Integration of noble metals on graphene is renowned for their catalytic and antioxidant prowess. However, utilization of toxic chemicals in the synthesis creates environmental pollution and poisonous nature of chemically synthesized materials. To address this, an economical and eco-friendly method for synthesizing graphene-gold (BRG-Au) nanocomposite by anchoring gold nanoparticles (Au NPs) onto reduced graphene oxide sheets using betel leaf extract as a reducing and stabilizing agent is presented. Comprehensive structural characterizations through UV–Visible, Raman, FT-IR, and XRD analyses confirm the successful formation of the BRG-Au nanocomposite. Morphological assessments utilizing FE-SEM and TEM techniques revealed the presence of transparent, twinkling graphene sheets embellished with 20 to 60 nm of Au NPs in various shapes, including spherical, triangular, pentagonal, circular, and trapezoids. The catalytic and antioxidant activities of the BRG-Au nanocomposite were thoroughly evaluated. In catalytic trials, the nanocomposite exhibited remarkable efficiency in the reduction of 4-nitrophenol to 4-aminophenol, accomplishing this transformation within a mere 30 min during the initial cycle and maintaining stable catalytic performance over three consecutive cycles. Additionally, antioxidant analyses employing Total Antioxidant Activity and 2,2-diphenyl-1-picrylhydrazyl methods demonstrated that BRG-Au nanocomposite possessed equal or superior antioxidant activity than the ascorbic acid standard. This research thus underscores the promising potential of environmentally benign synthesis method for graphene-gold nanocomposite with enhanced catalytic and antioxidant properties.

We have studied a method to prepare polydopamine-modified reduced graphene oxide-supported Pt nanoparticles (Pt– PDA–RGO). The Pt–PDA–RGO nanocomposites were synthesized by a wet-coating process, which was induced by selfpolymerization of dopamine. As an eco-friendly and versatile adhesive source in nature, dopamine could be easily adhered to surfaces of organic material and inorganic material via polymerization processes and spontaneous adsorption under weak alkaline pH conditions. To apply the unique features of dopamine, we synthesized Pt–PDA–RGO nanocomposites with a different quantity of dopamine, which are expected to preserve the improved Pt adsorption on graphene, resulting in the enhanced electrocatalytic performance. The morphology and micro-structure were examined by field emission scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Compared to pristine Pt–deposited RGO (Pt–RGO), Pt–PDA–RGO (30 wt% dopamine against RGO) nanocomposites showed a superior electrochemical active surface area for a methanol oxidation. This could be related to the fact that the optimized c

Carbon-based magnetic nanostructures in several instances have resulted in improved physicochemical and catalytic properties when compared to multi-wall carbon nanotubes (MWCNTs) and magnetic nanoparticles. In this study, magnetic MWCNTs with a structure of NixZnxFe2O4/MWCNT as peroxidase mimics were fabricated by the one-pot hydrothermal method. The structure, composition and morphology of the nanocomposites were characterized with X-ray diffraction (XRD), Fourier transform infrared spectroscopy and transmission electron microscopy. The magnetic properties were investigated with a vibrating sample magnetometer. The peroxidase-like catalytic activity of the nanocomposites was investigated by colorimetric and electrochemical tests with 3,3´,5,5´-tetramethylbenzidine (TMB) and H2O2 as the substrates. The results show that the synthesis of the nanocomposites was successfully performed. XRD analysis confirmed the crystalline structures of the NixZnxFe2O4/ MWCNT nanohybrids and MWCNTs. The main peaks of the NixZnxFe2O4/MWCNTs crystals were presented. The Ni0.25Zn0.25Fe2O4/MWCNT and Ni0.5Zn0.5Fe2O4/MWCNT nanocatalysts showed nearly similar physicochemical properties, but the Ni0.5Zn0.5Fe2O4/MWCNT nanocatalyst was more appropriate than the Ni0.25Zn0.25Fe2O4/MWCNT nanocatalyst in terms of the magnetic properties and catalytic activity. The optimum peroxidase-like activity of the nanocatalysts was obtained at pH 3.0. The Ni0.5Zn0.5Fe2O4/MWCNT nanocatalyst exhibited a good peroxidase-like activity. These magnetic nanocatalysts can be suitable candidates for future enzyme-based applications such as the detection of glucose and H2O2.

Cystatins (CSTs) are reversible and competitive inhibitors of C1A cysteine proteases, corresponding to papain-like cathepsins in plants and animals. A viral CST (CpBV-CST1) was identified from a polydnavirus, Cotesia plutellae bracovirus. Our previous study indicated that overexpression of CpBV-CST1 interfered with immune response and development of Plutella xylostella larvae. This study produced a recombinant CpBV-CST1 protein (rCpBV-CST1) using bacterial expression system to analyze its inhibitory activity against cysteine protease and physiological role in the parasitism of an endoparsitoid wasp, Cotesia plutellae. The open reading frame (ORF) of CpBV-CST1 encodes a polypeptide of 138 amino acids (15 kDa). rCpBV-cystatin protein in BL21 STAR (DE3) competent cells containing a recombinant pGEX4T-3:CpBV-CST1 was overexpressed by 0.5 mM IPTG for 4 h. In biological activity assay, partially purified GST-fused rCpBV-CST1 showed inhibitory activity against papain. It also inhibited larval development of P. xylostella in a dose-dependent manner. These results suggest that CpBV-CST1 plays a role in retardation of larval development of P. xylostella during parasitism.

