CO2 ACTIVATION BY IMMOBILIZED COMPLEX AND HYBRID MATERIALS

1. 1

2.  All human activities currently generate about 37 Gt of CO2 emissions.
At the current rate of increase in atmospheric CO2 concentration, the average
global temperature will increase some 6 °C up to end of century.
Several methods for mitigation of CO2 has been developed like conversion of
CO2 to chemicals such as carbonates polycarbonates polyols etc but all the
procedures are energy intensive and require heat as source of activation energy.
Sunlight is inexhaustible source of energy.
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.
Photocatalytic conversion of carbon dioxide into valuable products can provide
energy in a sustainable way with leveling off the concentration of CO2 in our
environment. 2
Chapter 1: photoreduCtion of Co2 to fuel
and ChemiCals: an overview

3. 3
CO2
+ 2H+
+ 2e-
→ CO + H2
O E0
= -0.53 V …………….(1)
CO2
+ 2H+
+ 2e-
→ HCOOH E0
= -0.61 V …………….(2)
CO2
+ 4H+
+ 4e-
→ HCHO + H2
O E0
= -0.48 V……………..(3)
CO2
+ 6H+
+ 6e-
→ CH3
OH + H2
O E0
= -0.38 V……………..(4)
CO2
+ 8H+
+ 8e-
→ CH4
+ 2H2
O E0
= -0.24 V……………..(5)
CO2
+ e-
→ CO2
-o
E0
= -1.90 V……………..(6)
Why CO2 photoreduction is difficult ?
The reduction of CO2 to CO2
.-
by one electron is unfavorable because reduction potential is
high due to bent structure of CO2
.-
Rapid reduction require overpotential of up to -0.6 V .
Potentials for the reduction of CO2 to various products and potentials for the oxidation of H2O to various products (at pH 7 in
aqueous solution versus NHE, 25 o
C, 1 atmosphere gas pressure, and 1 M for the other solutes)
Chem. Soc. Rev., 2009, 38, 89–99
Basic requirements for CO2 photo-reduction process

4. 4
Mechanism and pathways for photocatalytic oxidation
and reduction processes on the surface of heterogeneous
photocatalyst.
Chem. Rev. 1995, 95, 735 – 758
Semiconductor materials as heterogeneous photocatalyst:
 Semiconductor materials like TiO2, ZnO, CdS, etc have been extensively used as photocatalysts
for CO2 reduction.
 Among them, TiO2 owing to its low cost, nontoxicity and suitable band position has been widely
studied.
 Other nanostructured materials like Zn2GeO4, SrNb2O6, npg-C3N4 etc can also be used for the
reduction of CO2

5. 5Schematics of electron and hole capture by
metal doped semiconductor Catalysts 2013, 3(1), 189-218
Doping can improve photocatalytic performance
N doping can shift position of valance band upward
Band gap and band edge position of some semiconductors
Energy Conversion and Management 76 (2013) 194–
214
• Due to large band gap
most of semiconductors
works in UV light
• UV is only 5% in solar
spectrum
• Electron hole pair
recombination rate is
higher so conversion
efficiency is very low

6. But the main challenges are:
Less robust!
Non-recoverable.
Requires tertiary amines as sacrificial donor.6
Homogeneous metal complexes as photocatalyst
 Transition metal complexes may provide
alternative pathway by forming metal CO2
hybrid bond.
 Macrocyclic metal complexes like :
phthalocyanines, ruthenium bipyridyl, rhenium
and iridium complexes are more attractive due
to their wide spectrum of absorption.
By changing ligands, catalyst can also be
tuned for desired product like methanol.
Inorg. Chem., 2012, 51, 890−899

7. 7
Advantages:
Make the catalyst recoverable and recyclable
Visible light active.
 Show increased efficiency if anchored to photoactive supports.
 More robust.
Can be tuned for desired products.
 No need of sacrificial donor.
Immobilization of homogeneous photocatalysts or photosensitizers to
various photoactive supports.
How immobilized system works ?
 After absorbing visible light homogeneous catalyst
transfer electrons to conduction band of active
supporting materials.
 These electrons in conduction band is used for
reduction of CO2.
 Due to continuous pumping of electrons the electron
hole recombination rate get decreased
Mechanism of sensitization of semiconductors
with metal complexes for reduction of CO2

8. 8
Part A: Cobalt phthalocyanine immobilized on graphene oxide: an efficient visible
active catalyst for the photoreduction of carbon dioxide
Chapter 2: Phthalocyanine-semiconductor hybrids for photoreduction of CO2
Chem. Eur. J. 2014, 20, 6154-61611
GO GO-COOH
GO-COCl
GO-CoPc
1. Synthesis of GO-CoPc photocatalyst.

