Catalytic activity of different sizes of Pt n /Co 3 O 4 in the oxidative degradation of Methylene Blue with H 2 O 2

Morena S. Xaba, Ji Hyang Noh, Reinout Meijboom

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

In this work, we demonstrate the catalytic activity and kinetic analyses of generation six poly(amido-amine) hydroxyl-terminated (PAMAM), G6-OH(Pt n ) (n = 55, 140, 225) dendrimer-encapsulated nanoparticles (DENs) immobilized onto mesoporous cobalt oxide (Co 3 O 4 ) for the catalytic oxidation of methylene blue (MB). Ultra-Violet Visible (UV–Vis) spectrophotometry showed the ligand to metal charge transfer (LMCT) band of metal precursor ions coordinated to the tertiary amines of the dendrimer. The size of fully reduced Pt DENs and supported Pt nanoparticles were investigated using High-Resolution Transmission Electron Microscopy (HR-TEM). The mesoporous Co 3 O 4 was synthesized by inverse micelle method, prior to Pt n DENs being supported on the Co 3 O 4 via wet impregnation procedure. The crystallite structure and size of Co 3 O 4 was investigated by powder X-ray diffraction (p-XRD) spectroscopy. Immobilized Pt n /Co 3 O 4 structural analysis was investigated for the pore size and pore volume using N 2 sorption techniques. Thermal gravimetric analyses (TGA) also indicated the dendrimer decomposition on the G6-OH(Pt n )/Co 3 O 4 materials to be 550 °C. Hydrogen temperature programmed reduction (H 2 -TPR) analyses were conducted and the reducibility of the supported cobalt oxide showed only one temperature peak that was ascribed to the reduction of surface lattice oxygens. The experimental kinetic data was analyzed and fitted to the Langmuir-Hinshelwood model using elementary first-order reaction kinetics and the thermodynamic parameters were calculated. Catalyst Pt 55 /Co 3 O 4 showed stability during the reusability investigation of up to 8 cycles. The G6-OH(Pt n ) were immobilized on silica and tested for catalytic oxidation of MB as a control experiment.

Original languageEnglish
Pages (from-to)868-880
Number of pages13
JournalApplied Surface Science
Volume467-468
DOIs
Publication statusPublished - 15 Feb 2019

Keywords

  • Catalysis
  • Galvanic exchange
  • Langmuir-Hinshelwood
  • Mesoporous Co O
  • Platinum DENs
  • Reaction kinetics

ASJC Scopus subject areas

  • General Chemistry
  • Condensed Matter Physics
  • General Physics and Astronomy
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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