Charge Transfer Dynamics and Their
Advisor : Dr. Yung-Jung Hsu
• Au-CdS Core−Shell Nanocrystals with Controllable Shell Thickness and
Photoinduced Charge Separation Property and Interfacial Charge Carrier
Dynamics Interfacial Charge Carrier Dynamics
• Au/ZnS Core/Shell Nanocrysals As an Eficient Anode Photocatalyst in
Direct Methanol Fuel Cells
• L-Cysteine-Assisted Growth of Core-Satellite ZnS-Au Nanoassembles with
Remarkable Photocatalytic Efficiency
• Know Thy Nano Neighbor. Plasmonic versus Electron Charging Effects of
Metal Nanoparticles in Dye-Sensitized Solar Cells
• Realizing Visible Photoactivity of Metal Nanoparticles. Excited State
Behavior and Electron Transfer Properties of Silver (Ag8) Clusters
Chem. Mater. 2008, 20, 7204–7206
J. Phys. Chem. C 2010, 114, 11414–11420
• Why metal/semiconductor hetrostructures?
Ultrafast charge transfer!
Long-live charge separation time!
[Wu et al., J. Am. Chem. Soc. 2012, 134, 10337]
[Costi et al., Nano lett. 2008, 8, 637]
1. Prevention of Chemical poisoning
2. Visible-Light-Driven Catalytic Activity
[V. Iliev, D. Tomova, L. Bilyarska, G. Tyuliev, J. Mol. Catal. A: Chem. 2007, 263, 32.]
[P. V. Kamat et. al., J. Phys. Chem. C 2007, 111, 2834.]
[J. Qi et. al., ACS nano 2011, 5, 7108.]
Synthesis of Au-CdS core-shell nanocrystals
• Tri-functional reagent, L-Cysteine (Cys):
- SH : complexing with Cd2+ (Cys/Cd)
- NH2 : coupling Cys/Cd with Au
- COOH : promoting the dispersion of Au
Theoretical calculation of SPR position for AuCdS :
[T. Hirakawa et. al., J. Am. Chem. Soc. 2005, 127, 3928.]
[G. Oldfield et. al., Adv. Mater. 2000, 12, 1519.]
[A. C. Templeton,et. al., J. Phys. Chem. B 2000, 104, 564.]
Excited state interaction studies
Au-CdS excited state interaction studies
Time-resolved PL spectra
Electron transfer rate constant , ket
(Au - CdS) -
Department of Materials Science and Engineering, National Chiao Tung
University, Hsinchu, Taiwan 30010, Republic of China.
Photo-assisted direct methanol fuel cell
Hole participates methanol oxidation reaction
Reduce precious metal usage by light irradiation!!
Efficient hole exaction process by coupling metal with semiconductor!!
Chem. Commun., 2013, 49, 8486-8488
TEM images of Au-ZnS core-shell nanocrystals
Effective degradation containment catalyst!
Convert to harmless form
Langmuir 2010, 26, 5918–5925
ZnS- Au + hν Au(e–)–ZnS(h+) (1)
Au(e–)–ZnS(h+) + TH ZnS(h+) + Au + TH. (colorless
ZnS(h+) + EtOH ZnS + EtOH.(3)
• The results show that the Au/CdS and ZnS core-shell structure
provides excellent oxidation reaction efficiency because the
electron-hole pathway results in oxidation(reduction)
reaction, rather than self-recombination.
• Reaction rate and electron transfer rate significantly enhances
increasing CdS shell thickness.
• Our study provides an alternative design for such photoassisted methanol oxidation applications, photocatalysis,
electron storage, nonvolatile memory device, etc.
Synthesis of Au-TiO2 and Au-SiO2 core-shell
Increasing n value by coating shell layer
Increasing Au core charge density
Dye-Sensitized Solar Cell by Incorporating with Au/TiO2 and Au/SiO2
I-V curve measurment
Current density (mA/cm 2)
TiO2 + N719
TiO2 + Au@TiO2 + N719
TiO2 + Au@SiO2 + N719
Dye-Sensitized Solar Cell Performance
Performances of DSSCs were measured with 0.18 cm2 working area under AM 1.5 illumination. Electrolyte: 0.6 M
Distinguish the role of core/shell nanocrystals in solar cell devices
By incorporating these Au core@oxide shell nanoparticles in the DSSC, we have succeeded in
identifying the influence of these effects.
The examples discussed in the presents study provides a convenient way to isolate the two
effects. The surface plasmon resonance effects increases the photocurrent of DSSC while the
charging effects leads to increase in photovoltage.
These observations opens up new opportunity to introduce both these paradigms and
synergetically enhance the photocurrent and photovoltage of DSSC.
Radiation Laboratory, Department of
Chemistry and Biochemistry, University of
Notre Dame, Notre Dame, Indiana 46556,
Clusters size larger than theory of Ag8 ?
Ag core/Ag8 Shell
Charge transfer between Ag8 and MV2+
Ag8 - MV2+ -light
Ag8 - MV2+ -dark
Formation of MV.+
e- transfer occurred
Ag8-MV2+ Interfacial charge transfer dynamics
Ag8 + MV2+
Formation of MV.+
• Ag8 cluster excited state electron transfer event have
• The photochemical activity established in the present study
offers another dimension to the fascinating properties of
small metal nanostructures.
• Basic understanding of excited state processes in fluorescent
metal clusters paves the way towards the development of
biological using and catalysts in energy conversion devices.
ket = 2.74 x 1010 s-1
h + h+
Those papers can be found in
Chemistry of Materials 2008, 20, 7204-7206
Journal of Physical Chemistry C 2009, 113, 17342-17346
Chem. Comm. 2013, 2013, 49, 8486-8488
Langmuir 2010, 26, 5918-5925
Journal of Physical Chemistry C 2010, 114,11414-11420
ACS Nano 2012, 6, 4418–4427
J. Phys. Chem. Lett. 2012, 3, 2493–2499