The influence of synthesis method on the properties of iron contained N doped TiO2 photocatalysts

Fe contained TiO2−xNy were prepared by two different methods to control the status of Fe in the final products. By a 1-step hydrothermal method, Fe and N co-doped TiO2 which showed similar crystalline phases, photo absorption properties and specific surface areas to TiO2−xNy were formed. However, the Fe and N co-doping caused the decrease in photocatalytic activity, due to the formation of lattice vacancy. On the other hand, by a 2-step hydrothermal method, TiO2−xNy/Fe2O3 composites were formed, which showed superior visible light absorption ability to TiO2−xNy regardless the decrease in specific surface areas. The excellent deNOx abilities of TiO2−xNy/Fe2O3 composites may be due to the heterogeneous electron transfer from TiO2−xNy to Fe2O3 to retard the quick recombination of photoinduced electrons and holes.

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► By simply altering the synthesis sequence, Fe status in the final products could be controlled, which showed great influence on property and photocatalytic activity.
► The statuses of Fe in the products were distinguished by XPS analysis, and the observation of Fe–N peak in the sample prepared by 2-step method confirmed the co-doping of Fe into the TiO2−xNy.
► The photocatalytic activities in deNOx experiment revealed the negative effect of Fe co-doping and the positive effect of Fe2O3 coupling, which provided a clue to design high-activity photocatalyst.