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In this study, a series of cobalt-based spinel ferrites catalysts, including nickel, cobalt, zinc, and copper ferrites, were synthesized using the sol–gel auto-combustion method followed by a chemical reduction process. These catalysts were employed for accelerating hydrogen generation via the sodium borohydride hydrolysis process. A continuous stirred tank reactor was used to perform catalytic reactor tests. All samples were subjected to analysis using XRD, FESEM, EDX, FTIR, and nitrogen adsorption–desorption techniques. The results revealed that the cobalt-based copper ferrite sample, Co/Cu-Ferrite, exhibited superior particle distribution, and porosity characteristics, as it achieved a high hydrogen generation rate of 2937 mL/min.gcat. In addition, the higher electrical donating property of Cu-Ferrite which leads to the increase in the electron density of the cobalt active sites can account for its superior performance towards hydrolysis of NaBH4. Using the Arrhenius equation and the zero-order reaction calculation, activation energy for the sodium borohydride hydrolysis reaction on the Co/Cu-Ferrite catalyst was determined to be 18.12 kJ/mol. This low activation energy compared to other cobalt-based spinel ferrite catalysts confirms the catalyst's superior performance as well. Additionally, the outcomes from the recycling experiments revealed a gradual decline in the catalyst's performance after each cycle during 4 repetitive cycles. The aforementioned properties render the Co/Cu-Ferrite catalyst an efficient catalyst for hydrogen generation through NaBH4 hydrolysis. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) has shown a strong Raman enhancement with bimetallic nanoparticles. The combination of the different bimetallic nanoparticles is used in the field of SERS sensors. These sensors can resonate with the organic molecules adsorbed on their surfaces for SERS enhancement. Fabricating these bimetallic, cost-effective and ultrasensitive SERS sensors is a great challenge. To overcome this challenge, a rapid fabrication method of ultrasensitive noble SERS sensors that enable sub-femtomolar detection of molecular analytes, is reported here. SERS sensor is obtained by application of the silver nanorods (AgNRs) deposited on copper nanoflowers (CuNFs) fabricated by chemical reduction and chemical etching, respectively. Purity and structural characteristics of the SERS sensor are measured qualitatively by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared microscopy and Raman analysis. Rhodamine 6 g as an analyte analyses the sensitivity of the SERS sensor. The detection limit and enhancement factor are found to be 10−13 M and 109 respectively for AgNRs deposited CuNFs etched for 30 min. This study reveals that the AgNRs deposited CuNFs are practically found to be sensitive SERS sensors. [ABSTRACT FROM AUTHOR]

A reliable, rapid, and inexpensive nano-sized chemosensor is presented for methamidophos (MET) — an insecticide. Poly(lactic acid) (PLA)-stabilized gold nanoparticles (AuNPs) were synthesized by a simple one-pot, two-phase chemical reduction method. The synthesized PLA-AuNPs were subsequently employed for selective, efficient, and quantitative detection of MET. MET is one of the highly toxic pesticides used for eradication of agricultural and urban insects. Upon the addition of MET, the wine-red color of PLA-AuNPs swiftly transformed into greyish-blue, further corroborated by a significant bathochromic and hyperchromic shift in the SPR band. The presence of other interfering insecticides, metal salts, and drugs did not have any pronounced effect on quantitative MET detection. The detection limit, the quantification limit, and linear dynamic range of MET utilizing PLA-AuNPs were 0.0027 µM, 0.005 µM, and 0.005–1000 µM, respectively. The PLA-AuNP-based assay renders an efficient, rapid, accurate, and selective quantification of MET in food, biological, and environmental samples. The proposed sensor provides an appropriate platform for fast and on-the-spot determination of MET without requiring a well-equipped lab setup. [ABSTRACT FROM AUTHOR]

