For achieving high-power and low-platinum direct methanol fuel cell(DMFC)under proton-exchange-membrane,we introduce the oxidation-state ruthenium species as H2O-activation centers stabilized on PtZn NPs to boost m...For achieving high-power and low-platinum direct methanol fuel cell(DMFC)under proton-exchange-membrane,we introduce the oxidation-state ruthenium species as H2O-activation centers stabilized on PtZn NPs to boost methanol-oxidation reaction(MOR).The Zn-regulated Ru centers,approaching bivalent states,enhance interfacial H2O-capture/dissociation and OH-transfer,enabling rapid CO*removal from adjacent Pt sites.It exhibits an outstanding mass activity of MOR at 2.71 A mgPt-1 and powers a DMFC with 191.2 mW cm-2 peak density(382.4 W gPt-1)while maintaining 125-hour stability,higher than documented results to date,essentially different from traditional alloy catalysts.Combined ab initio molecular dynamics simulations and in-situ spectroscopy reveal a dense O-down water network around Ru centers,where intermediate RuO(OH)2 structure significantly deceases the H2O-dissociation barrier.Kinetic isotope effect tests(CH3OH/H2O vs.D2O)show J H2O/D2O=4.2 for RuOx-PtZn/C at 0.85 VRHE,versus 16.2 for RuOx-Pt/C,directly confirming superior water activation efficiency of RuOx-PtZn/C.We envision that the comprehensive understanding of high-performance MOR on RuOx-PtZn/C through experimental-theoretical approaches will contribute to the practical application of DMFC as early as possible.展开更多
Commercial cathode material (LiCoO2) was modified by coating with a thin layer of SrO/Li2O/La2O3/Ta2O5/TiO2 for improving its performance in lithium ion battery. The morphology and structure of the modified cathode ...Commercial cathode material (LiCoO2) was modified by coating with a thin layer of SrO/Li2O/La2O3/Ta2O5/TiO2 for improving its performance in lithium ion battery. The morphology and structure of the modified cathode material were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The performance including cycling stability, diffusion coefficient under different voltage, C-rate discharge of the batteries with this modified cathode material was examined. The results showed that the battery with the coated cathode material could discharge at a large current density, and it possessed a stable cycle performance in the range from 3.0 V to 4.2 V. It was explained that the rate of Li ion diffusion increased in the batteries using SrO/Li2O/La2O3/Ta2O5/TiO2-coated LiCoO2 as the cathode and the coated layer could act as a fast ion conductor (SrO/Li2O/La2O3/Ta2O5/TiO2) and as a protecting shell to prevent LiCoO2particles from being attacked by the acidic electrolyte.展开更多
采用热分解法制备了不同比例钴酸镧掺杂Ti/RuO_2电极材料。通过扫描电镜(SEM)、能谱分析(EDS)、X射线粉末衍射(XRD)等分析方法表征电极涂层的物相结构与形貌特征,采用电化学测量表征电极的物理化学性能。分析表明电极涂层由不规则的颗...采用热分解法制备了不同比例钴酸镧掺杂Ti/RuO_2电极材料。通过扫描电镜(SEM)、能谱分析(EDS)、X射线粉末衍射(XRD)等分析方法表征电极涂层的物相结构与形貌特征,采用电化学测量表征电极的物理化学性能。分析表明电极涂层由不规则的颗粒组成,颗粒间有一定的孔隙,掺杂钴酸镧电极涂层含有Ti,Ru,La及Co金属元素,相结构主要为金红石相,掺杂钴酸镧电极涂层的晶粒较小,不同掺杂量对晶粒大小影响不大。电化学研究表明,电极具有典型的钌氧化物所具备的电化学性能,掺杂钴酸镧电极的电化学面积较大,电极的可逆性能得到改善。所制备的电极具有大致相同的析氧电位(1.19 V vs. SCE),随着钴酸镧掺杂量的增多,Tafel斜率依次减小,表明掺杂钴酸镧电极的活性较高,且掺杂钴酸镧后电极强化寿命得到显著提高。展开更多
TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transm...TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniforrrdy coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.展开更多
Petal-like ZnO nanosheets were synthesized with zinc nitrate hexahydrate and sodium hydroxide as starting materials in ammonia and ethanol mixture solution. RuO2 modified ZnO nanosheets were also prepared by a calcina...Petal-like ZnO nanosheets were synthesized with zinc nitrate hexahydrate and sodium hydroxide as starting materials in ammonia and ethanol mixture solution. RuO2 modified ZnO nanosheets were also prepared by a calcination route. The as-prepared products were characterized by X-ray powder diffraction and field emission scanning electron microscopy, and its specific BET surface area was calculated by nitrogen adsorption method. The sensitivity, response and recovery speed were examined. The results show that RuO2 modified petal-like ZnO based sensor exhibits a high sensitivity, a low detection limit, fast response and recovery properties to ethanol and acetone. The sensitivities of the RuO2 modified petal-like ZnO based sensor to 100×10^-6 ethanol and acetone at 360 °C are 33 and 67, respectively. The response and recovery times of the sensor are 4 s and 9 s to 10×10^-6 ethanol, and are 3 s and 10 s to 10×10^-6 acetone, respectively.展开更多