9. 9
TEM image of a) GO, b) GO-CoPc, c) GO-COOH and
d) SAED pattern of GO-CoPc
XRD of a) GO and b) GO-CoPc.
FT-IR of a) CoPc, b) GO and c) GO-CoPc
Chem. Eur. J. 2014, 20, 6154-61611
UV/Vis spectra of a) CoPc; b) GO; and c) GO-CoPc.
(001)
(002)
S band Q band

10. 10
N1s XPS of a) CoPc and b) GO-CoPc
TGA pattern of; a) GO; b) GO-CoPc
Chem. Eur. J. 2014, 20, 6154-61611
Step 1: Borosil vessel charged with water and triethylamine (45 mL/5 mL)
Step 2: Purged with N2 than saturated with CO2
Step 3: Added 100 mg catalyst and irradiated with 20 W white cold LED
light λ >400 nm. Intensity on vessel- 85 W/m2
Step 4: Sample withdrawn after fixed intervals and analyzed with GC-FID
and HPLC.
Step 5: Blank experiments were carried out to confirm that the product
was originated from the CO2 reduction
Photocatalytic CO2 reduction experiment
398.95 - C– N
400.43 – NH2
401.58 - C=N
400.69 – NH

11. 11
Table: Photoreduction of carbon dioxide to methanol
Chem. Eur. J. 2014, 20, 6154-61611
Calibration curve for quantitative determination of
methanol Methanol conversion rate for a) GO, b) GO:Co-
Pc (1:1) and c) GO-CoPc
Recycling Experiment
Cobalt content
Fresh catalyst- 1.13 wt%
After one recycling – 1.05 wt%
Methanol- 3781.8881
μmol g-1
cat
Gaseous analysis-
99.17% CO2
0.82% CO
Varian CP-3800, having
30 m long Stabilwax®
w/Integra-Guard® column) at
flow rate 0.5 mL min−1
, injector
temp., 250 °C, and FID detector
temp., 275 °C

12. 12
Possible Mechanistic Pathway of CO2
reduction
Chem. Eur. J. 2014, 20, 6154-61611
CoPc + Visible light = CoPc*
(excited Singlet state)
CoPc*
= CoPc+
+ e-
GO (electron transfer in CB)
CoPc+
+ TEA = CoPc + TEA o+
e-
GO (electron in CB) + CO2
+ H+ = CH3
OH

13. 13
Part B: Heterostructured nanocomposite tin phthalocyanine@mesoporous
ceria (SnPc@CeO2) for photoreduction of CO2 in visible light
Synthesis of SnPc@CeO2
catalyst
RSC Adv., 2015, 5, 42414-42421

14. 14
SEM images of a) uncalcined CeO2
b) meso-CeO2
and c) SnPc@CeO2
and EDX pattern of d)
uncalcined CeO2
e) meso-CeO2
and f) SnPc@CeO2
TEM images of a) meso-CeO2
b) SnPc@CeO2
and c)
SAED pattern of SnPc@CeO2
UV/Vis absorption spectra of a) SnPcCl2
b) meso-CeO2
c) SnPc@CeO2RSC Adv., 2015, 5, 42414-42421
O-2p to Ce-4f transition
Broad Q band-
aggregated form
Sharp Q band-
monomeric form
5–10 nm

15. 15
FT-IR Spectra of a) SnPcCl2
b) meso-CeO2
c) SnPc@CeO2
XRD diffraction Pattern of a) meso-CeO2
b) SnPc@CeO2
N2
adsorption desorption isotherm and pore size distribution of (a) meso-CeO2
and
(b) SnPc@CeO2RSC Adv., 2015, 5, 42414-42421
fcc cubic space
group Fm3m (225)
structure
JCPDS card no.
34-0394
SBET-75.92 m2
g-1 SBET-
20.52 m2
g-1

16. 16
DT-TGA thermogram of a) SnPcCl2
b)
meso-CeO2
c) SnPc@CeO2
Photocatalytic methanol formation versus time by
using a) Blank reaction b) meso-CeO2
and c) SnPcCl2
equimolar amount as in SnPc@CeO2
and d) SnPc@CeO2
Methanol yield after repurging CO2
Reuse experiments of photocatalytic CO2
reduction by using SnPc@CeO2
catalyst
DMF + water + TEA
(3 : 1 : 1)
Photoreduction experiment
tin content:
fresh catalyst
0.38 wt%
After 5 recycling-
0.34 wt%
Methanol –
2342 μmol g-1
cat
Quantum Yield - 2.23%
CO- 840 μmol g-1
cat

