Synthesis and application of graphene-αMoO₃ nanocomposite for improving visible light irradiated photocatalytic decolorization of methylene blue dye

Mahalingam, Shanmugam,Ramasamy, Jayavel,Ahn, Young-Ho Elsevier 2017 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.80 No.-

<P><B>Abstract</B></P> <P>Graphene-alpha-molybdenum trioxide (α-MoO<SUB>3</SUB>) nanocomposites were synthesized using a facile hydrothermal method. The synthesized material was characterized by various physico-chemical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), ultra-violet–visible diffuse reflectance spectroscopy (DRS) and Raman spectroscopy. Raman spectroscopy revealed a D to G band intensity ratio of approximately one, which confirmed the good graphitization of the synthesized graphene and graphene-MoO<SUB>3</SUB> nanocomposite. The I<SUB>D</SUB>/I<SUB>G</SUB> ratio of the G-αMoO<SUB>3</SUB> nanocomposite was calculated to be 1.2. HRTEM revealed graphene sheets decorated with MoO<SUB>3</SUB> nanoparticles. The size of the MoO<SUB>3</SUB> nanoparticles dispersed over the wrinkled graphene sheets layers was 10 ± 5 nm. The chemical state functionality and composition (carbon, oxygen and molybdenum) of the G-αMoO<SUB>3</SUB> nanocomposite was examined by XPS. TGA was performed to examine the thermal stability and decomposition of the nanomaterials and nanocomposite. The photocatalytic performance of the bare synthesized MoO<SUB>3</SUB> nanoparticles and graphene-αMoO<SUB>3</SUB> nanocomposite was analyzed by the degradation of MB dye under ultra-violet and visible light irradiation. The G-αMoO<SUB>3</SUB> nanocomposite showed an extraordinarily higher photocatalytic activity than the bare MoO<SUB>3</SUB> nanoparticles. Up to 97% and 96% of the MB dye was removed under UV and visible light irradiation, respectively. A comparison of the photocatalytic effect of the bare MoO<SUB>3</SUB> and G-MoO<SUB>3</SUB> nanocomposite showed that the bare MoO<SUB>3</SUB> induced less photocatalytic degradation than the G-MoO<SUB>3</SUB> nanocomposite. The photocatalytic result suggested that graphene plays an important role in enhancing the photocatalytic activity. These results show that the G-αMoO<SUB>3</SUB> nanocomposite is an efficient catalyst for the degradation of MB dye and has potential in industrial wastewater treatment. The mechanism of the degradation process was examined by calculating the rate constant and half-life of the degradation process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Synthesis of G-αMoO<SUB>3</SUB> nanocomposites by a surfactant free hydrothermal method. </LI> <LI> The G-αMoO<SUB>3</SUB> nanocomposite possess improved visible light photocatalytic activity. </LI> <LI> The highest degradation efficiency of 97% and 96% was achieved for the G-αMoO<SUB>3</SUB> catalyst. </LI> <LI> G-αMoO<SUB>3</SUB> can be used as an efficient catalyst for industrial waste water treatment. </LI> </UL> </P> <P><B>Graphic abstract</B></P> <P>[DISPLAY OMISSION]</P>

Influence of the incorporation of small conjugated molecules on the thermoelectric properties of carbon nanotubes

Kang, Young Hun,Lee, Young-Chul,Lee, Changjin,Cho, Song Yun Elsevier 2018 Organic electronics Vol.57 No.-

<P><B>Abstract</B></P> <P>Small-bundled single-walled carbon nanotube (SSWCNT) nanocomposite films made with various small molecules were facilely fabricated using the micronizing mill process. Finely dispersed small molecules in the SSWCNT film can effectively reduce the in-plane thermal conductivity of the nanocomposite due to π-π interactions. Furthermore, the micronizing mill process ensures the uniform distribution of the small molecules and the SSWCNTs in the nanocomposite film without any damage or deformation of the SSWCNT structure. Moreover, the influence of the shape of the small molecules on the thermoelectric properties of SSWCNT nanocomposite was systematically investigated. The thermoelectric properties of the pyrene/SSWCNT nanocomposite were found to have been greatly improved by the planar pyrene molecules with a slightly increased electrical conductivity of 978.6 S cm<SUP>−1</SUP> and a significantly decreased in-plane thermal conductivity of 13.5 W m<SUP>-1</SUP> K<SUP>-2</SUP>. The evaluated <I>ZT</I> value of the pyrene/SSWCNT nanocomposite was 4.4 × 10<SUP>−3</SUP> and is about 20 times higher than that of the pristine SSWCNT nanocomposite. A planar-type thermoelectric generator (TEG) consisting of 20 legs was also fabricated using this pyrene/SSWCNT nanocomposite. The TEG showed an open circuit voltage of 20 mV and a short circuit current of 350 μA, resulting in a maximum output power of 1.5 μW at <I>ΔT</I> = 20 °C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SSWCNT nanocomposite films with various small molecules were fabricated using the micronizing mill process. </LI> <LI> Finely dispersed small molecules in the SSWCNT film effectively reduce the in-plane thermal conductivity of the nanocomposite. </LI> <LI> The influence of the shape of the small molecules on the thermoelectric properties of SSWCNT nanocomposite was systematically investigated. </LI> <LI> The thermoelectric properties of the nanocomposite were greatly improved by the planar pyrene molecules. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Thermoelectric behavior of bulk-type functionalized-SWCNT incorporated Te nanowire/PMMA hybrid nanocomposites with a segregated structure

