Formation, Phase Transition, Surface, and Catalytic Properties of Cubic ZrO2 Nanocrystals

abstract

ZrO2 is a relevant industrial and technological material with structure-dependent properties. The high-temperature tetragonal and cubic phases can be stabilized at room temperature through the incorporation of stabilizing cations. Tetragonal pure ZrO2 can additionally be stabilized by reducing the crystallite size to the nanoscale; however, stabilizing cubic pure ZrO2 at room temperature remains challenging. Here, cubic ZrO2 nanocrystals are synthesized by reacting a low concentration of ZrCl4 (0.025 mol L-1) with acetophenone. Pair distribution function and extended X-ray absorption fine structure analyses reveal that the local structure around the zirconium atoms is highly distorted relative to that of the ideal cubic. The structure can be modified by increasing the precursor concentration (up to 0.1 mol L-1), eventually leading to the formation of entirely monoclinic nanocrystals. The surface properties and catalytic behavior of cubic ZrO2 are investigated for establishing structure-property correlations and comparisons with the monoclinic phase. An optimized combination of activity, product yields, and recyclability in the multistep conversion of alpha-angelica lactone to gamma-valerolactone is achieved with small cubic ZrO2 particles of 2.3 +/- 0.4 nm size. Our results provide insights into the stabilization of cubic ZrO2 and phase transitions at room temperature and demonstrate the potential of cubic-type pure ZrO2 for catalytic applications.

keywords

X-RAY-ABSORPTION; ALPHA-ANGELICA LACTONE; TETRAGONAL ZIRCONIA; IN-SITU; TRANSFER HYDROGENATION; GAMMA-VALEROLACTONE; METHYL LEVULINATE; CO ADSORPTION; STABILIZATION; PURE

subject category

Chemistry; Materials Science

authors

Yao, XY; Antunes, MM; Buzanich, AG; Cabanelas, P; Valente, AA; Pinna, N; Russo, PA

Groups

G4 - Renewable Materials and Circular Economy

Projects

Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)

CICECO-Aveiro Institute of Materials R&D Unit Pluriannual Funding (CICECO-Aveiro Institute of Materials)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

acknowledgements

X.Y. acknowledges the fellowship from China Scholarship Council (CSC no. 202206220025). Christoph Erdmann is acknowledged for the transmission electron microscopy measurements. XAS experiments were performed at the BAMline at the BESSY-II storage ring (Helmholtz Centre Berlin). We thank the Helmholtz-Zentrum Berlin fur Materialien und Energie for the allocation of synchrotron radiation beamtime. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at P02.1 of PETRA-III, and we would like to thank Dr. Martin Aaskov Karlsen for assistance in using the photon beamline for PDF measurements. Beamtime was allocated for proposal I-20230735. Yanchen Liu is acknowledged for assistance with the PDF and XAS measurements. M.M.A., P.C., and A.A.V. acknowledge the project CICECO - Aveiro Institute of Materials, UID/50011/2025 & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), and Project FCT-2023.14213.PEX financed by national funds through the FCT/MCTES (PIDDAC). The position held by M.M.A. was funded by national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23 of the Decree-Law 57/2016 of 29 August, changed by Law 57/2017 of 19 July (10.54499/DL57/2016/CP1482/CT0062).