Transcript
Operando Soft X ray Spectroscopy of
Nanoparticulate Hematite Film
Using UHV Electrochemical Flow Cell
Dr. Debajeet K. BORA, Laboratory for High Performance Ceramics
Empa. Swiss Federal Laboratories for Materials Science & Technology, 8600
Dubendorf, Switzerland
1
• Jinghua Guo , ALS, LBNL
• Artur Braun, Empa
• Per – Anders Glans, ALS, LBNL
• AXIS group members, ALS
• ALS support groups members, LBNL
• Dunwei Wang, Boston College
• Chun Du, Boston College
• Juan Valesco Valez, MSD, LBNL
LDRD: Soft X-Ray Spectroscopy for In-situ ElectronicStructure Study of Artificial Photosynthesis
Acknowledgements
2
Outline
• Motivation
• Introduction
• How the operando spectroscopy helps in finding the role of electron hole in PEC system – a brief overview
• Snapshots of in – situ advanced absorption chember – BL 6.3.1.2, ALS, LBNL
• First generation electrochemical flow cell
• How we can make a sustainable operando condition
Answer : Deisgn of new In-Situ Electrochemical Flow cell
• In-Situ XAS study on nanoparticulate n- type hematite film
deposited with Atomic Layer deposition
• O K and Fe L edge NEXAFS spectroscopy – hematite electronic structure during photoelectrochemical condition
• Conclusion 3
Motivation
• To study the electronic structure of nanoparticulate
hematite under artificial photosynthetic condition
• How we can employ electrochemistry inside the soft X ray
absorption chamber
• Focus is to built an in - situ electrochemical flow cell
which allows better control of chamber pressure with
good signal to noise ratio for the detector
• To increase the experimental feasibility for running higher
cycle of CV in order to have more informaiton during
operando condition
• To reproduce the two electronic transitions obtained in
earlier operando study with n- type hematite doped with
Si
• To relate soft x ray spectrosocpy results with charge
transfer chacracterisics4
.
h
h'
UnoccupiedMOs
OccupiedMOs
O 1s
Inte
nsi
ty (
a.u)
540535530525520515
Energy (eV)
XASXES
4a1
2b2
3a1
1b2
1b1
Soft X ray absorption spectroscopyPhotoelectrochemisty
SC- electrolyte interface Hematite Electronic structure
Introduction
5
How the operando spectroscopy helps in finding the role of
electron - hole in PEC system – a brief overview
6
First direct observation of molecular glance of watersplitting reaction
Artur Braun et. al., J. Phys. Chem. C, 2012, 116 (32), pp 16870–168757
Sequence of O1s NEXAFS spectra vs. V and h
Ref: Artur Braun et. al., J. Phys. Chem. C, 2012, 116 (32), pp 16870–16875 9
First generation electrochemical flow cell
P. Jiang et. Al., Electrochem. Comm. 12, 820–822 (2010) 11
12
How we can make a sustainable operando condition?
Answer : Deisgn of new In-Situ Electrochemical Flow cell
Bora et. al., Rev. Sci. Instrum. 85, 043106 (2014)
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