Kim, Seil,Song, Yoseb,Ryu, Seung Han,Hwang, Tae-Yeon,Lee, Youngsuk,Lim, Jae-Hong,Lee, Joo-Yul,Lee, Kyu-Hwan,Choa, Yong-Ho Elsevier Sequoia 2019 Synthetic metals Vol.254 No.-

<P><B>Abstract</B></P> <P>A three-dimensional thermoelectric (TE) nanocomposite based on functionalized single-walled carbon nanotubes (f-SWCNTs), tellurium nanowires (Te NWs), and polymethyl methacrylate (PMMA) microbeads was fabricated by a hot compaction via solvent casting. We chose a minimum content of f-SWCNTs of 1 wt% for fabricating the nanocomposite based on percolation threshold. The nanocomposite containing 2 wt% f-SWCNTs and 48 wt% Te NWs exhibited an electrical conductivity of 0.93 S/cm, a Seebeck coefficient of 303 μV/K, a thermal conductivity of 0.23 W/mK and a figure-of-merit (<I>ZT</I>) of 0.01 at RT. The electrical conductivity of the nanocomposite were higher than that of the Te NW/PMMA nanocomposite. In contrast, the thermal conductivity value showed a trend opposite to that of the electrical conductivity. This is because the f-SWCNTs formed bridges between the Te NWs into the nanocomposite, resulting in heterostructured interfaces. We believe that this-type nanocomposite can be widely used for thermoelectric generators at low temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hybrid TE nanocomposite was fabricated by hot compaction via solvent casting. </LI> <LI> Functionalized-SWCNTs formed bridges between the Te NWs in the TE nanocomposite. </LI> <LI> The thermal conductivity is insensitive to f-SWCNT density due to poor thermal transfer between Te NW and f-SWCNTs. </LI> <LI> The hybrid nanocomposite exhibited a figure-of-merit (<I>ZT</I>) of 0.01 at room temperature. </LI> </UL> </P>

Tensile Properties and Thermal Stability of Cellulose Nanofibril/Clay Nanocomposites

Byung-Dae Park,Adya P. Singh,In Chul Um 경북대학교 농업생명과학대학 2013 Current Research on Agriculture and Life Sciences Vol.31 No.1

This work attempted to fabricate organic/inorganic nanocomposite by combining organic cellulose nanofibrils (CNFs), isolated by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation of native cellulose with inorganic nanoclay. The morphology and dimension of CNFs, and tensile properties and thermal stability of CNF/clay nanocomposites were characterized by transmission electron microscope (TEM), tensile test, and thermogravimetry (TG), respectively. TEM observation showed that CNFs were fibrillated structure with a diameter of about 4.86±1.341 nm. Tensile strength and modulus of the hybrid nanocomposite decreased as the clay content of the nanocomposite increased, indicating a poor dispersion of CNFs or inefficient stress transfer between the CNFs and clay. The elongation at break increased at 1% clay level and then continuously decreased as the clay content increased, suggesting increased brittleness. Analysis of TG and derivative thermogravimetry (DTG) curves of the nanocomposites identified two thermal degradation peak temperatures (Tp1 and Tp2), which suggested thermal decomposition of the nanocomposites to be a two steps-process. We think that Tp1 values from 219.6℃ to 235℃ resulted from the sodium carboxylate groups in the CNFs, and that Tp2 values from 267℃ to 273.5℃ were mainly responsible for the thermal decomposition of crystalline cellulose in the nanocomposite. An increase in the clay level of the CNF/clay nanocomposite predominately affected Tp2 values, which continuously increased as the clay content increased. These results indicate that the addition of clay improved thermal stability of the CNF/clay nanocomposite but at the expense of nanocomposite’s tensile properties.

