The Role of Cerium Valence in the Conversion Temperature of H(2)Ti(3)O(7) Nanoribbons to TiO(2)-B and Anatase Nanoribbons, and Further to Rutile

CeO(2)-TiO(2) is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiO(2) nanostructures decorated with CeO(2) nanoparticles at the surface. As the precursor, we used H(2)Ti(3)O(7) nanoribbons prepared from sodium titanate nanoribbons by ion exchange. Two cerium sources with an oxidation state of +3 and +4 were used to obtain mixed oxides. HAADF–STEM mapping of the Ce(4+)-modified nanoribbons revealed a thin continuous layer at the surface of the H(2)Ti(3)O(7) nanoribbons, while Ce(3+) cerium ions intercalated partially between the titanate layers. The phase composition and morphology changes were monitored during calcination between 620 °C and 960 °C. Thermal treatment led to the formation of CeO(2) nanoparticles on the surface of the TiO(2) nanoribbons, whose size increased with the calcination temperature. The use of Ce(4+) raised the temperature required for converting H(2)Ti(3)O(7) to TiO(2)-B by approximately 200 °C, and the temperature for the formation of anatase. For the Ce(3+) batch, the presence of cerium inhibited the conversion to rutile. Analysis of cerium oxidation states revealed the existence of both +4 and +3 in all calcined samples, regardless of the initial cerium oxidation state.