Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO 2 thin films

In-situ pure TiO 2 and Fe-doped TiO 2 thin films were synthesized on Ti plates via the micro-arc oxidation (MAO) technique. The as-fabricated anatase TiO 2 thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO 2 thin films by adding precursor K 4 (FeCN) 6 ·3H 2 O into the Na 3 PO 4 electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of K 4 (FeCN) 6 ·3H 2 O increasing, eventually affecting the ethanol sensing performances of TiO 2 thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant (1.28at%), by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275°C. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe 3+ substituting for Ti 4+ .