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To modify the oxygen permeability of Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3 − δ (BSCF) membrane, Co 3 O 4 nanorod catalysts were self-assembled onto the surface of the BSCF membrane by a hydrothermal process. Phase structures and morphology of the BSCF membrane self-assembled with Co 3 O 4 nanorod catalysts were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that Co 3 O 4 nanorods with spinel structure and of about 100 nm in diameter and 3 μm in length were grown on the surfaces of BSCF membrane. The loading of Co 3 O 4 nanorods can effectively improve the oxygen permeability of BSCF membrane. At 600 °C, the oxygen permeation rate of BSCF membrane with 1 mm in thickness modified by Co 3 O 4 nanorod catalysts reaches 0.47 ml · min − 1 · cm − 2 , which is 11.5 times higher than that of the bare BSCF membrane under Air/He gradient. At 850 °C, the oxygen permeation rate of the modified BSCF membrane reaches 1.76 ml · min − 1 · cm − 2 , which is 0.3 ml · min − 1 · cm − 2 higher than that of bare BSCF membrane. [ABSTRACT FROM AUTHOR]

An inertial mass measurement project, which is expected to precisely measure the Planck constant, $h$ , for possible comparisons with known gravitational mass measurement projects, e.g., the watt balance and the Avogadro project, is being carried out at the National Institute of Metrology, China. The principle, apparatus, and experimental investigations of the inertial mass measurement are presented. The prototype of the experiment and the Planck constant with a relative uncertainty of several parts in 10^{4} have been achieved for principle testing. [ABSTRACT FROM PUBLISHER]

The development of the joule balance method to measure the Planck constant, in support of the redefinition of the kilogram, has been going on at the National Institute of Metrology of China (NIM) since 2007. The first prototype has been built to check the feasibility of the principle. In 2011, the relative uncertainty of the Planck constant measurement at NIM is 7.7\times 10^-5 . Self-heating and swing of the coils are the main uncertainty contributions. Since 2012, some improvements have been made to reduce these uncertainties. The relative uncertainty of the joule balance is reduced to 7.2\times 10^-6 at present. The Planck constant measured with the joule balance is h=6.6261041(470)\times 10^-34 Js. The relative difference between the determined $h$ and the CODATA2010 recommendation value is 5\times 10^{-6} . Further improvements are still being carried out on the NIM-1 apparatus. At the same time, the design and construction of a brand new and compact joule balance NIM-2 are also in progress and presented here. [ABSTRACT FROM PUBLISHER]

Abstract: A composite oxygen electrode based on Co3O4-loaded La0.8Sr0.2MnO3 (LSM)-BaCe0.5Zr0.3Y0.16Zn0.04O3−δ (BCZYZ) is investigated for steam electrolysis in a proton-conducting solid oxide electrolyzer. The conductivity of LSM is studied with respect to temperature and oxygen partial pressure and correlated to the electrochemical properties of the composite oxygen electrodes in symmetric cells and solid oxide electrolyzers at 800 °C. The optimal Co3O4 loading in the composite oxygen electrode is systematically investigated in symmetric cells; loading catalytically active Co3O4 significantly enhances the electrode performance, unlike the bare LSM-BCZYZ electrode. Steam electrolysis was then performed using LSM-BCZYZ and 6 wt.% Co3O4-loaded LSM-BCZYZ oxygen electrodes, respectively. The Co3O4-loaded catalyst significantly improves the electrode process and enhances the current density below a certain applied voltage. The current efficiencies reach approximately 46% with a 10% H2O/air feed for the oxygen electrode. [Copyright &y& Elsevier]

