Setting Targets for
Photoelectrochemical
Cells
Priyanka deSouza, Balasubramaniam R Kavaipatti, Rangan Banerjee
Department ...
Setting Targets
Metric Y

Energy
available

Energy
output
Energy Conversion System
Energy
input
Metric X
Energy Conversion...
Taking a leaf out of…

Melvin Calvin, 1982: It is time to
build an actual artificial
photosynthetic system, to learn
what ...
Mimicking Nature

Single Semiconductor Liquid Junction

Two Semiconductor Liquid Junctions

A. Currao, Chimia 61
(2007) 81...
Scenarios
I

III

II
CB

CB
H2/H+

CB
CB
VB

VB

H2O/O2
VB
VB

McKone, J. R., E. L. Warren, et al. (2011). Energy & Enviro...
Viability of PEC cells?

6
Embedded energy calculations
Energy MJ/sq m
Si wire growth
320.07
Chamber (PVC)
252
Cover (Glass)
114.12
environmental con...
Photoelectrodes – embedded
energy
Photocathodes
InP
Cu2O

Photoanodes
Fe2O3
TiO2

Calculation of embedded energy of the el...
Photocathode - InP
Material

Embedded Energy

InP

(MJ/m2 )
171

2nm TiO2

0.4

Source
Embedded Energy
of ITO[16], another...
Photocathode – Cuprite
Material

embedded
Energy (MJ/m2 )

Source

Lactic Acid

1

Data for poly-lactic
acid used [17]

Co...
Photoanode – Haematite
Material Embedded
Source
Energy
(MJ/m2)
Fe(CO)5
900
Data for Fe used [19]
TEOS

9923

Data for Meta...
Photoanode - Anatase
Material embedded
Energy
(MJ/m2)
Ti
3.4
Gases

0

1 mm Glass
substrate

41.3

Source

[19]
Gas pressu...
Embedded energy - Summary
Electrode Fabrication Energy Material Energy Total Energy
(MJ/m2)
(MJ/m2)
(MJ/m2)
p-Si
InP
Cu2O
...
Applied bias
• Contour lines for the lifetime primary energy requirement of hydrogen equaling 120 MJ/kg
for different phot...
Sacrificial reagent
embedded energy of photocathode
+ sacrificial reagent energy = 120
hydrogen production x stability

15
Photoanode-photocathode
combinations

16
Conclusions
• Methodology to identify the feasible range of
efficiencies and lifetimes a given PEC cell must have to
be en...
PEC cells - Current status
Target
dates
solar to
hydrogen
efficiency
durability
(hours)
project
hydrogen
cost $/kg

2005

...
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  • (embedded energy of a solar cell is 2730MJ/m2 )
  • Contour lines for the lifetime primary energy requirement of hydrogen equaling 120 MJ/kg for different InP and Cu2O under bias. The region above each contour line is the energy feasible region. Different contour lines corresponding to different sacrificial reagent energies used in conjunction with both electrodes are also depicted. The sacrificial reagent energy corresponding to each of these contour lines is written next to each line.
  • Contour lines for the lifetime primary energy requirement of hydrogen equaling 120 MJ/kg for different photoelectrode pairs are depictedThe lines corresponding to photoelectrochemical cells formed by each electrode under bias only are superimposed
  • 352 icaer