17. 17
Part A: Photocatalytic reduction of carbon dioxide to methanol using ruthenium trinuclear
polyazine complex immobilized to graphene oxide under visible light irradiation
Synthesis of trinuclear ruthenium complex 1
Synthesis of Ru-phen-GO 2J. Mater. Chem. A, 2014, 2, 11246-11253
Step 1
Step 2
Chapter 3: Heterogenized Ruthenium based photocatalysts for conversion of
CO2 to methanol

18. 18
ESI-Mass spectra of ruthenium trinuclear complex 1
(Expanded form)
ESI-Mass spectra of ruthenium trinuclear complex 1
XRD Pattern
SEM images of a) GO, b) Ru-phen-GO 2 and c) EDX
pattern of 2
J. Mater. Chem. A, 2014, 2, 11246-11253
M+
-2Cl-
+2H+
[M+
- 2PF6 + F-
]
(001)
(002)

19. 19
XPS spectra of a) survey scan of Ru-phen-GO 2 and b) C(1s) and Ru (3d)
J. Mater. Chem. A, 2014, 2, 11246-11253
281.94
285.85
1621
1680
FTIR spectra of a) Ru-complex 1, b) GO and c) Ru-phen-GO 2

20. 20
UV/Vis absorption spectra of a) Ru complex1, b) GO and
c) GO attached complex 2
Tauc plot for calculating band gap of GO
J. Mater. Chem. A, 2014, 2, 11246-11253
2.9–3.7 eV

21. 21
Conversion of CO2
to methanol with time
a) using photocatalyst 2 and b) with GO
Recycling of the Ru-phen-GO catalyst for
photoreduction of CO2
to methanol
J. Mater. Chem. A, 2014, 2, 11246-11253
Methanol - 3977.57 ±5.60
μmol g-1
cat
DMF: Water: TEA- (3:1:1)
20 W LED
Photocatalytic CO2 reduction
Ru content-
fresh catalyst - 4.14%
After four recycling – 4.12%

22. e
e
e
e
e
CB
VB
e
2.9–3.7eV
MLCT
22
J. Mater. Chem. A, 2014, 2, 11246-11253

23. 23
Part B: Visible light assisted photocatalytic reduction of CO2 using a graphene
oxide supported heteroleptic ruthenium complex
Synthesis of 2-thiophenylbenzimidazole ligand and heteroleptic Ruthenium (II) complex 1
Synthesis of GO-Ru catalyst 2Green Chem, 2015, 17, 1605-1609
Step 1
Step 2

24. 24
ESI-HRMS of ruthenium complex 1
Green Chem, 2015, 17, 1605-1609
TEM images of a) GO, b) GO-Ru catalyst 2 and c) SAED
pattern of of GO-Ru catalyst 2
SEM images of a) GO, b) GO-Ru catalyst 2
and c) EDX pattern of 2

25. 25
Green Chem, 2015, 17, 1605-1609
XRD Pattern: a) Ruthenium complex 1, b) GO and c) GO-Ru catalyst 2
UV/Vis absorption spectra of a) Ru complex 1, b)
GO, c) 5% RuCl3
/GO and d) GO-Ru catalyst 2

26. 26
Cyclic voltametry of homogeneous Ru
complex 1
Green Chem, 2015, 17, 1605-1609
Tauc plots for calculating band gap of (a) ruthenium
complex 1 (b) GO (c) GO-Ru catalyst 2.
1.90 eV
2.29 eV 2.9-3.7 eV
1.15 eV
2.9 eV
difference in the HOMO–LUMO
(half wave potential, E1/2) – 1.915 eV

27. 27
CO2
to methanol yield a) blank reaction,
b) using GO-COOH, c) GO, d) 5%
RuCl3
/GO, e) Ru complex equimolar
amount to GO-Ru catalyst 2 and f) GO-Ru
catalyst 2
Reuse experiments for catalyst 2
Green Chem, 2015, 17, 1605-1609
Photocatalytic CO2 reduction experiment
Ruthenium content –
Fresh catalyst - 5.15 wt%
After three recycling – 5.07 wt%
Methanol - 2050 μmol g−1
cat
DMF + Water - (4:1)
Quantum Yield- 0.180
No sacrificial donor

28. 28
Plausible mechanism of photoreaction
Green Chem, 2015, 17, 1605-1609
Ru(HOMO–LUMO) → Ru*(HOMO+
+ LUMOe-) MLCT
Ru*(HOMO+
+ LUMOe-) → Ru*(HOMO+
+ LUMO) + e- (CB of GO)
Ru*(HOMO+
+ LUMO) + e- (derived from water splitting) → Ru(HOMO–LUMO)
6e- CB (GO) + CO2 + 6H+
(derived from water splitting) → CH3OH + H2O

