Through Space Sigma Donation pi Acceptor Assisted Photocatalytic Degradation of Ciprofloxacin on TCPP Supported g-C3N4

摘要

Photocatalysis on pristine g-C3N4 (CN) often suffers from fast recombination of photogenerated electrons and holes. Herein, we demonstrate the superior photocatalytic performance of free base tetrakis(4-carboxyphenyl) porphyrin (TCPP) - g-C3N4 (CN/TCPP) hybrids synthesised by a facile ultrasound aided impregnation. Structural and morphological characterisation confirmed the successful formation of the hybrid via noncovalent pi-pi stacking. Optical/electrochemical characterisation, as well as DFT study, designates the shifting of the optical absorption edge to visible range along with inhibition of carrier recombination through enhanced charge transfer. The CN/TCPP hybrids exhibited superior performance towards the degradation of persistent antibiotic ciprofloxacin under visible irradiation signifying its enhanced visible light sensitivity. The enhanced photocatalytic activity of CN/TCPP is ascribed to the charge transfer by through-space conjugation by migration of electrons and holes in opposite directions, which minimises the possibility of electron-hole recombination. From the LCMS data, scavenging studies, and first principles DFT analysis, the photodegradation of CIP is proposed to proceed via the destruction of the piperazine ring initiated mainly through the electrophilic attack by the holes.