1 research outputs found
Reduction and Diffusion of Cr-Oxide Layers into P25, BaLa<sub>4</sub>Ti<sub>4</sub>O<sub>15</sub>, and Al:SrTiO<sub>3</sub> Particles upon High-Temperature Annealing
Chromium
oxide (Cr2O3) is a beneficial metal
oxide used to prevent the backward reaction in photocatalytic water
splitting. The present work investigates the stability, oxidation
state, and the bulk and surface electronic structure of Cr-oxide photodeposited
onto P25, BaLa4Ti4O15, and Al:SrTiO3 particles as a function of the annealing process. The oxidation
state of the Cr-oxide layer as deposited is found to be Cr2O3 on the surface of P25 and Al:SrTiO3 particles
and Cr(OH)3 on BaLa4Ti4O15. After annealing at 600 °C, for P25 (a mixture of rutile and
anatase TiO2), the Cr2O3 layer diffuses
into the anatase phase but remains at the surface of the rutile phase.
For BaLa4Ti4O15, Cr(OH)3 converts to Cr2O3 upon annealing and diffuses
slightly into the particles. However, for Al:SrTiO3, the
Cr2O3 remains stable at the surface of the particles.
The diffusion here is due to the strong metal–support interaction
effect. In addition, some of the Cr2O3 on the
P25, BaLa4Ti4O15, and Al:SrTiO3 particles is reduced to metallic Cr after annealing. The
effect of Cr2O3 formation and diffusion into
the bulk on the surface and bulk band gaps is investigated with electronic
spectroscopy, electron diffraction, DRS, and high-resolution imaging.
The implications of the stability and diffusion of Cr2O3 for photocatalytic water splitting are discussed