LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-preci...LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.展开更多
The beneficial acclimation hypothesis (BAH) predicts that animals acclimated to a particular temperature have enhanced performance or fitness at that temperature in comparison with animals acclimated to other temperat...The beneficial acclimation hypothesis (BAH) predicts that animals acclimated to a particular temperature have enhanced performance or fitness at that temperature in comparison with animals acclimated to other temperatures. The BAH has been tested by a variety of empirical examinations, and was rejected by some of them. In order to provide new evidences for the BAH, the effects of acute and acclimation temperature (AT) on locomotor performance of Macrobiotus hufelandi (Tardigrada: Macrobiotidae) were investigated. The tardigrades were collected from Nanwutai, Qinling Mountains which traverse from west to east in central China. The subjects were acclimated to either 2℃ or 22℃ for 2 weeks. The animal was transferred onto a frosted slide and allowed to walk freely at the performance temperature (PT) 2℃ or 22℃. Only one individual was tested per test bout, which lasted from three to five minutes. To avoid occurrence of thermal acclimation effect, the standard adaptation time was limited to 1.5 min. Each subject was tested for once at the same PT, and was tested only at one PT. A total of 25 individuals were tested and measured at the same PT. The locomotor performance of the animals was recorded with a digital video camera mounted on a microscope at 4×10 amplification and replayed on a PC. Every subject was identified. Walking speed (WS) and percentage of time moving (PTM) at both PTs (2℃ or 22℃) were selected as the rate parameters of locomotor performance. The two-way repeated measures ANOVA with a significance level of α= 0.05 and Duncan multiple range test were used to analyze the data. WS of the animals acclimated to and tested at the same temperatures was significantly faster than that for animals acclimated to and tested at the different temperatures, similarly, PTM of the animals acclimated to 22℃ and tested at 22℃ was significantly greater than PTM of animals acclimated to 22℃ and tested at 2℃, which indicated that the animals acclimated to a particular temperature have enhanced locomotor performance in that temperature relative to the animals acclimated to that temperature in other thermal environment. WS of the animals acclimated to 22℃ and tested at 22℃ was significantly faster than WS of animals acclimated to 2℃ and tested at 22℃, PTM of the animals acclimated to 22℃ and tested at 22℃ was significantly greater than PTM of animals acclimated to 2℃ and tested at 22℃. These results supported the BAH. It could be concluded that the PT and thermal acclimation as well as the interaction between the PT and AT significantly influence the locomotor performance of M.hufelandi, and that, despite the existence of a few results of this study that don’t support the BAH, some results of this study support for this hypothesis, and that the animals acclimated to a particular temperature have enhanced locomotor performance in that temperature relative to the animals acclimated to that temperature in other thermal environment, implying that any performance temperature that deviates from the acclimation temperature could cause the reduction of the walking speed which is closely related to the fitness of the M.hufelandi.展开更多
A large specific surface area perovskite-type mixed oxide PbTiO3 supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H2-TPR before and after NO d...A large specific surface area perovskite-type mixed oxide PbTiO3 supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H2-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO3 was inactive for the reactions, but 1wt % Cu/PbTiO3 catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ)and most probably incorporated into surface crystal lattice of the nano-sized PbTiO3. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO3 support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.展开更多
Pt-based magnetic nano catalysts are one of the most suitable cand idates for electrocatalytic materials due to their high electrochemistry activity and retrievability.Unfortunately,the inferior durability prevents th...Pt-based magnetic nano catalysts are one of the most suitable cand idates for electrocatalytic materials due to their high electrochemistry activity and retrievability.Unfortunately,the inferior durability prevents them from being scaled-up,limiting their commercial applications.Herein,an antiferromagnetic element Mn was introduced into PtCo nanostructured alloy to synthesize uniform Mn-PtCo truncated octahedral nanoparticles(TONPs)by one-pot method.Our results show that Mn can tune the blocking temperature of Mn-PtCo TONPs due to its an tiferromag netism.At low temperatures,Mn-PtCo TONPs are ferromag netic,and the coercivity in creases gradually with in creasi ng Mn contents.At room temperature,the Mn-PtCo TONPs display superparamag netic behavior,which is greatly helpful for in dustrial recycling.Mn doping can not only modify the electronic structure of PtCo TONPs but also enhanee electrocatalytic performance for methanol oxidation reaction.The maximum specific activity of Mn-PtCo-3 reaches 8.1 A`m^-2,3.6 times of commercial Pt/C(2.2 A·m^-2)and 1.4 times of PtCo TONPs(5.6 A`m^-2),respectively.The mass activity decreases by only 30%after 2,000 cycles,while it is 45%and 99%(nearly inactive)for PtCo TONPs and commercial Pt/C catalysts,respectively.展开更多
文摘LiCoO2 gradient coated LiNi0.96Co0.04O2 material and iso-structure LiNi0.8Co0.2O2 material (the same molar ratio 8/2 of Ni/Co in the two materials) as cathode for lithium-ion batteries were synthesized with a co-precipitation method. Microstructure of iso-structure LiNi0.8Co0.2O2 were about the same as that of LiNiO2, and the structure of the coated material was much more similar to that of LiCoO2 based on the X-ray diffraction patterns. The cycling voltammetry and galvanostatic cycle tests show that the properties of the coated material were improved significantly. The first specific charge and discharge capacity for the coated material was 249.20 mAh·g-1 and 207.90 mAh·g-1 respectively, and the specific discharge capacity for the 100th cycle was still 186.02 mAh·g-1 with an irreversible loss of only 21.1 mAh·g-1. This showed that the new material had a good lithium intercalation-deintrercalation performance. Meanwhile, the mechanism of the sintering reaction was proposed. During the sintering reaction of the precursor with LiOH, the Li+-ion permeated into the body of precursors because the shape of the precursor particles was not changed basically based on scanning electronic microscopy. So, the layer microstructure of the precursor is important for the layer microstructure of lithium nickel cobalt oxides electrode material.
