Fabrication of ternary nano-heterojunction via hierarchical deposition of a-Fe2O3 and b-La2S3 on cubic CoCr2O4 for enhanced photodegradation of doxycycline

The current study offers the design of a novel photocatalyst for the effective removal of pharmaceuticals wherein the heterojunction was constructed with the objective of capturing maximum solar spectrum and to ensure effective separation of photogenerated charge carriers. The nano-heterojunction was fab-ricated through ultrasonication-assisted co-precipitation method by the hierarchical deposition of a- Fe2O3 and b-La2S3 on cubic CoCr2O4 spinel. The fabricated nanomaterials were extensively characterized by using XRD, Raman, FTIR, XPS, SEM, TEM, EDAX, PL, EIS, BET, and DRS. The photoluminescence and EIS analysis revealed the mitigated charge carrier recombination in CoCr2O4/a-Fe2O3/b-La2S3 (CFL) that resulted in superior photodegradation of doxycycline (DOX) (92.83 %) under visible light irradiation. Mineralization percentage of 92.5 % was affirmed by TOC analysis. Further, the influence of pH, ions, con-centration of DOX and CFL dosage on the photodegradation process was studied. The active participation of the reactive species involved in the reaction were identified by scavenging assay and ESR. Finally, a possible photocatalytic mechanism of CFL for the degradation of DOX with underlying pathway is pro-posed with the help of GC-MS/MS analysis. The study highlights the great promise of CFL photocatalyst as well as the potential of n-n-p heterojunction for appliances in the photodegradation of organic pollutants. (c) 2022 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The current study presents the design of a novel photocatalyst, which utilizes a heterojunction to capture a broad solar spectrum and effectively separate photogenerated charge carriers. A nano-heterojunction of a-Fe2O3 and b-La2S3 on cubic CoCr2O4 spinel was fabricated using ultrasonication-assisted co-precipitation method. Extensive characterization using various techniques confirmed the superior photodegradation performance of the CoCr2O4/a-Fe2O3/b-La2S3 (CFL) catalyst, achieving a 92.83% degradation of doxycycline (DOX) under visible light. The study also investigated the factors influencing the photodegradation process and proposed a possible photocatalytic mechanism of CFL for DOX degradation.