Intraphase Switching of Hollow CoCuFe Nanocubes for Efficient Electrochemical Nitrite Reduction to Ammonia

This study addresses the urgent need to focus on the nitrite reduction reaction (NO2-RR) to ammonia (NH3). A ternary-metal Prussian blue analogue (CoCuFe-PBA) was utilized as the template material, leveraging its tunable electronic properties to synthesize CoCuFe oxide (CoCuFe-O) through controlled calcination. Subsequently, a CoCuFe alloy (CoCuFe-A) was obtained via pulsed laser irradiation in liquids. The electrochemical properties of CoCuFe-O, derived from the PBA crystal structure, demonstrated a high yield of NH4+ at a rate of 555.84 μmol h-1 cm-2, with the highest Faradaic efficiency of 91.8% and a selectivity of 97.3% during a 1-h NO2-RR under an optimized potential of -1.0 V vs. Ag/AgCl. In situ Raman spectroscopy revealed the collaborative role of redox pairs (Co3+/Co2+ and Fe3+/Fe2+) as proton (H+) suppliers, with Cu centers serving as NO2- binders, thereby enhancing the reaction rate. Additionally, theoretical studies confirmed that Fe and Co atoms are more reactive than Cu toward intermediates playing crucial roles in hydrogenation, while Cu primarily activates NO owing to hydrogenation by the Fe and Co atoms and a high kinetic barrier in H2O* adsorption. This comprehensive investigation provides valuable insights into the electrochemical NO2-RR, establishing a foundation for efficient and sustainable NH3 synthesis strategies.

Shape-controlled synthesis of micro-/nanosized Cu particles with spherical and polyhedral shapes using the polyol process

This study reports the synthesis of Cu micro-/nanosized particles through the polyol process. Cu particles were synthesized by reducing copper(ii) chloride in ethylene glycol (EG), polyvinylpyrrolidone (PVP), and potassium bromide (KBr) at low temperatures with or without the use of sodium borohydride (NaBH4).

Systematic Investigation of Structural, Morphological, Thermal, Optoelectronic, and Magnetic Properties of High-Purity Hematite/Magnetite Nanoparticles for Optoelectronics

Iron oxide nanoparticles, especially hematite (α-Fe2O3) and magnetite (Fe3O4) have attained substantial research interest in various applications of green and sustainable energy harnessing owing to their exceptional opto-magneto-electrical characteristics and non-toxicity. In this study, we synthesized high-purity hematite and magnetite nanoparticles from a facile top-down approach by employing a high-energy ball mill followed by ultrasonication. A systematic investigation was then carried out to explore the structural, morphological, thermal, optoelectrical, and magnetic properties of the synthesized samples. The experimental results from scanning electron microscopy and X-ray diffraction corroborated the formation of highly crystalline hematite and magnetite nanoparticles with average sizes of ~80 nm and ~50 nm, respectively. Thermogravimetric analysis revealed remarkable results on the thermal stability of the newly synthesized samples. The optical studies confirmed the formation of a single-phase compound with the bandgaps dependent on the size of the nanoparticles. The electrochemical studies that utilized cyclic voltammetry and electrochemical impedance spectroscopy techniques verified these iron oxide nanoparticles as electroactive species which can enhance the charge transfer process with high mobility. The hysteresis curves of the samples revealed the paramagnetic behavior of the samples with high values of coercivity. Thus, these optimized materials can be recommended for use in future optoelectronic devices and can prove to be potential candidates in the advanced research of new optoelectronic materials for improved energy devices.

Pt-Based Multimetal Electrocatalysts and Potential Applications: Recent Advancements in the Synthesis of Nanoparticles by Modified Polyol Methods

