Visible-light-driven Efficient Photocatalytic Reduction of Organic Azides to Amines over CdS Sheet–rGO Nanocomposite

Article abstract of DOI:10.1002/asia.201701614

CdS sheet–rGO nanocomposite as a heterogeneous photocatalyst enables visible-light-induced photocatalytic reduction of aromatic, heteroaromatic, aliphatic and sulfonyl azides to the corresponding amines using hydrazine hydrate as a reductant. The reaction shows excellent conversion and chemoselectivity towards the formation of the amine without self-photoactivated azo compounds. In the adopted strategy, CdS not only accelerates the formation of nitrene through photoactivation of azide but also enhances the decomposition of azide to a certain extent, which entirely suppressed formation of the azo compound. The developed CdS sheet-rGO nanocomposite catalyst is very active, providing excellent results under irradiation with a 40 W simple household CFL lamp.

Full text of DOI:10.1002/asia.201701614

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Accepted Article
Title: Visible-light-driven efficient photocatalytic reduction of organic
azides to amine over CdS sheet-rGO nanocomposite
Authors: Subhash Chandra Ghosh
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Visible-light-driven efficient photocatalytic reduction of organic
azides to amine over CdS sheet-rGO nanocomposite
Krishnadipti Singha, Aniruddha Mondal, Subhash Chandra Ghosh* and Asit Baran Panda*
Abstract: CdS sheet-rGO nanocomposite as heterogeneous
photocatalyst enables visible light induced photocatalytic-reduction of
aromatic, heteroaromatic, aliphatic and sulfonyl azides to the
corresponding amines using hydrazine hydrate as a reductant. The
reaction shows excellent conversion and chemoselectivity towards
the formation of the amine without self-photoactivated azo
compounds. In the adopted strategy, CdS not only accelerate the
formation of nitrene through photo-activation of azide but also
enhance the decomposition of azide to a certain extent which entirely
suppressed the azo compound formation. The developed catalyst
CdS sheet-rGO nanocomposite is very active to provide excellent
results under 40W simple household CFL lamp.
Recent years, development of efficient visible light driven
photocatalytic chemical conversion, i.e., harvesting of solar
energy to chemical energy, have been activated globally, as the
solar energy is the only sustainable energy resource on earth and
provides energy efficient greener routes. However, most of the
organic molecules are photo transparent, and the photoactive
molecules resulted in the undesired product.[4] Thus, a suitable
light active catalyst is needed for desired photoinduced
transformation. Most of the developed heterogeneous visible light
[5]
active catalyst utilize precious metals
and till date, very few
heterogeneous catalyzed photo induced organic transformations
are known, such as alcohol to carbonyls/esters, nitro to amine,
an amine to imine and hydrocarbon oxidation.[6] Thus, it is highly
desirable to develop visible light active precious metal-free
catalyst and exploration to photoinduced new organic
Introduction
transformations.
Notably,
the
photo-induced
selective
transformation of azide to amine is challenging. Azides are
photoactive and resulted in azo compounds through self-
activation and to the best of our knowledge; there is no such
report on the photocatalytic reduction of organic azides to the
corresponding amine.
Reduction of organic azide to the corresponding amine is one
of the most important straightforward protocols for amine
synthesis, owing to the easy accessibility of azides from
respective halides, alcohols, and sulfonates and has potential
industrial applications in organic chemistry, chemical biology as
well as in chemical industry, e.g., synthesis of natural products
and bioactive molecules.[1-3] A large number of synthetic protocols,
using homogeneous sensitive reducing agents, have been
developed for this reaction.[2] Although these developed protocols
were ended with satisfactory results, however, most of them have
several disadvantages concerning general applicability, cost,
waste generation, safety, and most importantly chemo-selectivity
and energy efficiency.[2] To overcome the drawbacks mentioned
above, a heterogeneous catalyst using mild reducing agent was
developed for this reaction.[3] Mainly, Ranu and co-workers
utilized Cu(0) nanoparticle-HCOONH4 system,[3a] and Pagoti et
al.[3b] reported Fe3O4-N2H4 for azide to amine conversion.
However, both the reaction needed higher reaction temperature
(100-120°C) to complete the reaction. In addition to this, Cu(0)
nanoparticle is not reusable.[3a] Thus, an efficient, simple
heterogeneous catalyst system which can work at room
temperature is highly desirable to make it energy efficient.