29. 29
Part C: In situ Ru/TiO2 hybrid nanocomposite catalyzed photo-reduction of
CO2 to methanol under visible light
Synthetic outline of the in situ Ru(bpy)3/TiO2 photocatalyst
Nanoscale 2015, 7, 15258-15267

30. 30
SEM images of a) in situ TiO2
, b) in situ
Ru(bpy)3
/TiO2
, EDX pattern of c) In situ TiO2
, d) In
situ Ru(bpy)3
/TiO2
, elemental mapping of e) in situ
TiO2
and f) in situ TiO2
HR-TEM images of a) in
situ TiO2, b) in situ
Ru(bpy)3/TiO2, c) SAED
patterns of c) in situ TiO2
and d) in situ
Ru(bpy)3/TiO2
Nanoscale 2015, 7, 15258-15267
STEM Elemental
Mapping and HR-TEM
EDX Pattern of
Ru(bpy)3/TiO2 a)
showing image of area
scanned, b) Ti, c) O and
d) Ru
25–35 nm 25–35 nm 0.35 nm (101)

31. 31
XRD patterns of a) Ru(bpy)3Cl2, b) in situ
TiO2 and c) in situ Ru(bpy)3/TiO2
Adsorption desorption patterns of a) in situ TiO2
and b) in situ
Ru(bpy)3
/TiO2
.
UV/Vis absorption spectra of a)
Ru(bpy)3Cl2, b) in situ Ru(bpy)3/TiO2 and
c) in situ TiO2
Nanoscale 2015, 7, 15258-15267
Anataase
tetragonal TiO2
JCPDS no. 21-1272
Rutile
JCPDS no. 88-1175
SBET -35.24 m2
g−1
rp - 7.58 nm rp – 9.37 nm
SBET – 26.96 m2
g−1

32. 32
Tauc plot for calculation of band gap of a) Ru(bpy)3Cl2, b)
in situ TiO2 and c) in situ Ru(bpy)3/TiO2
Wide scan XPS spectra of in -situ TiO2 and in- situ
Ru(bpy)3/TiO2 a) Ti2p, b) O 1s and c) N 1s region
Nanoscale 2015, 7, 15258-15267
Ru complex 4.05 eV LLCT and 2.55 eV MLCT
TiO2 –3.15 eV
Insitu Ru(bpy)3@TiO2 – 2.65 eV
464.23
458.39

33. 33
Methanol formation from CO2 photoreduction: a) blank
reaction, b) Ru(bpy)3Cl2 complex equimolar to in situ
Ru(bpy)3/TiO2, c) in situ TiO2, d) Ru-complex adsorbed on
P25 TiO2 and e) in situ Ru(bpy)3/TiO2
Nanoscale 2015, 7, 15258-15267
Catalyst recycling data for four cycles
Water + DMF (4:1)
1876 μmol g−1
cat,
Quantum Yield –
0.024 mol Einstein−1
Ru content –
Fresh catalyst – 1.38 wt%
After four recycling
1.34 wt %
Possible mechanism of the reaction

34. Synthetic scheme of rGO@CuZnO@Fe3O4 microspheres 4
34
Part A: Reduced graphene oxide wrapped core-shell structured magnetically separable
rGO@CuZnO@Fe3O4 microspheres for enhanced visible light CO2 reduction efficiency
Communicated
Chapter 4: Magnetically separable nanocomposites for CO2 reduction
20 mL (0.2 mg/mL)
iii) Hydrated
with water

35. 35
FE-SEM images of a) Fe3O4 microspheres (1), b)
CuZnO@Fe3O4 microspheres (2), c) GO@CuZnO@Fe3O4
microspheres (3) and d) rGO@CuZnO@Fe3O4 microspheres
(4)
FE-SEM EDX patterns of a) Fe3O4 microspheres (1), b)
CuZnO@Fe3O4 microspheres (2), c) GO@CuZnO@Fe3O4
microspheres (3) and d) rGO@CuZnO@Fe O microspheres (4)
~ 300 nm200 to 250 nm
TEM images of a) Fe3O4
microsphere 1 b)
CuZnO@Fe3O4
microspheres 2, High
resolution TEM of c)
rGO@CuZnO@Fe3O4
microspheres 4 d) showing
at scale 10 nm e) at 2 nm
resolution showing d
spacing and f) SAED
pattern
STEM elemental mapping
of rGO@CuZnO@Fe3O4
microsphere 4 for a)
showing mapping scale
bar b) mapping for O c)
Cu d) C e) Fe f) Zn and g)
EDX pattern of selected
area in yellow highlighted
circle

