Though investigations have been made on several metal chalcogenides in hydrogen evolution reactions (HERs) and hydrogen oxidation reactions (HORs), antimony sulfide (Sb2S3) has not generated much ...attention. In this direction, the present work reports on the synthesis of N, Ru codoped pellet drum bundle-like antimony sulfide (Sb2S3) via a simple reflux method. Subsequent HER and HOR electrocatalytic investigations in 1 M KOH revealed their suitability as an efficient and inexpensive alternative to platinum, as is evident from the overpotential (72 mV at a current density of 10 mA cm–2), Tafel slope (193 mV/decade), exchange current density (1.42 mA/cm2), and breakdown potential at ∼0.6 V vs RHE, respectively. Such remarkable HER and HOR performance of N, Ru codoped Sb2S3 could be ascribed to the presence of relatively larger active sites compared to Sb2S3 and N-doped Sb2S3 individually due to synergistic effects arising from N and Ru dopants. Further, N, Ru codoped Sb2S3 demonstrated high intrinsic catalytic activity as indicated by its turnover frequency (2.03 s–1) and current loss, corresponding to 35% after 10 h of continuous amperometric i–t operation. Alternatively, such excellent catalytic performance of N, Ru codoped Sb2S3 arises due to geometric lattice defects with surface oxygen vacancy, and the availability of abundant edges and its pellet drum-like morphology also cannot be overruled.
Tuning of the defect is critical for specific application of a material worth exploring and researching. In view of this, additional defects have been incorporated in single-walled carbon nanotubes ...(SWCNTs) by subjecting them to camphor-mediated combustion and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and electron paramagnetic resonance. Subsequently, we compared electromagnetic interference (EMI) shielding performance of SWCNTs vis-à-vis multiwalled carbon nanotube (MWCNT)-filled polystyrene (PS) nanocomposites. Interestingly, induced defects in SWCNT played a contrasting role with respect to MWCNT in their performance as EMI shielding materials. These findings have been correlated with the aspect ratio and percolation threshold of CNTs as well as dc conductivity of PS/CNT nanocomposites in the light of electromagnetic theory.
Inthe current work, we reported the in situ fabrication of a nickel vanadate (Ni 3 V 2 O 8 )-anchored N-doped reduced graphene oxide (NRGO) hybrid by a simple one-step reflux method. Subsequently, ...the electrocatalytic performance of the Ni 3 V 2 O 8 /NRGO hybrid was investigated in an alkaline medium (1.0 M KOH) for the hydrogen evolution reaction (HER). It was noted that the optimization of the NRGO content (∼5.6 wt%) highly influenced the homogeneous distribution of quasi-spherical Ni 3 V 2 O 8 nanoparticles over NRGO sheets and enhanced the water reduction ability. This hybrid material exhibited a sufficiently high electrochemical active surface area (517.5 cm 2 ) and remarkably low charge transfer resistance (∼1.6 Ω). Furthermore, the very low overpotential (∼43 mV) and the high exchange current density (∼1.24 mA cm −2 ) of Ni 3 V 2 O 8 /NRGO (5.6 wt%) demonstrated its promising HER performance. Additionally, superior long-term and accelerated stability compared to that of the benchmark Pt/C in a strong basic medium clearly signified that Ni 3 V 2 O 8 /NRGO (5.6 wt%) can act as an efficient, cost-effective, and durable electrocatalyst for water electrolyzers.
Fe3O4@SiO2@PPy core–shell nanocomposites were fabricated by the coating of SiO2 on Fe3O4 through base catalyzed hydrolysis of tetraethyl orthosilicate followed by encapsulation of polypyrrole (PPy). ...Subsequently, these trilaminar composites have been characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller, superconducting quantum interference devices, and measurement of the total shielding efficiency in the frequency range of 2–8 GHz. Our findings showed the highest total shielding efficiency (∼32 dB) of Fe3O4@SiO2@PPy (Fe3O4@SiO2/pyrrole wt/wt = 1:9) and followed reflection as the dominant shielding mechanism. Such performance was attributed to poor impedance matching between the PPy (conducting)/SiO2 (insulating) and high electrical conductivity of Fe3O4@SiO2@PPy. Alternatively, electromagnetic (EM) waves incident on the SiO2@PPy interface could also account for enhancing the total shielding efficiency of Fe3O4@SiO2@PPy because of multireflection/refraction. Our earlier work also showed excellent total shielding efficiency of Fe3O4@C@PANI nanocomposites, through absorption as the dominant shielding mechanism. These findings clearly suggest that EM interference shielding in Fe3O4@SiO2@PPy and Fe3O4@C@PANI trilaminar core@shell nanocomposites is controlled by tuning of the shells through switching of the mechanism.