[4]
CdS is an important visible light active, efficient
semiconductor photocatalyst.[7] However; its photocatalytic
activity is not satisfactory originating from tremendous
photogenerated electron-hole recombination. The extent of
recombination for 2D CdS nanosheets are quite low owing to their
high surface area, quantum confinement and most importantly
improved lifetime of photo-generated electron originating from
transportation of electron through its long-range lattice
periodicity.[8] Recently we have developed a simple procedure for
the synthesis of ultrathin 2D sheet mediated CdS flower, which
showed good photocatalytic activity.[9] In the recent past, CdS-
reduced graphene oxide (rGO) nanocomposites have received
tremendous attention as an efficient visible light active
photocatalyst, owing to stabilization of photo-generated electron,
due to shifting of an excited electron from CdS to conducting
rGO.[10] Thus it is expected that the ultrathin CdS sheet-rGO
nanocomposite would be the efficient photocatalyst, which has
not been explored yet.
In continuation of our previous work on the development of
visible light active potent photocatalyst for energy efficient green
11]
organic transformation,[9,
herein we report the selective
K. Singha, A. Mondal, Dr. S. C. Ghosh, Dr. A. B. Panda
Central Salt and Marine Chemicals Research Institute (CSIR-
CSMCRI) and CSMCRI-Academy of Scientific and Innovative
Research (AcSIR)
G. B. Marg, Bhavnagar-364002, Gujarat,
India.
E-mail: scghosh@csmcri.org, abpanda@csmcri.res.in
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.200xxxxxx.
reduction of organic azides to the corresponding amine at room
temperature using ultrathin CdS sheet-rGO nanocomposite as
photocatalyst and hydrazine hydrate (N2H4·H2O) as hydrogen
source under 40W simple household CFL lamp. Here it is
essential to mention that we have used CFL lamp to make the
procedure simple and acceptable, to avoid the required special
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Results and discussion
AFM image of CdS-rGO nanocomposite also depicts the
dispersion of nearly uniform spheres (~100 nm) over rGO surface
(Figure S3, Supporting Information). In the FTIR spectrum of
CdS-rGO nanocomposite, the C=C stretching at around 1650 cm-
1 of pristine GO is shifted to 1580 cm-1, ascribed to the interaction
of aromatic ring π electrons with Cd of CdS. Also, the band
intensity of all oxygen-containing functional groups of bare GO is
reduced reasonably in nanocomposite (Figure S4, Supporting
Information). The phenomena indicate the efficient reduction of
GO by hydrogen and good interaction between CdS and rGO in
Fig. 1 (a) XRD pattern, (b-d) TEM and HR-TEM images, (e) UV-Vis. absorption
the
nanocomposite.
Raman
spectrum
of
CdS-rGO
nanocomposite showed the presence of two intense peaks at 298
and 597 cm-1 ascribed to CdS, and two low intense peaks at 1354
and 1593 cm-1, for D and G bands of GO (Figure S5, Supporting
Information). The corresponding ID/IG ratios are 1.02 and 0.84 for
rGO–CdS and bare GO. Enhancement of corresponding ID/IG
ratios for CdS-rGO nanocomposite confirmed the reasonable
reduction and retention of order structure of GO in the composite.
Figure 1e illustrates the UV−Vis. absorption spectra of bare CdS
and CdS/rGO composite. Bare CdS flower showed an
unstructured spectrum with an absorption edge at ~407 nm. The
obtained absorption edge is reasonably blue shifted compared to
that of bulk CdS (490 nm, 2.5 eV), ascribed to the strong quantum
confinement due to the ultra-thin sheet. Whereas, absorption
spectra of CdS-rGO nanocomposite showed reasonably
enhanced visible light absorption with identical absorption
characteristic of CdS. Adsorption in the visible region can be
ascribed to the absorption of rGO itself and further validate the
composite formation. In corresponding PL spectra, reduction in
PL peak intensity for CdS-rGO nanocomposite compared to that
of PL of pristine CdS confirms the efficient interfacial charge
transfer the junction of CdS and rGO (Figure 1f). Further, the
photoluminescence lifetime experiment showed that the lifetime
of rGO-CdS nanocomposite (0.6814 ns) is higher to that of bare
CdS (0.4086 ns), and confirmed the reasonable enhancement in
charge separation for CdS-rGO composites (Figure S6,
Supporting Information). The PL observation confirms the CdS
flowers formed an appropriate composite with rGO through
strong electrostatic interaction.
