Synthesis and shielding properties of PVP-stabilized-AgNPs-based graphene nanohybrid in the Ku band

Bansala, Taruna; Mukhopadhyay, Samrat; Joshi, Mangala; Doong, Ruey‐an; Chaudhary, Manchal

doi:10.1016/j.synthmet.2016.07.034

Cited by 23 publications

(17 citation statements)

References 61 publications

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“…As can be seen, the Ag 3d XPS spectrum of 2.5wt %Ag/ZrO 2 consists of two bands corresponding to the 3d 3/2 and 3d 5/2 transitions, which can each be deconvoluted into two different peaks (a total of 4 peaks): at 367.8 and 373.8 eV, ascribed to the silver oxides Ag 2 O, at 374.4 and 368.3 eV, assigned to the Ag 0 metal. 50,51 For 2.5wt %Ag−PVP/ZrO 2 (1:1), besides the two bands associated with the Ag 3d 3/2 and 3d 5/2 transitions, a new peak at 367.7 eV is observed, together with another deconvoluted peak at 373.7 eV, which are attributed to the silver oxides Ag 2 O. An upshift of the binding energy for Ag 0 in the presence of PVP is observed, implying a charge transfer between the PVP molecules and the Ag 0 metal.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Aerobic Oxidation of 5-Hydroxymethylfurfural to High-Yield 5-Hydroxymethyl-2-furancarboxylic Acid by Poly(vinylpyrrolidone)-Capped Ag Nanoparticle Catalysts

Sun

Xia

2019

ACS Sustainable Chem. Eng.

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An efficient method for the catalytic aerobic oxidation of 5hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) was developed using size-controlled Ag nanoparticles (NPs) in an aqueous solution. A series of AgNPs catalysts stabilized by poly(vinylpyrrolidone) (PVP) supported on ZrO 2 with different Ag loadings were prepared. XRD, TEM, XPS, and FT-IR techniques were used to characterize the nature of these catalysts. The impact of the Ag loading, the molar ratio of PVP to Ag, the reaction temperature and time, and the base type on the conversion of HMF and yield of HMFCA was investigated. The reaction results show that Ag−PVP/ZrO 2 catalysts with a bigger particle size (>10 nm) exhibited superior catalytic activity and HMFCA selectivity compared to Ag/ZrO 2 with a smaller particle size (ca. 8.5 nm), indicating that the addition of PVP has a promoting effect on the aerobic oxidation of HMF into HMFCA. The 2.5%Ag−PVP/ZrO 2 (1:1) catalyst presents an excellent activity with 100% conversion of HMF and 98.2% yield of HMFCA in oxygen flow at 20 °C for 2 h.The basicity is also very critical to obtain a high HMFCA yield, especially for the use of high concentration of HMF; i.e., Ca(OH) 2 afforded a higher selectivity toward HMFCA compared to the use of NaOH or Na 2 CO 3 under an identical reaction condition. It is revealed for the first time that the presence of a capping agent (PVP) can effectively modulate the metal−support interaction. Interestingly, it is found that the relatively weak interaction between Ag NPs and the ZrO 2 support has a beneficial effect on the conversion of HMF. This work provides new insights into the relationship between the metal−support interaction mediated by PVP molecule and the activity and selectivity of the oxidation reaction.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Aerobic Oxidation of 5-Hydroxymethylfurfural to High-Yield 5-Hydroxymethyl-2-furancarboxylic Acid by Poly(vinylpyrrolidone)-Capped Ag Nanoparticle Catalysts

Sun

Xia

2019

ACS Sustainable Chem. Eng.

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“…A shielding material reduces the incident EM wave energy by three main basic shielding mechanisms such as (1) reflection of the incident EM wave radiation from the front surface of the shield material (SE R ), (2) absorption of EM wave energy through various dissipation paths as EM radiation penetrates through the thickness of the shield (SE A ), (c) multiple reflections of the EM waves occurring at several internal interfaces (SE M ) . A shielding material's absolute shielding effectiveness (SE) can be given as follows

SE ((), dB) = {SE}_{R} + {SE}_{A} + {SE}_{M}

…”

Section: Resultsmentioning

confidence: 99%

Electromagnetic interference shielding behavior of chemically and thermally reduced graphene based multifunctional polyurethane nanocomposites: A comparative study

