Enhanced Photodegradation of Antibiotics and Antimicrobial Activity by a g-C<sub>3</sub>N<sub>4</sub>/g-C<sub>3</sub>N<sub>5</sub> Nanosheet Heterojunction Photocatalyst
Aslisha Champati, Pratyush Kumar Sahu, Alaka Rath, Brundabana Naik, Abanti Pradhan
Abstract
High Resolution Image Download MS PowerPoint Slide An organic C–N polymeric nanocomposite, g-C 3 N 4 /g-C 3 N 5 sheet (ECN45), was designed through thermal polymerization, followed by KBr-assisted exfoliation, to investigate its potential as a photocatalyst for the photodegradation of organic antibiotic pollutants and antimicrobial activities. Graphitic carbon nitride (g-C 3 N 4 ) is a 2D material recognized as a highly promising photocatalyst; however, it possesses an elevated frequency of photogenerated electron–hole pair recombination and a constricted absorption range for visible light of up to 450 nm. Therefore, the formation of a heterojunction of 1D g-C 3 N 5 upon g-C 3 N 4 can minimize the charge recombination of g-C 3 N 4 . Furthermore, due to a lack of sufficient surface activation, the bulk composite (BCN45) was exposed to KBr exfoliation, resulting in a g-C 3 N 4 /g-C 3 N 5 sheet (ECN45). The 1D/2D hybrid catalyst exhibits a reduction in band gap of up to 1.81 eV due to the presence of azo linkages and π-conjugated bonds compared to its pristine elements. The nanocomposite shows a red shift toward the visible light spectrum compared to its pristine forms. The morphological, spectroscopic, and physicochemical investigations of the nanocomposite are confirmed by TEM, SEM-EDX, BET, XRD, UVDRS, FTIR, XPS, PL, and electrochemical analysis techniques. The photocatalytic application is shown by the composite for degrading the antibiotic CIP (ciprofloxacin) for about 93.1% at an acidic environment of pH 3 at its lowest concentration of 10 mg L –1 in 120 min. Further, the catalyst is examined to show antimicrobial action against Gram-negative bacteria Escherichia coli ( E. coli ) and Gram-positive bacteria Staphylococcus aureus ( S. aureus ) with the help of the inhibition zone test, MIC (minimum inhibition concentration), and photocatalytic cellular leakage of the microbial body. Also, the plausible Z-scheme mechanisms exhibited by the formed 2D/1D heterostructure for CIP degradation and antimicrobial activity are explained. The enhanced photoactivity is attributed to the synergistic effects of 1D/2D hybrid nanostructure, extended conjugation leading to enriched light harvesting, and Z-scheme heterojunction for better photogenerated charge separation. This approach makes grounds to establish an effective metal-free composite showing efficient photocatalytic activity.