Microbial infections originating from medical care facilities are raising serious concerns across the globe. Therefore, nanotechnology-derived nanostructures have been investigated and explored due ...to their promising characteristics. In view of this, silver-based antimicrobial hydrogels as an alternative to antibiotic-based creams could play a crucial role in combating such infections. Toward this goal, we report a simple method for the synthesis and assembly of silver nanoparticles in a biopolymer physical gel derived from Abroma augusta plant in imparting antimicrobial properties against nosocomial pathogens. Synthesized silver nanoparticles (diameter, 30 ± 10 nm) were uniformly distributed inside the hydrogel. Such synthesized hydrogel assembly of silver nanoparticles dispersed in the biopolymer matrix exhibited hemocompatibility and antimicrobial and antibiofilm characteristics against nosocomial pathogens. The developed hydrogel as a surface coating offers reduced hardness and modulus value, thereby minimizing the brittleness tendency of the gel in the dried state. Hence, we believe that the hierarchical assembly of our hydrogel owing to its functional activity, host toxicity, and stability could possibly be used as an antimicrobial ointment for bacterial infection control.
Currently, transition metal disulfides are used as promising non-noble metal-based electrocatalysts for the hydrogen evolution reaction (HER) from water splitting in quest for alternative renewable ...and clean energy sources. In view of this, the present study reports the fabrication of N and P co-doped exfoliated tungsten disulphide (PNEWS 2 ) as a superior electrocatalyst for HER. The high performance of PNEWS 2 imparts a significantly low potential (59 mV), which corresponds to a geometrical current density of 10 mA cm −2 and Tafel slope of 35 mV per decade. This could be attributed to the presence of highly active sites in the exfoliated single-layered porous 1T-WS 2 network and synergistic effect of N and P doping. Furthermore, evaluation of durability tests suggested excellent stability of the PNEWS 2 catalyst. Our multifaceted strategy for the formation of a flake-like 1T (metallic) phase with expanded interlayer spacings in the PNEWS 2 catalyst compared with that in WS 2 results in an increase in S active edges and presence of sulphur vacancies, facilitating extremely high electrochemically active surface area ( C dl = 37.1 mF cm −2 ) and high turnover frequency (0.791 s −1 ). Furthermore, the downshift in the d band, high lifetime (0.239 ms) and low Gibbs free energy (−0.26 eV) of PNEWS 2 account for its excellent mass transport properties. We also established that the electrochemical performance of PNEWS 2 is not associated with the dissolution/redeposition of platinum from the counter electrode (Pt). In summary, the superior performance of the nonprecious, promising N–P-co-doped WS 2 provides an alternative substitute for Pt-based electrocatalysts.
Molybdenum disulphide, MoS2, thin films have been deposited by chemical bath deposition method on glass and quartz substrate using ammonium tetrathiomolybdate as a single source precursor for Mo and ...S and subjected to vacuum heat treatment at different temperatures. X-ray diffraction of as-deposited film indicated its amorphous character and showed the development of poorly crystalline MoS2 thin film on increasing annealing temperature. The film has been characterized by energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, scanning electron micrograph and the optical properties also have been studied.
Successful utilization of natural anionic clays like montmorillonite and hectorite for the homogeneous dispersion of multiwalled carbon nanotubes (MWCNTs) in ethylene-
co
-vinyl acetate (EVA), ...motivated us to investigate the role of magnesium aluminium layered double hydroxide (MgAl-LDH) in a similar role. MWCNT/MgAl-LDH 3D hybrid filler (HML) was prepared from the unmodified constituents in 1:1 wt. ratio by simple dry grinding method. The dispersion of this hybrid filler with extraordinary stability was subsequently used in the preparation of EVA/HML nanocomposites by solution intercalation method. Analysis shows MWCNTs to be homogeneously dispersed in the polymer matrix in presence of LDH layers. Reinforcing efficiency of HML in EVA matrix was evaluated through detailed studies of the nanocomposites. Mechanical, thermal and dielectric properties of neat EVA are substantially improved with HML content. Maximum improvement observed in tensile strength, elongation at break and toughness are 182%, 87%, and 300% respectively at 4 wt% HML. However, best dielectric response with ~400 and ~89 times enhancement in AC conductivity and dielectric constant are observed 1 wt% HML content. Comparison of HML with previously reported MWCNT/montmorillonite (MMT) and MWCNT/hectorite 3D hybrid fillers confirms superior reinforcing efficiency of the former. Improvements in properties are attributed to homogeneous dispersion of fillers and improved polymer-filler interaction on account of synergy between MWCNTs and LDH.
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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