TiO2/BiVO4 Nanowire Heterostructure Photoanodes based on Type II ...
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TiO2/BiVO4 Nanowire Heterostructure Photoanodes based on Type II Band Alignment Joaquin Resasco1, Hao Zhang2, Nikolay Kornienko2, Nigel Becknell2, Hyunbok Lee3 Jinghua Guo4, Alejandro L. Briseno5, and Peidong Yang2,6,7* 1.Department of Chemical Engineering, and 2.Department of Chemistry, University of California, Berkeley, California 94720, United States. 3. Department of Physics, Kangwon National University, Chuncheon-si, Gangwon-do 200-701, South Korea. 4. Advanced Light Source Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States. 5.Department of Polymer Science & Engineering, Conte Polymer Research Center, University of Massachusetts, Amherst, Massachusetts 01003,United States. 6.Materials Sciences Division, and 7. Kavli Energy NanoSciences Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
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Table of contents: Supplementary Figures 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32.
Characterization of TiO2 nanowires Optimization of Ta2O5 ALD conditions X-ray photoelectron spectroscopy of Ta2O5 ALD films Characterization of TiO2|Ta2O5 core-shell nanowires X-ray diffraction of TiO2 and Ta:TiO2 nanowires Mott Schottky of Ta:TiO2 nanowires Statistics of BiVO4 particle sizes on Ta:TiO2 nanowires Statistics of BiVO4 particle sizes in thin films Characterization of BiVO4 thin films Effect of Ta doping on PEC performance Optimization of Ta doping for Ta:TiO2|BiVO4 PEC performance of TiO2|BiVO4 nanowire samples PEC performance of TiO2|BiVO4 nanowire samples under backside illumination PEC performance of Ta:TiO2|BiVO4 nanowire samples under backside illumination UV Vis spectrum and Tauc plot for BiVO4 thin films Effect of BiVO4 loading on PEC performance APCE data for Ta:TiO2|BiVO4 and Planar BiVO4 Mott-schotty plots at varying pH for TiO2 and BiVO4 PEC performance of BiVO4 thin films Tauc plot for BiVO4 thin films for an indirect transition UV Vis spectra and Tauc plots for TiO2 nanowires UV Vis spectra for TiO2 and Ta:TiO2 nanowires Band gap calculation using X-ray absorption and emission for TiO2 Band gap calculation using X-ray absorption and emission for BiVO4 Work function measurements for TiO2 and BiVO4 using Ar APXPS Valence band electronic structure of TiO2 and BiVO4 Ti L edge and O K edge X-ray absorption spectra of TiO2 V L edge and O K edge X-ray absorption spectra of BiVO4 X-ray emission spectra of BiVO4 and TiO2 Core-level XPS of BiVO4 and TiO2 Resonant Inelastic X-ray Scattering of BiVO4 Resonant Inelastic X-ray Scattering of TiO2
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Figure S1: (a) Cross--sectional SE EM of TiO2 nanowires (bb) HRTEM of TiO2 nannowires consistent with a sin ngle crystal rutile r TiO2 structure s and d c-axis grow wth directionn.
Figure S2 2: (a) Growtth rate per cycle c of Ta2O5 ALD film ms under inccreasing pulse time of thhe Ta precursorr. Saturation n was observ ved after 1.0 0 s. (b) Thicckness of Taa2O5 ALD fiilms measureed by ellipsomeetry as a fu unction of number n of cycles. c A liinear growthh rate of ~ ~0.6 Å/cyclee was observed d.
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Figure S3: (a) X-ray y photoelectrron spectrum m of Ta2O5 ALD thin ffilm depositeed on a Si w wafer g a 1 min Ar A sputter. Th he lack of orrganic contaamination signifies compplete substittution following of ligand ds by oxygen n from the H2O precursorr pulse.
Figure S4: S (a) Line scan of TiiO2|Ta2O5 core-shell naanowire showing a unifform Ta2O5 film coating th he high surfa face area nan nowires.
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Figure S5: S (a) X-R Ray Diffracction pattern ns of TiO2 nanowire samples bbefore and after incorporaation of Ta dopants. d Thee crystal stru ucture of thee nanowiress is unchanged by the dooping process.
hottky plots of various levels of Taa doping showing an inncrease in carrier Figure S6: Mott-Sch concentraation with in ncreased con ncentration of o Ta. S5
Figure S7 7: (a,b) Partticle size staatistics and representativve SEM imagge of Ta:TiO O2|BiVO4 saample with 100 0 nm Bi plan nar equivalen nt loading. Average A partticle sizes foor 25, 50, annd 100 nm pplanar equivalen nts are 45 nm m, 85 nm, an nd 148 nm, respectively. r Scale bar iss 500 nm.
nar vs nanow wire loadedd BiVO4. Thhe nanowire array Figure S8: (a) Particcle size statisstics for plan b) Representtative SEM iimage of a pplanar BiVO O4 sample wiith 40 prevents large particlle growth. (b g. Average particle sizes for nanowirre and planaar samples aare 72 nm Bi pllanar equivalent loading nm and 117 1 nm, resp pectively. Scale bar is 50 00 nm.
