Andersen, Mie

Nefedov, Alexei

Reuter, Karsten

Wang, Yuemin

Wöll, Christof

Yu, Xiaojuan

English

KITopen

Institute of Functional Interfaces (IFG)www.kit.eduKIT – The Research University  in the Helmholtz Association Xiaojuan Yu, Mie Andersen, Alexei Nefedov, Karsten Reuter, Christof Wöll and Yuemin WangIRRAS and DFT Investigations of Ultrathin ZnOFilms Formed on Ag(111)2“Surface Science” approach to heterogeneous catalysisProf. Gerhard ErtlThe Nobel Prize winner in Chemistry 2007Ø Fundamental understanding of nanostructured catalystsbased on comprehensive reference data acquired formodel systemsCu/CeO2 Nanoparticleswater on ZnO(10-10) single-crystal surfaces CO on ZnO thin filmsModel catalystsTheory Real catalysts3Metal oxide thin filmsH2COCO2 CH3OHcatalystCatalyst : Cu/ZnO/Al2O3 Catalyst : Cu/ZnO/Al2O3S. Kuld et al., Science. 2016, 352, 969.M. Behrens et al., Science. 2012, 336, 893.ZnO thin filmsS. Tusche et al., Phys. Rev. Lett. 2007, 99, 026102.C. L. Freeman et al., Phys. Rev. Lett. 2006, 96, 066102.wurtzitegraphiticIRRAS: ZnO/Cu(111)V. Schott, et al.,  Angew. Chemie, Int. Ed. 2013, 52, 11925 IRRAS: ZnO/Ag(111)M. Andersen, X. Yu, et al., J. Phys. Chem. C 2018, 122, 49634UHV-FTIR apparatus “THEO”Y. Wang, C. Wöll, Chem. Soc. Rev., 2017, 46, 1875.UHV-FTIR(Bruker Vertex 80v)Distribution chambersXPS, UPS and AES analyzer(VG Scienta R4000)Preparation chamberwith LEED, AES, TDSand effusion cellsAnalysis chamberPolarization-resolved IRRASon flat model catalystsTemperature-dependent and time-resolved transmission measurements on real catalystsØSingle crystalsØSupported thin filmsØNanoparticles5Y. Wang, C. Wöll, Chem. Soc. Rev., 2017, 46, 1875.Infrared reflection-absorption spectroscopy (IRRAS) incident IR light Single-crystal surfacepnEptEsEΔA# $ = −16πln 10cos θn12 − 1n2k2d2λΔA67 $ = −16πln 10cos θξ12 $n19 − cos2 θ− ξ12 $n19n2k2d2λΔA6: $ = −16πln 10cos θξ12 $n19 − cos2 θsin2 θn22 + k222n2k2d2λ0 20 40 60 80-0.03-0.02-0.010.00s-polarized Light incidence angle q (°) p-polarized qBx100TiO2(R0-Rs)x103(R0-Rs)x103MetalMetal oxide× 1 0Reflectivity difference [10-3 ]Reflectivity difference [10-5 ]Sensitivity: 1 ✕ 10-56ZnO/Ag(111): growth of ZnO thin films monitored by XPSM. Andersen, X. Yu, et al., J. Phys. Chem. C 122 (2018), 4963−4971.600 K300 K  540 535 530 525IntensityBinding energy (eV)O 1s530.2980 985 990 995 1000IntensityKinetic energy (eV)Zn L3M45M45989.2Zn2+992.4Zn0Increase of the surface Zn concentration due to the formation of ZnO thin filmsAgZnO thin layerGrazing angle ! = #$°7ZnO/Ag(111): growth of ZnO thin films monitored by XPSM. Andersen, X. Yu, et al., J. Phys. Chem. C 122 (2018), 4963−4971.600 K300 K  Increase of the surface Zn concentration due to the formation of ZnO thin filmsAgFigure S3. Grazing-emission (a) Zn 2p and (b) Ag 3d spectra recorded before (black curve) andafter oxidation of the AgZn(111) sample with O2 (1 x 10-3 mbar for 10 min) at 300 K (redcurve), 420 K (blue curve), 500 K (magenta curve) and 600 K (olive curve).1050 1040 1030 1020 1010 380 375 370 365 3602p1/21044.4 1021.4 2p3/2IntensityBinding energy (eV)Zn 2p3d3/2374.1368.13d5/2IntensityBinding energy (eV)Ag 3d (a) (b)Grazing angle ! = #$°ZnO thin layer8ZnO/Ag(111): thickness of ZnO thin filmsOxidation with O2 at 600K for 10 min: 1.9 Å (assuming graphitic-type ZnO)             1 ML20 min: 3.4 Å (assuming graphitic-type ZnO)             2 ML40 min: 4.4 Å (assuming graphitic-type ZnO) or 3.7 Å (assuming wurztite-type ZnO)3-4 MLS. V. Merzlinkin et al., Surf. Sci. 2008, 602, 755-767The atomic density of ZnOwurzite – 4.89 × 10-2 atoms/Å3, graphitic – 4.08 × 10-2 atoms/Å3. M. Andersen, X. Yu, et al., J. Phys. Chem. C 122 (2018), 4963−4971.F. Claeyssens et al., J. Mater. Chem. 2005, 15, 139-148.          