The hydrothermal in situ construction of AgVO3/LaVO4 phase junctions for the efficient visible-light-driven disposal of pollutants and photoelectrocatalytic methanol oxidation

Abstract

The design and fabrication of heterojunctions has been proven to be a facile method for improving photocatalytic performance. Herein, in this work, a high performance photocatalyst based on AgVO₃/LaVO₄ was successfully synthesized via a one-step in situ hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL) spectra were used to characterize the structural and physicochemical characteristics. AgVO₃/LaVO₄ composites exhibited enhanced photocatalytic activity for the disposal of simulated pollutants (66% and 36% degradation rates for methyl orange and acid orange II) and superior photoelectrocatalytic oxidation of methanol compared with noble metal (Au, Ag and Pt) supported LaVO₄ and bare LaVO₄ photocatalysts (a lower Tafel slope of 24 mV dec⁻¹ and a higher peak current density of 0.22 mA cm⁻² over 2% β-AgVO₃/LaVO₄). This could be due to the introduction of β-AgVO₃ in the form of phase junctions, leading to enhanced light harvesting and the promoted separation and transfer of photogenerated electrons/holes pairs, which was proved using ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), and photoelectrochemical and time-resolved PL measurements. Density functional theory (DFT) calculations revealed that the interaction of β-AgVO₃ and LaVO₄ would enhance the optical absorption and electron transfer.