The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method ...The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method within the generalised gradient approximation (GGA) for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant (~1 and z2, respectively) and the refractive index (n); and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.展开更多
TiO2-coated activated carbon surface (TAs) composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to es...TiO2-coated activated carbon surface (TAs) composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to estimate activity of catalysts and determine the kinetics. And the effects of parameters including the initial concentration of AY, light intensity and TiO2 content in catalysts were examined. The results indicate that TAs has a higher efficiency in decomposition of AY than P25, pure TiO2 particles as well as the mixture of TiO2 powder and active carbon. The photocatalytic degradation rate is found to follow the pseudo-first order kinetics with respect to the AY concentration. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation, and the rate constant is proportional to the square root of the light intensity in a wide range. However, its absorption performance depends on the surface areas of catalysts. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO2 content in TAs on the degradation rate.展开更多
摘要For achieving high-power and low-platinum direct methanol fuel cell(DMFC)under proton-exchange-membrane,we introduce the oxidation-state ruthenium species as H2O-activation centers stabilized on PtZn NPs to boost methanol-oxidation reaction(MOR).The Zn-regulated Ru centers,approaching bivalent states,enhance interfacial H2O-capture/dissociation and OH-transfer,enabling rapid CO*removal from adjacent Pt sites.It exhibits an outstanding mass activity of MOR at 2.71 A mgPt-1 and powers a DMFC with 191.2 mW cm-2 peak density(382.4 W gPt-1)while maintaining 125-hour stability,higher than documented results to date,essentially different from traditional alloy catalysts.Combined ab initio molecular dynamics simulations and in-situ spectroscopy reveal a dense O-down water network around Ru centers,where intermediate RuO(OH)2 structure significantly deceases the H2O-dissociation barrier.Kinetic isotope effect tests(CH3OH/H2O vs.D2O)show J H2O/D2O=4.2 for RuOx-PtZn/C at 0.85 VRHE,versus 16.2 for RuOx-Pt/C,directly confirming superior water activation efficiency of RuOx-PtZn/C.We envision that the comprehensive understanding of high-performance MOR on RuOx-PtZn/C through experimental-theoretical approaches will contribute to the practical application of DMFC as early as possible.
基金supported by the Natural Science Foundation of Guangdong Province,China (06105562)the Foundation of Manyang Bureau of Sci-ence and Technology,China (07Y003-1)
摘要Commercial cathode material (LiCoO2) was modified by coating with a thin layer of SrO/Li2O/La2O3/Ta2O5/TiO2 for improving its performance in lithium ion battery. The morphology and structure of the modified cathode material were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The performance including cycling stability, diffusion coefficient under different voltage, C-rate discharge of the batteries with this modified cathode material was examined. The results showed that the battery with the coated cathode material could discharge at a large current density, and it possessed a stable cycle performance in the range from 3.0 V to 4.2 V. It was explained that the rate of Li ion diffusion increased in the batteries using SrO/Li2O/La2O3/Ta2O5/TiO2-coated LiCoO2 as the cathode and the coated layer could act as a fast ion conductor (SrO/Li2O/La2O3/Ta2O5/TiO2) and as a protecting shell to prevent LiCoO2particles from being attacked by the acidic electrolyte.
