Arsenic Removal from Contaminated Water Using Three-Dimensional Graphene-Carbon Nanotube-Iron Oxide Nanostructures

Vadahanambi, Sridhar,Lee, Sang-Heon,Kim, Won-Jong,Oh, Il-Kwon American Chemical Society 2013 Environmental science & technology Vol.47 No.18

<P>We report a highly versatile and one-pot microwave route to the mass production of three-dimensional graphene-carbon nanotube-iron oxide nanostructures for the efficient removal of arsenic from contaminated water. The unique three-dimensional nanostructure shows that carbon nanotubes are vertically standing on graphene sheets and iron oxide nanoparticles are decorated on both the graphene and the carbon nanotubes. The material with iron oxide nanoparticles shows excellent absorption for arsenic removal from contaminated water, due to its high surface-to-volume ratio and open pore network of the graphene-carbon nanotube-iron oxide three-dimensional nanostructures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2013/esthag.2013.47.issue-18/es401389g/production/images/medium/es-2013-01389g_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es401389g'>ACS Electronic Supporting Info</A></P>

3-D graphene-carbon nanotube-nickel nano-architectures for supercapacitors

( Vadahanambi Sridhar ),권고은,박현 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

We report a simple and facile technique to transform naphthenic acid treated 2-D graphene oxide to 3-D, mesoporous graphene-carbon nanotube (G-CNT) hierarchical nano-architectures using nickel as the catalyst and microwave as the energy source. The as-prepared G-Ni-CNT structure is highly porous and exhibit good conductivity. When applied as electrodes in super-capacitor, our G-Ni-CNT shows high specific capacitance of 894 F g-1 at a current density of 1 A g-1 in 6 M KOH electrolyte solution, with good rate capability and cycling stability. Furthermore, the utility of our newly.

Manganese nitride stabilized on reduced graphene oxide substrate for high performance sodium ion batteries, super-capacitors and EMI shielding

Sridhar, Vadahanambi,Park, Hyun Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.808 No.-

<P><B>Abstract</B></P> <P>Though the utility of manganese compounds such as oxides, sulphides has been well researched in energy storage applications such as super-capacitors and lithium-ion batteries, the utility of manganese nitrides hasn't been reported yet, especially as anode in sodium-ion batteries. In this manuscript we report synthesis of manganese nitride decorated reduced graphene oxide (MnN@rGO) prepared by simple microwave nitridation technique and its utility as anode material in sodium-ion batteries, electrodes in super-capacitors and in EMI shielding applications. In energy storage applications such as sodium ion batteries, MnN@rGO electrodes exhibited sodium storage capacity of 716 mAhg<SUP>−1</SUP> whereas when used as electrodes in super-capacitors, a high capacitance value of 639.2 Fg<SUP>-1</SUP> at scan rates of 10 mVs<SUP>−1</SUP> in 1 M Na<SUB>2</SUB>SO<SUB>4</SUB> aqueous electrolyte was achieved. The EMI shielding effectiveness measured in the X-band region of 2–18 GHz was about 30–32 dB which is 300% more than reduced graphene oxide.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We report microwave synthesis of manganese nitride nano-particles dispersed on reduced graphene oxide substrate (MnN@rGO). </LI> <LI> The applicability of MnN@rGO in sodium-ion batteries, super-capacitors and EMI shielding applications is reported. </LI> <LI> The versatility of our newly developed technique to synthesize MnN nanoparticles on carbon fibers is also demonstrated. </LI> </UL> </P>

Microwave syntheses of graphene and graphene decorated with metal nanoparticles

Vadahanambi, Sridhar,Jung, Jung-Hwan,Oh, Il-Kwon Elsevier 2011 Carbon Vol.49 No.13

<P><B>Abstract</B></P><P>We report a simple and rapid method to synthesize pure graphene sheets and those decorated with metal nanoparticles by combining chemical foaming agents, green oxidizers, and microwave radiation. Under microwave radiation, an intercalated foaming agent between graphite oxide layers plays a key role in the rapid and large expansion of the graphene worm along the thickness direction and in the reduction process of the graphite oxide. By adding metal precursors to the reactant mixture, this technique can also be extended to a one-pot method to synthesize graphene decorated with metal nanoparticles. A variety of metal precursors was used to yield iron, platinum, and palladium decorated graphene sheets. These were tested for their electrocatalytic performance in organic glucose sensing and inorganic electro-active compounds, all of which showed a remarkable increase in electrochemical performance for all cases.</P>

Defect-Engineered Three-Dimensional Graphene–Nanotube–Palladium Nanostructures with Ultrahigh Capacitance

Sridhar, Vadahanambi,Kim, Hyun-Jun,Jung, Jung-Hwan,Lee, Changgu,Park, Sungjin,Oh, Il-Kwon American Chemical Society 2012 ACS NANO Vol.6 No.12

