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Mesporous surface-fluorinated TiO 2 (F-TiO 2 ) powders of anatase phase with high photocatalytic activity are prepared by a one-step hydrothermal strategy in a NH 4 HF 2 -H 2 O-C 2 H 5 OH mixed solution with tetrabutylorthotitanate (Ti(OC 4 H 9 ) 4 , TBOT) as precursor. The prepared samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N 2 adsorption-desorption isotherms, UV-vis absorption spectroscopy, and transmission electron microscopy. The production of hydroxyl radicals ( • OH) on the surface of UVilluminated TiO 2 is detected by a photoluminescence (PL) technique with use of terephthalic acid as a probe molecule. The photocatalytic activity is evaluated by photocatalytic oxidation decomposition of acetone in air under UV light illumination. The results show that the photocatalytic activity of F-TiO 2 powders is obviously higher than that of pure TiO 2 and commercial Degussa P25 (P25) powders due to the fact that the strong electron-withdrawing ability of the surface tTi-F groups reduces the recombination of photogenerated electrons and holes, and enhances the formation of free OH radicals. Especially, the F-TiO 2 powder prepared at the nominal atomic ratio of fluorine to titanium (R F ) of 0.5 shows the highest photocatalytic activity and its rate constant k exceeds that of P25 by a factor of more than 3 times.

Both plants and animals possess analogous tissues containing hierarchical networks of pores, with pore size ratios that have evolved to maximize mass transport and rates of reactions. The underlying physical principles of this optimized hierarchical design are embodied in Murray's law. However, we are yet to realize the benefit of mimicking nature's Murray networks in synthetic materials due to the challenges in fabricating vascularized structures. Here we emulate optimum natural systems following Murray's law using a bottom-up approach. Such bio-inspired materials, whose pore sizes decrease across multiple scales and finally terminate in size-invariant units like plant stems, leaf veins and vascular and respiratory systems provide hierarchical branching and precise diameter ratios for connecting multi-scale pores from macro to micro levels. Our Murray material mimics enable highly enhanced mass exchange and transfer in liquid–solid, gas–solid and electrochemical reactions and exhibit enhanced performance in photocatalysis, gas sensing and as Li-ion battery electrodes.