摘要采用热分解法制备了不同比例钴酸镧掺杂Ti/RuO_2电极材料。通过扫描电镜(SEM)、能谱分析(EDS)、X射线粉末衍射(XRD)等分析方法表征电极涂层的物相结构与形貌特征,采用电化学测量表征电极的物理化学性能。分析表明电极涂层由不规则的颗粒组成,颗粒间有一定的孔隙,掺杂钴酸镧电极涂层含有Ti,Ru,La及Co金属元素,相结构主要为金红石相,掺杂钴酸镧电极涂层的晶粒较小,不同掺杂量对晶粒大小影响不大。电化学研究表明,电极具有典型的钌氧化物所具备的电化学性能,掺杂钴酸镧电极的电化学面积较大,电极的可逆性能得到改善。所制备的电极具有大致相同的析氧电位(1.19 V vs. SCE),随着钴酸镧掺杂量的增多,Tafel斜率依次减小,表明掺杂钴酸镧电极的活性较高,且掺杂钴酸镧后电极强化寿命得到显著提高。
基金financially supported by the National Natural Science Foundation of China (No.20873046)the Specialized Research Fund for the Doctoral Program of HigherEducation (No.200805740004)Natural Science Foundation of Guangdong Province (No.10351063101000001)
摘要TiO2-coated SnO2 (TCS) hollow spheres, which are new anode materials for lithium ion (Li-ion) batteries, were prepared and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniforrrdy coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.
基金Projects(61079010)supported by the National Natural Science Foundation of China and the Civil Aviation Administration of ChinaProject(3122013P001)supported by the Significant Pre-research Funds of Civil Aviation University of ChinaProject(2014)supported by the Science and Technology Innovation Guide Funds of Civil Aviation Administration of China
摘要Petal-like ZnO nanosheets were synthesized with zinc nitrate hexahydrate and sodium hydroxide as starting materials in ammonia and ethanol mixture solution. RuO2 modified ZnO nanosheets were also prepared by a calcination route. The as-prepared products were characterized by X-ray powder diffraction and field emission scanning electron microscopy, and its specific BET surface area was calculated by nitrogen adsorption method. The sensitivity, response and recovery speed were examined. The results show that RuO2 modified petal-like ZnO based sensor exhibits a high sensitivity, a low detection limit, fast response and recovery properties to ethanol and acetone. The sensitivities of the RuO2 modified petal-like ZnO based sensor to 100×10^-6 ethanol and acetone at 360 °C are 33 and 67, respectively. The response and recovery times of the sensor are 4 s and 9 s to 10×10^-6 ethanol, and are 3 s and 10 s to 10×10^-6 acetone, respectively.
基金supported by the China Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant Nos. 10676025 and 10574096)the Science-Technology Foundation for Young Scientist of Sichuan Province,China (Grant No. 09ZQ026-049)
摘要The systematic trends of electrionic structure and optical properties of rutile (P42/mnm) RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory (DFT) method within the generalised gradient approximation (GGA) for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant (~1 and z2, respectively) and the refractive index (n); and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.
基金Project(50802034) supported by the National Natural Science Foundation of ChinaProject(11A093) supported by the Key Project Foundation by the Education Department of Hunan Province,China
摘要TiO2-coated activated carbon surface (TAs) composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow (AY) was investigated under UV radiation to estimate activity of catalysts and determine the kinetics. And the effects of parameters including the initial concentration of AY, light intensity and TiO2 content in catalysts were examined. The results indicate that TAs has a higher efficiency in decomposition of AY than P25, pure TiO2 particles as well as the mixture of TiO2 powder and active carbon. The photocatalytic degradation rate is found to follow the pseudo-first order kinetics with respect to the AY concentration. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation, and the rate constant is proportional to the square root of the light intensity in a wide range. However, its absorption performance depends on the surface areas of catalysts. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO2 content in TAs on the degradation rate.