<P>The development of three-dimensional carbon-based nanostructures is the next step forward for boosting industrial applications of carbon nanomaterials such as graphenes and carbon nanotubes. Some defects, which have been considered as detrimental factors for maintaining exceptional materials properties of two-dimensional graphene, can be actively used to synthesize three-dimensional graphene-based carbon nanostructures. Here we describe a fast and heretofore unreported defect-engineered method to synthesize three-dimensional carbon nanohybrid structures with strong bonding between graphene nanoplatelets and carbon nanotubes using simple microwave irradiation and an ionic liquid. Our one-pot method utilizes defect-engineered sequential processes: microwave-based defect generation on graphene nanoplatelets, anchoring of palladium nanoparticles on these defects, and subsequent growth of carbon nanotubes by use of an ionic liquid. The unique three-dimensional nanostructures showed an ultrahigh redox capacitance due to high porosity, a high surface-to-volume ratio from the spacer role of vertically standing one-dimensional carbon nanotubes on graphene sheets, and capacitance-like redox response of the palladium nanoparticles. The proposed defect-engineered method could lead to novel routes to synthesizing three-dimensional graphene-based nanostructures with exceptionally high performance in energy storage systems.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-12/nn3046133/production/images/medium/nn-2012-046133_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn3046133'>ACS Electronic Supporting Info</A></P>

Blister Packing of Copper Hydroxide and Titania Nanoparticles on Graphene and Its Recycling

Sridhar, Vadahanambi,Gangaraju, Deepa,Chun, Ho-Hwan,Park, Hyun American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.23

Microwave synthesis of nitrogen-doped carbon nanotubes anchored on graphene substrates

Sridhar, Vadahanambi,Lee, Inwon,Chun, Ho-Hwan,Park, Hyun Elsevier 2015 Carbon Vol.87 No.-

<P><B>Abstract</B></P> <P>We report a fast and facile microwave technique to synthesize nitrogen-doped carbon nanotubes anchored on graphene substrates from azobis(cyclohexanecarbonitrile), a commodity chemical, commonly used as a radical initiator in polymerization reactions as the nanotube precursor. Micrometer-long, nitrogen-doped carbon nanotubes vertically anchored on graphene was obtained to produce mesoporous, hierarchical nanostructures. X-ray photoelectron spectroscopy reveals that nitrogen moieties exist as pyridinic and graphitic nitrogen. When applied as anodes in lithium-ion batteries, our materials exhibit a high capacity of 1342mAhg<SUP>−1</SUP> even after prolonged cycling reflecting the ability of the three-dimensional network to accommodate the extreme volume changes occurring during the lithiation/delithiation reactions.</P>

Nickel-based metal organic framework/carbon nanotubes nanocomposite (Ni-MOF/CNTs) as efficient catalysts for electro-catalytic oxidation of urea

( Vadahanambi Sridhar ),( Deepa Gangaraju ),( A. M. Shanmugharaj ),박현 한국공업화학회 2022 한국공업화학회 연구논문 초록집 Vol.2022 No.1

2LN-8 Microwave synthesis of nitrogen doped carbon nanotubes anchored on graphene substrates

( Vadahanambi Sridhar ),박현 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

In this manuscript, we report a one-step, all solid-state microwave procedure for simultaneous reduction, nitrogen-doping and concurrent growth of carbon nanotube ‘spacers’ on graphene from a single sustainable precursor, namely urea. Our newly developed technique not only effectively reduces graphene oxide but also results in growth of vertically anchored nitrogen doped carbon nanotubes on graphene substrate to give unique mesoporous, hierarchical, 3D nano-architectures. The utility of our newly developed G-NCNT in energy storage applications such as lithium-ion batteries and super-capacitors will also be reported. ^**This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2011-0030013, 2016R1A2B1013276).

Carbon encapsulated cobalt sulfide nano-particles anchored on reduced graphene oxide as high capacity anodes for sodium-ion batteries and glucose sensor

Sridhar, Vadahanambi,Park, Hyun Elsevier 2018 Journal of alloys and compounds Vol.764 No.-

<P><B>Abstract</B></P> <P>Cobalt sulfide is a promising anode material for a sodium-ion battery because of its high capacity and abundance. However, practical issues such as huge volume changes during sodiation/desodiation result in a low capacity retention during cycling, thus posing a serious challenge to practical applications. In this work, we report a rather easy, single pot microwave synthesis technique having the ability to create carbon-coated, uniformly distributed cobalt sulfide nanoparticles (20–40 nm) on reduced graphene oxide (CoS<SUB>2</SUB>@C-rGO). In this structure, the graphene substrate acts as a robust conductive platform to anchor cobalt sulfide, and the outer carbon encapsulation guarantees both the structural integrity and conductivity of the composite. When evaluated as an anode material in a sodium-ion battery, CoS<SUB>2</SUB>@CrGO exhibited a stable cycling performance and superior high-rate capability, delivering a reversible capacity as high as 794.9 mAhg<SUP>−1</SUP> at 0.5 A, after 175 cycles. Furthermore, our CoS<SUB>2</SUB>@C-rGO electrodes can be used as enzyme-less glucose sensors that exhibit a wide linear response within a range of up to 3 mM of glucose and a low detection limit of 0.078 M.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microwave synthesis of carbon encapsulated cobalt sulfide on graphene was developed. </LI> <LI> CoS<SUB>2</SUB>@C-rGO shows a reversible capacity of 794.9 mAhg<SUP>−1</SUP> in sodium ion batteries. </LI> <LI> When applied as glucose sensor, CoS<SUB>2</SUB>@C-rGO sensor shows excellent performance. </LI> </UL> </P>