C. L. Freeman et al., Phys. Rev. Lett. 2006, 96, 066102.92300 2200 2100 2000AbsorbanceWavenumber (cm-1)   CO-Zn2+   (island) 2138CO on ZnO/Ag(111), 65 K2x10-421212183CO-AgCO-Zn2+(thin layer) 2126non-polclean AgsubmonolayerAg(111)ZnO bilayerislandZn ZnOococ2138 cm-1 2183 cm-1Wurtzite ZnOoc 2138 cm-1ZnO thin layeroc 2138 cm-1ZnO thin layeroc oc2138 cm-1 2126 cm-1ZnO thin layerZnO/Ag(111): growth of ZnO thin films monitored by IRRASoc 2121 cm-1Ag(111)M. Andersen, X. Yu, et al., J. Phys. Chem. C 122 (2018), 4963−4971.102250 2200 2150 2100 20501x10-422022183 2138150 K130 K140 K120 K110 K95 K100 K90 K86 K82 K78 K74 K70 K66 KAbsorbanceWavenumber (cm-1)214660 80 100 120 140020406080100Relative Intensity (%)Temperature (K)2183-2202 cm-165 70 75 80 85 90 95100020406080100Relative Intensity (%)Temperature (K)2138-2146 cm-1BE: 0.30 eV(29 kJ/mol)BE: 0.24 eV(23 kJ/mol)ZnO/Ag(111): Temperature-dependent IRRAS dataM. Andersen, X. Yu, et al., J. Phys. Chem. C 122 (2018), 4963−4971.Ag(111)ZnO bilayerislandZn ZnOococ2138 cm-1 2183 cm-1Wurtzite ZnO11ZnO/Ag(111): growth of ZnO thin films calculated by DFTM. Andersen, X. Yu, et al., J. Phys. Chem. C 122 (2018), 4963−4971.DFT-optimized structures (top and side view) of CO adsorbed on (a) the wurtzite (10$10)surface, (b) the large (7×7)ZnO/(8×8)Ag structure. In (b) the dashed black circles highlightadsorption site I (shown structure) and II (empty circle).System Method)*+(eV),-*+(cm-1)ZnO(./0./) DFT 0.47 +37Exp. 0.32[1] +42[1](1×1)ZnO/(2×2)AgDFT: Site I 0.36 +5DFT: Site II 0.24 −3Exp. 0.24 +3)*+: CO adsorption energies,-*+: shift of the CO vibrational frequency withrespect to the gas phase value[1] Y. Wang, C. Wöll, Chem. Soc. Rev., 2017, 46, 1875.12Ø CO on wurtzite-type ZnO islands(2183-2202 cm-1)Binding energy : 0.30 eV (29 kJ/mol)• CO on ZnO(10$10)BE : 0.32 eV [1]• CO on ZnO(0001)BE : 0.28 eV [1]Ø CO on graphitic-like ZnO bilayer(2138-2146 cm-1)Binding energy : 0.24 eV (23 kJ/mol)n CO on ZnO/Cu(111) : corrugated bilayer2116 cm-1, BE : 0.54 eV [2]Comparison: different ZnO thin films monitored by IRRAS[1] Y. Wang, C. Wöll, Chem. Soc. Rev., 2017, 46, 1875.[2] V. Schott, et al.,  Angew. Chemie, Int. Ed. 2013, 52, 11925 Graphitic ZnOAgAg(111)ZnO bilayerislandZn ZnOWurtzite ZnOCorrugated ZnOCu13ConclusionsØ Metal support plays a crucial role in the chemicalactivity of ZnO thin layers.Ø CO on ZnO/Ag(111) (<2 ML, graphitic bilayer)n(C-O): 2146 cm-1; BE: 0.24 eVØ Weak interaction between ZnO thin layers and AgsubstrateØ CO on ZnO/Ag(111) (3-4 ML, wurtzite-like islands)n(C-O): 2183 cm-1; BE: 0.30 eVThank you for your attention!Ag(111)ZnO bilayerislandZn ZnOococ2138 cm-1 2183 cm-1Wurtzite ZnOAcknowledgementsThe China Scholarship Council (CSC)“Science and Technology of Nanosystems” Programme (432202)Deutsche Forschungsgemeinschaft (DFG)

IRRAS and DFT Investigations of Ultrathin ZnO Films Formed on Ag(111)

https://publikationen.bibliothek.kit.edu/1000089696/21734657

IRRAS and DFT Investigations of Ultrathin ZnO Films Formed on Ag(111)

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