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Figure S9 9: (a) X-Ray y Diffraction n patterns off planar BiVO O4, showingg the diffracttion pattern oof the monoclin nic scheelite BiVO4 phasse.
S (a) Liinear sweep p voltammo ograms of T TiO2 and T Ta:TiO2 naanowire sam mples. Figure S10: Decreaseed activity fo or water oxiidation is ob bserved afterr Ta doping.. (b) IPCE ddata for TiO O2 and Ta:TiO2 nanowire saamples.
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Figure S11: (a) Lineear sweep voltammogra v ams of TiO2 and Ta:TiO O2 nanowiree samples looaded n BiVO4. An A optimum m in performaance is obserrved for 1% Ta doping. with 40 nm
Figure S12: S (a) Lin near sweep voltammogr v rams of TiO O2 and TiO2|BiVO4 sam mples. Decreeased activity for f water ox xidation is observed o afteer addition oof BiVO4, ppossibly due to poor eleectron transportt between TiO2 and BiVO O4.
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Figure S13: S (a) Lin near sweep voltammogrrams of TiO O2|BiVO4 samples undder frontsidee and backside illumination. Electron transfer fro om TiO2 to BiVO4 wouuld result inn higher bacckside photocurrrent as carriiers generateed in TiO2 near n the bacck electrode would be collected. Insstead, the frontsside current is much high her, indicatin ng electron ttransfer is frrom BiVO4 tto TiO2.
Figure S14: Linear sweep s voltam mmograms of 1% Ta:T TiO2|BiVO4 samples undder frontsidee and backside illumination n. At optimaal loading, performance p e is similar uunder frontsside and bacckside illuminattion. S9
Figure S15: S (a) Op ptical absorp ption and (b b) Tauc ploot of a BiV VO4 thin fillm depositeed on FTO/glasss assuming the optical band b gap of BiVO4 is a ddirect transittion.
s voltam mmograms of different loadings off BiVO4 on 1% Ta:TiO2. An Figure S16: Linear sweep m is observed d for 40 nm Bi. B optimum
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CE for Ta:TiiO2|BiVO4 samples s withh increasing loading. Hiigh APCE vvalues Figure S17: (a) APC Planar BiVO O4 shows hiigher APCE E than are obserrved for plaanar equivaleent thicknesss
TiO2/BiVO4 Nanowire Heterostructure Photoanodes based on Type II Band Alignment Joaquin Resasco1, Hao Zhang2, Nikolay Kornienko2, Nigel Becknell2, Hyunbok Lee3 Jinghua Guo4, Alejandro L. Briseno5, and Peidong Yang2,6,7* 1.Department of Chemical Engineering, and 2.Department of Chemistry, University of California, Berkeley, California 94720, United States. 3. Department of Physics, Kangwon National University, Chuncheon-si, Gangwon-do 200-701, South Korea. 4. Advanced Light Source Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States. 5.Department of Polymer Science & Engineering, Conte Polymer Research Center, University of Massachusetts, Amherst, Massachusetts 01003,United States. 6.Materials Sciences Division, and 7. Kavli Energy NanoSciences Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
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Table of contents: Supplementary Figures 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32.
Characterization of TiO2 nanowires Optimization of Ta2O5 ALD conditions X-ray photoelectron spectroscopy of Ta2O5 ALD films Characterization of TiO2|Ta2O5 core-shell nanowires X-ray diffraction of TiO2 and Ta:TiO2 nanowires Mott Schottky of Ta:TiO2 nanowires Statistics of BiVO4 particle sizes on Ta:TiO2 nanowires Statistics of BiVO4 particle sizes in thin films Characterization of BiVO4 thin films Effect of Ta doping on PEC performance Optimization of Ta doping for Ta:TiO2|BiVO4 PEC performance of TiO2|BiVO4 nanowire samples PEC performance of TiO2|BiVO4 nanowire samples under backside illumination PEC performance of Ta:TiO2|BiVO4 nanowire samples under backside illumination UV Vis spectrum and Tauc plot for BiVO4 thin films Effect of BiVO4 loading on PEC performance APCE data for Ta:TiO2|BiVO4 and Planar BiVO4 Mott-schotty plots at varying pH for TiO2 and BiVO4 PEC performance of BiVO4 thin films Tauc plot for BiVO4 thin films for an indirect transition UV Vis spectra and Tauc plots for TiO2 nanowires UV Vis spectra for TiO2 and Ta:TiO2 nanowires Band gap calculation using X-ray absorption and emission for TiO2 Band gap calculation using X-ray absorption and emission for BiVO4 Work function measurements for TiO2 and BiVO4 using Ar APXPS Valence band electronic structure of TiO2 and BiVO4 Ti L edge and O K edge X-ray absorption spectra of TiO2 V L edge and O K edge X-ray absorption spectra of BiVO4 X-ray emission spectra of BiVO4 and TiO2 Core-level XPS of BiVO4 and TiO2 Resonant Inelastic X-ray Scattering of BiVO4 Resonant Inelastic X-ray Scattering of TiO2
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Figure S1: (a) Cross--sectional SE EM of TiO2 nanowires (bb) HRTEM of TiO2 nannowires consistent with a sin ngle crystal rutile r TiO2 structure s and d c-axis grow wth directionn.
