International Winter School 2021

(1)

Subhajit Chakraborty Under the supervision of

Prof. Sebastian C. Peter

Systematic Assessment of Solvent Selection in Photocatalytic CO 2 Reduction

Das, R.; Chakraborty, S.; Peter, S. C. ACS Energy Lett. 2021, 6 (9), 3270–3274.

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Introduction

• Atmospheric CO 2 concentration 413.93 ppm upto October 2021

• Energy reaching to the earth surface from Sun 4.3*1020 J/h with that energy we can sustain 9200 h

Catalyst Light Additi Result

µmol/g/h

Article

MWCN T /TiO

₂

8 W UV-A, full arc

TEOA H

₂

: 2360, CH

₃

OH: 3246

Carbon 2019, 147, 385 CMP3-

Pd

300 W (>295 nm) TEA H

₂

: 6076 Chem. Mater.

2019, 31, 305 CsPbBr

₃

NCs/GO

300 W (>400 nm) Ethyl acetate

CO: 5 J. Am. Chem.

Soc. 2017, 139, 5660 Cs

₂

AgBi

Br

₆

NCs

450 W Xe lamp (>420nm)

Ethyl acetate

CO: 2.35 Small 2018, 14, 1703762.

Phys. Chem. Chem. Phys. 2012, 14, 16745.

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Catalyst Design (CS1)

Case Study

Case study-1 (reported catalyst) Pt/TiO 2 @g-C 3 N 4

Case study-2 (new catalyst) CsPbBr 3 /BCN

0 200 400 600 800 1000 1200 1400 1600 0

100 200 300 400 500 600 700

800 TiO₂

Pt-TiO g-C₃N₄

Pt-TiO₂@g-C₃N₄

-Z'' (ohm)

Z' (ohm)

0 20 40 60 80 100 120 140

0 1 2 3

Photocurrent(mA cm-2 )

Time (Second) TiO₂ Pt-TiO₂ g-C₃N₄

Pt-TiO₂@g-C₃N₄

300 400 500 600 700

0 1 2 3 4 5 6

2.50 2.75 3.00 3.25 3.50 3.75 4.00 0

500 1000 1500 2000 2500 3000 3500 4000

2.93 eV 3.28 eV

(ahn)2(eV cm-1)2

Bandgap (eV) TiO₂

Pt_TiO₂ g-C₃N₄ Pt_TiO₂@g-C₃N₄

377 nm

436 nm

Absorbance

Wavelength (nm)

.

350 400 450 500 550 600

0 20 40 60 80 100

Intensity (a.u.)

Wavelength (nm) TiO₂ Pt_TiO₂ g-C₃N₄

Pt_TiO₂@g-C₃N₄

350 400 450 500 550 600

0 20 40 60 80 100

Intensity (a.u.)

Wavelength (nm)

TiO2 Pt_TiO2 g-C3N4

Pt_TiO2@g-C3N4

0 200 400 600 800 1000 1200 1400 1600 0

100 200 300 400 500 600 700

800 TiO2

Pt/TiO2 g-C3N4

Pt-TiO2/g-C3N4

Z'' (ohm)

Z' (ohm)

300 400 500 600 700

0 1 2 3 4 5 6

2.50 2.75 3.00 3.25 3.50 3.75 4.00 (ahn)2 (eV cm-1)2

Band gap (eV) 3.58 eV

3.42 eV 2.93 eV 3.38 eV

366 nm

436 nm

Absorbance

Wavelength (nm)

TiO2 Pt_TiO2 g-C3N4 Pt_TiO2/g-C3N4

-2 -1 +0 +1 +2 +3 +4

-1.08 V

+1.9 V

+3.11 V -0.31 V g-C₃N₄

Pt@TiO₂ V vs. NHE (PH=7)

H⁺/H₂

H₂O/O₂ +1.23 V

CH₄ -0.24 V C₂H₄ -0.34 V CO -0.53 V

2.93 eV

3.42 eV

0 20 40 60 80 100 120 140

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Photocurrent (mA cm-2 )

Time (Second)

TiO2 Pt/TiO2 g-C3N4

Pt/TiO2@g-C3N4

(a)

(f) (c)

(e) (b)

(d) e

^-

e

^-

e

^-

e

^-

h

⁺

h

⁺

h

⁺

h

⁺

h

⁺

CO

₂

H

₂

, CH

₄

CO

₂

H

₂

,CO, C

₂

H

₄

, CH

₄

H

₂

O, TEOA

O

₂

, TEOA

⁺

T iO

2

g -C

3

N

4

e

^-

Pt

(4)

Solvent Photolysis (CS1)

