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

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 (${\mathrm{O}}_2^{\bullet -}$). Finally, a photocatalytic mechanism is proposed based on the spectroscopic data and reference reactions using sacrificial agents to identify the predominant active species.

KEYWORDS:

• Carbon nitride
• silver phosphate
• Z-scheme photocatalyst
• heterojunction
• organic pollutants
• dye

Acknowledgments

Financial support from the French National Research Agency(ANR) under the Program “Make Our Planet Great Again” (ANR-18-MOPGA-0014) and the Democritus University of Thrace (project 82268) is fully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Democritus University of Thrace [82268].