Strong adsorption and effective photocatalytic activities of one-dimensional nano-structured silver titanates Original Research Article

Two kinds of one-dimensional (1D) nano-structured silver titanates, (Ag,H)2Ti4O9-nanowire (ATW) and (Ag,H)2Ti4O9-nanorod (ATR), were prepared by treating sodium titanate nanowires (STW) and titanic acid nanorods (TAR), respectively with molten AgNO3 through the ion-exchanged method. STW, TAR, ATW, and ATR all belong to the monoclinic crystallinity systems, and their band gaps are 3.6, 3.5, 2.8, and 2.8 eV, respectively. Interestingly, all of the four photocatalysts show strong and fast adsorption abilities for methylene blue (MB) and Alizarin Red S (ARS) dyes. MB and ARS can be adsorbed by the silver titanates completely within 5 and 10 min, respectively. The photocatalytic activities of the two kinds of silver titanates were evaluated by degradation of the MB and ARS dye solutions with high concentration, and by the decomposition of gaseous isopropyl alcohol (IPA) under visible light (λ ≥ 410 nm) irradiation. After the adsorption–desorption equilibrium, MB and ARS could be degradated almost completely within 60 and 80 min, respectively. In addition, the mineralization yield of IPA on ATW reached 80% after 6.5-h irradiation. The high photocatalytic activities of the silver titanates may be due to their large BET surface areas and strong adsorption abilities. Moreover, both of the silver titanates showed good stabilities in the long-time-run photocatalytic reactions.