Improvement of pore structure stability of disordered nanoporous TiO₂ material by nano-propping effect

Disordered nanoporous TiO₂ was successfully prepared via in-situ hydrolysis of titanium glycolate without templates. The nanoporous TiO₂ material exhibited a disordered pore structure with a large surface area (279 m²/g) induced by the aggregation of primary TiO₂ particles (about 2 nm in size). Thermal treatment is required for various applications of disordered nanoporous TiO₂. However, thermal treatment results in the agglomeration of primary TiO₂ nanoparticles and the subsequent collapse of the nanoporosity. Impregnation of cerium oxide on the nanoporous TiO₂ interrupted contacts among primary TiO₂ particles and obstructed the agglomeration of TiO₂ particles through nano-propping effect. Even after thermal treatment at high temperature (700°C), cerium oxide-impregnated TiO₂ materials exhibited nanoporosity (surface area of 34 m²/g and total pore volume of 0.22 cm³/g) with relatively small grain sizes (15.0 nm). In contrast, the disordered nanoporous TiO₂ without cerium oxide showed a non-porous structure with very large rutile grains (56.1 nm). Therefore, the addition of cerium oxide enhanced the pore structure stability of disordered nanoporous TiO₂.