Figure S2 2: (a) Growtth rate per cycle c of Ta2O5 ALD film ms under inccreasing pulse time of thhe Ta precursorr. Saturation n was observ ved after 1.0 0 s. (b) Thicckness of Taa2O5 ALD fiilms measureed by ellipsomeetry as a fu unction of number n of cycles. c A liinear growthh rate of ~ ~0.6 Å/cyclee was observed d.
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Figure S3: (a) X-ray y photoelectrron spectrum m of Ta2O5 ALD thin ffilm depositeed on a Si w wafer g a 1 min Ar A sputter. Th he lack of orrganic contaamination signifies compplete substittution following of ligand ds by oxygen n from the H2O precursorr pulse.
Figure S4: S (a) Line scan of TiiO2|Ta2O5 core-shell naanowire showing a unifform Ta2O5 film coating th he high surfa face area nan nowires.
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Figure S5: S (a) X-R Ray Diffracction pattern ns of TiO2 nanowire samples bbefore and after incorporaation of Ta dopants. d Thee crystal stru ucture of thee nanowiress is unchanged by the dooping process.
hottky plots of various levels of Taa doping showing an inncrease in carrier Figure S6: Mott-Sch concentraation with in ncreased con ncentration of o Ta. S5
Figure S7 7: (a,b) Partticle size staatistics and representativve SEM imagge of Ta:TiO O2|BiVO4 saample with 100 0 nm Bi plan nar equivalen nt loading. Average A partticle sizes foor 25, 50, annd 100 nm pplanar equivalen nts are 45 nm m, 85 nm, an nd 148 nm, respectively. r Scale bar iss 500 nm.
nar vs nanow wire loadedd BiVO4. Thhe nanowire array Figure S8: (a) Particcle size statisstics for plan b) Representtative SEM iimage of a pplanar BiVO O4 sample wiith 40 prevents large particlle growth. (b g. Average particle sizes for nanowirre and planaar samples aare 72 nm Bi pllanar equivalent loading nm and 117 1 nm, resp pectively. Scale bar is 50 00 nm.
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Figure S9 9: (a) X-Ray y Diffraction n patterns off planar BiVO O4, showingg the diffracttion pattern oof the monoclin nic scheelite BiVO4 phasse.
S (a) Liinear sweep p voltammo ograms of T TiO2 and T Ta:TiO2 naanowire sam mples. Figure S10: Decreaseed activity fo or water oxiidation is ob bserved afterr Ta doping.. (b) IPCE ddata for TiO O2 and Ta:TiO2 nanowire saamples.
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Figure S11: (a) Lineear sweep voltammogra v ams of TiO2 and Ta:TiO O2 nanowiree samples looaded n BiVO4. An A optimum m in performaance is obserrved for 1% Ta doping. with 40 nm
Figure S12: S (a) Lin near sweep voltammogr v rams of TiO O2 and TiO2|BiVO4 sam mples. Decreeased activity for f water ox xidation is observed o afteer addition oof BiVO4, ppossibly due to poor eleectron transportt between TiO2 and BiVO O4.
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Figure S13: S (a) Lin near sweep voltammogrrams of TiO O2|BiVO4 samples undder frontsidee and backside illumination. Electron transfer fro om TiO2 to BiVO4 wouuld result inn higher bacckside photocurrrent as carriiers generateed in TiO2 near n the bacck electrode would be collected. Insstead, the frontsside current is much high her, indicatin ng electron ttransfer is frrom BiVO4 tto TiO2.
Figure S14: Linear sweep s voltam mmograms of 1% Ta:T TiO2|BiVO4 samples undder frontsidee and backside illumination n. At optimaal loading, performance p e is similar uunder frontsside and bacckside illuminattion. S9
Figure S15: S (a) Op ptical absorp ption and (b b) Tauc ploot of a BiV VO4 thin fillm depositeed on FTO/glasss assuming the optical band b gap of BiVO4 is a ddirect transittion.
s voltam mmograms of different loadings off BiVO4 on 1% Ta:TiO2. An Figure S16: Linear sweep m is observed d for 40 nm Bi. B optimum
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CE for Ta:TiiO2|BiVO4 samples s withh increasing loading. Hiigh APCE vvalues Figure S17: (a) APC Planar BiVO O4 shows hiigher APCE E than are obserrved for plaanar equivaleent thicknesss
