Development of novel catalytic systems for photoreduction of CO2 to fuel and chemicals

1. Development of novel catalytic systems for photoreduction of CO2
to fuel and chemicals
Supervisor: Dr. Bir Sain,
Co-Supervisor: Dr. Suman L. Jain
1

2.  Global energy consumption was 15–17 TW in 2010 and will increase to 25–27
TW by 2050.
 81% of the energy needs were met by fossil fuels, while renewable sources
accounted for 13% in 2011.
If we can capture 10% of the solar energy falling on 0.3% of the land surface it
will be suffice for meeting our energy demand in 2050.
The CO2 global average concentration in Earth's atmosphere was increased from
270 ppm in 1958 to 395 ppm in 2012.
Photocatalytic conversion of this greenhouse gas into valuable products can
provide energy in a sustainable way with levelling off the concentration of CO2 in
our environment.
2
Introduction

3.  CO2 is highly stable molecule
 One electron reduction is highly unfavorable due to bent structure of CO2
.-
and require -2.14 eV reduction potential including over potential.
 Transition metal complexes may provide alternative pathway by forming
metal CO2 hybrid bond.
 Macrocyclic complex such as metal phthalocyanines, ruthenium bipyridyl
complexes etc. are more attractive due to their wide spectrum of absorptions

4. Transition metal complexes as photocatalysts ?
 Transition metal complexes provide higher quantum efficiency in
comparison to heterogeneous semiconductor based catalysts.
 By changing ligand catalyst can be tuned for desired product like
methanol.
 Highly visible light absorber and can yield higher hydrocarbons if
attached to electron transporting moiety.
 Generally one unit works as photosensitizer and another work as
catalyst.
Tamaki et. al. PNAS Early Edition, 1-6
But the main challenges are:
Less robust!
Non-recoverable.
Requires tertiary amines as sacrificial
donor.
 Easily recoverable and recyclable
 Visible light active
 Exhibit increased efficiency if anchored to
photoactive supports.
Can be tuned for desired products.
How immobilized system works ?
 After absorbing visible light metal complex transfer
electrons to the conduction band of active supporting
material.
 These electrons in conduction band are used for
reduction of CO2.
 Owing to the continuous pumping of electrons the
electron hole recombination rate get decreased

5. 5
Work done so far
1. Photocatalytic reduction of carbon dioxide to methanol using
ruthenium trinuclear polyazine complex immobilized to graphene
oxide under visible light irradiation
2. Cobalt phthalocyanine immobilized on graphene oxide: an efficient
visible active catalyst for the photoreduction of carbon dioxide
3. Photoreduction of CO2 to methanol with hexanuclear
molybdenum [Mo6Br14]2- cluster units under visible light irradiation.

6.  In the current study we have synthesized graphene oxide attached Ruthenium
trinuclear complex
 Characterization of synthesized catalyst was done with FTIR, 1H NMR, 13C NMR,
ESI-HRMS, XPS, XRD, SEM, TEM, ICP-AES, UV-VIS, BET and CO2 photo reduction
product was analysed with GC-FID and.
 The developed photocatalyst was visible light active and exhibited significantly
higher catalytic activity and selectivity to give methanol yield 3977.57±5.60 μmol.g-1 cat
after 48h in presence of sacrificial donor (Triethyl amine). While GO show methanol
yield 2201.40±8.76 μmol.g-1 cat.
 Standard error was measured by three measurements
 Possible mechanism for conversion of CO2 to methanol with catalyst was
proposed on the basis of band gap difference.
6
1. Photocatalytic reduction of carbon dioxide to methanol using ruthenium trinuclear
polyazine complex immobilized to graphene oxide under visible light irradiation
J. Mater. Chem. A, 2014, 2, 11246-11253

7. Step-wise synthesis of Ruthenium trinuclear complex attached GO catalyst
a) Synthesis of Ru trinuclear complex 1
b) Attachment of Ru complex 1 to GO
7
J. Mater. Chem. A, 2014, 2, 11246-11253

8. Characterization :
SEM Image of a) GO, b) GO
attached Ru complex2
and EDX pattern of 2
ESI-HRMS of Ru trinuclear complex 1
8
IR Spectra
XRD Pattern
XPS spectra a) survey scan of GO-Ru comp
2, b) C(1s) and Ru (3d)
UV Absorbance
J. Mater. Chem. A, 2014, 2, 11246-11253

9. C% H% N% Ru%
56.13 3.20 4.43 4.14
DT-TGAAdsorption desorption isotherm of a) GO and b) GO-
Ru catalyst2
Pore size distribution of a) GO, b) GO-Ru catalyst2
Tauc plot for calculating band gap of GO
CHN and ICP-AES analysis of catalyst 9
J. Mater. Chem. A, 2014, 2, 11246-11253

