TY - JOUR

T1 - ZnO Nanoparticle Formation from the Molecular Precursor [MeZnOtBu]4by Ozone Treatment in Ionic Liquids

T2 - in-situ Vibrational Spectroscopy in an Ultrahigh Vacuum Environment

AU - Bauer, Tanja

AU - Voggenreiter, Markus

AU - Xu, Tao

AU - Wähler, Tobias

AU - Agel, Friederike

AU - Pohako-Esko, Kaija

AU - Schulz, Peter

AU - Döpper, Tibor

AU - Görling, Andreas

AU - Polarz, Sebastian

AU - Wasserscheid, Peter

AU - Libuda, Jörg

N1 - Funding Information: This project was financially supported by the Deutsche Forschungsgemeinschaft (DFG) within the SPP 1708 “Material Synthesis near Room Temperature”. The authors acknowledge further support within the Excellence Cluster “Engineering of Advanced Materials” in the framework of the excellence initiative and by the Clariant AG. T.B. gratefully acknowledges financial support from the Fonds der Chemischen Industrie.

PY - 2017/1/30

Y1 - 2017/1/30

N2 - As reported previously, novel ZnO nanostructures can be grown by oxidation of [MeZnOtBu]4“building blocks” with O3in ionic liquids (ILs). In this study, we have explored the role of the IL during ZnO formation by in-situ infrared reflection absorption spectroscopy (IRAS) in ultrahigh vacuum (UHV). [MeZnOtBu]4and [C2C1Im][OTf] were (co-)deposited as thin films by physical vapor deposition (PVD) onto Au(111), separately or simultaneously. The IR spectrum of [MeZnOtBu]4was analyzed between 300 and 4000 cm–1based on calculated spectra from density-functional theory (DFT). Spectral changes in the IL-related bands during the thermal treatment of [MeZnOtBu]4in [C2C1Im][OTf] indicate the loss of the precursor ligands and the interaction of the IL with the growing ZnO aggregates. The films were treated with ozone (10–6mbar) in UHV and the spectral changes were monitored in-situ by IRAS. Slow ozonolysis of [C2C1Im][OTf] is observed. Spectroscopically we identify the primary ozonide formed by addition of O3to [C2C1Im]+and suggest a reaction mechanism, which leads to a biuret derivative. Upon ozone treatment of mixed [MeZnOtBu]4/[C2C1Im][OTf] films, ZnO aggregates are formed at the IL/vacuum interface. Ozonolysis of [C2C1Im][OTf] is suppressed. Upon annealing to 320 K, further ZnO aggregates are formed, leading to enclosure of [C2C1Im][OTf] in the ZnO film. At 380 K the IL is released from the mixed film. The pure [C2C1Im][OTf] desorbs at 420 K, leaving behind the ZnO phase.

AB - As reported previously, novel ZnO nanostructures can be grown by oxidation of [MeZnOtBu]4“building blocks” with O3in ionic liquids (ILs). In this study, we have explored the role of the IL during ZnO formation by in-situ infrared reflection absorption spectroscopy (IRAS) in ultrahigh vacuum (UHV). [MeZnOtBu]4and [C2C1Im][OTf] were (co-)deposited as thin films by physical vapor deposition (PVD) onto Au(111), separately or simultaneously. The IR spectrum of [MeZnOtBu]4was analyzed between 300 and 4000 cm–1based on calculated spectra from density-functional theory (DFT). Spectral changes in the IL-related bands during the thermal treatment of [MeZnOtBu]4in [C2C1Im][OTf] indicate the loss of the precursor ligands and the interaction of the IL with the growing ZnO aggregates. The films were treated with ozone (10–6mbar) in UHV and the spectral changes were monitored in-situ by IRAS. Slow ozonolysis of [C2C1Im][OTf] is observed. Spectroscopically we identify the primary ozonide formed by addition of O3to [C2C1Im]+and suggest a reaction mechanism, which leads to a biuret derivative. Upon ozone treatment of mixed [MeZnOtBu]4/[C2C1Im][OTf] films, ZnO aggregates are formed at the IL/vacuum interface. Ozonolysis of [C2C1Im][OTf] is suppressed. Upon annealing to 320 K, further ZnO aggregates are formed, leading to enclosure of [C2C1Im][OTf] in the ZnO film. At 380 K the IL is released from the mixed film. The pure [C2C1Im][OTf] desorbs at 420 K, leaving behind the ZnO phase.

KW - Ionic liquid; Ozone; IR spectroscopy; ZnO nanoparticles; Surface science

UR - http://www.scopus.com/inward/record.url?scp=85006365132&partnerID=8YFLogxK

U2 - 10.1002/zaac.201600345

DO - 10.1002/zaac.201600345

M3 - Article

AN - SCOPUS:85006365132

VL - 643

SP - 31

EP - 40

JO - Zeitschrift fur Anorganische und Allgemeine Chemie

JF - Zeitschrift fur Anorganische und Allgemeine Chemie

SN - 0044-2313

IS - 1

ER -