Tensile Properties and Thermal Stability of Cellulose Nanofibril/Clay Nanocomposites

Park, Byung-Dae,Singh, Adya P.,Um, In Chul Institute of Agricultural Science and Technology 2013 慶北大農學誌 Vol.31 No.1

This work attempted to fabricate organic/inorganic nanocomposite by combining organic cellulose nanofibrils (CNFs), isolated by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation of native cellulose with inorganic nanoclay. The morphology and dimension of CNFs, and tensile properties and thermal stability of CNF/clay nanocomposites were characterized by transmission electron microscope (TEM), tensile test, and thermogravimetry (TG), respectively. TEM observation showed that CNFs were fibrillated structure with a diameter of about $4.86{\pm}1.341nm$. Tensile strength and modulus of the hybrid nanocomposite decreased as the clay content of the nanocomposite increased, indicating a poor dispersion of CNFs or inefficient stress transfer between the CNFs and clay. The elongation at break increased at 1% clay level and then continuously decreased as the clay content increased, suggesting increased brittleness. Analysis of TG and derivative thermogravimetry (DTG) curves of the nanocomposites identified two thermal degradation peak temperatures ($T_{p1}$ and $T_{p2}$), which suggested thermal decomposition of the nanocomposites to be a two steps-process. We think that $T_{p1}$ values from $219.6^{\circ}C$ to $235^{\circ}C$ resulted from the sodium carboxylate groups in the CNFs, and that $T_{p2}$ values from $267^{\circ}C$ to $273.5^{\circ}C$ were mainly responsible for the thermal decomposition of crystalline cellulose in the nanocomposite. An increase in the clay level of the CNF/clay nanocomposite predominately affected $T_{p2}$ values, which continuously increased as the clay content increased. These results indicate that the addition of clay improved thermal stability of the CNF/clay nanocomposite but at the expense of nanocomposite's tensile properties.

Bioactivity and osteoblast responses of novel biomedical nanocomposites of bioactive glass nanofiber filled poly(lactic acid)

Kim, Hae-Won,Lee, Hae-Hyoung,Chun, Gae-Sig Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of biomedical materials research. Part A Vol.a85 No.3

<P>Biomedical nanocomposites constituted of bioactive ceramic and resorbable polymer have shown promise for the successful regeneration of bone tissues. We developed herein a novel nanocomposite made up of a bioactive glass in a nanofibrous form and a degradable synthetic polymer, poly(lactic acid) (PLA). The glass nanofiber with a bioactive composition was generated via an electrospinning process with an average diameter of ∼320 nm. The nanofiber was homogenized with PLA solution at various concentrations (up to 35% nanofiber), followed by drying and thermal pressing to produce dense nanocomposites. The nanocomposites showed an internal morphology of uniformly dispersed nanofibers within the PLA matrix. The nanocomposites induced rapid formation of a hydroxycarbonate apatite layer on the surface under a simulated physiological medium. As the amount of bioactive nanofiber increased (from 5 to 25%), the in vitro bioactivity of the nanocomposite was improved. The osteoblast responses to the nanocomposites (compositions with 5 and 25% nanofiber) were assessed in terms of cell proliferation, differentiation, and mineralization. Osteoblasts attached and grew well on the nanocomposites and secreted collagen protein at initial culturing periods. The differentiation of cells, as assessed by the expression of alkaline phosphatase, was significantly improved on the nanocomposites as compared to those on pure PLA. Moreover, the mineralized product by the cells was observed to be significantly higher on the nanocomposites with respect to pure PLA. The newly developed nanocomposite constituted of bioactive nanofiber and degradable polymer is considered as a promising bone regeneration matrix with its excellent bioactivity and osteoblast responses. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008</P>

Preparation, characterization, and photocatalytic degradation of methylene blue of SnO2/RGO nanocomposite produced by facile hydrothermal process

Moghaddas S.,Salehi M.,Bagheri-Kazemabad S. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5

A facile hydrothermal route has been used to produce a SnO 2 (tin oxide)/RGO (reduced graphene oxide) nanocomposite. The microstructure and properties of the prepared nanocomposite were studied by an X-ray diffraction (XRD), fi eld emission scanning electron microscope (FE-SEM), Fourier transformed infrared (FTIR), UV–Vis analysis, and transmission electron microscope (TEM). The formation of SnO 2 phase over RGO is confirmed by the XRD and FTIR results. The absence of a distinct peak of GO in the SnO 2 /RGO nanocomposite produced hydrothermally shows the reduction of GO to RGO com- pletely. FE-SEM and TEM images show that SnO 2 nanoparticles with size about 20 nm distributed homogeneously on the graphene surface. UV–Vis analysis of the SnO 2 /RGO sample exhibits broad absorption in the visible range (400–700 nm) indicating the SnO 2 formation on the sheets of reduced graphene oxide. Moreover, the nanocomposite was employed as a photocatalyst under UV light irradiations to the removal of methylene blue (MB). The produced SnO 2 /RGO nanocomposite removes the absorption peak of MB at around 665 nm within 20 min, implying the nanocomposite possesses good photo- catalytic efficiency under UV light irradiations.

