[en] (La_0.75Sr_0.25)_0.95MnO_3-δ (LSM)/MnO₂ composite for supercapacitor (SC) electrode is successfully synthesized via a facile hydrothermal method. The LSM/MnO₂ composite shows a flower-like structure and possesses numerous active sites and better conductivity. The as-prepared LSM/MnO₂ electrode exhibits a larger specific capacitance of 437.2 F g⁻¹, much better than that of pure MnO₂. Furthermore, the composite electrode also has a higher rate capability (capacitance improvement can reach to 70%) and better cycling stability. It is believed that the present results provide an efficient electrode materials design and a novel composite for the future practical application of high-performance supercapacitor.

[en] In this study, the valence state of Pr in Mg doped PrGaO₃ perovskites was investigated. It is found that Pr⁴⁺ ions are created in samples doped with low-valence ions, for example, with Mg²⁺. The color of the doped samples changes from black to light green after being treated in H₂ atmosphere, which shows that the Pr⁴⁺ ions in the sample are reduced to Pr³⁺ ions. The open circuit voltage of the solid oxide fuel cell (SOFC) using PrGa_0.95Mg_0.05O₃ as the electrolyte increases with time and the X-ray photoelectron spectroscopy (XPS) data of PrGa_0.9Mg_0.1O₃ also show the existence of Pr⁴⁺ ions in Mg doped PrGaO₃

[en] A (CCO)_0.25(YSZ)_0.75 solid solution (YSZ is Y₂O₃-stabilized ZrO₂; CCO is an abbreviation of Ce_0.9Ca_0.1O_1.9) was successfully synthesized by a solid-state method. A composite anode material, NYC_x (60 wt% NiO+40 wt% (CCO)_x(YSZ)_1-x), for SOFCs (solid oxide fuel cells) was prepared. XRD results suggest that a solid solution reaction occurs between YSZ and CCO after sintering at 1400 deg. C for 10 h. From the impedance results, the conclusion can be drawn that the (CCO)_0.25(YSZ)_0.75 solid solution is a mixed conductor (ionic and electronic). Its total conductivity is greater than that of YSZ. The NYC_x (x>0) anodes exhibited better performance than the commonly used Ni+YSZ anode with regards to overpotential and anode interfacial impedance, with the NYC_0.25 anode exhibiting the best performance

[en] In this work, a novel La_1.7Sr_0.3Co_0.5Ni_0.5O_4+δ with a layered perovskite structure was synthesized by the sol-gel method and characterized by the X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Catalytic activities of La_1.7Sr_0.3Co_0.5Ni_0.5O_4+δ toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were systematically investigated by the rotating disk electrode (RDE) technique in alkaline media. Compared to La₂NiO_4+δ, La_1.7Sr_0.3Co_0.5Ni_0.5O_4+δ demonstrated more active for ORR in terms of the higher limiting current density (−4.05 mA·cm⁻²) and higher half-wave potential (0.568 V vs. RHE) at 1600 rpm. Zinc-air batteries using La_1.7Sr_0.3Co_0.5Ni_0.5O_4+δ as the catalyst exhibited the higher peak power density (60 mW·cm⁻²), the lower discharge-charge voltage gap (1.26 V) after 100 cycles and good discharge-charge cycling stability than that of La₂NiO_4+δ.

[en] Highlights: • Single-step sintering fabricates both anode and cathode of solid oxide fuel cell, saving energy consumption effectively. • Composite hydrogen electrode generated in situ. • Button cells show stable galvanostatic operation for ∼40 h. - ABSTRACT: In this paper, a unit cell with La_0_._6Sr_0_._4Co_0_._2Fe_0_._8O_3_-_δ as anode, Sm_0_._2Ce_0_._8O_1_._9 as electrolyte and PrBaCo_2O_5_+_δ as cathode (LSCF|SDC|PBCO) was fabricated using a cost-effective way by single-step sintering. During testing in reducing atmosphere, the LSCF electrode was in situ decomposed and generated a novel composite electrode material. It is interesting that this composite anode shows an excellent electrochemical performance. The peak power density of a fuel cell based on this innovative anode reaches 325 mW cm"−"2 when use hydrogen as fuel at 800 °C. The constant current discharge result shows that the output voltage drop is only 2% over the entire testing of nearly 40 h. The scanning electron micrographs (SEM) images present a distinct morphology evolution derived from the in situ decomposition of LSCF. The XRD result indicates that the decomposition products of LSCF are consist of LaSrFeO_4, CoO, Fe_7Co_3, and La_2O_3 phases. The present results indicate that LSCF can potentially be a promising precursor for the anode material of solid oxide fuel cell

