Stabilization of ZrO2 Powders via ALD of CeO2 and ZrO2

Abstract

ZrO 2 powders were modified by atomic layer deposition (ALD) with CeO 2 and ZrO 2 , using Ce(TMHD) 4 and Zr(TMHD) 4 as the precursors, in order to determine the effect of ALD films on the structure, surface area, and catalytic properties of the ZrO 2 . Growth rates were measured gravimetrically and found to be 0.017 nm/cycle for CeO 2 and 0.031 nm/cycle for ZrO 2 . The addition of 20 ALD cycles of either CeO 2 or ZrO 2 was found to stabilize the surface area of the ZrO 2 powder following calcination to 1073 K and to suppress the tetragonal-to-monoclinic transition. Shrinkage of ZrO 2 wafers was also suppressed by the ALD films. When used as a support for Pd in CO oxidation, the CeO 2 -modified materials significantly enhanced rates due to interactions between the Pd and the CeO 2 . Potential applications for modifying catalyst supports using ALD are discussed.

A Thermodynamic Investigation of Ni on Thin-Film Titanates (ATiO3)

“…The evacuated samples were exposed to vapors from the precursors for approximately 10 min before purging excess precursor by evacuation. The precursors choices for the A-site cations were the same as one of the previous publications [17], bis(2,2,6,6-tetramethyl-3,5-heptanedionato) calcium (Ca(TMHD) 2 , Strem, Newburyport, MA, USA), bis(2,2,6,6-tetramethyl-3,5-heptanedionato) strontium hydrate (Sr(TMHD) 2 , Strem, USA), and bis(2,2,6,6-tetramethyl-3,5-heptanedionato) barium hydrate (Ba(TMHD) 2 , Strem, USA) were chosen for Ca, Sr, and Ba ALD processes, respectively, and the exposure was carried out at 573 K. Because the TMHD ligands can only be removed at elevated temperatures by air [26], the oxidation step of the ALD cycle for these precursors was performed by transferring the samples to a muffle furnace at 773 K for 5 min. For the TiO 2 -ALD process, Titanium chloride (TiCl 4 , Sigma-Aldrich, St. Louis, MO, USA) was chosen as the precursor.…”

Direct Hydrodeoxygenation of m-Cresol to Toluene over Bifunctional NbOx–Pt

“…The sample was then heated to 637 K while being exposed to a flowing steam of He in order to remove any weakly bound precursor and organic ligands. 24 It was then oxidized in air at 473 K for 30 min to oxidize the niobium. A single ALD cycle was used to produce the NbO x −Pt/C and NbO x /C catalysts used in this study.…”

Atomic Layer Deposition for Preparing Isolated Co Sites on SiO2 for Ethane Dehydrogenation Catalysis

“…The cobalt was deposited onto different supports by ALD using a home-built, static system that has been described in detail previously [23,24]. The ALD precursor was Co(TMHD) 3 (Strem Chemicals).…”