyl Ag salt were prepared. TEM photos show that Ag + was homogeneously distributed in the microspheres. The Ag + was reduced in situ by photochemical method. For linear polyurethane particles, as the extent of the reduction reaction of silver ions increased, the silver particles grew larger, but the number of the silver particles kept almost constant. In crosslinked polymer system, the number of silver particles increased, but the size of silver particles remained almost the same. We concluded that nucleation and growth of the silver particle are the result of the silver atom movement in the polymer matrix. In the linear polymer system, the movement of silver atom and aggregation of silver particles result in the formation and growth of several silver particles; in the cross linked polymer system, the polymer chain prevents the movement of silver particles, resulting in a number increase of silver particles.展开更多
A facile hydrothermal synthetic method, followed by in situ reduction and galvanic replacement processes, is used to prepare PtCo-modified Co304 nanosheets （PtCo/C0304 NSs） supported on Ni foam. The prepared nanomat...A facile hydrothermal synthetic method, followed by in situ reduction and galvanic replacement processes, is used to prepare PtCo-modified Co304 nanosheets （PtCo/C0304 NSs） supported on Ni foam. The prepared nanomaterial is used as an electrocatalyst for NaBH4 oxidation in alkaline solution. The morphology and phase composition of PtCo/C0304 NSs are characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）. The catalytic performance of PtCo/Co3O4 NSs is investigated by cyclic voltammetry （CV） and chronoamperometry （CA） in a standard three-electrode system. Current densities of 70 and 850 mA·cm^-2 were obtained at -0.4 V for Co/Co3O4 and PtCo/Co3O4 NSs, respectively, in a solution containing 2 mol·L^-1 NaOH and 0.2 mol·L^-1 NaBH4. The use of a noble metal （Pt） greatly enhances the catalytic activity of the transition metal （Co） and Co3O4. Besides, both Co and Co3O4 exhibit good B-H bond breaking ability （in NaBH4）, which leads to better electrocatalytic activity and stability of PtCo/Co3O4 NSs in NaBH4 electrooxidation compared to pure Pt. The results demonstrate that the as-prepared PtCo/Co3O4 NSs can be a promising electrocatalyst for borohydride oxidation.展开更多
采用ASBR/SBR原位臭氧污泥减量工艺,重点研究了原位臭氧氧化对SBR段污泥产率和出水水质的影响。两个相同的ASBR/SBR组合工艺同时运行,每隔3个周期向臭氧投加组SBR的曝气阶段原位间歇投加臭氧,臭氧投加量为0.027 g O3/g MLSS,连续运行40...采用ASBR/SBR原位臭氧污泥减量工艺,重点研究了原位臭氧氧化对SBR段污泥产率和出水水质的影响。两个相同的ASBR/SBR组合工艺同时运行,每隔3个周期向臭氧投加组SBR的曝气阶段原位间歇投加臭氧,臭氧投加量为0.027 g O3/g MLSS,连续运行40 d;对照组不投加臭氧作为对比。结果表明,原位臭氧氧化实现污泥减量约43.9%,臭氧投加组SBR段平均污泥产率系数为0.1447 g SS/g SCOD,而对照组为0.2580 g SS/g SCOD,投加组没有惰性污泥的累积,并且污泥沉淀性能得到改善。原位臭氧氧化对出水水质影响不大,投加组与对照组相比,臭氧投加3周期后的出水COD、NH4+-N、TN和TP平均值分别为47.8、0.76、14.1和6.4 mg/L,去除率分别下降了4%、2%、3%和7.7%,其中COD、NH4+-N和TN均能达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准。展开更多
文摘Silicon is considered an exceptionally promising alternative to the most commonly used material, graphite, as an anode for next-generation lithium-ion batteries, as it has high energy density owing to its high theoretical capacity and abundant storage. Here, microsized walnut-like porous silicon/reduced graphene oxide （P-Si/rGO） core-shell composites are successfully prepared via in situ reduction followed by a dealloying process. The composites show specific capacities of more than 2,100 mAh-g-1 at a current density of 1,000 mA-g-1, 1,600 mAh.g-1 at 2,000 mA-g-1, 1,500 mAh-g 1 at 3,000 mA-g-1, 1,200 mAh-g-1 at 4,000 mA.g-1, and 950 mAh.g~ at 5,000 mA.g-~, and maintain a value of 1,258 mAh.g-~ after 300 cycles at a current density of 1,000 mA-g 1. Their excellent rate performance and cycling stability can be attributed to the unique structural design： 1） The graphene shell dramatically improves the conductivity and stabilizes the solid- electrolyte interface layers; 2） the inner porous structure supplies sufficient space for silicon expansion; 3） the nanostructure of silicon can prevent the pulverization resulting from volume expansion stress. Notably, this in situ reduction method can be applied as a universal formula to coat graphene on almost all types of metals and alloys of various sizes, shapes, and compositions without adding any reagents to afford energy storage materials, graphene-based catalytic materials, graphene-enhanced composites, etc.
