The Critical Effect of Niobium Doping on the Formation of Mesostructured TiO₂: Single‐Crystalline Ordered Mesoporous Nb‐TiO₂ and Plate‐like Nb‐TiO₂ with Ordered Mesoscale Dimples

Abstract

Highly ordered mesoporous niobium-doped TiO2 with a single-crystalline framework was prepared by using silica colloidal crystals with ca. 30 nm in diameter as templates. The preparation of colloidal crystals composed of uniform silica nanoparticles is a key to obtain highly ordered mesoporous Nb-doped TiO2 . The XPS measurements of Nb-doped TiO2 showed the presence of Nb(5+) and correspondingly Ti(3+) . With the increase in the amount of doped Nb, the crystalline phase of the product was converted from rutile into anatase, and the lattice spacings of both rutile and anatase phases increased. Surprisingly, the increase in the amount of Nb led to the formation of plate-like TiO2 with dimpled surfaces on one side, which was directly replicated from the surfaces of the colloidal silica crystals.

Porous Single‐Crystal‐Based Inorganic Semiconductor Photocatalysts for Energy Production and Environmental Remediation: Preparation, Modification, and Applications

“…Due to relatively large bandgap (3–3.2 eV for various phases), TiO 2 only absorbs ultraviolet light. Several metal elements have been doped in TiO 2 PSCs by simple addition of metal salts, for example of Zn or Nb, to the solution submitted to hydrothermal reactions in TiO 2 synthesis 113,114. Compared to metal doping, nonmetal doping for TiO 2 PSCs is more difficult to be achieved by in‐site wet methods, since nonmetallic anions employed as dopant elements can influence nucleation and growth of well‐faceted crystals in solution synthesis.…”

A Single‐Crystalline Mesoporous Quartz Superlattice

“…Mesoporous non-silica materials with single-crystalline frameworks are also very rare (e.g. gold, [21] TiO 2 , [22] and Nbdoped TiO 2 [23] ). Thepresent method is promising as ageneral concept for the design of nanostructured materials with single-crystalline frameworks.…”

Boosting the Efficiency of Perovskite Solar Cells with CsBr‐Modified Mesoporous TiO2 Beads as Electron‐Selective Contact

“…Theoretical calculations for TiO 2 suggest that electrons prefer to localize just below the surface being trapped by oxygen vacancies and Ti(IV) ions . One of the most effective methods to reduce the trap states in the TiO 2 is surface or bulk doping, which has been widely investigated for mesoporous TiO 2 electrodes in dye‐sensitized solar cells and more recently in perovskite solar cells . Some inorganic/organic dopants suppress the charge recombination and increase electron transport by passivating oxygen defects in the TiO 2 lattice and reducing trap states below the conduction band (CB) of TiO 2 in PSCs.…”