Sequential ionic layer adsorption reaction formation of LaVO4–TiO2 nanocomposites for photocatalytic water treatment

Abstract

Lanthanum vanadate (LaVO₄) has been successfully deposited as a thin conformal layer onto the surface of P25 TiO₂ particles immobilized on the surface of macroscopic glass beads. Using a simple sequential ionic layer adsorption reaction (SILAR) method, the LaVO₄ layer is deposited in situ with good control over the loading. Both the prepared composites and individual LaVO₄ and TiO₂ materials have been thoroughly characterized by X-ray diffraction, electron microscopies, X-ray photoelectron spectroscopy. The coated bead samples have been applied in the photocatalytic degradation of the model organic pollutant 4-chlorophenol, with the optimal LaVO₄ loading displaying ∼3× higher degradation of the pollutant than the pristine P25 sample. Using electrochemical and spectroscopic methods, band energies for both materials and the composite have been determined, and a provisional mechanism for degradation proposed upon the basis of this band alignment and upon scavenging experiments.