G-C3N4/Ag3PO4 based binary and ternary heterojunction for improved photocatalytic removal of organic pollutants

Abstract

ABSTRACT Ag3PO4 (AP) was effectively coupled with bare and modified graphitic carbon nitride through a facile wet-chemistry process for the development of hybrid organic/inorganic heterojunctions. The prepared materials were thoroughly characterised using a multimethodology approach including XRD, IR, DR-UV-Vis, nitrogen adsorption/desorption isotherms, photoluminescence and EPR spectroscopy. The photoactive hybrid materials were applied as photocatalysts for the degradation of organic pollutants, namely rhodamine B (RhB), under pure visible light irradiation. The prepared nanocomposites were proven stable under working conditions and more active than their individual counterparts. The study highlighted the importance of CN modification and the development of preformed Ag nanoparticles in photoactivity. The enhanced activity is attributed to the improved charge separation efficiency as evidenced by PL due to the formation of a heterojunction. In-situ EPR spin-trap experiments provide direct evidence for the formation of a Z-scheme heterojunction through the detection of superoxide anion radicals (). Finally, a photocatalytic mechanism is proposed based on the spectroscopic data and reference reactions using sacrificial agents to identify the predominant active species.