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Control of chemical state of cerium in doped anatase TiO

DOI: 10.1039/C5TA01474C DOI Help

Authors: Juliana Fonseca De Lima (University of Warwick) , Hilni Harunsani (University of Warwick) , David Martin (Department of Chemical Engineering, University College London) , Dan Kong (Department of Chemical Engineering, University College London) , Peter Dunne (University of Warwick) , Diego Gianolio (Diamond Light Source) , Reza J. Kashtiban (Department of Physics, University of Warwick) , Jeremy Sloan (Department of Physics, University of Warwick) , Osvaldo Serra (Department of Chemistry, FFCLRP) , Junwang Tang (Department of Physics, University of Warwick) , Richard Walton (University of Warwick)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Materials Chemistry A , VOL 3 (18) , PAGES 9890 - 9898

State: Published (Approved)
Published: March 2015
Diamond Proposal Number(s): 9741

Abstract: Solvothermal synthesis at 240 °C in ethanol from titanium(IV) isopropoxide and cerium(III) nitrate hexahydrate produces nanocrystalline powders of anatase-structured TiO2. At low Ce content (0.5 mol% Ti replaced by Ce) the materials contain mixtures of Ce3+ and Ce4+, seen from Ce LIII-edge X-ray absorption near-edge structure (XANES) spectroscopy, which are well dispersed in the anatase structure as evidenced from nanometre-scale electron energy loss spectroscopy maps and powder X-ray diffraction (XRD). The addition of lactic acid to the solvothermal reaction produces less crystalline samples, proved by powder XRD and Raman spectroscopy, with higher surface areas from nitrogen adsorption, and that contain a higher proportion of Ce3+. This leads to material with high activity for photocatalytic hydrogen production from water under UV irradiation in the presence of sacrificial methanol and Pt catalyst. Further in situ XANES experiments at the Ce LIII-edge recorded on heating the materials in air above 300 °C shows that oxidation to Ce4+ occurs. This process, typical of the conditions usually used in the synthesis of Ce-doped titania materials, yields materials with lower photocatalytic activity.

Subject Areas: Chemistry

Instruments: B18-Core EXAFS