RESUMO
Herein, the efficient serotonin (5-HT) sensing studies have been conducted using the (ZnO NRs)1-x(CNs)x nanocomposites (NCs) having appropriate structural and electrochemical properties. Initially, the different compositions of ZnO nanorods (NRs), with varying content of carbon nanostructures (CNs=MWCNTs and RGO), are prepared using simple in-situ wet chemical method and thereafter these NCs have been characterized for physico-chemical properties in correlation to the 5-HT sensing activity. XRD Rietveld refinement studies reveal the hexagonal Wurtzite ZnO NRs oriented in (101) direction with space group 'P63mc' and both orientation as well as phase of ZnO NRs are also retained in the NCs due to the small content of CNs. The interconnectivity between the ZnO NRs with CNs through different functional moieties is also studied using FTIR analysis; while phases of the constituents are confirmed through Raman analysis. FESEM images of the bare/NCs show hexagonal shaped rods with higher aspect ratio (4.87) to that of others. BET analysis and EIS measurements reveal the higher surface area (97.895 m2/g), lower charge transfer resistance (16.2 kΩ) for the ZCNT 0.1 NCs to that of other NCs or bare material. Thereafter, the prepared NCs are deposited on the screen printed carbon electrode (SPCE) using chitosan as cross-linked agent for 5-HT sensing studies; conducted through cyclic voltammetry (CV) and square wave voltammetry (SWV) measurements. Among the various composites, ZCNT0.1 NCs based electrodes exhibit higher sensing activity towards 5-HT in accordance to its higher surface area, lower particle size and lower charge transfer resistance. SWV measurements provide a wide linear response range (7.5-300 µM); lower limit of detection (0.66 µM), excellent limit of quantification (2.19 µM) and good reproducibility to ZCNT 0.1 NCs as compared to others for 5-HT sensing studies.
RESUMO
Herein, a protocol strategy has been designed for the preparation of ternary silver nanoparticles-supported polyaniline multiwalled carbon nanotube (Ag NPs-PANI/MWCNT) nanocomposites with a chemical interaction for catalytic and antibacterial activity. The morphological study confirmed that Ag NPs were immobilized on the surface of PANI, and afterward, Ag NPs-PANI were mixed with the MWCNTs. The X-ray diffraction technique revealed the face-centered cubic structure of Ag NPs, and the X-ray photoelectron spectroscopy study revealed the chemical constituent and signature of π-π* and C-N interactions in the nanocomposites. The ternary Ag NPs-PANI/MWCNTs nanocomposites have the apparent rate of reaction (K app) as 5.4 × 10-3 s-1, higher than binary nanocomposites for catalytic reduction of 4-nitrophenol to 4-aminophenol at room temperature. Antibacterial activity of Ag NPs-PANI/MWCNT nanocomposites is higher against pathogenic bacteria. Thereafter, because of multifold applications of ternary nanocomposites, they have a broad scope in the field of environmental and healthcare sectors.
RESUMO
In the present investigation, the silver present in photographic waste is reclaimed catalytically using magnetically separable TiO2@CuFe2O4 nanocomposites (NCs), and further, the recovered silver nanoparticles [Ag(0) NPs] are tested against the representative bacteria for the antibacterial activity. Initially, a series of the different composites between TiO2 nanoparticles and CuFe2O4 nanoparticles are synthesized by a sol-gel "ex situ" method to enhance the catalytic activity of bare nanomaterials toward the visible region of the electromagnetic spectrum. X-ray diffraction reveals the presence of characteristic patterns for the tetragonal structure in the bare materials or TiO2@CuFe2O4 NCs; however, the dominance in the phase as well as intensity of the respective XRD reflections in the NCs is observed according to the content of TiO2 or CuFe2O4 in the NCs. Field-emission electron microscopic images show the uniform spherical particles for the representative TiO2@CuFe2O4 NCs, which is also confirmed through the HRTEM images. The magnetically separable behavior of the representative TiO2@CuFe2O4 NCs is confirmed through the VSM measurements, which also shows the superparamagnetic properties due to the S-shaped nature of the hysteresis loop. Thereafter, a photoconversion reaction of Ag(I) ions to Ag(0) NPs as a model reaction is carried out using the different TiO2@CuFe2O4 NCs under visible light irradiation, and hence, the higher catalytic recovery of Ag(0) NPs is observed for a composite containing 10 wt % TiO2 and 90 wt % CuFe2O4 than that of other NCs or the bare one alone. The optimized protocol of the model reaction is adopted for reclaiming Ag(0) NPs from photographic waste. The progress of the catalytic reclamation reaction is monitored using UV-visible, and then sizes of the recovered Ag(0) NPs are confirmed through the HRTEM images. Thereafter, the recovered Ag(0) NPs are tested for complete photoinactivation of Escherichia coli bacteria within 120 min.
RESUMO
In this study, the in situ sol-gel method has been deployed to prepare the titanium dioxide/multiwalled carbon nanotubes (TiO2/MWCNTs) nanocomposite (NCs) powders with varying content of MWCNTs (0.01-1.0 wt %), to construct the dye-sensitized solar cells (DSSCs). First, binder-free NCs were deposited on a transparent-conducting F:SnO2 (FTO) glass substrate by a doctor-blade technique and then anchored with Ru(II)-based dyes to either N719 or ruthenium phthalocyanine (RuPc). The structural and optical properties and interconnectivity of the materials within the composite are investigated thoroughly by various spectral techniques (XRD, XPS, Raman, FT-IR, and UV-vis), electron microscopy (HRTEM), and BET analysis. The experimental results suggest that the ratio of MWCNTs and TiO2 in NCs, morphology, and their interconnectivity influenced their structural, optical, and photovoltaic properties significantly. Finally, the photovoltaic performances of the assembled DSSCs with different content of MWCNTs to TiO2 films anchored with two different dyes were tested under one sun irradiation (100 mW/cm2). The measured current-voltage (IV) curve and incident photon-to-current conversion efficiency (IPCE) spectra of TiO2/0.1 wt % MWCNTs (T@0.1 C) for N719 dye show three times more power conversion efficiency (η = 6.21%) which is opposed to an efficiency (η = 2.07%) of T@0.1 C for RuPc dye under the same operating conditions.
