Through in situ redox deposition and growth of MnO2 nanostructures on hierarchically porous carbon （HPC）, a MnOR/HPC hybrid has been synthesized and employed as cathode catalyst for non-aqueous Li-O2 batteries. Owin...Through in situ redox deposition and growth of MnO2 nanostructures on hierarchically porous carbon （HPC）, a MnOR/HPC hybrid has been synthesized and employed as cathode catalyst for non-aqueous Li-O2 batteries. Owing to the mild synthetic conditions, MnO2 was uniformly distributed on the surface of the carbon support, without destroying the hierarchical porous nanostructure. As a result, the as-prepared MnO2/HPC nanocomposite exhibits excellent Li-O2 battery performance, including low charge overpotential, good rate capacity and long cycle stability up to 300 cycles with controlling capacity of 1,000 mAh·g^-1. A combination of the multi-scale porous network of the shell-connected carbon support and the highly dispersed MnO2 nanostructure benefits the transportation of ions, oxygen and electrons and contributes to the excellent electrode performance.展开更多
Electronic adjustment is one of the most commonly used strategies to improve the catalytic performance of heterogeneous catalysts. We prepared hexagonal ultrathin Pd nanosheets with edges modified by gold nanoparticl...Electronic adjustment is one of the most commonly used strategies to improve the catalytic performance of heterogeneous catalysts. We prepared hexagonal ultrathin Pd nanosheets with edges modified by gold nanoparticles （Au@Pd nanosheets） using galvanic replacement method. By virtue of the electronic interactions between the Pd nanosheets and Au nanoparticles, the Au@Pd nanosheets exhibited excellent catalytic performances in the carbonylation of iodobenzene by carbon monoxide. The novel nanocomposites could be applied as model catalysts to explore electronic effects in catalysis.展开更多
CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate(TEOS) as Si source,and aqueous solution of Cu,Co and Mn acetates as the precursors via sol-gel process and ethanol supercritical ...CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate(TEOS) as Si source,and aqueous solution of Cu,Co and Mn acetates as the precursors via sol-gel process and ethanol supercritical drying technique.The gelatination mechanism was investigated by nuclear magnetic resonance(NMR) and X-ray photoelectron spectroscopy(XPS).The microstructure and composition of the CuO-CoO-MnO/SiO2 nanocomposite aerogels were characterized by field emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM),electron dispersive spectroscopy(EDS) and XPS.The specific surface area,pore size and pore size distribution of the nanocomposite aerogels were determined by the Brunauer–Emmett–Teller(BET) method.The products were analyzed by gas chromatography(GC).The results show that the CuO-CoO-MnO/SiO2 nanocomposite aerogels are porous,with a particle size distribution of 10–150 nm,a pore size distribution of 2–16 nm,an average pore size of 7.68 nm,and a specific surface area of 664.4-695.8 m2/g.The molar fraction of transition metals in the nanocomposite aerogels is 0.71%-13.77%.This kind of structure is favorable not only to increase the loading of catalysts,but also to make full use of the effect of transition metal oxides as cocatalysts;CuO-CoO-MnO/SiO2 nanocomposite aerogels can be used as a novel catalyst carrier in the safer and environment-friendly synthesis of diphenyl carbonate and other fields of catalysis.展开更多
