House-of-cards composites of MWW monolayers and TiO2 nanoparticles with (photo)catalytic activity

• Exfoliated MWW monolayers in solution enable intimate composites with TiO 2 NPs. • Random mixing of monolayers and TiO 2 NPs resulted in house-of-cards structures. • Composites are more active in (photo)catalysis than equivalent physical mixture. • Selectivity to diphenyl sulfone in diphenyl sulfide oxidation by H 2 O 2 is enhanced. The exfoliation of layered zeolites affording monolayer nanosheets in solution enables for the first time preparation of molecularly intimate composites of zeolites with other components like nanoparticles, other layers, etc. This ability is not possible with the conventional 3D and even solid 2D zeolite forms. It allows synthesizing composites with desired combination of functionalities and additional benefits like open accessible architectures. The present article illustrates this novel approach by reporting the preparation of catalysts comprising 2.5 nm thick monolayers of the zeolite MWW and TiO 2 nanoparticles with approximate diameter 4–8 nm. The chosen ratio is 1:1 w/w but it is readily adjustable to different values if desired. Two solutions of exfoliated zeolite MWW monolayers were used: as-made and after purification by dialysis. The composites precipitated upon mixing with TiO 2 nanoparticle solutions. TEM investigation confirmed random mixing of the components producing house-of-cards structures. The composites were additionally characterized by X-ray powder diffraction, nitrogen sorption and FTIR. The efficacy of the new approach was demonstrated through testing in two catalytic oxidation reactions, and both showed advantage over the equivalent physical mixture of the components. One of the test reactions, diphenyl sulfide oxidation by H 2 O 2 revealed both catalytic (in the dark) and photocatalytic (with irradiation) activity. The hydroxylation of terephthalic acid occurred by radical oxidation. The presented approach can be applied to design desired systems, e.g., with other semiconductors to allow more precise control not only of the content in mixed phases but also of optical and electronic properties of these materials.