36. 36
Communicated
GO – 1.01
rGO - 0.41
GO@CuZnO@Fe3O4 - 1.13
rGO@CuZnO@Fe3O4 - 0.87
ID/IG
ZnO 325 cm-1
A1
664 cm-1
Fe3O4 A1g
Fe3O4 face centered cubic inverse spinal
- JCPDS No. 19-0629
ZnO hexagonal wurtzite - JCPDS No. 36-1451
XRD diffractogram
Raman spectra

37. GO@CuZnO@Fe3O4 3 rGO@CuZnO@Fe3O4 4
Elements
C1s
O1s
N1s
Fe2p
Si2p
Zn2p
Binding
energy(eV)
285
530
400
710
103
1022
At%
56.16
28.86
3.05
7.34
3.05
1.54
Elements
C1s
O1s
N1s
Fe2p
Si2p
Zn2p
Binding
energy(eV)
285
530
400
710
103
1022
At%
48.50
36.00
3.53
3.98
4.01
3.98
XPS specturm
Elemental composition
37
Wide scan
C1s high resolution XPS spectra of a) GO@CuZnO@Fe3O4 and b) rGO@CuZnO@Fe3O4,
c) Fe2p and d) Zn2p of rGO@CuZnO@Fe3O4
Communicated
1043.1 eV
1022.0 eV

38. 38
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0
0.2
0.4
0.6
0.8
1
1.2
1.4
200 300 400 500 600 700 800
Absorbance/a.u.
Photon Wavelength/ nm
Fe3O4
CuZnO@Fe3O4
ZnO
a)
0
1
2
0
1
2
200 300 400 500 600 700 800
Absorbance/a.u.
Photon Wavelength / nmc)
GO
GO@CuZnO@Fe3O4
rGO@CuZnO@Fe3O4
rGO
0
100
200
300
400
500
600
700
0 2 4 6 8 10 12 14
Absorbance(400-800nm)/a.u.
GO ZnO GO@CuZnO CuZnO rGO@CuZnO Fe3O4 rGO
d)
GO ZnO GO@CuZnO CuZnO rGO@CuZnO Fe3O4 rGO
@Fe3O4 @Fe3O4 @Fe3O4d)
Fig. a) and c): absorbance curves of a) Fe3O4 microspheres (2), ZnO, CuZnO@ Fe3O4 microspheres (2); b) GO, rGO,
GO@CuZnO@ Fe3O4 microspheres (3) and rGO@CuZnO@ Fe3O4 microspheres (4); c) Total absorbance measured
between 400 and 800 nm for all the samples
Communicated
b)
c)

39. 39
CO2 conversion to methanol for a) Blank reaction, b) Fe3O4
microspheres (1), c) CuZnO@Fe3O4 microspheres (2), d)
GO@CuZnO@Fe3O4 microspheres (3) and f) rGO@CuZnO@Fe3O4
microspheres (4)
Methanol –
2656 µmol g-1
cat
Recycling experiments by using rGO@CuZnO@Fe3O4
Hydrogen as byproduct
CuZnO@Fe3O4 2, - 16.2 µmol g-1
cat
GO@CuZnO@Fe3O4 3 - 28.5 µmol g-1
cat
rGO@CuZnO@Fe3O4 4 - 45.5 µmol g-1
cat

40. 40
Part B: Photo-induced reduction of CO2 using magnetically separable Ru-
CoPc@TiO2@SiO2@Fe3O4 catalyst under visible light irradiation
Dalton Trans, 2015, 44, 4546-4553 Synthesis of catalyst

41. 41
FESEM images of a) Fe3O4, b)
SiO2@Fe3O4, c) TiO2@SiO2@Fe3O4 1, d)
Ru-CoPc@TiO2@SiO2@Fe3O4 6, e) EDX
of 1, f) EDX of SiO2@Fe3O4, g) EDX of
TiO2@SiO2@Fe3O4 and h) EDX of 6
Dalton Trans, 2015, 44, 4546-4553
TEM Image of a-b) Ru-CoPc@TiO2
@SiO2
@Fe3
O4
6, c) SAED
pattern of 6

42. 42
UV-Vis spectra of a) CoPcS, b)
CoPc@TiO2
@SiO2
@Fe3
O4
, c)
TiO2
@SiO2
@Fe3
O4
and d) Ru-
CoPc@TiO2
@SiO2
@Fe3
O4
6
DT-TGA curve of
Ru-CoPc@TiO2
@SiO2
@Fe3
O4
6
Dalton Trans, 2015, 44, 4546-4553