10. Calibration curve for quantitative
determination of methanol
GC chromatogram image of photoreaction
productReaction Illumination condition
CO2 Photoreduction experiment and quantification of methanol
10
Methanol formation rate Recycling experiment
Ru%
4.12
ICP-AES
after recycling
J. Mater. Chem. A, 2014, 2, 11246-11253

11. e
e
e
e
e
CB
VB
e
2.9–3.7eV
MLCT
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J. Mater. Chem. A, 2014, 2, 11246-11253

12. 12

13. 13
Raman spectra of a) GO and b) GO-CoPc
N1s XPS of a) CoPc and b) GO-CoPc
XRD diffractogram of a) GO and b) GO-CoPc
TEM image of a) GO; b) GO-CoPc; c) GO-
COOH; and d) SAED pattern of GO-CoPc
UV-Vis spectra ofa) CoPc b) GO and
c) GO-CoPc
Chem. Eur. J. 2014, 20, 6154-6161

14. RSC Adv., 2014, 4, 10420.
3. Hexanuclear molybdenum [Mo6Br14]2- cluster units for
photoreduction of CO2 under visible light irradiation
Schematic representation of the
[Mo6Bri8La6]2 cluster unit
 Octahedral molybdenum clusters were found
to be efficient visible light induced homogeneous
photocatalysts for the reduction of carbon dioxide
(CO2) to methanol.
 Photoreduction was carried out by using 20
watt white cold LED flood light in dimethyl
formamide/water or acetonitrile water solutions
containing triethylamine as a reductive quencher.
 Cs2[Mo6Br14] exhibited higher photocatalytic
efficiency 6679.45 μmol.g-1cat and afforded higher
yield of methanol
 (TBA)2Mo6Br14 after illumination for 24 h, the
yield of methanol was found to be 5550.53
μmol.g-1cat
Fig: Mechanistic of CO2 reduction
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16. 16
1. Pawan Kumar, Subodh Kumar, Stephene Cordier, Serge Paofai, Rabah Boukherroub and
Suman L. Jain, Photoreduction of CO2 to methanol with hexanuclear molybdenum
[Mo6Br14]2- cluster units under visible light irradiation, RSC Adv., 2014, 4, 10420.
2. Pawan Kumar, Arvind Kumar, Bojja Sridhar, Bir Sain, Siddharth S. Ray and Suman L. Jain,
Cobalt Phthalocyanine Immobilized on Graphene Oxide: An Efficient Visible-Active
Catalyst for the Photoreduction of Carbon Dioxide, Chem. Eur. J. 2014, 20, 6154-6161.
3. Pawan Kumar, Sanny Varma and Suman L. Jain, A TiO2 immobilized Ru(II) polyazine
complex: a visible-light active photoredox catalyst for oxidative cyanation of tertiary
amines, J. Mater. Chem. A, 2014,2, 4514-4519.
4. Pawan Kumar, Bir Sain and Suman L. Jain, Photocatalytic reduction of carbon dioxide to
methanol using ruthenium trinuclear polyazine complex immobilized to graphene oxide
under visible light irradiation. J. Mater. Chem. A, 2014, 2, 11246-11253.
5. Subodh Kumar, Pawan Kumar, and Suman L.Jain, Ruthenium-carbamato-complex
derived from siloxylated amine and carbon dioxide for the oxidative cyanation of
aromatic and cyclic tertiary amines, RSC Adv., 2013, 3, 24013-24016.
6. Pawan Kumar, Garima Singh, Deependra Tripathi and Suman L. Jain, Visible light
driven photocatalytic oxidation of thiols to disulfides using iron phthalocyanine
immobilized on graphene oxide as a catalyst under alkali free conditions, RSC Adv., 2014,
4, 50331-50337.
7. Subodh Kumar, Pawan Kumar and Suman L. Jain, Graphene oxide immobilized copper
phthalocyanine tetrasulphonamide: the first heterogenized homogeneous catalyst for
dimethylcarbonate synthesis from CO2 and methanol, J. Mater. Chem. A, 2014, 2, 18861-
18866.
8. Pawan Kumar, Amit Bansiwal, Nitin Labhsetwar and Suman L. Jain, Visible light assisted
photocatalytic reduction of CO2 using graphene oxide supported heteroleptic ruthenium
complex, Accepted Manuscript
Publications

17. Acknowledgement :
1. Director, CSIR-IIP for his kind permission to publish these
results.
2. Dr. Suman L. Jain and Dr. Bir Sain for their moral support and
for providing Ideas and in-depth knowledge of the field.
3. Dr. Umesh Kumar for enriching my knowledge in photo-
catalysis.
4. CSIR, New Delhi is acknowledged for providing research
fellowship under Emeritus Scientist Scheme.
5. Analytical Division of the Institute is kindly acknowledged for
providing support in analysis of samples
6. Finally I would like to thanks to my colleagues.
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