Surfactant-Free Monodispersed Pd Nanoparticles Template for Core-Shell Pd@PdPt Nanoparticles as Electrocatalyst towards Methanol Oxidation Reaction (MOR)

An eco-friendly two-step synthetic method for synthesizing Pd@PdPt/CNTs nanoparticles was introduced and studied for the methanol oxidation reaction. The Pd@PdPt alloy core-shell structure was synthesized by preparing a surfactant-free monodispersed Pd/CNTs precursor through the hydrolysis of tetrachloropalladate (II) ion ([PdCl4]2−) in the presence of carbon nanotubes (CNTs) and the subsequent hydrogen reduction and followed by a galvanic replacement reaction. This method opens up an eco-friendly, practical, and straightforward route for synthesizing monometallic or bimetallic nanoparticles with a clean surfactant-free electrocatalytic surface. It is quite promising for large-scale preparation. The Pd@PdPt/CNTs electrocatalyst demonstrated a high specific mass activity for methanol oxidation (400.2 mAmgPt−1) and excellent stability towards direct methanol oxidation compared to its monometallic counterparts.

Synthesis and Introducing Au-Cu Alloy Nanoparticles/Porous Silicon as a Novel Modifier of Screen Printed Carbon Electrode in Simultaneous Electrocatalytic Detection of Codeine and Acetaminophen

In the present study, a bimetallic nanostructure of gold-copper (Au-CuNPs) was decorated on the surface of porous silicon (PSi) using an easy galvanic replacement reaction between metal ions and PSi in the presence of 0.1 M hydrofluoric acid solution. The morphology and structures of the Au-CuNPs@PSi nanocomposite were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) energy-dispersive X-ray spectroscopy (EDX) and cyclic voltammetry (CV) techniques. Then, prepared nanocomposite was used as a modifier in screen-printed carbon electrode (SPCE) for the highly sensitive simultaneous determination of codeine (COD) and acetaminophen (ACE). The combination of PSi and metals nanoparticles provide a porous and high surface area with excellent electrical conductivity which leads to reduce the peak potentials and enhance the oxidation peak currents of COD and ACE at the surface of the Au-CuNPs@PSi/SPCE nanosensor. The dynamic linear ranges were obtained from 0.06 to 0.6 µM for both COD and ACE and the detection limits (3.0 S/N) estimated 0.35 µM for COD and 0.30 µM for ACE, respectively. Moreover, recovery tests were carried out in real samples such as urine, human blood plasma, and tablets.

Synthesis of gold nano-mushrooms via solvent-controlled galvanic replacement to enhance phototherapeutic efficiency

In galvanic replacement, it was found that the solvent polarity had a significant effect on the formed nanostructure. Hollow-tailed Au nano-mushrooms were synthesized under co-solvent conditions and used in effective cancer phototherapy.

“Green” Synthesis of Metallic Nanoparticles by Sonoelectrochemical and Sonogalvanic Replacement Methods

The main features of the “green” synthesis of metallic nanoparticles (MNPs) by the sonoelectrochemical methods are manufacturability, environmental friendliness, and the possibility of controlling the geometry of the forming particles. The electrochemical reduction technique allows efficiently designing the metal nanoparticles and provides the control of the content of components of bimetallic nanoparticles, as well as minimizing the number of precursors in working solutions. Due to the generation of turbulence, microjets, and shock waves, ultrasound increases mass transfer and formation of radicals in aqueous solutions and, accordingly, accelerates the processes of nucleation and growth of MNPs. Therefore, this hybrid method, which combines electrolysis and ultrasound, has attracted the interest of researchers in the last two decades as one of the most promising techniques. The present work presents a short analysis of the reference literature on sonoelectrochemical synthesis of metallic and bimetallic nanoparticles. The main factors influencing the geometry of nanoparticles and their size distribution are analyzed. The use of pulsed ultrasound and pulsed current supply during sonoelectrochemical synthesis is especially effective in designing MNPs. Emphasis is placed on the role of surfactants in the formation of MNPs and sacrificial anodes in providing the algorithm: “anodic dissolution-electrochemical reduction of metal-nucleation and formation of МNPs.” It is noted that ultrasound allows synthesizing the MNPs and M1M2NPs during the galvanic replacement, and an analogy of the formation of nanoparticles by sonogalvanic replacement and sonoelectrochemical method is shown.

Synthesis of Antibacterially ActiveSilver Nanoparticles by Galvanic Replacement on Magnesium in Solutions of Sodium Polyacrylate in an Ultrasound

“Green” synthesis of silver nanoparticles (AgNPs) by a galvanic replacement (GR) on magnesium in solutions of sodium polyacrylate (NaPA) under ultrasound (42 kHz) is reported. The mechanism of combined action of GR and ultrasound on the formation of nanoparticles is proposed. Synthesized solutions of AgNPs are characterized by an absorption maximum at 410 nm, the value of which does not depend on the concentrations of precursors (AgNO3 and NaPA) and the duration of the process. The dimensions of nanoparticles that have a spherical shape do not exceed 30 nm. With increasing concentration of surfactant, there is a tendency to decrease in size. The rate of synthesis of AgNPs increases almost in proportion to the concentration of AgNO3 in the solution, while the effect of NaPA concentration is negligible. The synthesized nanoparticles efficiently demonstrated a bactericide effect on Escherichia coli and Staphylococcus aureus.