Exfoliation and Restacking Route to Anatase-Layered Titanate Nanohybrid with Enhanced Photocatalytic Activity

A new microporous TiO 2 -pillared layered titanate has been prepared by hybridizing the exfoliated titanate with the anatase TiO 2 nanosol. The stable colloidal nano-sheet was obtained by intercalating tetrabutylamine into the layered protonic titanate, H x Ti 2 - x /4 □ x /4 O 4 ·H 2 O ( x = 0.67), with a lepidocrocite-like structure. The colloidal suspension of exfoliated titanate sheets was mixed with the monodispersed anatase TiO 2 nanosol solution prepared by the hydrolysis of titanium isopropoxide with acetylacetone. The obtained nanohybrid was heated at 300 °C for 2 h in order to complete the grafting reaction of intercalated anatase TiO 2 nanosol on the interlayer surface of layered titanate. According to the X-ray diffraction analysis and N 2 adsorption−desorption isotherms, it was found that the TiO 2 -pillared layered titanate showed a pillar height of ∼2 nm, a high surface area of ∼460 m 2 /g, and a pore size of ∼0.95 nm, indicating the formation of a microporous pillar structure. Its photocatalytic activity was evaluated by measuring the total volume of H 2 gas evolved during the irradiation of the catalyst suspensions in water. The H 2 gas evolution was found to increase from the layered titanate (cesium and protonic form) to the unsupported TiO 2 (acac-TiO 2 ) and the TiO 2 -pillared layered titanate, because the electron and hole recombination in the pillared system is thought to be effectively suppressed because of electron transfer between guest and host. A marked enhancement in the activity by ca. 40 times was obtained for TiO 2 -pillared layered titanate compared to pristine compounds such as layered titanate and anatase TiO 2 nanosol when Pt (0.3 wt %) was doped on the surface of the sample.