An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the s...An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the specific surface area of the bare CoSnO3 nanoboxes(104.3 m2 g–1),the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g–1 and the electronic conductivity also improved.The increased specific surface area provided more space for the deposition of Li2O2,while the improved electronic conductivity accelerated the decomposition of Li2O2.Compared to bare CoSnO3,the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g?1 when CoSnO3@rGO was used as the catalyst.A Li‐O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g–1 with a limited capacity of 1000 mAh g–1,which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.展开更多
本实验采用共还原法合成了Mo掺杂的非晶态CuCoMo/氮化硼纳米片(记为CuCoMo/BNNSs)复合催化剂,BNNSs通过聚乙烯吡咯烷酮(PVP)辅助氢氧化钠结晶法剥离获得。通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)...本实验采用共还原法合成了Mo掺杂的非晶态CuCoMo/氮化硼纳米片(记为CuCoMo/BNNSs)复合催化剂,BNNSs通过聚乙烯吡咯烷酮(PVP)辅助氢氧化钠结晶法剥离获得。通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)及选区电子衍射(SAED)等对纳米复合催化剂的结构和形貌进行表征,并考察了Mo掺杂对CuCoMo/BNNSs纳米复合催化剂催化氨硼烷(AB)水解产氢活性的影响。结果表明:Mo作为给电子体将电子转移到CuCo NPs,从而增强了催化剂内部金属间的相互作用,提高了催化剂的催化性能。活性测试表明,非晶态(CuCo)0.85 Mo 0.15/BNNSs纳米复合催化剂在室温及pH=14条件下对AB水解产氢的催化活性极高,转化频率(TOF)值高达179.17 mol H 2·mol-1 metal·min-1,首次证明了非晶态CuCoMo NPs是催化AB水解过程中的关键活性组分。这种电子转移不局限于CuCoMo NPs,可以扩展到CuCoW(156.77 mol H 2·mol-1 metal·min-1)和CuCoCr(125.42 mol H 2·mol-1 metal·min-1)NPs。本工作结合表征及实验结果对纳米复合催化剂用于AB水解的催化机理进行了分析。展开更多
In the present investigation,a series of nanocomposite material such as MoO3,Fe3O4 synthesized by co-precipitation method and Beta cyclodextrin(β-CD)doped MoO3-Fe3O4 and Graphite doped MoO3-Fe3O4 have been synthesize...In the present investigation,a series of nanocomposite material such as MoO3,Fe3O4 synthesized by co-precipitation method and Beta cyclodextrin(β-CD)doped MoO3-Fe3O4 and Graphite doped MoO3-Fe3O4 have been synthesized successfully by Sol-Gel method.Synthesized nanomaterials were characterized in detail by XRD,FT-IR,TEM-HRTEM,UV-Vis DRS techniques.The crystalline size was in the range of 10±2 nm.The activity of the prepared material as a heterogeneous catalyst was successfully tested on the organic reaction of synthesis of substituted m-Chloro-Nitrobenzene and it was found to give excellent yield.展开更多
文摘Through in situ redox deposition and growth of MnO2 nanostructures on hierarchically porous carbon （HPC）, a MnOR/HPC hybrid has been synthesized and employed as cathode catalyst for non-aqueous Li-O2 batteries. Owing to the mild synthetic conditions, MnO2 was uniformly distributed on the surface of the carbon support, without destroying the hierarchical porous nanostructure. As a result, the as-prepared MnO2/HPC nanocomposite exhibits excellent Li-O2 battery performance, including low charge overpotential, good rate capacity and long cycle stability up to 300 cycles with controlling capacity of 1,000 mAh·g^-1. A combination of the multi-scale porous network of the shell-connected carbon support and the highly dispersed MnO2 nanostructure benefits the transportation of ions, oxygen and electrons and contributes to the excellent electrode performance.
基金supported by the National Natural Science Foundation of China(20803001,20973003,51121091,21133001)National Key Basic Research Special Foundation of China(2011CB808702)~~
文摘Electronic adjustment is one of the most commonly used strategies to improve the catalytic performance of heterogeneous catalysts. We prepared hexagonal ultrathin Pd nanosheets with edges modified by gold nanoparticles （Au@Pd nanosheets） using galvanic replacement method. By virtue of the electronic interactions between the Pd nanosheets and Au nanoparticles, the Au@Pd nanosheets exhibited excellent catalytic performances in the carbonylation of iodobenzene by carbon monoxide. The novel nanocomposites could be applied as model catalysts to explore electronic effects in catalysis.
