Facile synthesis of porous Bi₂O₃-BiVO₄p-n heterojunction composite microrods with highly efficient photocatalytic degradation of phenol

In the present work, high-quality porous Bi₂O₃-BiVO₄composite microrods (CMRs) with a uniform size distribution have been successfully prepared through a facile solvothermal method followed by an annealing treatment, in which Bi(OH)C₂O₄-BiVO₄precursors were first synthesized using Na₂C₂O₄and NaVO₃as starting materials and then thermally decomposed to produce porous Bi₂O₃-BiVO₄p-n heterojunction CMRs. The as-prepared Bi₂O₃-BiVO₄product was characterized by UV–Vis diffuse reflectance spectroscopy (DRS) and valence-band X-ray photoelectron spectroscopy (XPS). Significantly enhanced photocatalytic activity in degrading colorless organic phenol under visible-light illumination (λ > 420 nm) was observed with the porous CMRs, more than 48 times higher than that of the mixture of BiVO₄and Bi₂O₃, and 192 and 160 times higher than pure BiVO₄and Bi₂O₃, respectively. A direct Z-scheme mechanism was employed to describe the transfer of photogenerated electrons and holes in the Bi₂O₃-BiVO₄CMR system, and the dramatically enhancement of the observed photoactivity may be attributed to the high separation efficiency of electron-hole pairs, resulting from the p-n heterojunction formed in the porous structure.