Solar-light-active silver phosphate/titanium dioxide/silica heterostructures for photocatalytic removal of organic dye

Abstract

A synergistic combination of surface adsorption capabilities and photocatalytic efficiency is crucial for the removal of pollutants from water. Here, the efficacy of such a process is explored through the assembly of a heterostructured photocatalyst (Ag3PO4/TiO2/SiO2) by loading silver phosphate (Ag3PO4) onto titanium dioxide (TiO2: P25)-coated silica (SiO2) felt. This heterostructure demonstrated an enhanced tendency to absorb light due to its significantly low band-gap energy of 2.5 eV. As such, it exhibited enhanced photocatalytic performance to efficiently degrade an organic dye (methylene blue) under solar-light irradiation (e.g., 30% and 10% relative to pristine P25 and P25-coated SiO2 felt, respectively). The maximum degradation efficiency for methylene blue was 99% with a first-order kinetic model (k = 0.39 min(-1)). The calculated quantum yield of Ag3PO4/TiO2/SiO2 (3.26 x 10(-3) molecules/photon) was significantly higher than that of other photocatalytic systems (e.g., similar to 3260 times other reported hetrostructures, e.g., rGO/TiO2, Ni-doped/TiO2, and Cds/CoFe2O4) with good reusability in terms of the degradation efficiency (e.g., 99% for the first cycle and 81% for the fourth). Ag3PO4/TiO2/SiO2 is therefore recommended for the efficient treatment of organic pollutants in wastewater systems.