基金Project(10215606D) supported by the Science and Technology Development Foundation of Hebei province,China
文摘CuO-CoO-MnO/SiO2 nanocomposite aerogels were prepared by using tetraethyl orthosilicate(TEOS) as Si source,and aqueous solution of Cu,Co and Mn acetates as the precursors via sol-gel process and ethanol supercritical drying technique.The gelatination mechanism was investigated by nuclear magnetic resonance(NMR) and X-ray photoelectron spectroscopy(XPS).The microstructure and composition of the CuO-CoO-MnO/SiO2 nanocomposite aerogels were characterized by field emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM),electron dispersive spectroscopy(EDS) and XPS.The specific surface area,pore size and pore size distribution of the nanocomposite aerogels were determined by the Brunauer–Emmett–Teller(BET) method.The products were analyzed by gas chromatography(GC).The results show that the CuO-CoO-MnO/SiO2 nanocomposite aerogels are porous,with a particle size distribution of 10–150 nm,a pore size distribution of 2–16 nm,an average pore size of 7.68 nm,and a specific surface area of 664.4-695.8 m2/g.The molar fraction of transition metals in the nanocomposite aerogels is 0.71%-13.77%.This kind of structure is favorable not only to increase the loading of catalysts,but also to make full use of the effect of transition metal oxides as cocatalysts;CuO-CoO-MnO/SiO2 nanocomposite aerogels can be used as a novel catalyst carrier in the safer and environment-friendly synthesis of diphenyl carbonate and other fields of catalysis.
基金supported by the National Natural Science Foundation of China (11405144)the Fundamental Research Funds for the Central Universities (20720180081)~~
文摘An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the specific surface area of the bare CoSnO3 nanoboxes(104.3 m2 g–1),the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g–1 and the electronic conductivity also improved.The increased specific surface area provided more space for the deposition of Li2O2,while the improved electronic conductivity accelerated the decomposition of Li2O2.Compared to bare CoSnO3,the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g?1 when CoSnO3@rGO was used as the catalyst.A Li‐O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g–1 with a limited capacity of 1000 mAh g–1,which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.
文摘本实验采用共还原法合成了Mo掺杂的非晶态CuCoMo/氮化硼纳米片(记为CuCoMo/BNNSs)复合催化剂,BNNSs通过聚乙烯吡咯烷酮(PVP)辅助氢氧化钠结晶法剥离获得。通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)及选区电子衍射(SAED)等对纳米复合催化剂的结构和形貌进行表征,并考察了Mo掺杂对CuCoMo/BNNSs纳米复合催化剂催化氨硼烷(AB)水解产氢活性的影响。结果表明:Mo作为给电子体将电子转移到CuCo NPs,从而增强了催化剂内部金属间的相互作用,提高了催化剂的催化性能。活性测试表明,非晶态(CuCo)0.85 Mo 0.15/BNNSs纳米复合催化剂在室温及pH=14条件下对AB水解产氢的催化活性极高,转化频率(TOF)值高达179.17 mol H 2·mol-1 metal·min-1,首次证明了非晶态CuCoMo NPs是催化AB水解过程中的关键活性组分。这种电子转移不局限于CuCoMo NPs,可以扩展到CuCoW(156.77 mol H 2·mol-1 metal·min-1)和CuCoCr(125.42 mol H 2·mol-1 metal·min-1)NPs。本工作结合表征及实验结果对纳米复合催化剂用于AB水解的催化机理进行了分析。
基金University Grants Commission(WRO),New Delhi,for financial support in the form of a Minor Research Project.
文摘In the present investigation,a series of nanocomposite material such as MoO3,Fe3O4 synthesized by co-precipitation method and Beta cyclodextrin(β-CD)doped MoO3-Fe3O4 and Graphite doped MoO3-Fe3O4 have been synthesized successfully by Sol-Gel method.Synthesized nanomaterials were characterized in detail by XRD,FT-IR,TEM-HRTEM,UV-Vis DRS techniques.The crystalline size was in the range of 10±2 nm.The activity of the prepared material as a heterogeneous catalyst was successfully tested on the organic reaction of synthesis of substituted m-Chloro-Nitrobenzene and it was found to give excellent yield.