Initially, reduction of o-azidonitrobenzene to o-nitroaniline
was chosen as a model to check the catalytic efficiency of
synthesized CdS sheet-rGO nanocomposite using hydrazine as
a reducing agent under 40W simple household CFL lamp at room
temperature. Amount of catalyst, hydrazine with a variation of
solvent and time was varied to optimize the reaction condition
(Table S1, Supporting Information). It was observed that the
selective azide reaction in benzotrifluoride (BTF) solvent, with ten
equivalent of hydrazine and 10 mg of catalyst for 0.25 mmol of
the substrate provides the best result (100% selectivity, 95%
isolated yield) after 4h of the selective azide reaction. Although
the reaction proceeds quite satisfactory in toluene with 82% yield,
but the reactivity in the tested other solvent, e.g., DMF, MeOH,
and CH3CN were unsatisfactory. Here it is essential to mention
that till ten equivalent of hydrazine the reaction showed
chemoselectivity and strictly the azide was reduced, but further
increase in the amount of hydrazine to 15 equivalent the yield of
nitroaniline was decreased drastically to 30%. The nitro group
spectra, and (f) PL spectra of the synthesized CdS sheet mediated flower and
corresponding rGO composite (CdS-rGO).
precaution to manage enormous heat from commonly used high
power Xe lamp for good activity. The developed catalyst synthetic
strategy is based on the preparation of two separate colloidal
[9]
suspensions of ultrathin (~0.8nm) sheet mediated CdS flower
in toluene, and DMF dispersed graphene oxide (GO). Then
physical mixing of two suspended solutions followed ultra-
sonication and addition of hydrazine hydrate to mixed suspension
resulted in the precipitate of the desired composite. Addition of
CdS sheet to GO, the CdS sheets were bound to the graphene
surface through the interaction of a functional group of GO and
Cd of CdS and then GO reduced to rGO by hydrazine.[12]
(Experimental section, Supporting Information).
Figure 1a represents the XRD patterns of bare CdS flower
and CdS flower /rGO composite. The X-ray diffraction peaks of
bare CdS can be indexed to Zinc blend structure (cubic) of CdS
(JCPDS File No. 01-75–1546). The CdS-rGO nanocomposite
showed similar diffraction pattern to that of pristine CdS, except
a hump in the 2θ range 20- 25°, indexed to rGO, indicate the
successful incorporation of CdS in rGO moiety. TEM image of
bare CdS confirmed that the synthesized CdS are a flower in
shape, flowers are uniform, with a size of 100-125 nm and flowers
are made of assembled ultra-thin sheets (Figure S1, Supporting
Information). TEM image of corresponding CdS-rGO
nanocomposite indicates the uniform distribution of CdS flower
over graphene sheet (Figure 1b & Figure S2, Supporting
Information). The magnified TEM image depicts the presence of
two type of sheets, the dense sheets in inner part can be ascribed
to the CdS, and lighter part in the outer side may be the rGO
(Figure 1c & Figure S2, Supporting Information). As expected,
HR-TEM image also showed the presence of two types of distinct
fringes. The identifiable straight or cross fringes in inner side with
an inter planner distance of 0.33 ± 0.05 nm, indexed to (111) plain
of CdS ZB structure and random fringes in outer side ascribed to
the rGO, the inherent characteristic of graphene sheet (Figure 1d
& Figure S2, Supporting Information). Thus, TEM image confirms
the formation of nanocomposite and revalidate the XRD result.
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was started to reduce, and o-phenylenediamine became the
major product (65%), which was further decreased gradually with
enhancement of hydrazine amount and with 20 equivalent of
hydrazine the yield of product 2-nitroaniline is reduced to 20%.
From the result, it is evidenced that in the CdS-rGO
nanocomposite/hydrazine system reduction of azide functionality
is more facile to that of the nitro group, which required an
enhanced amount of hydrazine.[3a] So, in a lesser amount of
hydrazine, the azide group was reduced selectively.
