The role of size-controlled CeO2 nanoparticles in enhancing the stability and photocatalytic performance of ZnO in natural sunlight exposure

Mohammad Aslam; Muhammad Tariq Qamar; Muhammad Tahir Soomro; Ekram Y Danish; Iqbal M I Ismail; Abdul Hameed

doi:10.1016/j.chemosphere.2021.133092

The role of size-controlled CeO₂ nanoparticles in enhancing the stability and photocatalytic performance of ZnO in natural sunlight exposure

Chemosphere. 2022 Feb:289:133092. doi: 10.1016/j.chemosphere.2021.133092. Epub 2021 Nov 29.

Authors

Mohammad Aslam¹, Muhammad Tariq Qamar², Muhammad Tahir Soomro³, Ekram Y Danish⁴, Iqbal M I Ismail⁵, Abdul Hameed⁶

Affiliations

¹ Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia. Electronic address: aslam312@gmail.com.
² Department of Chemistry, Forman Christian College (A Chartered University), Ferozepur Road, Lahore, 54600, Pakistan.
³ Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia.
⁴ Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.
⁵ Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia; Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah, 21589, Saudi Arabia.
⁶ Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, 21589, Saudi Arabia; National Centre for Physics, Quaid-e-Azam University, Islamabad, 44000, Pakistan. Electronic address: ahfmuhammad@gmail.com.

PMID: 34856239
DOI: 10.1016/j.chemosphere.2021.133092

Abstract

In order to enhance the photocatalytic performance and stability, the various proportions of the size controlled cerium oxide (CeO₂) nanoparticles were dispersed at the pre-synthesized ZnO. Although, the expected dual absorption onsets, probably due to the diminutive difference between the bandgaps of CeO₂ (∼2.9 eV) and ZnO (∼3.1 eV), were not observed however, a blue shift in the bandgap energy of ZnO was witnessed with the increasing surface density of CeO₂ particles. The delayed excitons recombination process with the increasing concentration of CeO₂ nanoparticles was verified by the PL spectra. The structural investigation by Raman and XRD analysis revealed the surface attachment of CeO₂ particles without altering the rock-salt lattice of ZnO. The morphological and fine microstructural analysis established the uniform distribution of evenly sized CeO₂ particles at the surface of ZnO with the discrete fringe patterns of both the entities whereas the XPS analysis confirmed the majority of Ce⁴⁺ in dispersed CeO₂. In comparison to pure ZnO, cyclic voltammetric (CV) analysis, under illumination, exposed the supportive role of surface residing CeO₂ particles in eradicating the photo-corrosion of ZnO whereas the chronopotentiometry (CP) predicted the prolonged life-span of the excitons. Compared to pure ZnO, an appreciably high activity was revealed for 10% CeO₂ loading as compared to pure ZnO for the removal of mono and di-nitrophenol derivatives and their mixtures under natural sunlight exposure. The variations in the removal rates in the mixture as compared to individual nitrophenol exposed the structure-based priority of ROS for the respective phenol. The significantly enhanced photocatalytic activity of the composite catalysts revealed the incremental role of surface-mounted CeO₂ entities in boosting the generation of ROS under sunlight irradiation. The experimental observations were correlated and compiled to establish the mechanism of the removal process.

Keywords: CeO(2) dispersed ZnO; Degradation; Dinitrophenols; Monochlorophenols; Mononitrophenols; Natural sunlight.

MeSH terms

Catalysis
Nanoparticles*
Sunlight
Zinc Oxide*

Substances

Zinc Oxide