Investigation of Rh-titanate (ATiO) interactions on high-surface-area perovskite thin films prepared by atomic layer deposition

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 33; pp. 16973 - 16984
• Main Authors: Lin, Chao, Foucher, Alexandre C, Ji, Yichen, Stach, Eric A, Gorte, Raymond J
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.09.2020
• Subjects: Atomic Layer Deposition (ALD); Atomic layer epitaxy; Barium titanates; BaTiO3; Calcium titanate; Carbon monoxide; Catalysts; Catalytic activity; CaTiO3; Chemical synthesis; CO oxidation; Deposition; Growth rate; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Oxidation; Perovskite structure; Perovskites; Reduction; Rh catalyst; Rhodium; SrTiO3; Strontium titanates; Thin films; X-ray diffraction; “Intelligent” catalyst
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta05981a

Thin, ∼1 nm films of CaTiO 3 , SrTiO 3 , and BaTiO 3 were deposited onto MgAl 2 O 4 by Atomic Layer Deposition (ALD) and studied as catalyst supports for Rh. Scanning Transmission Electron Microcopy (STEM) and X-Ray Diffraction (XRD) demonstrated that the films had the perovskite structure and formed uniform coatings stable up to 1073 K. Rh, added by ALD, interacted strongly with CaTiO 3 and somewhat less strongly with SrTiO 3 , while Rh on BaTiO 3 was similar to Rh on unmodified MgAl 2 O 4 . STEM measurements of Rh on CaTiO 3 films showed Rh remained well dispersed after repeated oxidations and reductions at 1073 K; however, the Rh was inactive for CO-oxidation. Rh formed small particles on SrTiO 3 films and was active for CO oxidation after reduction at 1073 K. The reducibility and catalytic activity of Rh/BaTiO 3 /MgAl 2 O 4 were similar to that of Rh/MgAl 2 O 4 . Evidence from CO-TPR, FTIR, and XPS all indicated that the degree of interaction between Rh and the three perovskite films can be ranked in the following order: Rh/CaTiO 3 /MgAl 2 O 4 > Rh/SrTiO 3 /MgAl 2 O 4 > Rh/BaTiO 3 /MgAl 2 O 4 . Bulk ex-solution catalysts, synthesized by reduction of ATi 0.98 Rh 0.02 O 3 (A = Ca, Sr, and Ba), were also examined for comparison. Thin, ∼1 nm films of CaTiO 3 , SrTiO 3 , and BaTiO 3 were deposited onto MgAl 2 O 4 by Atomic Layer Deposition (ALD) and studied as catalyst supports for Rh.