The photocatalytic activity of TiO 2 photocatalysts depends mainly on its crystal phase composition, primary particle size and specific surface area. Shape manipulation is an interesting way to increase the photocatalytic efficiency. The shape-tuning can be carried out at different levels, both at single crystal and polycrystalline agglomeration levels. The aim of our present study was to compare the structural and photocatalytic performances of two type/level of crystal organization of TiO 2 , namely single crystal shaping vs. polycrystalline/shape tailored agglomeration. The morphological analysis was achieved by XRD, SEM, TEM, Raman spectroscopy, DRS. The photocatalytic performance of the materials was evaluated by the degradation of a model pollutant (phenol). It was found, that both shape manipulating approaches bear the necessary potential which can be exploited in future development of efficient photocatalysts' synthesis procedures.

One of the most fundamental aspects of the heterogeneous catalysis field is the manipulation of the catalysts' activity. In photocatalysis this is carried out by maximizing the right crystal plane of a semiconductor oxide. Until now, most of the papers have achieved this by a combination of different oxides, with noble metals and sometimes with carbon nanomaterials. In this work MWCNTs (multiwalled carbon nanotubes) were applied as "crystallization promoters" in a very simple, safe, one-step hydrothermal method. By this method TiO 2 nano/micro crystals with exposed {001} facets were obtained in the first step. The next episode in the crystal manipulation "saga" was the modification of the (001) crystallographic plane's structure by creating ordered/own faceted "crystallographic holes". These elements are capable of further enhancing the obtained activity of titania microcrystals to a higher extent, as shown by the UV driven photocatalytic phenol degradation experiments. The appearance of the holes was "provoked" by simple calcination and their presence and influence were demonstrated by XPS and HRTEM.

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In the present study, a commercial TiO 2 , several BiVO 4 photocatalysts, a WO 3 nanomaterial, and their composites were used to prepare photocatalytic polyvinylidene fluoride (PVDF) ultrafilter membranes. Their photocatalytic activities and the effects of coatings on the filtration of oil-in-water emulsion (crude oil; c oil = 100 mg L −1) were investigated. Fluxes, filtration resistances, purification efficiencies, and fouling resistance abilities-like flux decay ratios (FDRs) and flux recovery ratios (FRRs)-were compared. The solar light-induced photocatalytic decomposition of the foulants was also investigated. WO 3 was used as a composite component to suppress the electron-hole recombination with the goal of achieving higher photocatalytic activity, but the presence of WO 3 was not beneficial concerning the filtration properties. However, the application of TiO 2 , one of the investigated BiVO 4 photocatalysts, and their composites was also beneficial. In the case of the neat membrane, only 87 L m −2 h −1 flux was measured, whereas with the most beneficial BiVO 4 coating, 464 L m −2 h −1 flux was achieved. Pure BiVO 4 coating was more beneficial in terms of filtration properties, whereas pure TiO 2 coating proved to be more beneficial concerning the photocatalytic regeneration of the membrane. The TiO 2 (80%)/BiVO 4 (20%) composite was estimated to be the most beneficial combination taking into account both the aspects of photocatalytic activity and filtration properties.

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