Controlled synthesis of tungsten trioxide with globular clusters constructed of nanoplates by rapid breakdown anodization

Herein, the electrochamical synthesis of tungsten trioxide (WO3·H2O) with globular clusters constructed of nanoplates is demonstrated. On applying a breakdown anodization potential of 25 V at 50 °C, tungsten foil anode is efficiently electro-oxidized into WO3 globular clusters constructed of nanoplates powder, instead of a thin film structure as conventional anodization occurs. The resulting globular clusters were characterized using SEM, TEM, and XRD. The effect of the composition of electrolyte on the breakdown anodization of the W substrate is discussed. And we suggest that the growth of the nanoplates is initiated by localized anodic dielectric breakdown, followed by a effectively crystal growth in electrolyte at high breakdown field.

Fabrication of TiO2 sensor using rapid breakdown anodization method to measure pressure, humidity and sense gases at room temperature

Rapid breakdown anodization (RBA) process was used to fabricate TiO2 sensor to measure pressure and humidity and sense gases at room temperature. This chemical process transformed Ti to its oxide (TiO2) as a powder with amorphous phase as X ray diffraction (XRD) technique confirmed. This oxide consisted from semi spherical nanoparticles and titania nanotubes (TNTs) as Scanning electron microscope (SEM) technique showed. TiO2 powder was deposited on Ti substrates by using electrophoretic deposition (EPD) method. Average pressure sensitivity was 0.34 MΩ/bar and hysteresis area was 1.4 MΩ .bar. Resistance of TiO2 decreased exponentially with the increasing of relative humidity (RH%). The sensitivity% of TiO2 for RH% was greater than 70% in the range of (50-95). TiO2 was tested as a sensor for Ammonia, Ethanol and Methanol. Its sensitivity and selectivity towards Ammonia were the greatest but the shortest response and recovery times were recorded toward Methanol.