The doped and undoped nanocrystals with exposed {001} crystal facets were synthesized by a solvothermal method. The morphological structure of TiO2 nanocrystals (a,b) changed with Mg2+ doping. The nanoplates became larger and pilled one on top of the other forming this way a separate bigger nanocrystal (c,d). As the content of Mg2+ ions increases, more nanoplates pile up making the crystal more dense and thicker (e,f). With the further increase of Mg2+ content in the anatase lattice the nanoplates are densely stocked together forming a sea-urchin morphological structure (g,h). The corresponding SAED patterns show how the nanoplates gradually lose their perfect alignment and perfect single crystal structure and become randomly oriented one on top of the other for the highest Mg2+ content.

TEM micrographs of the pure TiO2 anatase nanoplates, in the insert corresponding SAED pattern (a,b), 2 at% Mg2+/TiO2, in the insert corresponding SAED pattern (c,d), 5.1 at% Mg2+/TiO2 in the insert corresponding SAED pattern(e,f), 6.2 at% Mg2+/TiO2 anatase nanoplates, in the insert corresponding SAED pattern (g,h)

TEM micrographs of the pure TiO2 anatase nanoplates, in the insert corresponding SAED pattern (a,b), 2 at% Mg2+/TiO2, in the insert corresponding SAED pattern (c,d), 5.1 at% Mg2+/TiO2 in the insert corresponding SAED pattern(e,f), 6.2 at% Mg2+/TiO2 anatase nanoplates, in the insert corresponding SAED pattern (g,h).

The TEM micrographs of the doped nanocrystals with Mn2+ ions in different atomic ratios reveal that the obtained doped TiO2 product consists of uniform, well-defined plate-shaped structures possessing a rectangular outline. The HRTEM images (f,g) of the anatase samples viewed along the [001] and [010] crystallographic directions, as well as the SAED pattern (h) confirm that the square surfaces are {001} facets of the single-crystalline nanoplate (e).

TEM micrographs of the pure TiO2 anatase nanoplates, in the insert corresponding SAED pattern (a,b), 2 at% Mg2+/TiO2, in the insert corresponding SAED pattern (c,d), 5.1 at% Mg2+/TiO2 in the insert corresponding SAED pattern(e,f), 6.2 at% Mg2+/TiO2 anatase nanoplates, in the insert corresponding SAED pattern (g,h)

TEM micrographs of the pure TiO2 anatase nanoplates (a,e), 2 at% Mn2+/TiO2 nanoplates (b), 6 at% Mn2+/TiO2 nanoplates (c), 7 at% Mn2+/TiO2 nanoplates (d), individual nanoplate recorded along [001] (f), individual nanoplate recorded along [010] (g), SAED pattern of the nanoplate (h).

The photocatalytic tests that were performed to all samples revealed that Mg2+ and Mn2+ ion doping in small amounts causes better separation of electrons and holes thus enhancing the photocatalystic activity in comparison to the pure TiO2 nanoplates. Lastly, the manganese doped nanoplates showed photocatalytic activity towards the visible light region in comparison to the pure anatase sample.

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