基金The work was financially supported by the National Natural Science Foundation of China （Nos. 51203182 and 51173202）, Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics （No. KF201312）, Key Laboratory of High Performance Fibers ＆ Products, Ministry of Education, Donghua University, Guangxi Key Laboratory of Information Materials （Guilin University of Electronic Technology） （No. 1210908-01-K）, Research Project of NUDT （No. JC13-01-05）, Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province, and Aid Program for Innovative Group of National University of Defense Technology.
文摘The strategy of combining highly conductive frameworks with abundant active sites is desirable in the preparation of alternative catalysts to commercial Pt/C for the oxygen reduction reaction （ORR）. In this study, N-doped graphene （NG） and carbon nanotubes （CNT） were grown in-situ on Co-containing carbon nanofibers （CNF） to form three-dimensional （3D） interconnected networks. The NG and CNT bound the interlaced CNF together, facilitating electron transfer and providing additional active sites. The 3D interconnected fiber networks exhibited excellent ORR catalytic behavior with an onset potential of 0.924 V （vs. reversible hydrogen electrode） and a higher current density than Pt/C beyond 0.720 V. In addition, the hybrid system exhibited superior stability and methanol tolerance to Pt/C in alkaline media. This method can be extended to the design of other 3D interconnected network architectures for energy storage and conversion applications.
基金National Natural Science Fund of China(22025203, 21872072)the Municipal Natural Science Fund of Tianjin (18JCJQJC47400) for supporting the work。
文摘Propane dehydrogenation(PDH), employing Pt-or Cr-based catalysts, represents an emerging industrial route for propylene production. Due to the scarcity of platinum and the toxicity of chromium, alternative PDH catalysts are being pursued. Herein, we report the construction of Zn-containing zeolite catalysts,namely Zn@S-1, for PDH reaction. Well-isolated zinc cations are successfully trapped and stabilized by the Si-OH groups in S-1 zeolites via in-situ hydrothermal synthesis. The as-prepared Zn@S-1 catalysts exhibit good dehydrogenation activity, high propylene selectivity, and regeneration capability in PDH reaction under employed conditions. The in-situ partial reduction of zinc species is observed and the partially reduced zinc cations are definitely identified as the active sites for PDH reaction.
基金This study was supported by the National Natural Science Foundation of China(Nos.21675032 and 81861138040)the Fundamental Research Funds for the Central Universities and DHU Distinguished Young Professor Program.We appreciate the kind help from Dr.Li Wang in Center of Analysis and Measurement,Fudan University for preparation of complicated samples and elemental analysis.
文摘Single atom catalyst is of great importance for the oxygen reduction reaction(ORR).However,facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an urgent challenge.Herein,a simple pyrolysis of Fe3+-loaded mesoporous phenolic resin(mPF)-melamine precursor is used to prepare the single atom iron-anchored N-doped mesoporous graphitic carbon nanospheres(Fe/N-MGN).Investigation of the synthesis reveals the appropriate Fe-assisted catalysis effect and mPF template effect,which not only spurs the highly graphitic porous framework of Fe/N-MGN with plentiful pyridinic N/graphitic N,but also assures the dispersed single atom Fe anchoring without elaborated procedures.As a result,the as-synthesized Fe/N-MGN demonstrates high catalytic activity,good durability and excellent methanol tolerance for ORR.This work promises a facile method to regulate the graphitic carbon growth and single atom Fe loading for the highly efficient electrocatalysis.
基金supported by the Natural Science Foundation of Shandong Province(ZR2016EEM32)the Doctoral Fund of Shandong Jianzhu University in 2015(XNBS1511)Scientific and technological Innovation Project of Planning and Design Institute of Huaihe River Basin Water Conservancy Administration Bureau of Shandong Province in 2018(SFSJKY2018-01).
