Porous carbon nanofibers (PCNFs) were prepared through electrospinning, pre-oxidation and carbonization with polyacrylonitrile (PAN) as carbon precursor and polymethyl methacrylate (PMMA), CaCO3 as pore-forming agents...Porous carbon nanofibers (PCNFs) were prepared through electrospinning, pre-oxidation and carbonization with polyacrylonitrile (PAN) as carbon precursor and polymethyl methacrylate (PMMA), CaCO3 as pore-forming agents. The structure, morphology, specific surface area and electrochemical performance of the carbon nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption method and electrochemical tests. Compared with PCNFs without CaCO3, PCNFs(CaCO3 1%) had higher specific surface area, better dispersion of Pt nanoparticles, and the particle size become smaller, which was corresponding with the results of electrochemical performance test. It could be seen in cyclic voltammetry (CV) and linear sweep voltammetry (LSV) test, ECSA of Pt/PCNFs (CaCO3 1%) attained 82 m2?g?1, while that of JM20 and Pt/PCNFs without CaCO3 were 77 m2?g?1 and 60 m2?g?1, respectively. These results revealed that CaCO3 as the second pore-forming agent can further increase the mesoporous number and specific surface area of nanofibers, and can improve the electrochemical properties of Pt catalyst as the support.展开更多
Anas poecilorhyncha is one of improved variety of mallards, which was the protected bird species listed by International Union for Conservation of Nature （1UCN）. Little is known until now about behavioral characteri...Anas poecilorhyncha is one of improved variety of mallards, which was the protected bird species listed by International Union for Conservation of Nature （1UCN）. Little is known until now about behavioral characteristics of the mallard. The objective of this study was to compare the behavioral differentials between A. poecilorhyncha and domestic duck in order to make a strategy to manage A. poecilorhyncha under the condition of animal welfare. A total of 180 birds were distributed into six groups with 30 birds for each group. They were placed in a room of 3 m ~ 4 m and fed for one year old. Sansui ducks, a kind of native domestic duck （Sansui laying duck） were used for behavioral comparison. Two different rooms in the same building were applied, one room for A. poecilorhyncha and another one for Sansui ducks. All behaviors for A. poecilorhyncha and Sansui ducks were coded using the program The Observer XT 11.5 （Noldus Information Technology, Beijing）. The duration of observation was from 8：00 am to 18：00 pm daily and lasted 5 d. The results showed that there were similar behavioral percentages between A. poecilorhyncha and domestic duck. Percentages of standing activity spent for A. poecilorhyncha and Sansui duck were 34.59% and 30.25%, respectively. Accordingly, the activities, such as wing plugging, preening and head stretching, were more than 5.51%. The other activities, including walking, drinking and tail wagging, occupied less proportions （〈 3%）. While the specific behaviors, like aggression, alerting, wing dithering, clawing, nodding, pendulum clawing and crawling, took less than 1% of percentage. There were large differences between A. poecilorhyncha and domestic duck when comparing eight behavioral peaks. Lag sequential analysis was used to calculate frequency of transition between a pair of activities. Some parameters were very significant, like the frequency value from foraging converted to drinking in Sansui duck was 369-515, but 37-65 in A. poecilorhyncha. The best explaining could be given that Sansui duck was better domesticated than spot-billed duck. This study provides the basic data to study and develop spot-billed duck.展开更多
Heteroatoms doped Carbon materials have been proved as promising catalyst support material for oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC). In this paper, nitrogen-doped porous nanofi...Heteroatoms doped Carbon materials have been proved as promising catalyst support material for oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC). In this paper, nitrogen-doped porous nanofibers (N-PCNF) were fabricated via cost effective electrospinning technique by blending the PI and PAN as precursors, followed by heat treatment procedures. The N-PCNFs were used as support to prepare platinum (Pt) catalyst (Pt/N-PCNFs). SEM figure indicated that the porous structures not only existed on the surface but also in the cross session of the fibers. XPS and TEM displayed that with the help of heteroatoms nitrogen, the fiber had rougher surface and more defective structure, contributing to the dispersion of Pt nanoparticles. The catalytic performance for ORR was evaluated by cyclic voltammetry (CV) and liner sweep voltammetry (LSV) with a rotating disk electrode (RDE). According to the results, Pt/N-PCNF exhibited superior property (more positive onset potential and half-wave potential) than that of JM20. The excellent ORR activity of Pt/N-PCNF was attributed to the enriched nitrogen heteroatoms coordinated within the microstructure which increased the exposure of more active sites and dispersion of Pt nanoparticles.展开更多
Zn-air batteries are promising energy storage and conversion systems to replace the conventional lithiumbased ones.However,their applications have been greatly hindered by the formation of Zn dendrites and ZnO passiva...Zn-air batteries are promising energy storage and conversion systems to replace the conventional lithiumbased ones.However,their applications have been greatly hindered by the formation of Zn dendrites and ZnO passivation layer on the Zn anodes.Herein,we report the fabrication of an artificial protective layer comprised of N-doped threedimensional hollow porous multi-nanochannel carbon fiber with well-dispersed TiO_(2) nanoparticles(HMCNF).The incorporated TiO;nanoparticles and N dopants improve the ion flux distribution and promote the surface adsorption,facilitating the interfacial pseudocapacitive behaviors during Zn deposition.The hierarchical architecture also induces homogenous electric field distribution at the anode/electrolyte interface.Accordingly,the deposition behavior of Zn is regulated,giving rise to enhanced utilization and rechargeability of Zn.When integrated in alkaline Zn-air batteries,the HMCNF-coated Zn anodes exhibit improved electrochemical performances relative to those with the bare Zn anodes,demonstrating a versatile strategy to boost energy storage of metal anodes through optimizing surface adsorption properties.展开更多
文摘Porous carbon nanofibers (PCNFs) were prepared through electrospinning, pre-oxidation and carbonization with polyacrylonitrile (PAN) as carbon precursor and polymethyl methacrylate (PMMA), CaCO3 as pore-forming agents. The structure, morphology, specific surface area and electrochemical performance of the carbon nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption method and electrochemical tests. Compared with PCNFs without CaCO3, PCNFs(CaCO3 1%) had higher specific surface area, better dispersion of Pt nanoparticles, and the particle size become smaller, which was corresponding with the results of electrochemical performance test. It could be seen in cyclic voltammetry (CV) and linear sweep voltammetry (LSV) test, ECSA of Pt/PCNFs (CaCO3 1%) attained 82 m2?g?1, while that of JM20 and Pt/PCNFs without CaCO3 were 77 m2?g?1 and 60 m2?g?1, respectively. These results revealed that CaCO3 as the second pore-forming agent can further increase the mesoporous number and specific surface area of nanofibers, and can improve the electrochemical properties of Pt catalyst as the support.