This paper investigates potential fuel electrode materials NbTi0.5M0.5O4 (M = Ni, Cu) for solid oxide steam electrolysers. Efficient catalytic metallic Ni and Cu nanoparticles are exsolved and anchor onto the surface of the highly electronically conducting material Nb1.33Ti0.67O4, forming an enhanced composite fuel electrode in the in situ reduction. The XRD, SEM, EDS and XPS results together confirm that the exsolution or dissolution of the nanometallic catalyst is completely reversible in the redox cycles. The electrical properties of the reduced NbTi0.5M0.5O4 ceramic fuel electrode is systematically investigated and correlated to the electrochemical performance of the composite fuel electrodes in symmetric cells or electrolysis cells. The synergetic effect of the metallic catalyst and ceramic fuel electrode leads to the excellent stability as well as the superior performance of the direct steam electrolysis without a flow of reducing gas over the composite fuel electrodes. The Faradic efficiencies of the steam electrolysis reach 95% and 97% for the Ni- and Cu-enhanced fuel electrodes on flowing reducing gas over the fuel electrodes, respectively, however, comparable performance is achieved for the direct steam electrolysis with Ni- and Cu-enhanced fuel electrodes without flowing reducing gas over the composite fuel electrodes. [ABSTRACT FROM AUTHOR]

Abstract: Composite fuel electrode based on redox-reversible La0.75Sr0.25Cr0.5Mn0.5O3 − δ (LSCM) can be operated without a flow of reducing gas. We demonstrate the efficient electrolysis of CO2 using a symmetric solid oxide electrolyzer with a configuration of LSCM–SDC/YSZ/LSCM–SDC at 800 °C. The temperature dependence of LSCM conductivity in air and the oxygen partial pressure dependence are investigated and correlated to electrode polarization in the symmetric cell. The LSCM electrode exhibits low electrode polarization in air at 800 °C (0.325 Ω cm2), and the electrode polarization can be further reduced to 0.25 Ω cm2 when passing current to activate LSCM electrodes. In contrast, the electrode polarization of the symmetric cell in CO2 reached 5–10 Ω cm2 under OCV and low current. However, it is decreased to 0.5 Ω cm2 at large currents (e.g. 100–200 mA cm−2) for electrode activation. The results of AC impedance spectroscopy and I–V tests indicate two main processes: the electrochemical reduction of LSCM fuel electrode at low voltages and the electrolysis of CO2 at high voltages. The current efficiency reaches 69%, 58% and 56% at 1.0, 1.5 and 2.0 V for the electrolysis of CO2 at 800 °C, respectively. [Copyright &y& Elsevier]

Abstract: Solid oxide electrolyzers have attracted a great deal of interest in recent years because they can convert electrical energy into chemical energy with high efficiency. Ni/YSZ cathodes are generally utilized for high temperature electrolysis of H2O and CO2 in oxygen-ion conducting solid oxide electrolyzers; however, such electrodes can only operate under reducing conditions. In an atmosphere without a flow of reducing gas, cathodes based on La0.2Sr0.8TiO3+δ (LST) are a promising alternative. Solid Oxide Electrolyzers with LST cathodes without pre-reduction were used at 700 °C for the electrolysis of 3%H2O/97%N2 and 100%CO2, and promising polarization impedance data were obtained in both atmospheres. The electrochemical results indicated that the electrochemical reduction of the La0.2Sr0.8TiO3+δ cathode was the main process at low electrical voltages, while the electrolysis was the main process at high voltages because ion transportation in the electrolyte limited the overall efficiency. The electrolysis of H2O was determined to be more efficient than the electrolysis of CO2 under the same conditions. The Faraday efficiencies of H2O and CO2 were 85.0% and 24.7%, respectively, at 700 °C and a 2 V applied potential. [Copyright &y& Elsevier]

The precise measurement of Planck constant h to establish a kind of quantum mass standard is an important but very difficult work. The Joule Balance method, for the same purpose but different from Watt Balance method, has been going on at the National Institute of Metrology for three years. All the measurements were carried out in the atmosphere of an air-conditioned room. The uncertainty is several parts in 10^4 (k=1) and expected to be improved when superconducting coils and other approaches are used further. The principle and progress are described here. [ABSTRACT FROM AUTHOR]