As this methodology was found highly effective for selective
photocatalytic reduction of o-azidonitrobenzene to o-nitroaniline,
we extended the substrate scope to different aromatic azides,
containing different functional groups to establish the chemo-
selectivity, broad applicability of our developed catalyst and
methodology. The results were summarized in (Table 1). To our
delights, the reduction of azides took place very smoothly and
selectively with excellent yield. However, depending upon the
functional group present in the moiety reaction time differ. Similar
to that of o-azidonitrobenzene, m- and p- azidonitrobenzene
resulted in corresponding nitro aniline selectively with excellent
yield (entries 2a-2c, Table 1). Electron withdrawing
trifluoromethoxy group at para to azide also worked very well
(entry 2d, Table 1). It was observed, that in the presence of the
electron donating group, e.g. methyl and methoxy group,
irrespective of the position in the aromatic ring, reaction needed
longer time to complete and provided high to excellent yield
(entries 2e- 2h, Table 1). Chloro and iodo substituted azides also
efficiently Reduced to the corresponding amine in high yields
(entries 2k-2n, Table 1). To our delight, other azides functionality
like azidoformate, sulfonyl azide, benzoyl azide is also smoothly
reduced to carbamate, sulphonamide amide respectively with
excellent yield (entries 2o-2p, Table 1). As expected, aliphatic
azides also efficiently reduced to the corresponding amine in
good to excellent yield (entries 2r-2t, Table 1). 4-azido styrene is
also efficiently reduced without affecting the double bond (entry
2u, Table 1). Functional group like acid, ester, and amides are
also well tolerated. Other aromatic and heteroaromatic azides
especially 2-azido pyridines reduced to aminopyridines in good
yields (entries 2Z, Table 1). The obtained results for selective
reduction of azide for different organic substance, which include
aromatic azide, aliphatic, sulfonyl, and carbonyl azides, are
comparable or sometimes better concerning the reported
homogeneous and heterogeneous catalyst (Table S2, Supporting
Information).
To establish the necessity and superiority of CdS sheet-rGO
nanocomposite, reduction of o-azidonitrobenzene to o-
nitroaniline were performed using bare CdS sheet, CdS sphere,
and corresponding rGO composite, bulk CdS and without catalyst
(Table 2). It was observed that CdS sheet-rGO composite
showed superior activity, particularly to that of rGO composite of
5nm CdS sphere. This is due to the horizontal dispersion of thin
CdS sheet over rGO, as evidenced by TEM, which facilitate the
maximum possible interaction and electron transportation
through long-range lattice periodicity, in-turn charge separation,
and showed enhanced activity. It is surprising to note that the all
the azides resulted in an only single product of the corresponding
amine after performed photocatalytic hydrogenation reaction.
Table 1 Substrate scope of the chemoselective azide hydrogenation reaction.
Table 2. Variation of yield with catalyst
Entry
Catalyst(mg)
N2H4 (eqv.) a
Time
Yield b
1
2
4
5
6
CdSf c
0.15
0.15
0.15
0.15
0.15
4
73
95
45
69
84
CdSf-rGO
CdS(Bulk)
CdS sp d
CdS sp-rGO
4
12
6
6
a eqv.:Equivalent, b isolated yield, c CdSf: sheet mediated flower, d CdS sp:
5 nm spherical particle. Reaction condition: 2-azidonitrobenzene (0.25
mmol) , Catalyst (10 mg), hydrazine hydrate (10 eqv) , BTF (1.5 mL ) in 40W
CFL lamp.
Whereas the aromatic azides are very prone to photo-dissociate
to corresponding reactive aryl nitrene, which subsequently
dimerizes To azobenzene or rearrange to ketenimines, in the
presence of amine, it produces 2-amino-3H-azepines (Scheme
S1, entries 2r-2t, Table 1).[6] Thus, the obtained results indicate
that the self-transformation of nitrene was entirely suppressed by
plenty of proton in the adopted experimental condition, which was
subsequently resulted in the corresponding amine.
For further confirmation of the proposed mechanism and
identify the origin of obtained 100% selectivity of the
corresponding amine during performed photocatalytic
Condition: 0.25 mmol substrate, 10 eq. Hydrazine hydrate, 10 mg CdS-rGO,
1.5 mL BTF and visible light irradiation using 40W CFL lamp.
