Sustainable one-pot synthesis of strontium phosphate nanoparticles with effective charge carriers for the photocatalytic degradation of carcinogenic naphthylamine derivative

Abstract

In this work, a sustainable one-pot precipitation method was applied for synthesizing strontium phosphate nanoparticles (SrPO NPs), which can be utilized as effective charge separation photocatalysts for the degradation of oncogenic naphthylamine derivatives (congo red). Significant photocatalytic activity of SrPO NPs corresponding to the lowest optical band gap energy of 2.19 eV was calculated by the Tauc plot. The synthesized SrPO NPs belong to the orthorhombic Pnam E crystalline system in which phosphate groups are linked to strontium ions with an average size of 14 nm. The uniform formation of nanoflake-like morphology was analyzed by FE-SEM and HR-TEM techniques. Enhanced photodegradation owing to superior charge separation and interfacial charge transport resistance was confirmed by EIS analysis. The SrPO NPs photocatalyst achieved 98% degradation efficiency under visible light within a short span of time under optimal conditions. The rate constant K = 0.0892 × 10⁻¹ evidently proved that the photodegradation of CR obeys pseudo-first-order reaction kinetics. ROS involved in photodegradation, analyzed by various radical scavengers confirm the involvement of hydroxyl and superoxide radicals during degradation. Finally, the reusability after five consecutive measurements demonstrates that SrPO NPs are excellent and suitable photocatalysts for the detoxification of the anionic azo derivative congo red.