Effects of additives on the mechanical and thermal properties of epoxy-based nanocomposites produced using sonication

YoonKook Park,Chun-Hyung Cho 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.6

Epoxy nanocomposites were synthesized in the presence of hydroxyapatite with the aid of an ultrasonicator. In general, as the amount of hydroxyapatite increased from 0wt% to 10wt%, the mechanical properties of the hydroxyapatite-containing nanocomposite were enhanced. The mechanical properties of the nanocomposite were significantly enhanced by the simple addition of 10 wt% of hydroxyapatite. Specifically, the storage modulus of the 10 wt% hydroxyapatite-containing nanocompsote was 3.2GPa, which is 46% higher compared to that of the pristine epoxy nanocomposite. The glass transition temperature of hydroxyapatite-containing nanocomposites generally decreased by few degrees in Celsius. To investigate the effect of additives on the mechanical properties of the epoxy-based nanocomposite, nanocomposites were synthesized using both montmorillonite and tellurium dioxide instead of hydroxyapatite. Intrestingly, both additive-based nanocomposite materials resulted in an increase in the storage modulus while the glass transition temperature decreased. These results demonstrate that the addition of few wt% of all three additives (hydroxyapatite, montmorillonite, and tellurium dioxide) can enhance the mechanical properties of epoxy-based nanocomposites.

Photocatalytic performance of TiO₂/V₂O₅ nanocomposite powder prepared by DC arc plasma

Choi, S.,Lee, M.S.,Park, D.W. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.3

TiO<SUB>2</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite powder was synthesized by the DC arc plasma, and its photocatalytic activity was examined by decompositions of Rhodamine B solution and toluene gas. In the synthesis of TiO<SUB>2</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite powder, TiCl<SUB>4</SUB> and VOCl<SUB>3</SUB> precursors were introduced into thermal plasma flame with argon carrier gases through separated two gas bubblers. They were decomposed by Ar-N<SUB>2</SUB> thermal plasma generating Ti and V vapors, followed by the formation of oxides with the injection of additional oxygen into a plasma reactor. Nanocomposite composed of relatively small size V<SUB>2</SUB>O<SUB>5</SUB> nanoparticles on a spherical TiO<SUB>2</SUB> nanoparticle which was about 250 nm in diameter was identified by X-ray diffractometry, electronic microscopy, and energy dispersive spectroscopy when the ratio of carrier gas flow rates for TiCl<SUB>4</SUB> to VOCl<SUB>3</SUB> was 1:4 or 1:5. In ultraviolet-visible absorption spectroscopy, the absorbed wavelength of light for synthesized TiO<SUB>2</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite powder was wider than that for commercially available TiO<SUB>2</SUB> nanopowder. Therefore, Rhodamine B solution exposed to visible light was decomposed by TiO<SUB>2</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite, whereas it was not decomposed by TiO<SUB>2</SUB> nanopowder. In addition, toluene decomposition in a dielectric barrier discharge reactor was carried out with nano-sized photocatalysts of TiO<SUB>2</SUB> nanopowder and TiO<SUB>2</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite. Relatively higher removal rate of toluene was found in the case of TiO<SUB>2</SUB>/V<SUB>2</SUB>O<SUB>5</SUB> nanocomposite in virtue of improved photocatalytic performance.

MoS₂@VS₂ Nanocomposite as a Superior Hybrid Anode Material

Samad, Abdus,Shin, Young-Han American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.35

<P>Using density functional theory, MoS2@VS2 nanocomposite is reported as a hybrid anode with upgraded electronic conductivity and Li/Na storage capacity. The chemically active monolayer VS2 can be stabilized in energy and phonon vibrations by using the monolayer MoS2 as a substrate. The stability of the chemically active monolayer VS2 is attributed to the interfacial charge accumulation between the monolayer MoS2 and VS2. The maximum specific capacity of the nanocomposite has been enhanced to 584 mAh/g both for Li and for Na storage. We attribute the high enhancement in the Li/Na storage capacity of MoS2@VS2 nanocomposite to the charge redistribution in the formation of the nanocomposite. The lithiation/sodiation open-circuit voltage range of the nanocomposite is quite feasible to be used as anode. Diffusion barriers of Li/Na ions on the surfaces of the nanocomposite are comparable to the barriers on corresponding monolayers, while at the interface the barriers are lower than that for bulk MoS2. This study utilizes different aspects of the two different materials in a hybrid anode with highly enhanced electrochemical performance.</P>