Monodisperse-porous cerium oxide microspheres carrying iridium oxide nanoparticles as a heterogeneous catalyst for water oxidation


HAMALOĞLU K. Ö. , Tosun R. B. , Kayi H., AKKAŞ KAVAKLI P. , KAVAKLI C. , Tuncel A.

APPLIED SURFACE SCIENCE, cilt.547, 2021 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 547
  • Basım Tarihi: 2021
  • Doi Numarası: 10.1016/j.apsusc.2021.149219
  • Dergi Adı: APPLIED SURFACE SCIENCE

Özet

Iridium oxide nanoparticle (IrO2 NP) decorated-monodisperse, porous CeO2 (IrO2@CeO2) microspheres were synthesized as a heterogeneous catalyst for chemical water oxidation with cerium ammonium nitrate (CAN) or sodium periodate (NaIO4) as the sacrificial agent. Before synthesis of the proposed catalyst, considerable oxygen evolution was observed using only plain CeO2 microspheres as the catalyst. Individual catalytic activity of plain CeO2 microspheres was explained by the formation of oxidative oxygen species due to the coexistence of Ce(III) and Ce(IV) ions on the surface as demonstrated by deconvoluted XPS analysis. Hence, CeO2 component of IrO2@CeO2 microspheres acted either support or active center. In other words, another active center, IrO2 NPs, was immobilized on the satisfactorily high surface area of porous CeO2 microspheres acted a support. IrO2@CeO2 microspheres with double catalytic active centers exhibited superior catalytic activity with respect to IrO2 NP decorated-porous SiO2 (IrO2@SiO2) microspheres due to the contribution coming from CeO2 microspheres. The maximum turnover number (TON) and turnover frequency (TOF) were obtained as 483 and 724 h(-1) using CAN. By using IrO2@CeO2 microspheres as the catalyst, no significant decrease occurred in the oxygen evolution in the repeated runs with NaIO4 as the oxidant while the oxygen evolution apparently decreased using CAN.Y