Tuning electro-magnetic interference shielding efficiency of customized polyurethane composite foams taking advantage of rGO/Fe3O4 hybrid nanocomposites

Electromagnetic interference (EMI) has been recognized as a new sort of pollution and can be considered as the direct interference of electromagnetic waves among electronic equipment that frequently affects their typical efficiency. As a result, shielding the electronics from this interfering radiation has been addressed as critical issue of great interest. In this study, different hybrid nanocomposites consisting of magnetite nanoparticles (Fe3O4) and reduced graphene oxide (rGO) as (conductive/magnetic) fillers, taking into account different rGO mass ratios, were synthesized and characterized by XRD, Raman spectroscopy, TEM and their magnetic properties were assessed via VSM. The acquired fillers were encapsulated in the polyurethane foam matrix with different loading percentages (wt%) to evaluate their role in EMI shielding. Moreover, their structure, morphology, and thermal stability were investigated by SEM, FTIR, and TGA, respectively. In addition, the impact of filler loading on their final mechanical properties was determined. The obtained results revealed that the Fe3O4@rGO composites displayed superparamagnetic behavior and acceptable electrical conductivity value. The performance assessment of the conducting Fe3O4@rGO/PU composite foams in EMI shielding efficiency (SE) was investigated at the X-band (8–12) GHz, and interestingly, an optimized value of SE −33 dBw was achieved with Fe3O4@rGO at a 80:20 wt% ratio and 35 wt% filler loading in the final effective PU matrix. Thus, this study sheds light on a novel optimization strategy for electromagnetic shielding, taking into account conducting new materials with variable filler loading, composition ratio, and mechanical properties in such a way as to open the door for achieving a remarkable SE.Ministerio de Ciencia e Innovación | Ref. PID2020-113704RB-I00Xunta de Galicia | Ref. ED431G 2019/06Xunta de Galicia | Ref. IN607A 2018/5Xunta de Galicia | Ref. ED431C 2021/45Unión Europea-FEDER (Interreg V-A—España-Portugal) | Ref. 0245_IBEROS_1_EUnión Europea-FEDER (Interreg V-A—España-Portugal) | Ref. 0712_ACUINANO_1_EUnión Europea-FEDER (Interreg V-A—España-Portugal) | Ref. 0624_2IQBIONEURO_6_

Synergistic interaction of clusters of iron oxide nanoparticles and reduced graphene oxide for high supercapacitor performance

Supercapacitors have been recognized as one of the more promising energy storage devices, with great potential use in portable electronics and hybrid vehicles. In this study, a composite made of clusters of iron oxide (Fe3O4-γFe2O3) nanoparticles and reduced graphene oxide (rGO) has been developed through a simple one-step solvothermal synthesis method for a high-performance supercapacitor electrode. Electrochemical assessment via cyclic voltammetry, galvanostatic charge–discharge experiments, and electrochemical impedance spectroscopy (EIS) revealed that the Fe3O4-γFe2O3/rGO nanocomposite showed much higher specific capacitance than either rGO or bare clusters of Fe3O4-γFe2O3 nanoparticles. In particular, specific capacitance values of 100 F g−1, 250 F g−1, and 528 F g−1 were obtained for the clusters of iron oxide nanoparticles, rGO, and the hybrid nanostructure, respectively. The enhancement of the electrochemical performance of the composite material may be attributed to the synergistic interaction between the layers of graphene oxide and the clusters of iron oxide nanoparticles. The intimate contact between the two phases eliminates the interface, thus enabling facile electron transport, which is key to attaining high specific capacitance and, consequently, enhanced charge–discharge time. Performance evaluation in consecutive cycles has demonstrated that the composite material retains 110% of its initial capacitance after 3000 cycles, making it a promising candidate for supercapacitors.Ministerio de Ciencia e Innovación | Ref. PID2020-119242RB-I00Xunta de Galicia | Ref. ED431B 2021/14Ministerio de Economía y Competitividad | Ref. PID2020-113704RB-I00Xunta de Galicia/FEDER | Ref. IN607A 2018/5Xunta de Galicia | Ref. ED431G 2019-06Interreg España-Portugal | Ref. 0712_ACUINANO_1_EInterreg España-Portugal | Ref. 0624_2IQBIONEURO_6_

Síntese, caracterización e avaliación do rendemento de nanomateriais híbridos

-Synthesis of hybrid nano materials based on plasmonic nano structure particularly nano stars and coated it with metal nano oxides as TiO2, SiO2 . - plasmonic nano materials coated with different metallic particles as gold nano stars coated with silver. -Characterization of synthesized hybrid nano materials by TEM and SEM and other important characterization device . - Application of these hybrid nano materials in photocatalysis applications. - Application of these hybrid nano materials in energy production applications. - Application of these hybrid nano materials in the field of chemical engineering may be electrochemical engineering.-Síntesis de nano materiales híbridos basados ​​en nanoestructura plasmónica, particularmente nano estrellas y recubiertos con nanoóxidos metálicos como TiO2, SiO2 y Fe2O3 / y nano materiales plasmónicos recubiertos con diferentes metales partículas -Caracterización de nano materiales híbridos sintetizados por TEM y SEM y otros importantes dispositivo de caracterización. - Aplicación de estos nano materiales híbridos en aplicaciones de fotocatálisis. - Aplicación de estos nano materiales híbridos en aplicaciones de producción de energía. - Aplicación de estos nano materiales híbridos en el campo de la ingeniería química como ingeniería electroquímica.-Síntese de materiais nano híbridos baseados na estrutura nano plasmónica particularmente nano estrelas e revestidos en nano óxidos metálicos como TiO2, SiO2 e Fe2O3 / e materiais nano plasmónicos recubertos con diferentes metálicos partículas. -Caracterización de materiais nano híbridos sintetizados por TEM e SEM e outros importantes dispositivo de caracterización. - Aplicación destes nano materiais híbridos en aplicacións de fotocatalise. - Aplicación destes nano materiais híbridos en aplicacións de produción de enerxía. - Aplicación destes materiais nano híbridos no campo da enxeñaría química como enxeñería electroquímic

