The optical glow of ceramics that becomes established during the constant state of flash, known as Stage III in flash sintering experiments, is investigated. The specimen temperature in this state is obtained from in-situ experiments at the Pohang Light Source II. The measurements of the specimen temperature agree very well with the predictions from the black body radiation model. The optical emission spectrum from the specimen is measured from the visible into the deep infrared, and compared with black body radiation that would have been expected from Joule heating. It is concluded that the specimens radiate by electroluminescence, which is ascribed to electron-hole recombination of excitons. The phenomenon is likely the same as discovered by Nernst at the turn of the twentieth century.

Size-controlled Pt nanocatalysts embedded in TiO(2) were successfully synthesized by simultaneous dual-gun sputtering and were found to exhibit unique electronic properties depending on their size, which affected the potential of zero total charge, CO-bulk oxidation, and methanol oxidation reaction.

Pt−Ni alloy nanoparticles supported on carbon black (Pt:Ni = 1:1) were prepared by the borohydride reduction method using acetate anions as a stabilizer in anhydrous ethanol solvent. Here, we surveyed the effect of oxide phases in Pt−Ni alloy nanoparticles on the electrocatalytic activity toward oxygen reduction reaction (ORR). As-prepared Pt1Ni1/C, which showed a relatively high degree of alloying, possessed the lower oxygen reduction reaction (ORR) activity as compared to pure Pt. However, following heat treatment in a flow of Ar at 300 °C for 3 h, Pt1Ni1/C showed oxygen reduction activity higher than that of commercial Pt/C (40 wt % Pt/C, Johnson-Matthey). The potential of zero total charge (PZTC) was calculated from cyclic voltammograms and the CO-displacement charge at dosing potentials at which anions are the main adsorbed species. The calculated value then shifted to a more positive potential after heat treatment. This indicates that the surface of the Pt−Ni nanoparticles became less oxophilic mainly due to the clustering of Pt. This anodic shift of the PZTC is consistent with the results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure spectroscopy (XANES). Consequently, the observed catalytic enhancement by heat treatment is due to the increase of metallic Pt and NiO and the phase separation between metallic Pt and Ni oxides.

Efficient water oxidation catalysts are required for the development of water splitting technologies. Herein, the synthesis of layered hybrid NiFephenylphosphonate compounds from metal acetylacetonate precursors and phenylphosphonic acid in benzyl alcohol, and their oxygen evolution reaction performance in alkaline medium, are reported. The hybrid particles are formed by inorganic layers of NiO 6 and FeO 6 distorted octahedra separated by bilayers of the organic group, and template the formation in situ of NiFe hydroxide nanosheets of sizes between 5 and 25 nm and thicknesses between 3 and 10 nm. X-ray absorption spectroscopy measurements suggest that the hybrid also acts as a template for the local structure of the metal sites in the active catalyst, which remain distorted after the transformation. Optimum electrocatalytic activity is achieved with the hybrid compound with a Fe content of 16%. The combination of the synergistic effect between Ni and Fe with the structural properties of the hybrid results in an efficient catalyst that generates a current density of 10 mA cm −2 at an overpotential of 240 mV, and also in a stable catalyst that operates continuously at low overpotentials for 160 h.

intensively investigated and developed at a global level. Among several possible energy storage and power sources, lithium-ion batteries (LIBs) have been successfully used in applications ranging from portable electronic devices to electric vehicles and large-scale energy storage systems (ESSs) owing to their high energy density. However, some critical concerns have arose regarding LIBs such as the cost of lithium resources and safety issues from mobile to ESS applications. [1-6] Thus, rechargeable divalent-ion (e.g., Zn 2+ , Mg 2+ , and Ca 2+) batteries operated in aqueous electrolytes have recently received significant attention because the use of water results in low cost, improved safety, cell fabrication in ambient environment, and reasonable environmental impact. [7-9] Furthermore, the ionic conductivity of aqueous electrolytes for rechargeable divalent-ion batteries is several-ordersof-magnitude higher than that of organic electrolytes. [7,10-12] Among divalent-ion batteries, aqueous zincion batteries (ZIBs) have been intensively investigated owing to the high gravimetric capacity (820 mAh g −1) and sufficient earth abundance of Zn metal. Moreover, the high overpotential of Herein, the promising properties of open-structured NaV 3 O 8 as a cathode material for Zn-ion batteries (ZIBs) are investigated. First-principles calculations predict the insertion of Zn 2+ (0.74 Å) in NaV 3 O 8 with an interlayer distance of ≈7 Å, enabling delivery of a high discharge capacity of 353 mAh g −1 at 70 mA g −1 (0.2 C) for 300 cycles in the operating window of 0.3−1.5 V in 1 m Zn(CF 3 SO 3) 2 aqueous solution. Operando synchrotron X-ray diffraction, X-ray absorption near edge structure spectroscopy, and first-principles calculations validate the insertion of Zn 2+ into the NaV 3 O 8 structure within the operation range. Moreover, operando synchrotron X-ray diffraction and operando Raman spectroscopy reveal the formation of layered zinc hydroxytriflate (Zn 5 (OH) 8 (CF 3 SO 3) 2 •xH 2 O) as a side reaction below 0.8 V on discharge (reduction) and its dissolution into the electrolyte above 0.8 V on charge (oxidation). The formation of the Zn hydroxytriflate interfacial layer increases the charge-transfer activation energy from 15.5 to 48 kJ mol −1 , leading to kinetics fade below 0.8 V. The findings reveal the charge-storage mechanism for NaV 3 O 8 , which may also be applicable to other vanadate cathodes, providing new insights for the investigation and design of ZIBs.