文摘Biofilm is an effective simultaneous denitrification and in situ sludge reduction system,and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction.In this study,the performance and mechanism of in situ sludge reduction were compared between FSC-SBBR and SC-SBBR with constructed by composite floating spherical carriers(FSC)and multi-faceted polyethylene suspension carriers(SC),respectively.The variation of EPS concentration indicated that the biofilm formation of FSC was faster than SC.Compared with SCSBBR,the FSC-SBBR yielded 0.16 g MLSS/g COD,almost 27.27%less sludge.The average removal rates of COD and NH_(4)^(+)-N were 93.39% and 96.66%,respectively,which were 5.21% and 1.43% higher than the average removal rate of SC-SBBR.Investigation of the mechanisms of sludge reduction revealed that,energy uncoupling metabolism and sludge decay were the main factors for sludge reduction inducing 43.13%and 49.65%less sludge,respectively,in FSC-SBBR.EEM fluorescence spectroscopy and SUVA analysis showed that the hydrolytic capacity of biofilm attached in FSC was stronger than those of SC,and the hydrolysis of EPS released more DOM contributed to lysis-cryptic growth metabolism.In additional,Bacteroidetes and Mizugakiibacter associated with sludge reduction were the dominant phylum and genus in FCS-SBBR.Thus,the effect of simultaneous in situ sludge reduction and pollutant removal in FSC-SBBR was better.
文摘Linear or cross linked aqueous polyurethane dispersions with carboxyl Ag salt were prepared. TEM photos show that Ag + was homogeneously distributed in the microspheres. The Ag + was reduced in situ by photochemical method. For linear polyurethane particles, as the extent of the reduction reaction of silver ions increased, the silver particles grew larger, but the number of the silver particles kept almost constant. In crosslinked polymer system, the number of silver particles increased, but the size of silver particles remained almost the same. We concluded that nucleation and growth of the silver particle are the result of the silver atom movement in the polymer matrix. In the linear polymer system, the movement of silver atom and aggregation of silver particles result in the formation and growth of several silver particles; in the cross linked polymer system, the polymer chain prevents the movement of silver particles, resulting in a number increase of silver particles.
基金We gratefully acknowledge the financial support of this research by the National Natural Science Foundation of China （No. 51572052）, the Natural Science Foundation of Heilongjiang Province of China （No. LC2015004）, the China Postdoctoral Science Special Foundation （No. 2015T80329）, the Major Project of Science and Technology of Heilongjiang Province （No. GA14A101） and the Project of Research and Development of Applied Technology of Harbin （No. 2014DB4AG016）.
文摘A facile hydrothermal synthetic method, followed by in situ reduction and galvanic replacement processes, is used to prepare PtCo-modified Co304 nanosheets （PtCo/C0304 NSs） supported on Ni foam. The prepared nanomaterial is used as an electrocatalyst for NaBH4 oxidation in alkaline solution. The morphology and phase composition of PtCo/C0304 NSs are characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）. The catalytic performance of PtCo/Co3O4 NSs is investigated by cyclic voltammetry （CV） and chronoamperometry （CA） in a standard three-electrode system. Current densities of 70 and 850 mA·cm^-2 were obtained at -0.4 V for Co/Co3O4 and PtCo/Co3O4 NSs, respectively, in a solution containing 2 mol·L^-1 NaOH and 0.2 mol·L^-1 NaBH4. The use of a noble metal （Pt） greatly enhances the catalytic activity of the transition metal （Co） and Co3O4. Besides, both Co and Co3O4 exhibit good B-H bond breaking ability （in NaBH4）, which leads to better electrocatalytic activity and stability of PtCo/Co3O4 NSs in NaBH4 electrooxidation compared to pure Pt. The results demonstrate that the as-prepared PtCo/Co3O4 NSs can be a promising electrocatalyst for borohydride oxidation.
文摘采用ASBR/SBR原位臭氧污泥减量工艺,重点研究了原位臭氧氧化对SBR段污泥产率和出水水质的影响。两个相同的ASBR/SBR组合工艺同时运行,每隔3个周期向臭氧投加组SBR的曝气阶段原位间歇投加臭氧,臭氧投加量为0.027 g O3/g MLSS,连续运行40 d;对照组不投加臭氧作为对比。结果表明,原位臭氧氧化实现污泥减量约43.9%,臭氧投加组SBR段平均污泥产率系数为0.1447 g SS/g SCOD,而对照组为0.2580 g SS/g SCOD,投加组没有惰性污泥的累积,并且污泥沉淀性能得到改善。原位臭氧氧化对出水水质影响不大,投加组与对照组相比,臭氧投加3周期后的出水COD、NH4+-N、TN和TP平均值分别为47.8、0.76、14.1和6.4 mg/L,去除率分别下降了4%、2%、3%和7.7%,其中COD、NH4+-N和TN均能达到《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A标准。