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hydrogenation of azide, we did some controlled reactions with p-
nitroazide, a visible light active azide, in the absence of hydrazine
or catalyst and both. keeping all other parameters identical
(Scheme S2, Supporting Information). In the absence of
hydrazine, the corresponding azo compound was found to be the
only one product, which was 30% in the absence of a catalyst and
55% in the presence of a catalyst. This result indicates that the p-
nitroazide was self-photo-activated under visible light and
resulted in azo compound through nitrene intermediate with a
very less conversion, but CdS accelerate the photoactivation, in-
turn the conversion was increased. However, in the presence of
hydrazine and absence of a catalyst, conversion of azide was
60%, with the 70% p-nitroaniline as the major product and 27%
of the corresponding azo compound. Results indicate that
hydrazine enhances the conversion of azide to a certain extent
(60%) by shifting the reaction equilibrium through the formation
of the corresponding amine. However, hydrazine alone cannot
stop the azo compound formation. From the controlled reactions,
it is evident that CdS not only accelerate the formation of nitrene
through photo-activation of azide but also enhance the
decomposition of azide to a certain extent which fully suppressed
the azo compound formation.
Based on the experimental findings as mentioned above, a
probable reaction mechanism is proposed for the effective
photocatalytic reduction of azide to the corresponding amine.
According to the proposed mechanism, at first, the catalyst CdS
absorb energy (h) from visible light, then the valence band
electron transfers to its conduction band and generate a hole in
the valence band. The electron in high energy state directly
transforms to azide from CdS band or through rGO. After
accepting the electron, the azide transformed to nitrene radical
and liberated N2. Simultaneously, the hydrazine was
decomposed to N2, proton (H+) and electron. Subsequently, the
nitrene radical reacts with a proton from hydrazine and produced
amine, whereas the electron was shifted to the photogenerated
hole in VB of CdS (Figure 2, Scheme S3, Supporting Information).
Thus, hydrazine plays a dual role in the performed reaction
procedure; act as proton Source as well as a source of the
electron, which diminished the possible photo-corrosion of CdS.
Re-usability of a heterogeneous catalyst is a vital parameter. The
developed CdS sheet-rGO composite was reused consecutive
four times, after separation from the reaction mixture and washing
and no such substantial alteration in the catalytic efficiency were
observed compared to that of the fresh catalyst (Figure S7,
Supporting Information). There is
a high probability of
photocorrosion of the catalyst during the repeated reaction, which
may cause the structural and morphological damage. So, we
performed the XRD and TEM analysis of used CdS-rGO catalyst
after the second cycle (Figure S8). No such distinct structural and
morphological change is observed, and the issue of
photocorrosion for adopted reaction procedure can be ruled out.
Reduction of o-azidonitrobenzene in an identical reaction
condition under dark the conversion was of negligible and
confirmed that the performed reduction is strictly photocatalytic.
Conclusions
In summary, we have developed a simple visible light driven
photocatalytic protocol for selective reduction of organic azides to
corresponding amines using ultra-thin sheet mediated uniform
CdS flowers-rGO nanocomposite and 40W CFL lamp as light
source.
The
developed
protocol
showed
excellent
chemoselectivity and reduced azide group selectively in the
presence of other functional groups such as nitro, carboxylic acid,
ester, amide, ether, and halogen. The developed protocol is not
only applicable for aromatic azide but also applicable aliphatic,
sulfonyl, and carbonyl azides. The photocatalytic activity is
comparable or sometimes better concerning the literature
reported homogeneous as well as a heterogeneous catalyst.
Finally, our catalyst is very active under 40W CFL lamp and can
be utilized to develop a simple protocol of other organic
transformations through visible light-induced photocatalytic
reactions.
Experimental Section
Materials
Cadmium nitrate, 30% aqueous ammonium hydroxide solution
were purchased from S. D. Fine Chemical, India. Decanoic acid
ethyl xanthate and all the organic substrates were purchased
from Sigma-Aldrich. All the chemicals were used without further
purification. For all applications, water with a resistivity of 18 MΩ
cm was used, obtained from a Millipore water purifier.
Synthesis.
Synthesis of CdS flower. The ultrathin sheet assembled CdS
flower was synthesized following our previously reported
method.[9] In a typical experiment procedure, in the 10 ml,
aqueous solution with 0.5gm (1.88 mmol) cadmium nitrate 4ml
30% aqueous ammonium hydroxide solution was added
dropwise to get a clear solution of cadmium ammonium complex
solution. The prepared cadmium complex solution was added
dropwise with constant stirring to a pre-prepared hot (~60°C)
biphasic mixture of water (20ml) and decanoic acid (4g), which
gave a transparent solution. A 10 ml aqueous ethyl xanthate
Fig. 2: A Probable proposed photocatalytic pathway for reduction of azide to
the amine.