This study shows that catalytic activity of bimetallic RhPt nanoparticle arrays under CO oxidation can be tuned by varying the size and composition of nanoparticles. The tuning of size of RhPt nanoparticles was achieved by changing concentration of rhodium and platinum precursors in one-step polyol synthesis. Two-dimensional RhPt bimetallic nanoparticle arrays in different size and composition were prepared through Langmuir-Blodgett thin film technique. CO oxidation was carried out on these two-dimensional nanoparticle arrays, revealing higher activity on the smaller nanoparticles compared to the bigger nanoparticles. X-ray photoelectron spectroscopy (XPS) results indicate the preferential surface segregation of Rh compared to Pt on the smaller nanoparticles, which is consistent with the thermodynamic analysis. Because the catalytic activity is associated with differences in the rates of dissociative adsorption between Pt and Rh, this paper suppose that the surface segregation of Rh on the smaller bimetallic nanoparticles is responsible for the higher catalytic activity in CO oxidation. This result suggests a control mechanism of catalytic activity via synthetic approaches of colloid nanoparticles, with possible application in rational design of nanocatalysts.

Western blot analysis using acetylcholinesterase (AChE)-specific antibody was conducted to determine whether AChE gene (Tuace) duplication actually results in overproduction of AChE in Tetranychus urticae (TuAChE). The protein quantities of TuAChE in seven field-collected mite populations were precisely correlated with the copy numbers. To investigate the effects of each mutation on AChE insensitivity and possible fitness cost, eight variants of TuAChE were in vitro expressed using the baculovirus expression system. Kinetic analysis revealed that the Ala391Thr mutation did not change kinetic properties of AChE, whereas the Gly228Ser and Phe439Trp mutations significantly increased the insensitivity to monocrotophos. Moreover, when the Gly228Ser and Phe439Trp mutations are present together, insensitivity increased over a thousand-fold, showing that both mutations confer resistance in a synergistic manner. Presence of the mutations, however, reduced catalytic efficiency of AChE considerably, suggesting an apparent fitness cost in monocrotophosresistant mites. Reconstitution of the multiple copies of AChE having different compositions of mutations revealed that the catalytic efficiencies of the six-copy and two-copy AChEs (resembling the AD and PyriF strains of mite, respectively) were still lower but comparable to that of wildtype AChE. These finding clearly suggested that multiple rounds of Tuace duplication was needed to compensate the reduced catalytic activity of AChE caused by mutations.

Esterification reaction between succinic acid and 1,4-butanediol was kinetically investigated in the presence of nontoxic organometallic compound catalyst(ESCAT-100E) at 150-190℃. The reaction rates measured by the amount of distilled water from the reaction vessel. The Esterification reaction was carried out under the first order conditions respect to the concentration of reactants, respectively. The overall reaction order was 2nd. The linear relationship was shown between apparent reaction rate constant and reciprocal absolute temperature. By the Arrhenius plot the activation energy have been calculated as 376.13 kJ/mol under nontoxic organometallic compound catalyst and also apparent reaction rate constant, k' was found to obey first kinetics with respect to the concentration of catalyst.

A CNT-TiO2 nano composite was prepared from titanium chloride (TiCl4) via sol-gel process using multi walled carbon nano tube (MWCNT) followed by calcination at 450℃. Spectral analysis revealed that the formed TiO2 resided on the carbon in anatase form. The effect of adsorption was investigated using aqueous solution of methylene blue and procion blue dye. The photochemical reaction of CNT-TiO2 composite in aqueous suspensions was studied under UV illumination in batch process. The reaction was investigated by monitoring the discoloration of the dyes employing UV-Visible spectro-photometeric technique as a function of irradiation time. The catalyst composites were found to be efficient for the photodegradation of the dye.

Pt-loaded carbon black for the catalyst of a PEM fuel cell was synthesized with different molar ratios of polyvinylpyrrolidone and H2PtCl6 solution to improve the dispersion of Pt nanoparticles on carbon black and decrease the size of Pt nanoparticles. From transmission electron microscopy results, Pt nanoparticles of a size of approximately 2 nm were highly dispersed when the polyvinylpyrrolidone concentration was 10mM. The electrochemical activity of the synthesized Pt/C catalysts was investigated by cyclic voltammetry, showing that the as-synthesized Pt-loaded carbon black catalyst had the best activity at a polyvinylpyrrolidone concentration of 10 mM.

