•Pt/HxWO3 catalyst was obtained by electrodepositing directly on the carbon cloth.•A hydrophilic–hydrophobic double microporous layer was introduced.•The double MPL had a substantial effect on the morphology and loading of catalysts.•The addition of HxWO3 enhances the catalytic activity of Pt for hydrogen oxidation.Platinum/hydrogen tungsten bronze (Pt/HxWO3) composite catalysts were prepared by electrodeposition on the carbon cloth with varying HxWO3 content. To obtain highly dispersed catalyst layer, the carbon cloth was modified by introducing a hydrophilic–hydrophobic double microporous layer. The catalytic activity of prepared catalysts was investigated by single cell polarization test and in situ cyclic voltammetry (CV). The application of double microporous layer facilitates electrodeposition process, which benefits the dispersion of catalysts. HxWO3 used as auxiliary catalyst enhances the catalytic activity of Pt for hydrogen oxidation. Pt/HxWO3 hydrophilic electrode with composite catalyst loading of 0.35 mg cm−2 exhibits the higher current density of 340 mA cm−2 at 0.4 V and electrochemical active surface area (EASA) of 89.40 m2 g−1 than traditional Pt/C does at room temperature.

The apatite-type lanthanum silicates with formula La9.33Si6O26 are prepared by sol-gel process. The homogeneity of the sol affected by pH value of the solution is investigated. The viscosity of the sols slightly increases first and then increases abruptly because the predominant reaction mechanism changes from hydrolysis reaction to condensation reaction. In addition, the onset time of the increase for the viscosity shortens from pH 1 to pH 4. The gelation time decreases with increasing pH of the solution. Therefore, the pH of the sols should be less than 4 to form gel. The sol with initial pH 2 shows maximum value of zeta potential and maximum stability. For the sample with initial pH 2, pure apatite-type lanthanum silicates La9.33Si6O26 have been successfully prepared after the dried gel is calcined at 1 000 °C. In addition, this sample sintered at 1 550 °C exhibits the highest ionic conductivity. The activation energies are all less than 0.90 eV.

The effect of Fe doping on the electrical properties of lanthanum silicates was investigated. The apatite-type lanthanum silicates La10Si6−xFexO27−x/2 (x=0.2, 0.4, 0.6, 0.8, 1.0) were synthesized via sol-gel process. The unit cell volume increased with Fe doping because the ionic radius of Fe3+ ion is larger than that of Si4+ ion. The conductivities of La10Si6−xFexO27−x/2 first increased and then decreased with the increasing of Fe content. The increase of the conductivity might be attributed to the distortion of the cell lattice, which assisted the migration of the interstitial oxygen ions. The decrease of the conductivity might be caused by the lower concentration of interstitial oxygen ions. The optimum Fe doping content in lanthanum silicates was 0.6. La10Si5.4Fe0.6O26.7 exhibited the highest ionic conductivity of 2.712×10−2 S/cm at 800 °C. The dependence of conductivity on oxygen partial pressure p(O2) suggested that the conductivity of La10Si6−xFexO27−x/2 was mainly contributed by ionic conductivity.