This experimental study's main goal is to investigate the impact of various silver concentrations on the optical characteristics of Agshell/Aucore bimetallic nanoparticles. By using the pulsed laser ablation in liquid (PLAL) technique on the gold target at the bottom of the container full of silver colloids, the silver/gold nanoparticles are ablated. Colloidal silver nanoparticles, created through a chemical reduction process, are inside the container. The second harmonic of the pulsed Nd:YAG laser is used to irradiate the colloidal mixture of mixed nanoparticles at a wavelength of 532 nm. The Agshell/Aucore bimetallic nanoparticles are created by transferring laser energy to gold nanoparticles, which have a peak absorption of around 530 nm. The experimental variables are the volumetric ratio of nanoparticle solutions. X-ray diffraction pattern (XRD), spectroscopy in the UV–Vis-NIR and IR ranges, dynamic light scattering (DLS), energy-dispersive spectroscopy (EDS), photoluminescence spectrum (PL), and Fourier transform infrared spectroscopy (FT-IR) are used to identify bimetallic nanoparticles. Additionally, FE-SEM and TEM pictures are used to look at the size and morphology of nanoparticles. In order to test the reactivity of silver nanoparticles in the bimetallic system, one goal of this research is the production of stable bimetallic systems and the examination of optical properties. Additionally, a bimetallic structure with a variable silver concentration's shell thickness and catalytic qualities is examined. All samples in the visible range have dipole absorption observable. On the other hand, the first sample with a lower silver concentration exhibits quadrupole absorption. [ABSTRACT FROM AUTHOR]

A series of mesoporous nanoparticle P-CexZr1-xOy (PCZ) catalysts with abundant oxygen vacancies and high specific surface area were successfully prepared, exhibiting 100% formaldehyde conversion at room temperature (25 °C). The PCZ catalyst was investigated in depth utilizing TEM, BET, XRD, XPS, H2-TPR, and Raman characterization, it was found that the PCZ catalyst had an average particle size of 10 nm and a specific surface area of 108 m2/g; templating caused by P123 and effective doping of Zr atoms regulated the oxygen vacancies in the catalyst, altered the reduction characteristics and chemical state of cerium to formed the redox cyclic couple of Ce3+/Ce4+, which significantly enhanced the catalytic oxidation performance of the PCZ catalyst in the indoor environment. [ABSTRACT FROM AUTHOR]

The hydrogenation of a number of carbonyl compounds with the formation of the corresponding alcohols was studied. The process was carried out in a flow-type reactor in the presence of nickel catalysts supported on γ-Al2O3 obtained by the deposition-precipitation method with chemical reduction of the active phase. The effect of the catalyst preparation method on the yield of the resulting alcohols was studied. It has been shown that the increase in the nickel content in the catalyst leads to complete substrates conversion even at 20–80°C and atmospheric hydrogen pressure. [ABSTRACT FROM AUTHOR]

Conjugated polymers are promising tools to differentiate various types of semiconducting single-walled carbon nanotubes (s-SWCNTs). However, their synthesis is challenging. Insufficient control over molecular weights, and unpredictive/unrepeatable batches hinder possible applications and scale-up. Furthermore, commercial homogeneous catalysts often require inert conditions and are almost impossible to recycle. To overcome these problems, we present a nanocatalyst consisting of magnetic nickel nanowires decorated with highly active palladium nanoparticles. A two-step wet chemical reduction protocol with the assistance of sonochemistry was employed to obtain a heterogeneous catalyst capable of conducting step-growth Suzuki polycondensation of a fluorene-based monomer. Additionally, we enhanced the performance of our catalytic system via controlled microwave irradiation, which significantly shortened the reaction time from 3 d to only 1 h. We studied the influence of the main process parameters on the yield and polymer chain length to gain insight into phenomena occurring in the presence of metallic species under microwave irradiation. Finally, the produced polymers were used to extract specific s-SWCNTs by conjugated polymer extraction to validate their utility. [ABSTRACT FROM AUTHOR]

The chemical reduction of group 1 metal cations to their zero-valent species is challenging. Now, a bipyridine-stabilized borate anion joins the ranks of suitable reducing agents and also proves active in the two-electron reduction of CO2. [ABSTRACT FROM AUTHOR]