Mesoporous titania-based H3PW12O40 composite by a block copolymer surfactant-assisted templating route: Preparation, characterization, and heterogeneous photocatalytic properties

Mesoporous H3PW12O40/TiO2 composite with H3PW12O40 loading from 3.2 to 16.6% was prepared by the combination of sol–gel chemistry, templated self-assembly, and solvothermal treatment in the presence of a triblock copolymer surfactant. At relatively low solvothermal treatment temperature (80 to 120 °C), as-prepared composite exhibited an anatase phase structure. Bulk and surface sensitive probe testing results indicated that the primary Keggin structure remained intact after formation of the composite, and strong interaction between the Keggin unit and TiO2 network existed in the composite. Nitrogen gas porosimetry, low-angle XRD, and TEM testing results suggested the composite exhibited well-distributed three-dimensionally interconnected pore structure with pore diameter of 3.3–4.0 nm, BET surface area of 151.5–195.1 m2 g− 1, and pore volume of 0.17–0.26 cm3 g− 1. The composite was used as a heterogeneous photocatalyst to degradation of dyes with azoic (methyl orange), heteropolyaromatic (methylene blue), triarylmethane (crystal violet), and fluorescent (rhodamine B) structures; at the same time, adsorption behaviors of dyes on mesoporous H3PW12O40/TiO2 composite are tested. Finally, photodegradation pathway of dye crystal violet over mesoporous H3PW12O40/TiO2 was tentatively put forward based on the identified intermediates generated during the photocatalytic degradation process. The results shown in Fig. 9 demonstrate that PW12/TiO2 with higher H3PW12O40 loading has higher photocatalytic activity.