文摘The beneficial acclimation hypothesis (BAH) predicts that animals acclimated to a particular temperature have enhanced performance or fitness at that temperature in comparison with animals acclimated to other temperatures. The BAH has been tested by a variety of empirical examinations, and was rejected by some of them. In order to provide new evidences for the BAH, the effects of acute and acclimation temperature (AT) on locomotor performance of Macrobiotus hufelandi (Tardigrada: Macrobiotidae) were investigated. The tardigrades were collected from Nanwutai, Qinling Mountains which traverse from west to east in central China. The subjects were acclimated to either 2℃ or 22℃ for 2 weeks. The animal was transferred onto a frosted slide and allowed to walk freely at the performance temperature (PT) 2℃ or 22℃. Only one individual was tested per test bout, which lasted from three to five minutes. To avoid occurrence of thermal acclimation effect, the standard adaptation time was limited to 1.5 min. Each subject was tested for once at the same PT, and was tested only at one PT. A total of 25 individuals were tested and measured at the same PT. The locomotor performance of the animals was recorded with a digital video camera mounted on a microscope at 4×10 amplification and replayed on a PC. Every subject was identified. Walking speed (WS) and percentage of time moving (PTM) at both PTs (2℃ or 22℃) were selected as the rate parameters of locomotor performance. The two-way repeated measures ANOVA with a significance level of α= 0.05 and Duncan multiple range test were used to analyze the data. WS of the animals acclimated to and tested at the same temperatures was significantly faster than that for animals acclimated to and tested at the different temperatures, similarly, PTM of the animals acclimated to 22℃ and tested at 22℃ was significantly greater than PTM of animals acclimated to 22℃ and tested at 2℃, which indicated that the animals acclimated to a particular temperature have enhanced locomotor performance in that temperature relative to the animals acclimated to that temperature in other thermal environment. WS of the animals acclimated to 22℃ and tested at 22℃ was significantly faster than WS of animals acclimated to 2℃ and tested at 22℃, PTM of the animals acclimated to 22℃ and tested at 22℃ was significantly greater than PTM of animals acclimated to 2℃ and tested at 22℃. These results supported the BAH. It could be concluded that the PT and thermal acclimation as well as the interaction between the PT and AT significantly influence the locomotor performance of M.hufelandi, and that, despite the existence of a few results of this study that don’t support the BAH, some results of this study support for this hypothesis, and that the animals acclimated to a particular temperature have enhanced locomotor performance in that temperature relative to the animals acclimated to that temperature in other thermal environment, implying that any performance temperature that deviates from the acclimation temperature could cause the reduction of the walking speed which is closely related to the fitness of the M.hufelandi.
文摘A large specific surface area perovskite-type mixed oxide PbTiO3 supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H2-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO3 was inactive for the reactions, but 1wt % Cu/PbTiO3 catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ)and most probably incorporated into surface crystal lattice of the nano-sized PbTiO3. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO3 support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.
基金The work was supported by the National Natural Science Foundation(Nos.51625101,51431009,5180118&and 51701202)the State Key Development Program for Basic Research of China(No.2015CB921401)+3 种基金the Fundamental Research Funds for the Central University Universities of China(No.FRF-TP-16-001C2)the China Postdoctoral Science Foundation(No.2018M632792)Startup Research Fund of Zhengzhou University(No.32210815)Bejing Natural Science Foundation(No.Z180014).
文摘Pt-based magnetic nano catalysts are one of the most suitable cand idates for electrocatalytic materials due to their high electrochemistry activity and retrievability.Unfortunately,the inferior durability prevents them from being scaled-up,limiting their commercial applications.Herein,an antiferromagnetic element Mn was introduced into PtCo nanostructured alloy to synthesize uniform Mn-PtCo truncated octahedral nanoparticles(TONPs)by one-pot method.Our results show that Mn can tune the blocking temperature of Mn-PtCo TONPs due to its an tiferromag netism.At low temperatures,Mn-PtCo TONPs are ferromag netic,and the coercivity in creases gradually with in creasi ng Mn contents.At room temperature,the Mn-PtCo TONPs display superparamag netic behavior,which is greatly helpful for in dustrial recycling.Mn doping can not only modify the electronic structure of PtCo TONPs but also enhanee electrocatalytic performance for methanol oxidation reaction.The maximum specific activity of Mn-PtCo-3 reaches 8.1 A`m^-2,3.6 times of commercial Pt/C(2.2 A·m^-2)and 1.4 times of PtCo TONPs(5.6 A`m^-2),respectively.The mass activity decreases by only 30%after 2,000 cycles,while it is 45%and 99%(nearly inactive)for PtCo TONPs and commercial Pt/C catalysts,respectively.