    1. 1. Setting Targets for Photoelectrochemical Cells Priyanka deSouza, Balasubramaniam R Kavaipatti, Rangan Banerjee Department of Energy Science and Engineering IIT Bombay ICAER, IIT Bombay - 11/12/2013 Acknowledgements: IIT Bombay Seed Grant 12IRCCGS014 1
    2. 2. Setting Targets Metric Y Energy available Energy output Energy Conversion System Energy input Metric X Energy Conversion System  PEC system Metric X  Stability or longevity Metric Y  Efficiency Constraint  embodied energy of PEC 2
    3. 3. Taking a leaf out of… Melvin Calvin, 1982: It is time to build an actual artificial photosynthetic system, to learn what works and what doesn’t work, and thereby set the stage for making it work better 3
    4. 4. Mimicking Nature Single Semiconductor Liquid Junction Two Semiconductor Liquid Junctions A. Currao, Chimia 61 (2007) 815–819 What is the current status of this field? 4
    5. 5. Scenarios I III II CB CB H2/H+ CB CB VB VB H2O/O2 VB VB McKone, J. R., E. L. Warren, et al. (2011). Energy & Environmental Science 4(9): 3573-3583. Cao, B. B., J. J. Chen, et al. (2009). Journal of Materials Chemistry 19(16): 2323-2327 Boettcher, S. W., E. L. Warren, et al. (2011). Journal of the American Chemical Society 133(5): 1216-1219 Spurgeon, J. M., M. G. Walter, et al. (2011). Energy & Environmental Science 4(5): 1772-1780 5
    6. 6. Viability of PEC cells? 6
    7. 7. Embedded energy calculations Energy MJ/sq m Si wire growth 320.07 Chamber (PVC) 252 Cover (Glass) 114.12 environmental control 200 WO3 wire array growth 166.25 Membrane (Nafion) 138.93 Membrane fabrication 82.81 Pumping 31.3 Catalyst 14.99 Other chemicals 14.52 Cleaning 9.63 Photocathode (Si) 5.15 Intervening layer (PEDOT:PSS) 4.7 Photoanode (WO3) 0.12 Total 1354.59 Thermodynamic Models for heating and vacuum pumping Econinvent Ancillary processes from the PV industry Source: http://lcacenter.org/lcaxii/dra ft-presentations/654.pdf 7
    8. 8. Photoelectrodes – embedded energy Photocathodes InP Cu2O Photoanodes Fe2O3 TiO2 Calculation of embedded energy of the electrodes 1)Fabrication Energy 2)Material Energy 8
    9. 9. Photocathode - InP Material Embedded Energy InP (MJ/m2 ) 171 2nm TiO2 0.4 Source Embedded Energy of ITO[16], another In compound used as a proxy as that of InP is not known The fabrication energy of a 2.4 µm photoanode is calculated in the previous section. This value is scaled. Christopher Emmott et al, 97, 14-21(2012) 9
    10. 10. Photocathode – Cuprite Material embedded Energy (MJ/m2 ) Source Lactic Acid 1 Data for poly-lactic acid used [17] Copper sulphate 1.9 Data for Cu used [18] 1 mm Stainless Steel substrate 2 nm TiO2 256 Stainless Steel is 32MJ/kg[19] 0.4 Scaled value used J. Dflou et al, MRS Bulletin, 37, (2012) T.E. Norgate and W.j. Rankin, International conference on Minerals Processing 10 and Extractive Metallurgy, 133-138 (2012) http://web.mit.edu/2.813/www/readings/ICE.pdf, accessed 17/09/2103
    11. 11. Photoanode – Haematite Material Embedded Source Energy (MJ/m2) Fe(CO)5 900 Data for Fe used [19] TEOS 9923 Data for Metallurgical grade Si used[20] 1 mm Glass substrate 41.3 The embedded energy of Glass is 15.9 MJ/kg[19] http://web.mit.edu/2.813/www/readings/ICE.pdf, accessed 17/09/2103 I. Nawaz and G.N. Tiwari, Energy Policy, 34, 3144-3152 (2006 11
    12. 12. Photoanode - Anatase Material embedded Energy (MJ/m2) Ti 3.4 Gases 0 1 mm Glass substrate 41.3 Source [19] Gas pressure is 12mtorr. Vol. of a typical chamber is 1.5 x 105 cm3 [21]. Thus moles of gas present is 10−5 which is very small The embedded energy of Glass is 15.9 MJ/kg[19] http://web.mit.edu/2.813/www/readings/ICE.pdf, accessed 17/09/2103 Spuutering Systems Manual- Physics at Oregon State University 12
    13. 13. Embedded energy - Summary Electrode Fabrication Energy Material Energy Total Energy (MJ/m2) (MJ/m2) (MJ/m2) p-Si InP Cu2O 334.2 35421 906 5.15 172 259 339.35 35593 1165 WO3 Fe2O3 166.25 138 0.12 10864 166.37 11002 TiO2 518 45 563 Source for p-Si data: http://lcacenter.org/lcaxii/draftpresentations/654.pdf 13
    14. 14. Applied bias • Contour lines for the lifetime primary energy requirement of hydrogen equaling 120 MJ/kg for different photoelectrodes under bias • The region above each contour line is the energy feasible region Photoelectrode Efficiency Lifetime (days) p-Si nanowires 0.2% 0.92 InP nanowires 14% 1 Cu2 O 0.72% 7 WO3 nanowires 0.4% 0.25 Fe2 O3 1.84% 182.5 TiO2 6.8% 365 14
    15. 15. Sacrificial reagent embedded energy of photocathode + sacrificial reagent energy = 120 hydrogen production x stability 15
    16. 16. Photoanode-photocathode combinations 16
    17. 17. Conclusions • Methodology to identify the feasible range of efficiencies and lifetimes a given PEC cell must have to be energy feasible has been developed • Range of efficiencies and lifetimes possible for the cell to be energy feasible • Operation with bias seems to be infeasible • InP photocathode use only in combination with WO3 • Improved efficiencies needed • Longer stability times needed • Cu2O with a sacrificial reagent offers much better range 17
    18. 18. PEC cells - Current status Target dates solar to hydrogen efficiency durability (hours) project hydrogen cost $/kg 2005 2010 2015 7.5 9 14 1000 10000 20000 360 22 5 PEC system with GIP and Pt electrodes η = 12.4%, lifetime = 20 hours. Methodology to set targets for PEC cells? 18

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