Visible light active La-doped Ag₃PO₄ for photocatalytic degradation of dyes and reduction of Cr(VI)

Silver phosphate (Ag₃PO₄) has attracted considerable attention as a promising visible light-active photocatalyst. Ag₃PO₄ and 1, 3, and 5% La-doped Ag₃PO₄ have been synthesized using a facile precipitation method. Powder X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and scanning electron microscopy (SEM) have been used to characterize the synthesized materials. Both Ag₃PO₄ and La-doped Ag₃PO₄ exhibited body centered cubic structure with no impurities as confirmed using XRD analysis. FTIR measurements of the synthesized materials showed the presence of phosphate and La–O groups. From the SEM images, Ag₃PO₄ has tetrapod particles that change to irregular particles upon La doping. The incorporation of La into the lattice also changes the band gap energy of Ag₃PO₄ which was confirmed by DRS. The synthesized materials were then tested for the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) under visible light irradiation. 1% La-doped Ag₃PO₄ was found to exhibit outstanding photocatalytic performance where it completely degrades MB and MO within 60 min. Additionally, it was also found that La-doped Ag₃PO₄ showed improved performance of Cr(VI) photoreduction under visible light irradiation compared to Ag₃PO₄.