Bansala

Joshi

Mukhopadhyay

2019

J of Applied Polymer Sci

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This article presents the effect of exfoliation, dispersion, and electrical conductivity of graphene sheets onto the electrical, electromagnetic interference (EMI) shielding, and gas barrier properties of thermoplastic polyurethane (TPU) based nanocomposite films. The chemically reduced graphene (CRG) and thermally reduced/annealed graphene (TRG) having Brunauer–Emmett–Teller surface areas of 18.2 and 159.6 m2/g, respectively, when solution blended with TPU matrix using N,N‐dimethylformamide as a solvent. Graphene sheets based TPU nanocomposites have been evaluated and compared for EMI shielding in Ku band, electrical conductivity, and gas barrier property. TRG/TPU nanocomposite films showed excellent gas barrier against N2 gas as compared to CRG/TPU. The EMI shielding effectiveness for neat CRG and TRG graphene sheets is found to be −80, −45 dB, respectively, at 2 mm thickness. The EMI shielding data revealed that TRG/TPU nanocomposites showed better shielding at lower concentration (10 wt %), while CRG displayed better attenuation at higher concentrations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47666.

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“…Yang et al synthesized RGO conformally wrapped Ag nanowire networks and observed an EMI SE of 35.5 dB. In addition, the formation of several Ag-based polymer nanocomposites has also been reported for EMI-shielding applications, such as PANI/Ag@graphene, Ag/RGO-coated polyester, Ag/RGO-coated cotton fabrics, acrylic polymer-coated/RGO/Ag NW films, Ag-RGO/polymethyl methacrylate (PMMA), waterborne polyurethane (WPU)@Ag NPs@functionally reduced GO, PVP-stabilized Ag NP-based graphene hybrids, Ag NPs@graphite/polyvinylidene difluoride, and Ag platelets/RGO foam/epoxy . Most of these nanocomposites followed absorption as the dominant shielding mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…These investigations revealed that the preparation procedures of most of these materials are not environmentally friendly due to the requirements for hazardous chemicals, such as hydriodic acid, trisodium citrate, sodium citrate, sodium borohydride (NaBH 4 ), and hydrazine hydrate , and harsh high-temperature conditions, such as 90 °C, 100 °C, ,,, 120 °C, 156 °C, and 180 °C . Additionally, the involvement of multisteps in several preparations provided additional challenges.…”

Section: Introductionmentioning

confidence: 99%

Room-Temperature One-Step Synthesis of Silver/Reduced Graphene Oxide Nanocomposites as an Excellent Microwave Absorber

Mondal

Srivastava

2021

Langmuir

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The present study is focused on room-temperature synthesis carried out by reduction of an aqueous silver nitrate (AgNO3) and AgNO3/graphene oxide (GO) dispersion using a low-cost commercial Fehling B solution in one step to form silver quantum dots (Ag QDs) and their Ag/reduced graphene oxide (Ag/RGO) nanocomposites and their characterization. The crystallinity, surface chemistry, structural, and morphological studies indicated the formation of crystalline small-sized quasispherical-functionalized Ag particles distributed uniformly on the surface of RGO. The conductivity measurements further showed an improvement in the conductivity of Ag/RGO nanocomposites as compared to neat Ag QDs. Our findings showed that Ag/RGO nanocomposites prepared by using 0.055 wt % of GO exhibited a total enhanced electromagnetic interference (EMI)-shielding efficiency (SET) of ∼39.2–42.3 dB (2–8 GHz) with a maximum value of ∼43.8 dB at 7. 5 GHz due to conduction loss, an interconnected conducting network, and a synergistic effect, and it followed an absorption mechanism. Furthermore, this superior absorption-dominated shielding conferred reflection loss (R L) in the range of −79 to −82.5 dB with a R L minima of −88 dB at 7.5 GHz, considering an effective absorption bandwidth of ∼6 GHz with 99.9% absorptivity. It is anticipated that Ag/RGO nanocomposites prepared in one step at room temperature could find potential EMI-shielding applications.

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Synthesis and shielding properties of PVP-stabilized-AgNPs-based graphene nanohybrid in the Ku band

Cited by 23 publications

References 61 publications

Aerobic Oxidation of 5-Hydroxymethylfurfural to High-Yield 5-Hydroxymethyl-2-furancarboxylic Acid by Poly(vinylpyrrolidone)-Capped Ag Nanoparticle Catalysts

Aerobic Oxidation of 5-Hydroxymethylfurfural to High-Yield 5-Hydroxymethyl-2-furancarboxylic Acid by Poly(vinylpyrrolidone)-Capped Ag Nanoparticle Catalysts

Electromagnetic interference shielding behavior of chemically and thermally reduced graphene based multifunctional polyurethane nanocomposites: A comparative study

Room-Temperature One-Step Synthesis of Silver/Reduced Graphene Oxide Nanocomposites as an Excellent Microwave Absorber

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