[en] Oxygen functional groups are one of the most important subjects in the study of electrochemical properties of carbon materials which not only can change the wettability, conductivity and pore size distributions of carbon materials, but also can occur redox reactions. In the electrode materials of carbon-based supercapacitors, the oxygen functional groups have been widely used to improve the capacitive performance. In this paper, we systematically analyzed the reasons for the increase of the capacity that promoted by oxygen functional groups in the charge∕discharge cycling tests and the mechanism how the pseudocapacitance is provided by the oxygen functional groups in the acid/alkaline aqueous electrolyte. In addition, we in more depth discussed the effect of the oxygen functional groups in electrochemical impedance spectroscopy.

[en] In the present paper, the catalytic role of Ag in the oxygen adsorption of LaMnO₃(0 0 1) surface has been theoretically investigated using first-principles calculations based on the density functional theory (DFT) and pseudopotential method. The O₂ adsorption energy is larger for the vertical adsorption and the covalent bond was formed between O₂ molecule and surface Mn. The calculation of electronic properties of interaction between Ag atom and LaMnO₃(0 0 1) surface demonstrates that the most stable position for Ag adsorption is hollow site. The O₂ adsorption energy dramatically increased from 0.298 eV to 1.108 eV due to Ag pre-adsorbed. It is Ag pre-adsorbed that facilitates O₂ adsorption on surface. The bond length and bond population of O₂ molecule indicate that Ag atom facilitates O₂ molecule dissociative adsorption. The Ag atom strengthens LaMnO₃(0 0 1) substrate activity and activity center was formed on surface, which enhances the electrocatalytic activity of LaMnO₃ as solid oxide fuel cells cathode material at low temperature.

[en] In this paper, La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ (LSCrM) and Ni impregnated porous yttria-stabilized zirconia (YSZ) anodes have been fabricated in two different ways. The testing results demonstrated the excellent performance of the anode made by infiltrating a mixture of LSCrM and Ni(NO₃)₂ solutions into porous YSZ matrix. After reduction of the anode with hydrogen, an inner nano-network structure with mixed ionic-electronic conducting path has been formed within and between these added particles. A single cell with the anode at 800 deg. C exhibited the maximum power densities of 1151 and 704 mW cm^-2 when dry H₂ and CH₄ were used as the fuels, respectively; under the same conditions, the cell performances for LSCrM and Ni impregnated YSZ anode separately were 810 and 508 mW cm^-2. A cavity model was proposed to simulate the impregnating process and the loading was calculated. No carbon deposition was detected in the anode, even with the presence of Ni, after operation in dry CH₄ for about 6 h under open-circuit condition.

[en] The Ni-Zn ferrite/SiO₂ nanocomposites (ZNF/SiO₂ NCs) with core-shell structure were synthesized using Stoeber method and a modified one. The core-shell structure was confirmed by transmission electron spectroscopy (TEM). The product obtained by modified Stoeber method was more uniform than by Stoeber method. The strength of dipole-dipole interaction between Ni-Zn nanoparticles decreases and the coordination of surface atoms increases due to surface modification. The decrease of blocking temperature and coercivity of the magnetic particles at low temperature can be attributed to the coating of SiO₂, which weakens the surface spin disorder of magnetic nanoparticles.

[en] Before fabrication of dense yttria-stabilized zirconia films, several thin anode functional layers (AFL) were fabricated onto porous NiO/yttria-stabilized zirconia anode substrates using slurry spin coating. The effect of AFL thickness on gas impermeability and performance of a cell was investigated by studying the effect of AFL thickness on the open-circuit voltage, ohmic resistance, I-V characteristics and electrode overpotential of cells. The results of investigation indicated that as the AFL thickness increased, the gas impermeability of cells was generally improved and the ohmic resistance of cells was increased. The cell with a 5-μm-thick AFL exhibited an excellent cell performance, for example, a single cell with this AFL exhibited an output power of 2.63 W cm^-2 at 800 deg. C when hydrogen was used as fuel and an oxygen was used as oxidant