文摘Anas poecilorhyncha is one of improved variety of mallards, which was the protected bird species listed by International Union for Conservation of Nature （1UCN）. Little is known until now about behavioral characteristics of the mallard. The objective of this study was to compare the behavioral differentials between A. poecilorhyncha and domestic duck in order to make a strategy to manage A. poecilorhyncha under the condition of animal welfare. A total of 180 birds were distributed into six groups with 30 birds for each group. They were placed in a room of 3 m ~ 4 m and fed for one year old. Sansui ducks, a kind of native domestic duck （Sansui laying duck） were used for behavioral comparison. Two different rooms in the same building were applied, one room for A. poecilorhyncha and another one for Sansui ducks. All behaviors for A. poecilorhyncha and Sansui ducks were coded using the program The Observer XT 11.5 （Noldus Information Technology, Beijing）. The duration of observation was from 8：00 am to 18：00 pm daily and lasted 5 d. The results showed that there were similar behavioral percentages between A. poecilorhyncha and domestic duck. Percentages of standing activity spent for A. poecilorhyncha and Sansui duck were 34.59% and 30.25%, respectively. Accordingly, the activities, such as wing plugging, preening and head stretching, were more than 5.51%. The other activities, including walking, drinking and tail wagging, occupied less proportions （〈 3%）. While the specific behaviors, like aggression, alerting, wing dithering, clawing, nodding, pendulum clawing and crawling, took less than 1% of percentage. There were large differences between A. poecilorhyncha and domestic duck when comparing eight behavioral peaks. Lag sequential analysis was used to calculate frequency of transition between a pair of activities. Some parameters were very significant, like the frequency value from foraging converted to drinking in Sansui duck was 369-515, but 37-65 in A. poecilorhyncha. The best explaining could be given that Sansui duck was better domesticated than spot-billed duck. This study provides the basic data to study and develop spot-billed duck.
文摘Heteroatoms doped Carbon materials have been proved as promising catalyst support material for oxygen reduction reaction (ORR) in proton exchange membrane fuel cell (PEMFC). In this paper, nitrogen-doped porous nanofibers (N-PCNF) were fabricated via cost effective electrospinning technique by blending the PI and PAN as precursors, followed by heat treatment procedures. The N-PCNFs were used as support to prepare platinum (Pt) catalyst (Pt/N-PCNFs). SEM figure indicated that the porous structures not only existed on the surface but also in the cross session of the fibers. XPS and TEM displayed that with the help of heteroatoms nitrogen, the fiber had rougher surface and more defective structure, contributing to the dispersion of Pt nanoparticles. The catalytic performance for ORR was evaluated by cyclic voltammetry (CV) and liner sweep voltammetry (LSV) with a rotating disk electrode (RDE). According to the results, Pt/N-PCNF exhibited superior property (more positive onset potential and half-wave potential) than that of JM20. The excellent ORR activity of Pt/N-PCNF was attributed to the enriched nitrogen heteroatoms coordinated within the microstructure which increased the exposure of more active sites and dispersion of Pt nanoparticles.
基金supported by the National Natural Science Foundation of China(52002060)Shanghai Sailing Program(20YF1400600)the Fundamental Research Funds for the Central Universities(2232021D-06)。
文摘Zn-air batteries are promising energy storage and conversion systems to replace the conventional lithiumbased ones.However,their applications have been greatly hindered by the formation of Zn dendrites and ZnO passivation layer on the Zn anodes.Herein,we report the fabrication of an artificial protective layer comprised of N-doped threedimensional hollow porous multi-nanochannel carbon fiber with well-dispersed TiO_(2) nanoparticles(HMCNF).The incorporated TiO;nanoparticles and N dopants improve the ion flux distribution and promote the surface adsorption,facilitating the interfacial pseudocapacitive behaviors during Zn deposition.The hierarchical architecture also induces homogenous electric field distribution at the anode/electrolyte interface.Accordingly,the deposition behavior of Zn is regulated,giving rise to enhanced utilization and rechargeability of Zn.When integrated in alkaline Zn-air batteries,the HMCNF-coated Zn anodes exhibit improved electrochemical performances relative to those with the bare Zn anodes,demonstrating a versatile strategy to boost energy storage of metal anodes through optimizing surface adsorption properties.