43. 43
Graph for methanol yield
Dalton Trans, 2015, 44, 4546-4553
Magnetic separable
Methanol-
2570.18
μmol g-1
cat
Water + TEA
(4:1)
Fresh catalyst
Co- 1.26%
Ru- 1.17%
After recycling
Co-0.98 wt%
Ru-0.94 wt%)
Plausible mechanism

44. 44
Chapter 5: Metallic clusters as efficient photocatalysts for conversion of CO2 to
methanol
Schematic representation of octahedral
molybdnum cluster La
=Apical ligand
Li
=inner ligand.
 Metal cluster is a multimettalic oxide or halides aggregates with
general formula [Mo6X14]2-
 Metal clusters due to presence of multi-metallic centers can
undergo multi-electron redox process which is an essential
requirement for reduction of carbon dioxide to higher hydrocarbons.
The main drawback of metal clusters are their homogeneous
nature and non-recyclability.
 They strongly absorbs in visible region near 500 nm
 The halogen hydroxy or ligands situated on apical
position are labile and can be replaced with donor ligands
like pyridine derivatives, etc.

45. 45
Part A: Photoreduction of CO2 to methanol with hexanuclear molybdenum
[Mo6Br14]2-
cluster units under visible light irradiation
Schematic representation of the [Mo6
Bri
8
La
6
]2-
cluster unit
RSC Adv., 2014, 4, 10420-10423
CO2 photoreduction experiment
Methanol Yield by using Cs2[Mo6Br14] and
Cs Mo cluster - 6679
TBA Mo cluster - 5550

46. 46
Part B: Hexamolybdenum Clusters supported on Graphene Oxide: Visible-Light
Induced Photocatalyst for Reduction of Carbon Dioxide into Methanol
A schematic illustration of (a) GO nanosheet decorated with various oxygen functionalities
(b) immobilization of Cs2Mo6Bri
8Bra
6 / (TBA)2Mo6Bri
8Bra
6 clusters on the GO nano-sheets,
and (c) molecular structure of Mo6 cluster representing position of inner and apical ligands
Synthesis of graphene oxide supported Mo-cluster
=
50 mg clusters
water and ethanol(2:1)
50 mL GO (2.24 mg/mL)
46Carbon, 2015, 94, 91 –100

47. (a) GO nanosheets (b) GO-Cs2Mo6Bri
8Bra
x and (c)
GO-(TBA)2Mo6Bri
8Bra
x composites.
FESEM micrographs and element
mapping
(a) GO-Cs2Mo6Bri
8Bra
x (b) GO-(TBA)2Mo6Bri
8Bra
x
HRTEM images
47
Carbon, 2015, 94, 91 –100

48. (a) GO, Cs2Mo6Bri
8Bra
x clusters and GO- Cs2Mo6Bri
8Bra
x composite; and (b) GO,
(TBA)2Mo6Bri
8Bra
6 clusters and GO-(TBA)2Mo6Bri
8Bra
6 composite.
FTIR spectra
48
Carbon, 2015, 94, 91 –100

49. High resolution C 1s XPS spectra
49
Carbon, 2015, 94, 91 –100

50. Cs 3d XPS spectra Cs 3d5/2 (a) Cs 3d5/2
(b) Mo 3d
50
Carbon, 2015, 94, 91 –100

51. (c) Br 3d regions
(d) Br 3d region
Cluster
Br/Mo Found = 2.6
theoretical value= 2.33
After immobilization
Br/Mo Found =1.6
theoretical = (1.33).
51
Carbon, 2015, 94, 91 –100

52. DT-TGA patterns
52
Carbon, 2015, 94, 91 –100

53. UV-visible spectra
Tauc plot for band gap calculation
53
Carbon, 2015, 94, 91 –100
0.9 eV
GO- Cs2Mo6Bri
8Bra
x
1.25 eV
GO- (TBA)2Mo6Bri
8Bra
x

54. Methanol Yield from different components
54
Carbon, 2015, 94, 91 –100
Recycling experiments using
(a) GO- (TBA)2
Mo6
Bri
8
Bra
x
and (b) GO- Cs2
Mo6
Bri
8
Bra
x
.

