Cobalt-doped cerium oxide nanoparticles: Enhanced photocatalytic activity under UV and visible light irradiation

Jayapalan Saranya, Kugalur Shanmugam Ranjith, Padmanaban Saravanan, Devanesan Mangalaraj, Ramasamy Thangavelu Rajendra Kumar

Research output: Contribution to journalArticlepeer-review

108 Scopus citations

Abstract

CeO2 nanoparticles (NPs) were synthesized by coprecipitation using cerium(III) nitrate hexahydrate as the precursor and ethanol as the solvent. Different concentration of cobalt-doped cerium oxide NPs (3mol % and 6 mol %) were prepared by adding various concentrations of cobalt chloride to cerium nitrate. The as-synthesized NPs were characterized through X-ray diffraction (XRD) measurements, ultraviolet (UV)-visible spectroscopy, Photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). XRD results reveal that the as-prepared CeO2 NPs had a face-centered cubic structure with crystallite size in the range of 5-8 nm. TEM analyses showed that the CeO2 NPs and Co-doped CeO2 NPs had a homogenous size distribution (sizes were within 5-12 nm). Band-edge absorption of CeO2 NPs redshifted upon increasing the Co concentration as compared to undoped CeO2 NPs. PL spectra reveal a peak shift of CeO2 emission upon cobalt doping, which were due to an increase in oxygen defects localized between the Ce4f and O2p energy levels (i.e., via formation of Ce3+ states). Photocatalytic degradation of methylene blue in aqueous solution under UV and visible (sunlight) irradiation in the presence of pure CeO2 NPs and of Co-doped CeO2 NPs was investigated. The efficiency of photocatalytic degradation of CeO2 NPs increased with the Co concentration both under UV irradiation and under visible light. Co-doped CeO2 NPs (6 mol%) showed degradation efficiencies of 98% and 89% at 420 min of exposure to UV irradiation and to visible light, respectively.

Original languageEnglish
Pages (from-to)218-224
Number of pages7
JournalMaterials Science in Semiconductor Processing
Volume26
Issue number1
DOIs
StatePublished - Oct 2014

Keywords

  • Cerium oxide
  • Cobalt-doped cerium oxide
  • Methylene blue
  • Photocatalytic activity

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