S 5200 microscope

Scanning electron microscopy (SEM) observation and energy dispersive X-ray spectroscopy (EDS) analysis were performed on a JSM-7800F microscope (JEOL, Japan). The electrode was directly deposited on carbon tape. High-magnification SEM observation was performed on S-5200 microscope (Hitachi, Japan) with an operating voltage of 5 kV. Before the high-magnification observation, the sample deposited on carbon tape was coated with gold using an E-1030 ion sputter coater (Hitachi, Japan).
Nitrogen adsorption isotherms were recorded at 77 K in the relative pressure range between 0.05 and 0.30 with a BELSORP-mini system (MicrotracBEL, Japan). Before the measurements, the electrode was outgassed at 473 K for 2 h. The Brunauer–Emmett–Teller (BET) equation was used to calculate the surface area of WO₃/Ti fiber electrode. The BET specific surface area of the WO₃ particles was estimated from the measured surface area of the electrode and the loading amount of the WO₃ particles. The BET specific surface area of Ti microfibers was smaller than the measurement limit.

TPR experiments (ca. 45 mg of sample) were performed on a Micromeritics Autochem II within a temperature range of 60–900 °C (10 °C/min heating rate) under flowing (50 mL/min) 10%H₂/Ar. The specific surface areas of the samples were obtained by adsorption–desorption of N₂ at 77 K on a Micromeritics ASAP 2020 following the multi-point Brunauer–Emmett–Teller (BET) method. The samples were previously degassed at 300 °C under vacuum for 100 min. Powder XRD analyses were carried out on a Rigaku UltimaIV diffractometer employing CuKα radiation and a scanning rate of 2°/min. SEM observations were carried out on a Hitachi S5200 microscope, and samples were used without any further modification. Inductively coupled plasma atomic emission spectroscopy (ICP–AES) was used to determine the actual oxide content of the different samples. This measurement was made on a Varian Vista AX spectrometer, and samples were previously dissolved in 5 mL of aqua regia (HNO₃:HCl, 1:3 in volume).