Synthesis and characterization of tungsten and barium co-doped La2Mo2O9 by sol-gel process for solid oxide fuel cells

Herein,we demonstrate the synthesis of W and Ba co-doped La2Mo2O9(LBMWO)nanocrystalline powder by a sol-gel process.In all the compositions have general formulae La1.9Ba0.1Mo2-xWxO8.95(x=0-0.40).The crystal structure,microstructure and conductivity of LBMWO were characterized by X-ray diffraction,scanning electron microscopy and electrical impedance spectroscopy.In addition,the thermal and decomposition properties of the LBMWO gel were analyzed by differential scanning calorimetry-thermogravimetric.The results reveal that all LBMWO powders calcined at 700℃have a cubic structure;the average crystallite size is about 48 nm.The unit cell parameter of LBMWO powders increases with increase in W content.The as-synthesized nanocrystalline LBMWO samples exhibit excellent sinterability and a relatively lower sintering temperature of 900℃.A high relative density of-96%is achieved after sintering at 900℃which is in good agreeme nt with the re sults of the SEM.Moreover,W and Ba codoping suppresses the phase transition and effectively stabilizes theβ-phase at low temperature.At the same time,La1.9Ba0.1Mo1.85W0.15O8.95 exhibits high ionic conductivity,3.07 x 10^-2 S/cm at 800℃.It is therefore concluded that co-doping can improve the properties of La2MO2O9 electrolytes.

Developing hierarchical CdS/NiO hollow heterogeneous architectures for boosting photocatalytic hydrogen generation

The hierarchical binary CdS/NiO hollow heterogeneous architectures(HHAs)with p–n heterojunction are constructed by a facile microwave-assisted wet chemical process for high-efficient photocatalytic hydrogen evolution reaction(HER)from water.The as-designed CdS/NiO HHAs are composed of hexagonal n-type CdS nanoparticles with a size in the range of 20–40 nm attaching to cubic p-type NiO hollow microspheres(HMSs)which are aggregates of porous nanoplates with a thickness of about 20 nm.The photocatalytic water splitting over CdS/NiO HHAs is significantly increased under simulated solar irradiation,among which the most active sample of CdS/NiO-3(the mass ratio of CdS to NiO is 1:3)exhibits the fastest photocatalytic HER rate of 1.77 mmol∙g^(−1)∙h^(−1),being 16.2 times than that of pure CdS.The boosted photocatalytic HER could be attributed to the synergistic effect on the proportional p–n heterojunction with special hierarchical hollow and porous morphology,an enhancement of visible light absorption,and an improvement of photoinduced charge separation as well as the photo-stability given by the composite heterojunction.This work shows a viable strategy to design the heterojunction with special morphology for the efficient hydrogen generation by water splitting utilizing solar energy.

Mechanical property and biocompatibility of co-precipitated nano hydroxyapatite-gelatine composites

Uniform and well dispersed nano hydroxyapatite(HA)-gelatine composites were obtained by co-precipitation of hydroxyapatite and denatured calf skin collagen.The process allowed much higher concentration of hydroxyapatite to be produced over conventional hydrothermal process to improve the productivity.The effect of gelatine on the morphology,mechanical properties,and biocompatibility of hydroxyapatite particles was investigated.Fibroblast cell tests of the consolidated hydroxyapatite-gelatine composites showed that the composites have excellent biocompatibility.