Controlled synthesis of TiO 2 nanorod arrays immobilized on ceramic membranes with enhanced photocatalytic performance

Abstract In this work, TiO 2 nanorod arrays (NRAs) were synthesized directly on flat sheet Al 2 O 3 ceramic membrane (CM) substrates by a two-step hydrothermal method. The effects of the addition of anions and cations and the preparation parameters in the second step on the morphology and size of TiO 2 were investigated in detail, and the photocatalytic activities of the as-synthesized TiO 2 -loaded ceramic membranes were investigated by the degradation of methylene blue (MB) under UV light. The results highlighted that the growth of TiO 2 on the CM strongly depended on the synthesis conditions. The anions of Cl - and Br - were favorable for the further growth of TiO 2 nanorods, while the anions of SO 4 2- and PO 4 3- with larger ionic radius and higher charge number could retard the growth of TiO 2 nanorods. The SO 4 2- and PO 4 3- could accelerate the formation of nanospheres or nanosheets, respectively. The cation like Na + , K + , Mg 2+ and Ca 2+ had no obvious impact on the formation of TiO 2 NRAs. TiO 2 nanorods exhibited the highest photocatalytic activity, as about 2.2 and 1.9 times larger than those of TiO 2 nanosheets and TiO 2 nanospheres, respectively. More importantly, the as-synthesized TiO 2 NRAs-loaded ceramic membrane could be easily reused and exhibited better photocatalytic stability. These findings would aid the development of TiO 2 photocatalytic materials with high performance.