Catalytic activity changes of perovskite catalysts were examined with their A-site substitution. For the preparation of catalysts, Mn was used for B-site component and La, Ce, Sr, Ba, Ca, Ag were used for A-site component of the perovskite catalysts(ABO3) The effect of calcination temperature on methane combustion and perovskite structure was also investigated. The surface area and adsorbed oxygen species were tested with BET apparatus and O2-TPD, respectively. Perovskite catalysts whose A-site was partially substituted needed higher calcination temperature than un-substituted one to form the perovskite structure. From O2-TPD experiment, it was found that methane combustion activity was directly related to the oxygen desorbing ability of the catalysts. The prepared catalyst(LM-7) was stable at 600℃ for 72 hours of reaction.

Transesterification reactions (methyl methacrylate with monoethanolamine, methyl methacrylate with n-butyl alcohol, dimethylphthalate with ethylene glycol, dimethyl phthalate with monoethanolamine) were kinetically investigated in the presense of various metal acetate catalysts at 110℃. The amount of reactants was measured by gas and liquid chromatography, and the reaction rates also measured from the amount of reaction products and reactants upon each catalyst. The transesterification reactions were carried out under the first order conditions respect to the concentration of reactants, respectively. The overall reaction order was 2nd, Maximum reaction rates were appeared at the range of 1.4 to 1.6 in electronegativity of metal ions and maximum catalytic activities were obserbed at the range of 1.5 to 1,8 in instability constant of metal acetates.

The green synthesis of inorganic nanoparticles (NPs) using biomaterials has garnered considerable attention in recent years because of its eco-friendly, non-toxic, simple, and low-cost nature. In this study, we synthesized NPs of noble metals, such as Ag and Au using an aqueous extract of a marine seaweed, Ecklonia cava. The formation of AgNPs and AuNPs was confirmed by the presence of surface plasmon resonance peaks in UV-Vis absorption spectra at approximately 430 and 530 nm, respectively. Various properties of the NPs were evaluated using characterization techniques, such as dynamic light scattering, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. Phytochemicals in the seaweed extract, such as phlorotannins, acted as both reducing and stabilizing agents for the growth of the NPs. The green-synthesized AgNPs and AuNPs were found to exhibit high catalytic activity for the decomposition of organic dyes, including azo dyes, methylene blue, rhodamine B, and methyl orange.

Background : Panos extract is a mixture of four Panax plant extracts namely Dendropanax morbifera, Panax ginseng, Acanthopanax senticosus and Kalopanax septemlobus. We intended to use Panos extract for ZnO nanoparticles(NPs) synthesis and application for waste water treatment. Methods and Results : In the present study, we have synthesized Panos ZnO nanoparticles via co precipitation method. Characterization of the NPs has been done using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and UV-Visible spectroscopy. An average of 75% efficacy in degrading the methylene blue dye has been observed. The nanoparticles showed antibacterial activity against E. coli and S. aureus. Conclusion : The results shows that Panos ZnO NPs can be a potential eco-friendly and economical tool for waste water management in the current scenario where there an intense urge to remediate the polluted environment through novel approaches such as Nanobiotechnology.

Hydrogen gas is used as a fuel for the proton exchange membrane fuel cell (PEMFC). Trace amount of carbon monoxide present in the reformate H₂ gas can poison the anode of the PEMFC. Therefore, preferential oxidation (PROX) of CO is essential for reducing the concentration of CO from a hydrogen-rich reformate gas. In this study, conventional Pt/Al₂O₃catalyst was prepared for the preferential oxidation of CO. The effects of catalyst preparation method, additive, and hydrogen on the performances of PROX reaction of CO were investigated. Water treatment and addition of Ce enhanced catalytic activity of the Pt/Al₂O₃ catalyst at low temperature below 100℃.

Cobalt titanates (CoTiOx), such as CoTiO3 and Co2TiO4, have been synthesized via a solid-state reaction and characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) measurement techniques, prior to being used for continuous wet trichloroethylene (TCE) oxidation at 36℃, to support our earlier chemical structure model for Co species in 5 wt% CoOx/TiO2 (fresh) and (spent) catalysts. Each XRD pattern for the synthesized CoTiO3 and Co2TiO4 was very close to those obtained from the respective standard XRD data files. The two CoTiOx samples gave Co 2p XPS spectra consisting of very strong main peaks for Co 2p3/2 and 2p1/2 with corresponding satellite structures at higher binding energies. The Co 2p3/2 main structure appeared at 781.3 eV for the CoTiO3, and it was indicated at 781.1 eV with the Co2TiO4. Not only could these binding energy values be very similar to that exhibited for the 5 wt% CoOx/TiO2 (fresh), but the spin-orbit splitting (ΔE) had also no noticeable difference between the cobalt titanates and a sample of the fresh catalyst. Neither of all the CoTiOx samples were active for the wet TCE oxidation, as expected, but a sample of pure Co3O4 had a good activity for this reaction. The earlier proposed model for the surface CoOx species existing with the fresh and spent catalysts is very consistent with the XPS characterization and activity measurements for the cobalt titanates.