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(potassium salt, 0.32 g) solution was added to the resulted
transparent changes to yellowish, but it remains transparent. 33
ml of the yellowish solution was transferred into a preheated
(150°C) 50 ml Teflon-lined stainless autoclave for 2h with proper
sealing, allowed to cool naturally and resultant yellow CdS flower
was collected and washed with methanol for several times and
dried in air. Monodispersed spherical CdS particles (5 nm)
stabilized by decanoic acid has also been synthesized following
our previously reported method (ESI).[11c]
CSIR-CSMCRI Communication No. 132/2017. The Authors
would like to acknowledge DST, India for financial support
(EMR/2014/001219). The authors also acknowledge the
“AESDCIF” division of CSMCRI for providing instrumentation
facilities. K. Singha acknowledges CSIR, India, for fellowships.
Keywords: Organic azide • Reduction• Photocatalysis • CdS •
Visible light
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Synthesis of the rGO-CdS nanocomposite. First CdS (0.5
mmol) was dispersed in toluene. Separately GO (5 weight %),
synthesized following a typical modified Hummers method, was
dispersed in DMF. Then dispersed solution of GO were added to
CdS solution taking in a 500 mL beaker. The whole solution was
stirred and sonicate for 12h. Then 1.5 mL hydrazine was added
to this solution; again the whole solution was stirred for 2-3h. after
that solution was centrifuged, collect solid catalyst, and the
catalyst was dried in an oven at 60oC for 12h.
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For evaluation of X-ray diffraction patterns of synthesized
catalysts MINIFLEX-II (FD 41521) powder diffractometer was
used. JEOL JEM 2100 transmission electronic microscope (TEM)
was used for morphological and structural evaluation. Samples
were prepared by mounting dichloromethane dispersed samples
on lacey carbon formvar-coated Cu grids (300 mesh). The FT-IR
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spectroscopic measurements were carried out using
a
PerkinElmer GX spectrophotometer. The spectra were recorded
in the range 400–4000cm−1 in KBr media. UV-Vis absorption
spectra and photoluminescence spectra of toluene dispersed
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nanoparticles were recorded with
a Shimadzu UV-2550
spectrophotometer and Fluorolog, Horiba Jobin Yvon fluorometer
respectively.
General procedure for the selective reduction of azides to an
amine using rGO-CdS.
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Photocatalytic selective reduction of organic azides was
performed in a 15 mL test tube under irradiation of 40 W visible
light. In a typical process, a mixture of azide (0.25 mmol) in BTF
(1.5 mL), rGO-CdS (10 mg) and hydrazine monohydrate (0.125
mL, 10 eq) was transferred into15 mL test tube and stirred for 10
minutes under N2 atmosphere. Then the reaction mixture was
irradiated by 40 W lamp for 4-16h, the reaction mixture was
monitored by TLC. After the reaction, the mixture was centrifuged
to remove the catalyst particle. The aqueous layer was extracted
with ethyl acetate (3 x 10 mL). The combined organic extracts
were washed with water and brine, dried over Na2SO4 and
evaporated under reduced pressure. The crude product was
purified by flash chromatography (EtOAc/hexanes eluent) to
afford the desired pure amine. Most of the amines were
analytically pure before flash chromatography. The recovered
catalyst was washed with methanol (2 x 5 mL), dried under
vacuum, and reused for the next cycle of the reaction.
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Acknowledgements
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10.1002/asia.201701614
Chemistry - An Asian Journal
FULL PAPER
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FULL PAPER
Visible
light
induced
efficient
Krishnadipti Singha, Aniruddha Mondal,
Subhash Chandra Ghosh* and Asit
Baran Panda*
photocatalytic reduction of aromatic,
heteroaromatic, aliphatic and sulfonyl
azides
organic
azides
with
Page No. – Page No.
corresponding amines using hydrazine
hydrate as a reductant and CdS sheet-
Visible-light-driven
efficient
rGO
heterogeneous
nanocomposite
catalyst.
as
a
The
photocatalytic reduction of organic
azides to amine over CdS sheet-rGO
nanocomposite
developed catalyst is very active and
provided excellent results under 40W
simple household CFL lamp.
For internal use, please do not delete. Submitted_Manuscript
This article is protected by copyright. All rights reserved.