On the origin of the photocatalytic activity improvement of BIVO4 through rare earth tridoping

• We have obtained a rare-earth highly doped t-BiVO4 photoactive material.
• Dopant ions occupy the Bi3+ sites in BiVO4 structure and induce cell contraction.
• The more packed tetragonal structure would favor charge pairs diffusion.
• A cooperative luminescence mechanism is also involved.
• Photoactivity is improved under UV, visible and NIR irradiation.

Rare earth (Tm3+/Er3+,Yb3+,Y3+) tri-doped BiVO4 have been synthesized by means of a surfactant free hydrothermal method having good photoactivities under sun-like excitation for the degradation of methylene blue and O2 evolution reactions. The improved photocatalytic performance has been attained by multiple approach of the overall photocatalytic mechanism. From the structural and morphological characterization it has been stated that the presence of Y3+ induces the stabilization of the tetragonal phase probably due to its substitutional incorporation in the BiVO4 lattice. Moreover, the extensive doping with rare earth ions such as Yb3+ and Er3+/Tm3+ t-BiVO4 evidenced that important structural, electronic changes as well as the luminescence properties were also exalted. Ternary doping clearly prompts the higher photocatalytic activities. A more packed tetragonal structure in conjunction leading to improved charge carriers mobility, with the observed visible and NIR photoactivities of t-BiVO4 could be the responsible of the improved photocatalytic activity under solar-like irradiation.

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