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

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 (IPA) was carried out to test the photocatalytic 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 ppm h−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 Ag3PO4/Cr-SrTiO3 heterojunction with the mass ratio of 1:4 (Ag3PO4: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.

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► A new photocatalyst Ag3PO4/Cr-SrTiO3 was successfully synthesized and characterized.
► High efficiency in IPA photodegradation was obtained under visible light irradiation.
► The mechanism relies on electron-transfer and a new chemical reaction process.
► Mass ratio and calcination temperature are important for constructing heterojunction.
► Proper band structures and well interfacial connection should be controlled.