In situ synthesis of α-β phase heterojunction on Bi₂O₃ nanowires with exceptional visible-light photocatalytic performance

Visible-light-responsive α-β phase heterojunction on Bi₂O₃ nanowire photocatalysts were prepared via a facile in situ hydrothermal process in assistance with the post-heat treatment route. The as-prepared samples were characterized by X-ray diffraction (XRD), electron microscope (EM), Brunauer-Emmett-Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance absorption spectra (UV-vis). XRD patterns revealed that the α-β phase heterojunction over Bi₂O₃ composites with the monoclinic α-Bi₂O₃ and the tetragonal β-Bi₂O₃ structure were obtained and the relative ratios between α-Bi₂O₃ and β-Bi₂O₃ can readily be tailored by the control of the reaction temperature. Within the hydrothermal temperature range, the morphology of as-prepared samples transformed progressively from two-dimensional β-Bi₂O₃ sheets to the α-/β-Bi₂O₃ nanowires junction. The exceptional photocatalytic performance of α-/β-Bi₂O₃ heterojunction for the degradation of cationic rhodamine B and anionic methyl orange under visible-light irradiation is superior over that of β-Bi₂O₃ sheets, which is ascribed to the efficient charge separation and transfer across the α-β phase junction. The phase-junction approach will open new avenues for the development of efficient photocatalysts for environmental remediation and energy conversion.