Solar Hydrogen Productionphysics.sharif.edu/~naseri/wp-content/uploads/2019/05/WS.pdf ·...

1N. Naseri, Department of Physics, SUT

Solar Hydrogen Production

Production Storage Delivery Conversion

http://www.merlin.unsw.edu.au/energyh/hydrogen-faqs/



Chou et al. Nano Letters, 2011

Ronge et al. Chem Soc Rev, 2014

Nanostructures for Water splitting

PROS

• Shortened carrier collection pathway

• Improved light distribution

• Quantum size confinement

CONS

• Higher surface recombination

• Lower absorbed photon flux

• Slow inter particle charge transport

Principles of PEC H2 Production

5

Covering 0.1% of total surface (~ 70% of IRAN) by PV system with 10%

efficiency

Rev. Soc. Rev. 2012, 41, 7909



Brillet et al. Nature Photonics, 2012.

Pinaud et al. Energy Environmental Science, 2013.

Landman et al. Nature Materials, 2017.

Li et al. Catalysts Science & Technology, 2015.



Suitable band gap (Solar sensitive)

Suitable band vs H2O redox levels (in n-type VB more positive than OX state and

in p-type, CB more negative than RED state)

Stable in wide pH range and against photocorrosion

Low cost

Non-toxicity

Catalytic activity for HER and OER (low over potentials)

Finally, cheaper than PV+ EL & Fossil fuel

Efficient (light harvesting /charge transport)

DOE target for PEC hydrogen production solar-to-hydrogen (STH) efficiency of 10%

with durability of 5000 hours

Hierarchical Morphology

88


99

• Tuning morphology: Nanotubes

Enhancing transfer of electron to back contact and hole to

electrolyteUnique electronic properties Increasing surface interface

Hopping between particles

L~10 µm by annealing

Electron Diffusion Coe.200 times more than NPs

Highest surface area

PCCP, 2013, 15, 2632


10N Naseri, Department of Physics, SUT

1010

• Nano-branched structures Improving charge separation

Facility of hole consumption

Light trapping in systemh+ Ld ~ nm

Light diff. ~ µm

Increase surface

interface

Branched structure

PEC setup

Photoanode

Pt sheet

Ag/AgCl

Quartz window

Injection to GC



Naseri et al. Int J Hydrogen Energy, 2012.

Katu et al. Chem Soc Rev, 2014.

Gas chromatography

Take a look at the surface: CV

What is the controlling regime?Is there any other electro-active material on the surface?Is the window potential safe?

LSV to probe photo-responses

Comparing Dark and Light responseHow the photo-response is V-dependent?

Chopping and I-i linearity

Chronoamperometery technique

Stability test

Trap states

)/exp( tD

fi

ft

II

IID

ln

ti tf

Ii

If

On

Off

Transport life time

OC life time

0.01

0.1

1

10

100

-0.9-0.7-0.5-0.3

Potential (V)

Tim

e (

s)

1)( dt

dV

e

kT OCn

Electrochemical Impedance Spectroscopy

Efficiency: 1- IPCE

)/()(

)/(12402

2

mWPnm

mAJIPCE

ph

Efficiency: 2- STH

0

0 100)((%)

I

EEJ apprevP

Efficiency: 3-QE

0

100

200

300

400

500

600

0 50 100 150 200Time (min)

0%-air

0%

1%

2%

5%

10%

20%

inI

HmolAPE

)(2(%) 2

H2

(mm

ol)

For Electro-catalysts: Over Potential (OP)

For Electro-catalysts: Turnover Frequency

Measuring this factor is more beneficial when attemptingcompare intrinsic activity of the electro-catalysts withdifferent specific surface area. TOF (s-1) can be calculatedaccording to following formula:

Here, J(A), NA, F, RF and N are current density obtained fromunite area of the electrode (Am-2), Avogadro number,Faraday constant, roughness factor and the total number ofcobalt atoms expose to the surface in the smooth Co layer(1.25 × 1015), respectively. Furthermore, n is the number ofelectron transferred for evolution of one molecule of O2

which equals to 4

Measuring Real Surface: EC method

Measuring Real Surface: Dye Adsorption

26N Naseri, Department of Physics, SUT

26

ACS Nano, 2014

TNA Decorated with CdS NPs

2727

M. Qorbani et al. Applied Catal B: 2015, 162, 210



Gholami et al. RSC Advances, 2014.

Qorbani et al. Applied Catal B, 2014.

29

Current Enhancing Approaches

• Surface disorder engineering Making Oxygen vacancies in TiO2

lattice & narrowing band gap

Solar Energy Conversion ~ 24%

Current Enhancing Approaches

• Surface disorder engineeringIn

ten

sit

y (

a.u

.)

467 465 463 461 459 457 455

Ti (2p3/2)

Ti (2p1/2)

0%(air)

0%

1%

Ag mol% 0 (air) 0 1 2 5 10 20

APE (%) 3.6 5.8 9.6 7.4 6.2 6.0 5.0

ND (cm-3) 5.5×1018 6.5×1021 16.3×1021 17.6×1021 17.7×1021 20.7×1021 22.6×1021

Rct (W) 194.5 60.0 40.2 44.5 44.2 44.8 41.6

30

0

20

40

60

80

100

0 20 40 60 80 100 120

Time (s)P

ho

tocu

rren

t d

en

sit

y (

A/m

2)

0% 1% 2% 5% 10% 20%

Electro-catalysts

31

A Major Issue on the Way of Splitting Water: Overpotential

Electro-catalysts

32

Expectations from a proper electrocatalyst:

• Earth abundance,

• Non-toxicity,

• Stability,

• and hopefully, Light absorption.

Morales-Guio et al., Chem. Soc. Rev., 2014, 43, 6555–6569

Electrochemical

X. Deng; ACS Catal. 2014.

Photoelectrochemical

33



Gimenez & Bisquert, Photo-electrochemical solar fuel production, Springer, 2016



Jaramillo, Science, 2007Fabbri, Catal. Sci. Tech. 2014

Seh et al., Science, 2017

Subbaraman, Nature Materials, 2012

Chen et al, Nature Rev., 2007

Chowdhury et al, Nature Comm. , 2018



Scalability Stability Conductivity controllability

Naseri et al. J Phys. D, 2018, Naseri et al ACS Sustainable Chem. Eng., 2016

CoOx Nanoflakesfor OER



Naseri et al. RSC Adv. 2017, Naseri et al. J Ind. Chem. Eng. 2017



Qarechalloo et al, Submitted Saadati et al, to be Submitted

CoOx/TNA Photo anodePEC water splitting

TNA Photo anodePEC Glucose sensing

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