Facile synthesis of porous Bi2O3-BiVO4 p-n heterojunction composite microrods with highly efficient photocatalytic degradation of phenol

In the present work, high-quality porous Bi2O3-BiVO4 composite 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-BiVO4 precursors were first synthesized using Na2C2O4 and NaVO3 as starting materials and then thermally decomposed to produce porous Bi2O3-BiVO4 p-n heterojunction CMRs. The as-prepared Bi2O3-BiVO4 product 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 BiVO4 and Bi2O3, and 192 and 160 times higher than pure BiVO4 and Bi2O3, respectively. A direct Z-scheme mechanism was employed to describe the transfer of photogenerated electrons and holes in the Bi2O3-BiVO4 CMR 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.