Tuning the thermal properties of aqueous nanofluids by taking advantage of size-customized clusters of iron oxide nanoparticles

In this study, the thermal conductivity of aqueous nanofluids containing clusters of iron oxide (Fe3O4/γ-Fe2O3) nanoparticles has been investigated experimentally for the first time, with the aim of assessing the role of a controlled aggregation of nanoparticles in these final nanofluids. For that, clusters of iron oxide nanoparticles of different cluster size (46–240 nm diameter range) were synthesized by a solvothermal method and fully characterized by transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The rheological behavior of the optimal nanofluids was also studied by rotational rheometry. The nanofluids were obtained by dispersing the clusters of iron oxide nanoparticles in water taking into account different solid volume fractions (from 0.50 to 1.5 wt%) and the experiments were conducted in the temperature range from 293.15 K to 313.15 K. The study reveals and quantifies enhancements in the thermal conductivity of nanofluid with increase of cluster size and temperature. Furthermore, a 0.50 wt% concentration of clusters of iron oxide nanoparticles within the whole range of proposed nanofluids offers great stability and improved thermal conductivity for heat transfer applications with an small dynamic viscosity increase. In addition, the larger the size of the clusters of iron oxide nanoparticles, the greater the increase in thermal conductivity for the designed Fe3O4/γ-Fe2O3 cluster-based nanofluids, with thermal conductivity values following a constant upward trend and reaching a maximum increase of 4.4% for the largest synthesized clusters (average size of 240 nm). These results open the door for the development of iron oxide-based nanofluids on which taking advantage of an optimized aggregation of nanoparticles by using size-customized clustersMinisterio de Economía y Competitividad | Ref. ENE2017-86425-C2-1-RMinisterio de Economía y Competitividad | Ref. CTM2017-84050-RMinisterio de Ciencia e Innovación | Ref. PID2020-112846RB-C21Ministerio de Ciencia e Innovación | Ref. PID2020-119242RB-I00Ministerio de Ciencia e Innovación | Ref. PDC2021-121225-C21European Commission | Ref. CIG1511

Novel colored flames via chromaticity of essential colors

Colored flame compositions have distinctive variety of applications ranging from military signaling, rocket tracking, and illuminating devices. Certain elements and compounds when heated to high temperature are able to emit unique wavelengths in the visible region. This study, reports on the development of novel colored flames that cannot be generated by emitting atomic/molecular species. This was achieved by using chromaticity of basic colored flames. Mixing of high quality primary colored flames including Blue, Yellow, and Red in proper ratio was conducted; any interfering incandescent emission resulted from MgO was eliminated using Al metal fuel. The spectral characteristics in terms of luminous intensity, and color quality were evaluated using digital luxmeter and UV-Vis. spectrometer respectively. High quality mixed colored flames include violet, sweet pink, and marigold were developed. This study shaded the light on the state of the art for the real development of novel colored flame compositions and chromaticity of basic colored flames. Keywords: Pyrotechnics, Colored flame, Atomic spectroscopy, Molecular spectroscopy, Luminous intensity, Color quality, Chromaticit

Enhanced photocatalytic and antibacterial activities of novel Ag-HA bioceramic nanocatalyst for waste-water treatment

Abstract Hydroxyapatite (HA), the most common bioceramic material, offers attractive properties as a catalyst support. Highly crystalline mono-dispersed silver doped hydroxyapatite (Ag-HA) nanorods of 60 nm length was developed via hydrothermal processing. Silver dopant offered enhanced chemisorption for crystal violet (CV) contaminant. Silver was found to intensify negative charge on the catalyst surface; in this regard enhanced chemisorption of positively charged contaminants was accomplished. Silver dopant experienced decrease in the binding energy of valence electron for oxygen, calcium, and phosphorous using X-ray photoelectron spectroscopy XPS/ESCA; this finding could promote electron–hole generation and light absorption. Removal efficiency of Ag-HA nanocomposite for CV reached 88% after the synergistic effect with 1.0 mM H2O2; silver dopant could initiate H2O2 cleavage and intensify the release of active ȮH radicals. Whereas HA suffers from lack of microbial resistance; Ag-HA nanocomposite demonstrated high activity against Gram-positive (S. aureus) bacteria with zone of inhibition (ZOI) mm value of 18.0 mm, and high biofilm inhibition of 91.1%. Ag-HA nanocompsite experienced distinctive characerisitcs for utilization as green bioceramic photocatalyst for wastewater treatment