A combined hot-injection and heat-up method was developed to synthesize monodisperse and uniform CoMn2O4 quantum dots （CMO QDs）.CMO QDs with average size of 2.0,3.9,and 5.4 nm were selectively obtained at 80,90,and ...A combined hot-injection and heat-up method was developed to synthesize monodisperse and uniform CoMn2O4 quantum dots （CMO QDs）.CMO QDs with average size of 2.0,3.9,and 5.4 nm were selectively obtained at 80,90,and 105 ℃,respectively.The CMO QDs supported on carbon nanotubes （CNTs） were employed as catalysts for the oxygen reduction/evolution reaction （ORR/OER） in alkaline solution to investigate their size-performance relationship.The results revealed that the amount of surface-adsorbed oxygen and the band gap energy,which affect the charge transfer in the oxygen electrocatalysis processes,strongly depend on the size of the CMO QDs.The CMO-3.9/CNT hybrid,consisting of CNT-supported CMO QDs of 3.9 nm size,possesses a moderate amount of surfaceadsorbed oxygen,a lower band gap energy,and a larger charge carrier concentration,and exhibits the highest electrocatalytic activity among the hybrid materials investigated.Moreover,the CMO-3.9/CNT hybrid displays ORR and OER performances similar to those of the benchmark Pt/C and RuO2 catalysts,respectively,due to the strong carbon-oxide interactions and the high dispersion of CoMn2O4 QDs on the carbon substrate;this reveals the huge potential of the CMO-3.9/CNT hybrid as a bifunctional OER/ORR electrocatalyst.The present results highlight the importance of controlling the size of metal oxide nanodots in the design of active oxygen electrocatalysts based on spinel-type,nonprecious metal oxides.展开更多
In this paper, a series of zinc cobaltite catalysts with the general formula Znx-Co1-xCo2O4 (x = 0.25, 0.50, 0.75 and 1.0) has been prepared using the co-precipitation method. Thermal analyzes (TGA and DTA) were used ...In this paper, a series of zinc cobaltite catalysts with the general formula Znx-Co1-xCo2O4 (x = 0.25, 0.50, 0.75 and 1.0) has been prepared using the co-precipitation method. Thermal analyzes (TGA and DTA) were used to follow up the thermal events accompanying the heat treatment of the parent mixture. Based on these results, the various parent mixtures were calcined at 500℃. The obtained solid catalysts were characterized by using XRD, FT-IR and N2-adsorption. The catalytic decomposition of N2O to N2 and O2 was carried out on the zinc-cobaltite catalysts. It was found that partial replacement of Co2+ by Zn2+ in Co3O4 spinel oxide led to a significant improvement in their N2O decomposition activity. Moreover, the catalytic activity was found to be depended on the calcination temperature utilized.展开更多
The magnetic, conductivity, and dielectric properties have been investigated in single-phase polycrystalline Y0.1Co1.9MnO4. The temperature-dependent magnetisation reveals the ferromagnetic transition in sample at a l...The magnetic, conductivity, and dielectric properties have been investigated in single-phase polycrystalline Y0.1Co1.9MnO4. The temperature-dependent magnetisation reveals the ferromagnetic transition in sample at a low temperature （～186 K）. Magnetisation as a function of field H （M H loop） indicated the weak ferromagnetism of the sample at room temperature. The constant e and dielectric loss tg5 measurements represent a ferroelectric phase transition at a higher temperature （~650 K）, while the conductivity shows an insulator-metallic transition. The ferro- electric hysterisis loops and capacitance voltage measurements confirm the ferroelectric nature of the sample at room temperature. The observed ferromagnetism and ferroelectric nature in this material suggests a potential multiferroic application.展开更多
提出一种改进的熔盐化学合成方法,制备了表面磷酸盐改性的钴铁尖晶石氧化物,用于催化电解水过程的重要半反应—析氧反应(OER)。理化表征表明,熔盐保护热解法和表面磷酸盐均能优化钴铁尖晶石氧化物的电子结构,导致活性高价金属离子的富集...提出一种改进的熔盐化学合成方法,制备了表面磷酸盐改性的钴铁尖晶石氧化物,用于催化电解水过程的重要半反应—析氧反应(OER)。理化表征表明,熔盐保护热解法和表面磷酸盐均能优化钴铁尖晶石氧化物的电子结构,导致活性高价金属离子的富集,从而提高了该析氧反应电催化剂的本征活性。得益于上述结构优势,该电催化剂在电位为1.51 V vs.RHE时即可达到10 mA·cm^(-2)的电流密度。在外加电压为1.7 V vs.RHE时,析氧反应电流密度高达133.8 mA·cm^(-2)。此外,该催化剂显示出低至86 mV·dec-1的Tafel斜率、快速电荷传导和良好的OER操作稳定性,使其有望应用于大规模水裂解制氢电解槽。展开更多
用室温固态一步反应法制取纳米尖晶石N iM n2O4的前驱体N iM n2(C2O4)3.6H2O,经烧结,最终得到尖晶石相氧化物.通过IR、XRD证实了其为尖晶石结构,且用TEM表征了其最终产物的颗粒大小达到了大约10nm.通过TG、DSC技术,探讨了样品的基本组...用室温固态一步反应法制取纳米尖晶石N iM n2O4的前驱体N iM n2(C2O4)3.6H2O,经烧结,最终得到尖晶石相氧化物.通过IR、XRD证实了其为尖晶石结构,且用TEM表征了其最终产物的颗粒大小达到了大约10nm.通过TG、DSC技术,探讨了样品的基本组成及由前驱体分解成最终产物的反应动力学,寻找出了一定的规律.展开更多
基金supported by the National Natural Science Foundation of China(50572051,50672041)National High-Tech Research and Development Program of China(863)(2006AA03Z218)National Key Basic Research Program of China(973)(2007CB607504)~~
基金This work was supported by the National Key Research and Development Program of China （Nos. 2016YFA0202500 and 2016YFB0101201）, the National Natural Science Foundation of China （Nos. 21322101 and 21231005） and 111 Project （Nos. B12015 and IRT13R30）.