0 5 10 500 1000 1500 2000 5000 6000

EAA TEA

ACN TEOA

Only solvents under full arc CO

CH₄ C₂H₄ H₂

TEOA TEA EAA

0 5 10 15 20 Only solvents under visible light 25 CO

CH₄ H₂ 0

10 250 500 750 2000 4000 6000 8000

EAA CsCO₃

TEA ACN TEOA

Full arc, CO₂, Catalyst CO

CH₄ C₂H₄ H₂

0 5 10 15 45 60 75

CsCO₃ EAA TEOA TEA

ACN

Visible light, CO₂, Catalyst CO

CH₄ C₂H₄ H₂

Ra te of prod uct formatio n ( m mol h -1 )1 00 Ra te of prod uct formatio n ( m mol h -1 ) 100

ACN: Acetonitrile, TEOA: Triethanolamine, TEA: Triethyl amine

EAA: Ethyl acetate, CsCO 3 : 0.5 M CsCO 3 Solution 0

5 10 15 20 25 30 35 40

Visible light CsCO₃

full arc

TEA EAA TEOA

ACN

Evolved O

₂

O

₂

evolved (theoretically)

CsCO₃

Rate ( m mol h

-1

)*100

0 5 10 15 20 25 30 35 40

Expected rate ( m mol h

-1

)*100

CO

₂

→ CO + ½O

₂

CO

₂

+ H

₂

O → CH

₄

+ 2O

₂

H

₂

O → H

₂

+ ½O

₂

No. of moles of O

₂

evolved

= 2*n*CH

₄

+ ½*n* CO + ½*n* H

₂

Full arc: 200-2500 nm Light irradiation

Visible Light: 400-800 nm

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Catalyst Design (CS2)

0 50 100 150 200

-6 -5 -4 -3 -2 -1 0

Photocurrent density (mA cm-2)

Time (S)

BCN/CsPbBr₃ CsPbBr₃

0 10 20 30

0 1000 2000 3000 4000 5000 6000 7000 8000

0 2 4 6 8 10 12 14

Rct (Ohm)103

BCN/CsPbBr₃ CsPbBr₃

-Z' (Ohm)

Z" (Ohm)*10³ BCN/CsPbBr₃

CsPbBr₃

500 520 540 560 580

Intensity (a.u.)

Wavelength (nm) CsPbBr₃

BCN/CsPbBr₃

525 550 575 600 625 650

0 5 10 15 20 25 30

2.0 2.1 2.2 2.3 2.4

2.27 eV

2.29 eV (ahn)2 (eV cm-1)2

Bandgap (eV)

CsPbBr₃/BCN CsPbBr₃

Absorbance (a. u.)

Wavelength (nm)

2 0 0 nm

2 0 0 nm ^{1 0 0}^{1 0 0} ^{n m}^{n m}

e -

e - e - CO 2 CO

OH -

h +

h + VBM

1.27V

CBM -1V -0.53 V

Cs PbBr

C B N

BCN

CsPbBr 3

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Solvent Photolysis (CS2)

Full arc Visible light

BCN/CPB (l): Liquid phase reaction in CAN BCN/CPB (g): Vapor phase reaction By bubbling CO 2 through water

0 5 10 15 20 25 30 35

Visible light Full arc

CPB(g) BCN/CPB(g) BCN/CPB(g)

CPB(g)

Evolved O

₂

O

₂

evolved (theoretically)

Rate ( m mol h

-1

g

-1

)

0 5 10 15 20 25 30 35

Expected Rate ( m mol h

-1

g

-1

)

0 5 10 15 20 25 30

ND ND

Yield ( m mol/g )

CO

(7)

Guideline for solvent selection

UV-B UV-A UV-C

200 280 320

UV IR V isi ble

200 2400

400 800

Water

NaOH solution

CsCO 3 solution ACN

TEA

TEOA

EAA Strictly

prohibited Prohibited Should be avoided

Allowed Heat generation due to IR light should be considered IR

800 400

nm

Visible

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Summary

CO

₂

+ H

₂

O

Ex pec ted res ult Ov eres tim at ed In abs enc e of CO

2

and c ataly s t

AC N

Photolysis

Highest Viewed paper in ACS Energy Lett. In August 2021

Acknowledgement

• Prof. C. N. R. Rao (FRS) for the constant support and encouragement

• Prof. Sebastian C Peter For constant guidance

• Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR)

• Council of Scientific & Industrial Research (CSIR)

International Winter School 2021

Subhajit Chakraborty Under the supervision of

Catalyst Light Additi Result

Case study-2 (new catalyst) CsPbBr 3 /BCN

O, TEOA

EAA TEA

Ra te of prod uct formatio n ( m mol h -1 )*1 00 Ra te of prod uct formatio n ( m mol h -1 )* 100

TEA EAA TEOA

Evolved O

Absorbance (a. u.)

Yield ( m mol/g )

and c ataly s t

• Department of Science and Technology, India

Ra te of prod uct formatio n ( m mol h -1 )1 00 Ra te of prod uct formatio n ( m mol h -1 ) 100