55. Plausible mechanism of photoreduction of CO2
into methanol catalyzed
by GO-hexamolybdenum composite
55
Carbon, 2015, 94, 91 –100
E0
=E0
(pH0) – 0.06 (pH)

56. 56
Part C: Octahedral Rhenium K4[Re6S8(CN)6] and Cu(OH)2 cluster modified TiO2
for the Photoreduction of CO2 under Visible Light Irradiation
Schematic representation of the
[Re6S8(CN)6]4–
cluster unit
Applied Catalysis A 2015, 499, 32–38
Synthesis of photocatalyst
Step 1: First Cu(OH)2 modified P25 TiO2 was synthesized
P25 TiO2
4.0 g
Dispersed in 0.25 M
NaOH (250 mL)
100 ml of 0.0077 M
Cu(NO3)2drop-wise with
vigorous stirring
Cu(OH)2/TiO2
Cu(OH)2/TiO2
Step 2: Then Re clusters was attached to Cu(OH)2/TiO2
Re-cluster@Cu(OH)2/TiO2
K4[Re6S8(CN)6]
1 g
200 mg
Reflux in DMF, 24 h
Cu – 1.68 wt%
Re – 1.65 wt%
Energy Environ. Sci. 2011, 4, 1364–1371.
Covalent immobilization via Re-CN-M bridges

57. 57N2
adsorption-desorption isotherm and Pore size distribution
Applied Catalysis A 2015, 499, 32–38
SEM images of a) Cu(OH)2/TiO2, b) Re-
cluster@Cu(OH)2/TiO2, and EDX spectra
Elemental mapping of Re-cluster@Cu(OH)2/TiO2 for a) Ti
and b) Re
100-250nm
100-250nm
SBET- 40.91 m2
g−1
rp- 11.87 nm
Vp - 0.1215 cm3
g−1
SBET- 8.96 m2
g−1
rp- 83.51 nm
Vp - 0.1871 cm3
g−1
Type IV Type II

58. 58
Tauc plots for optical band gap determination of a) K4[Re6S8(CN)6], b) Cu(OH)2/TiO2 and
c) Re-cluster@ Cu(OH)2/TiO2
Applied Catalysis A 2015, 499, 32–38
TGA of a) K4
[Re6
S8
(CN)6
], b) Cu(OH)2
/TiO2
and c) Re-
cluster/Cu(OH)2
/TiO2
UV/Vis absorption spectra of a) K4[Re6S8(CN)6], b) Re-
cluster@Cu(OH)2/TiO2 and c) Cu(OH)2/TiO2 and d) TiO2
2.50 eV
2.69 eV,
3.11 eV 2.43 eV

59. 59Possible mechanism of the reaction
Applied Catalysis A 2015, 499, 32–38
CO2 conversion to methanol using a) Re-cluster@ Cu(OH)2/TiO2 , b) Re cclusters
at same equimolar amount and c) Cu(OH)2/TiO2
Methanol - 149 μmol/0.1 g cat
Gaseous analysis- CO2 (99.24%, 1772.14
μmol), H2(0.68%, 12.14 μmol) and CO
(0.08%, 1.43 μmol
TEOA sacrificial donor

