Exfoliation and restacking route to anatase-layered titanate nanohybrid with enhanced photocatalytic activity

A new microporous TiO₂-pillared layered titanate has been prepared by hybridizing the exfoliated titanate with the anatase TiO₂ nanosol. The stable colloidal nano-sheet was obtained by intercalating tetrabutylamine into the layered protonic titanate, H_xTi_2-x/4□ _x/4O₄·H₂O (x = 0.67), with a lepidocrocite-like structure. The colloidal suspension of exfoliated titanate sheets was mixed with the monodispersed anatase TiO₂ 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 TiO₂ nanosol on the interlayer surface of layered titanate. According to the X-ray diffraction analysis and N2 adsorption-desorption isotherms, it was found that the TiO₂-pillared layered titanate showed a pillar height of ∼2 nm, a high surface area of ∼460 m²/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 H₂ gas evolved during the irradiation of the catalyst suspensions in water. The H₂ gas evolution was found to increase from the layered titanate (cesium and protonic form) to the unsupported TiO₂ (acac-TiO₂) and the TiO₂-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 TiO₂-pillared layered titanate compared to pristine compounds such as layered titanate and anatase TiO₂ nanosol when Pt (0.3 wt %) was doped on the surface of the sample.