文摘A combined hot-injection and heat-up method was developed to synthesize monodisperse and uniform CoMn2O4 quantum dots （CMO QDs）.CMO QDs with average size of 2.0,3.9,and 5.4 nm were selectively obtained at 80,90,and 105 ℃,respectively.The CMO QDs supported on carbon nanotubes （CNTs） were employed as catalysts for the oxygen reduction/evolution reaction （ORR/OER） in alkaline solution to investigate their size-performance relationship.The results revealed that the amount of surface-adsorbed oxygen and the band gap energy,which affect the charge transfer in the oxygen electrocatalysis processes,strongly depend on the size of the CMO QDs.The CMO-3.9/CNT hybrid,consisting of CNT-supported CMO QDs of 3.9 nm size,possesses a moderate amount of surfaceadsorbed oxygen,a lower band gap energy,and a larger charge carrier concentration,and exhibits the highest electrocatalytic activity among the hybrid materials investigated.Moreover,the CMO-3.9/CNT hybrid displays ORR and OER performances similar to those of the benchmark Pt/C and RuO2 catalysts,respectively,due to the strong carbon-oxide interactions and the high dispersion of CoMn2O4 QDs on the carbon substrate;this reveals the huge potential of the CMO-3.9/CNT hybrid as a bifunctional OER/ORR electrocatalyst.The present results highlight the importance of controlling the size of metal oxide nanodots in the design of active oxygen electrocatalysts based on spinel-type,nonprecious metal oxides.
文摘In this paper, a series of zinc cobaltite catalysts with the general formula Znx-Co1-xCo2O4 (x = 0.25, 0.50, 0.75 and 1.0) has been prepared using the co-precipitation method. Thermal analyzes (TGA and DTA) were used to follow up the thermal events accompanying the heat treatment of the parent mixture. Based on these results, the various parent mixtures were calcined at 500℃. The obtained solid catalysts were characterized by using XRD, FT-IR and N2-adsorption. The catalytic decomposition of N2O to N2 and O2 was carried out on the zinc-cobaltite catalysts. It was found that partial replacement of Co2+ by Zn2+ in Co3O4 spinel oxide led to a significant improvement in their N2O decomposition activity. Moreover, the catalytic activity was found to be depended on the calcination temperature utilized.
基金supported by the Doctorial Start-up Fund of Guizhou University of China (Grant No. 2006/Z065020)
文摘The magnetic, conductivity, and dielectric properties have been investigated in single-phase polycrystalline Y0.1Co1.9MnO4. The temperature-dependent magnetisation reveals the ferromagnetic transition in sample at a low temperature （～186 K）. Magnetisation as a function of field H （M H loop） indicated the weak ferromagnetism of the sample at room temperature. The constant e and dielectric loss tg5 measurements represent a ferroelectric phase transition at a higher temperature （~650 K）, while the conductivity shows an insulator-metallic transition. The ferro- electric hysterisis loops and capacitance voltage measurements confirm the ferroelectric nature of the sample at room temperature. The observed ferromagnetism and ferroelectric nature in this material suggests a potential multiferroic application.
文摘提出一种改进的熔盐化学合成方法,制备了表面磷酸盐改性的钴铁尖晶石氧化物,用于催化电解水过程的重要半反应—析氧反应(OER)。理化表征表明,熔盐保护热解法和表面磷酸盐均能优化钴铁尖晶石氧化物的电子结构,导致活性高价金属离子的富集,从而提高了该析氧反应电催化剂的本征活性。得益于上述结构优势,该电催化剂在电位为1.51 V vs.RHE时即可达到10 mA·cm^(-2)的电流密度。在外加电压为1.7 V vs.RHE时,析氧反应电流密度高达133.8 mA·cm^(-2)。此外,该催化剂显示出低至86 mV·dec-1的Tafel斜率、快速电荷传导和良好的OER操作稳定性,使其有望应用于大规模水裂解制氢电解槽。
文摘用室温固态一步反应法制取纳米尖晶石N iM n2O4的前驱体N iM n2(C2O4)3.6H2O,经烧结,最终得到尖晶石相氧化物.通过IR、XRD证实了其为尖晶石结构,且用TEM表征了其最终产物的颗粒大小达到了大约10nm.通过TG、DSC技术,探讨了样品的基本组成及由前驱体分解成最终产物的反应动力学,寻找出了一定的规律.
