Substitution Effects of In³⁺ by Al³⁺ and Ga³⁺ on the Photocatalytic and Structural Properties of the Bi₂InNbO₇ Photocatalyst

A new series of photocatalysts, Bi 2 MNbO 7 (M = Al 3+, Ga 3+, In 3+ ), were synthesized by solid-state reaction and characterized by powder X-ray diffraction and Rietveld structure refinement. The substitution effect of In 3+ by Al 3+ and Ga 3+ on the photocatalytic and structural properties of the Bi 2 InNbO 7 photocatalyst was investigated. These photocatalysts crystallize in the same pyrochlore structure, but the lattice parameters decrease with decreasing M 3+ (M 3+ = Al 3+, Ga 3+, In 3+ ) ionic radii. The rates of H 2 and O 2 evolution from an aqueous methanol and cerium sulfate solution significantly increases with decreasing M 3+ ionic radii under UV irradiation. The Bi 2 AlNbO 7 photocatalyst exhibits much higher photocatalytic activity than the well-known TiO 2 photocatalyst.