In our review, we have presented a summary of the research accomplishments of nanostructured multimetal-based electrocatalysts synthesized by modified polyol methods, especially the special case of Pt-based nanoparticles associated with increasing potential applications for batteries, capacitors, and fuel cells. To address the problems raised in serious environmental pollution, disease, health, and energy shortages, we discuss and present an improved polyol process used to synthesize nanoparticles from Pt metal to Pt-based bimetal, and Pt-based multimetal catalysts in the various forms of alloy and shell core nanostructures by practical experience, experimental skills, and the evidences from the designed polyol processes. In their prospects, there are the micro/nanostructured variants of hybrid Pt/nanomaterials, typically such as Pt/ABO3-type perovskite, Pt/AB2O4-type ferrite, Pt/CoFe2O4, Pt/oxide, or Pt/ceramic by modified polyol processes for the development of electrocatalysis and energy technology. In the future, we suggest that both the polyol and the sol-gel processes of diversity and originality, and with the use of various kinds of water, alcohols, polyols, other solvents, reducing agents, long-term capping and stabilizing agents, and structure- and property-controlling agents, are very effectively used in the controlled synthesis of micro/nanoparticles and micro/nanomaterials. It is understood that at the levels of controlling and modifying molecules, ions, atoms, and nano/microscales, the polyol or sol-gel processes, and their technologies are effectively combined in bottom-up and top-down approaches, as are the simplest synthetic methods of physics, chemistry, and biology from the most common aqueous solutions as well as possible experimental conditions.

Probing the catalytic activity of highly efficient sulfonic acid fabricated cobalt ferrite magnetic nanoparticles for the clean and scalable synthesis of dihydro, spiro and bis quinazolinones

An exceptionally productive, rapid, simple, and eco-friendly approach for the synthesis of 2,3-dihydroquinazolin-4(1H)-one has been developed utilizing acidic magnetically retrievable cobalt ferrite nanoparticles (CFNP@SO3H).

Nanostructured spinel cobalt ferrites: Fe and Co chemical state, cation distribution and size effects by X-ray photoelectron spectroscopy

Nanostructured spinel cobalt ferrite samples having crystallite size ranging between 5.6 and 14.1 nm were characterized by X-ray photoelectron spectroscopy and X-ray induced Auger electron spectroscopy in order to determine the chemical state of the elements, the iron/cobalt ratio and the cation distribution within tetrahedral and octahedral sites. The presence of size-dependent trends in the binding energy of the main photoelectron peaks and in the kinetic energy of the X-ray induced O KLL signal was also investigated. The results showed that iron is present as Fe^III and cobalt is present as Co^II. The iron/cobalt ratio determined by XPS ranges between 1.8 and 1.9 and it is in very good agreement, within experimental uncertainty, with the expected 2 : 1 ratio. The percentage of Fe in octahedral sites ranges between 62% and 64% for all samples. The kinetic energy of the O KLL signals increases with crystallite size. These results are explained in terms of changes in the ionicity of the metal–oxygen bonds. The results of this investigation highlight how the XPS technique represents a powerful tool to investigate the composition, the chemical state and inversion degree of cobalt spinel ferrites, contributing to the comprehension of their properties.

XPS is exploited to study the composition, the chemical state and the cation distribution of metals in CoFe₂O₄.

On-command controlled drug release by diels-Alder reaction using Bi-magnetic core/shell nano-carriers

A novel bi-functional thermo-responsive system, consisting of core/shell bi-magnetic nanoparticles with furan surface functionality, is bonded with N-(2-Carboxyethyl)maleimide through Diels-Alder reaction. The chemotherapeutics doxorubicin is attached onto the surface, with a high loading efficiency of 92%. This system with high responsiveness to a high frequency external alternating magnetic field shows a very good therapeutic efficiency in hyperthermia and drug release at relatively low temperatures (50°C). Polyhedron-shaped bi-magnetic nanoparticles (Zn_0.4Co_0.6Fe₂O₄@Zn_0.4Mn_0.6Fe₂O₄) exhibit a significant increase of the specific energy absorption rate up to 455W/g compared with the core nanoparticles (200W/g). Real-time florescence spectroscopy studies demonstrate rapid release of doxorubicin up to 50% in 5min and up to 92% after 15min upon exposure to high frequency external alternating magnetic field. The stability is evaluated for 8 weeks in phosphate buffer saline with a doxorubicin payload of 85%. In vitro studies using standard MTT cell assays with HeLa and Hep G2 lines prove an excellent biocompatibility with about 90% of cell viability after 24h of treatment within the highest concentration of functionalized magnetic nanoparticles (200μg/mL). The results indicate a controlled drug release mediated by thermo-responsive switching under applied alternating magnetic field.

Yolk–shell structured CoFe2O4 microspheres as novel catalysts for peroxymonosulfate activation for efficient degradation of butyl paraben

Three-dimensional yolk–shell structured CoFe₂O₄ microspheres were successfully fabricated to activate peroxymonosulfate (PMS) for efficiently catalytic degradation of butyl paraben (BPB) in wastewater.