A new heterojunction Ag3PO4/Cr-SrTiO3 photocatalyst towards efficient elimination of gaseous organic pollutants under visible light irradiation

摘要

A new heterojunction Ag3PO4/Cr-SrTiO3 was designed to eliminate the gaseous pollutants under visible light irradiation. The phase compositions, optical properties, and morphologies of the heterojunction photocatalysts were systematically investigated via powder X-ray diffraction, UV-Visible absorption spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The photodegradation of Isopropyl alcohol (1PA) was carried out to test the photocat-alytic activity of the heterojunction. The results revealed that the heterojunction exhibited considerably improved efficiency in IPA photodegradation (CO2,13.2 ppm h~(-1)) in comparison with pure Ag3PO4 (CO2, 0.4 ppmh~(-1)) and Cr-SrTiO3 (CO2, 1.9 ppm h~(-1)) under visible light irradiation. In addition, the effects of mixing ratio and calcination temperature of the heterojunction were studied. The highest activity was observed in the Ag3 PO4/Cr-SrTiO3 heterojunction with the mass ratio of 1:4 (Ag3 PO4 :Cr-SrTiO3) sintered at 500 °C. An investigation of energy-band structure via valence-band X-ray photoelectron spectrum indicates that the conduction band (CB) and valence band (VB) of Ag3PO4 are both more positive than that of Cr-SrTiO3, which facilitates the separation and transfer of photogenerated electrons and holes between the two photocatalysts.