Effective Reinforcement of Visible Light Photocatalytic and Gas Sensing Characteristics of Nanocrystalline TiO 2 : Gd-Based Nb and Mo Dopants.

Efficient compositions for the selective detection of ethanol gas and the removal of organic contaminants were realized by codoping of (Gd, Nb) and (Gd, Mo) ions into TiO 2 . TiO 2 , Ti 0.96 Gd 0.01 Nb 0.03 O 2 , and Ti 0.96 Gd 0.01 Mo 0.03 O 2 samples were prepared by a coprecipitation method. For all compositions, a crystalline anatase phase of TiO 2 was detected. Compared to pure TiO 2 , the absorption edges of Ti 0.96 Gd 0.01 Nb 0.03 O 2 and Ti 0.96 Gd 0.01 Mo 0.03 O 2 samples were red-shifted, further broadening towards visible light. The morphological studies demonstrate that the grains of TiO 2 were more refined after (Gd, Nb) and (Gd, Mo) codoping. The photocatalytic efficiency of the Ti 0.96 Gd 0.01 Mo 0.03 O 2 catalyst for degrading 20 mg/L reactive yellow 145, brilliant green, and amoxicillin was 98, 95, and 93% in 90 min, respectively. The reusability experiments indicate that the Ti 0.96 Gd 0.01 Mo 0.03 O 2 catalyst had high stability during reuse. The high photocatalytic activity of the Ti 0.96 Gd 0.01 Mo 0.03 O 2 catalyst was correlated to the broad visible-light absorption and effective separation of electron-hole pairs by Gd 3+ and Mo 6+ cations. The gas sensing characteristic is reflected by the high sensitivity of the Ti 0.96 Gd 0.01 Nb 0.03 O 2 sensor to ethanol gas in the presence of different gases at 275 °C. The obtained results indicated that the (Gd, Mo) mixture could more effectively induce the photocatalytic properties of TiO 2 while (Gd, Nb) dopants were the best for reinforcing its sensing characteristics.