60. 60
List of Publications
1. P. Kumar, S. Varma and S. L. Jain, J. Mater. Chem. A, 2014, 2, 4514–4519.
2. P. Kumar, A. Kumar, B. Sreedhar, B. Sain, S. S. Ray and S. L. Jain, Chem. Eur. J. 2014, 20, 6154-61611.
3. P. Kumar, S. Kumar, S. Cordier, S. Paofai, R. Boubherroub and S. L. Jain, RSC Adv., 2014, 4, 10420.
4. P. Kumar, B. Sain and S. L. Jain, J. Mater. Chem. A, 2014, 2, 11246-11253.
5. P. Kumar, A. Bansiwal, N. Labhsetwar and S. L. Jain, Green Chem, 2015, 17, 1605-1609.
6. P. Kumar, H. P. Mungse, S. Cordier, R. Boukherroub, O P. Khatri, and S. L. Jain, Carbon, 2015, 94, 91 –100.
7. P. Kumar, H. P. Mungse, O. P. Khatri and S. L. Jain, RSC Adv., 2015,5, 54929-54935.
8. P. Kumar, N. G Naumov, R. Boukherroub, S. L Jain, Appl. Catal. A 2015, 499, 32–38.
9. P. Kumar, R. K. Chauhan, B. Sain, and S. L. Jain, Dalton Trans, 2015, 44, 4546-4553.
10. P. Kumar, A. Kumar, C. Joshi, R. Singh, S. Saran, S. L. Jain, RSC Adv., 2015, 5, 42414-42421.
11. P. Kumar, G. Singh, D. Tripathi and S. L. Jain, RSC Adv., 2014, 4, 50331-50337.
12. P. Kumar, K. Gill, S. Kumar, S. K Ganguly, S. L. Jain, J. Mol. Catal. A 2015, 401, 48–54.
13. P. Kumar, C. Joshi, N. Labhsetwar, R. Boukherroub and S. L. Jain, Nanoscale, 2015, 7, 15258-15267.
14. P. Kumar, C. Joshi, A. Barras, B. Sieber, A. Addad, L. Boussekey, S. Szunerits, R. Boukherroub and S. L. Jain, appl.
Catal. B 2017, 205, 654-665
15. P. Kumar, C. Joshi, A. K. Srivastava, P. Gupta, R. Boukherroub and S. L. Jain, ACS Sus. Chem. Eng. 2016, 4, 69-75
16. A. Kumar, P. Kumar, C. Joshi, S. Ponnada, A. K. Pathak, A. Ali, B. Sreedhar and S. L. Jain, Green Chem.
2016, 18, 2514-2521.
17. S. Kumar, P. Kumar and S. L. Jain, J. Mater. Chem. A, 2014, 2, 18861-18866.
18. S. Kumar, P. Kumar, and S. L. Jain, RSC Adv., 2013, 3, 24013-24016.
19. D. Chauhan, P. Kumar, C. Joshi, N. Labhsetwar, S. K. Ganguly and S. L. Jain, New J. Chem., 2015, 39, 6193-6200.
20. A. Bansal, P. Kumar, C. D. Sharma, S. S. Ray, S. L. Jain, J. Pol. Sci. A, 2015, 53, 2739-2746.
21. R. Gusain, P. Kumar, O. P. Sharma, S. L. Jain, O. P. Khatri, Appl. Cat. B 2015, 181, 352-362.
22. V. Panwar, P. Kumar, A. Bansal, S. S Ray, S. L Jain, Appl. Cat. A, 2015, 498, 25–31.
23. V. Panwar, P. Kumar, S. S Ray, S. L Jain, Tetrahedron letters, 2015, 56, 3948–3953.
24. C. Joshi, P. Kumar, B. Behera, A. Barras, S. Szunerits, R. Boukherroub and S. L. Jain, RSC Adv. 2015, 5, 100011-
100017.
25. A. Bansal, A. Kumar, P. Kumar, S. Bojja, A. K. Chatterjee, S. S. Ray, S. L. Jain, RSC Adv. 2015, 5, 21189-21196

61. 61
Book Chapter
1. P. Kumar, S. L. Jain and R. Boukherroub, Graphene-based nanocomposite materials for the photoreduction of carbon
dioxide into valuable organic compounds, Innovations in Nanomaterials , Nova Science Publishers, Inc. USA. (Editors: Al-
Nakib Chowdhury, Joe Shapter, and Abu Bin Imran. ISBN: 978-1-63483-572-5.
2. P. Kumar, A. Kumar, C. Joshi, R. Boukherroub, S. L. Jain,
Graphene-semiconductor hybrid photocatalysts and their
application in solar fuel production, Graphene Composites, WILEY-Scrivener Publisher, USA.
Awards
Awarded with Raman-Charpak fellowship to visited ‘Institut de Recherche Interdisciplinaire (IRI, USR 3078 CNRS),
Université Lille 1, France’ for six month under the supervision of Dr. Rabah Boukherroub (Group Director)
1. Pawan Kumar, Bir Sain, and Suman L. Jain, Magnetically separable Fe3
O4
@SiO2
@TiO2
functionalized by Co-Ru
complexes for the visible light induced photoreduction of CO2
., Research Scholars Day, 16-17 Dec 2013, IIST
Thiruvananthpurum, India (working under umbrella of Indian Space Research Organization).
2. Pawan Kumar, Bir Sain, Suman L. Jain, Visible light driven photoreduction of carbon dioxide to methanol using
trinuclear ruthenium complex immobilized to graphene oxide, National conference on nanotechnology and renewable
energy, 28-29 Apr 2014, Jamia Millia Islamia, New Delhi, India.
3. Pawan Kumar, Chetan Joshi and Suman L. Jain, Visible light assisted photocatalytic reduction of CO2 using
graphene oxide supported heteroleptic ruthenium complex, International conference on sustainable energy and
technologies(ICSET 2014), 11-13 Dec 2014, PSG College of Technology, Coimbatore, India (International host-
University of Exeter, UK, University of Oslo, Norway, IFE Norway)
Poster Presentation
Pawan Kumar, Bir Sain, and Suman L. Jain, Development of visible light active photocatalysts for reduction of CO2
to C1
chemicals, First International Seminar on Nanotechnology in Conventional and Alternate Energy Systems, 12-
13 Aug 2013, University of Petroleum and Energy Studies, Dehradun, India .
Workshop
Advanced Material Processing and characterization, 17-22 Aug 2014, organized by Dept. of Materials Science and
Engineering, Indian Institute of Technology, Kanpur
Oral talk in conference

62. 62
Thanks