Search Results (269)

Copper(II) oxide (CuO) nanoparticles are of growing interest due to their versatility in catalysis, energy storage, and environmental remediation. In this work, a novel air-assisted polyol–thermal decomposition method was developed to synthesize crystalline CuO nanoparticles with a controlled size. The reaction used copper(II) acetate in 1,4-butanediol at 140 °C under varying airflow conditions and reaction times, followed by calcination at 400 °C in air. Continuous air bubbling minimized the formation of Cu₂O and metallic Cu, while maximizing the CuO yield with shortened reaction times. The optimal conditions involved a 4 h polyol reaction while purging air at 1800 cm³/min, followed by 4 h of calcination. This method resulted in polycrystalline monoclinic CuO nanoparticles with a size of 73 ± 32 nm, as observed by TEM and XRD. FT-IR and Raman spectroscopy verified the compositional purity of the nanoparticles. To enhance colloidal stability, a citrate coating reaction of CuO was optimized using sodium citrate dihydrate or citric acid in either water or 1,4-butanediol. The optimal coating conditions employed sodium citrate in water with bath sonication and overhead stirring, yielding a zeta potential of −40.6 ± 0.4 mV at pH 7. This work provides a practical and tunable method for producing high-quality CuO nanoparticles suitable for diverse applications. Full article

The sluggish reduction kinetics of thionyl chloride and the cathode passivation induced by the densification deposition of discharge product LiCl are critical challenges that severely hinder the commercialization of lithium/thionyl chloride (Li/SOCl₂) batteries. In this work, a dual-catalyst cobalt tetrapyridine porphyrin (CoTAP) and copper phthalocyanine (CuPc) supported on activated carbon (AC) were proposed to synergically regulate SOCl₂ reduction and product deposition. When the CoTAP/CuPc/AC catalyst was synthesized and applied as the cathode of Li/SOCl₂ batteries, UV-Vis spectroscopy, crystal field coordination structure analysis, DFT calculations and XPS measurements collectively demonstrated that CoTAP catalyzes SOCl₂ reduction through coordination at Co sites and strongly adsorbs Cl⁻, while CuPc features a weakly coordinated Cu center that facilitates the migration of LiCl products from the cathode surface. This collaborative effect in CoTAP/CuPc/AC cathodes effectively accelerates the reduction kinetics of SOCl₂ and promotes the ordered deposition of product LiCl, thereby guaranteeing the continuous and progressive discharge process in Li/SOCl₂ batteries. As a result, the CoTAP/CuPc/AC-catalyzed batteries exhibited excellent electrochemical performance with a stable discharge voltage of 3.16 V and high discharge capacity of 15.08 mAh, superior to the counterpart batteries without catalysts. This work provides a design idea for the development of advanced Li/SOCl₂ batteries. Full article

The hydrogenation of CO₂ to methanol is a crucial route for achieving carbon recycling. Among the extensively studied catalysts, copper-based catalysts suffer from insufficient activity and stability, while noble metal catalysts are limited by prohibitively high cost. In contrast, metal–organic framework (MOF) materials demonstrate unique advantages due to their designable architectures and high dispersion. Conventional thermal catalysis relies on high temperature and pressure; photocatalysis suffers from low efficiency; and electrocatalysis shows poor selectivity. These limitations motivate the exploration of new catalytic approaches. Plasma catalysis, particularly dielectric barrier discharge (DBD) technology, can efficiently activate CO₂ via high-energy electrons and reactive species at ambient temperature and pressure, and generate a synergistic effect with catalysts, significantly enhancing methanol production efficiency and selectivity. Studies have shown that plasma–catalyst synergistic systems, such as those employing Cu/γ-Al₂O₃ or Pt/In₂O₃, exhibit superior performance to individual processes under mild conditions. Future research should focus on elucidating the plasma–catalyst interface mechanism, optimizing reactor design, and developing compatible, high-efficiency catalysts to establish a novel pathway for CO₂ conversion with low energy consumption and high efficiency. Full article

Lignin’s complex structure makes it a valuable resource for producing aromatic chemicals, but selectively converting it into specific products remains challenging. This study explores the use of technical hydrolysis lignin as a renewable support for palladium (Pd) and copper (Cu) catalysts in hydrogenation reactions. The materials were characterized using NMR, FTIR, XRF, AAS, XPS, and TEM. The reduction of nitrobenzene to aniline was tested with various Pd/Cu catalysts with different metal contents. The hydrogenation results showed that the Pd-only catalyst (catalyst-1) performed best on most substrates. In contrast, catalysts with only Cu or with Pd-Cu bimetallic showed no catalytic activity. The study discusses the effects of Pd incorporation and the Pd-Cu synergistic effect on catalyst stability, highlighting potential limitations in active-site stability and suggesting ways to enhance catalyst longevity. Overall, this research reveals that lignin is a promising, renewable support for catalysts, offering alternatives to traditional supports. These findings provide valuable insights into improving lignin modification and developing eco-friendly catalytic processes aligned with green chemistry principles. Full article

The synthesis of enantiomerically pure chiral β-nitroalcohols is a crucial objective in asymmetric catalysis. In order to efficiently obtain such chiral products, we developed a series of thermoresponsive, oxazoline–copper catalysts (Cu^II-PN_xFe_yO_z) via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization. These catalysts can self-assemble in water into single-chain nanoparticles (SCNPs) with biomimetic behavior, in which intramolecular hydrophobic and metal-coordination interactions generate a confined hydrophobic cavity. Comprehensive characterization by FT-IR, TEM, DLS, CD, CA, and ICP analysis confirmed the nanostructure and composition. When applied to the aqueous-phase asymmetric Henry reaction between nitromethane and 4-nitrobenzaldehyde, the optimal catalyst (2.0 mol%) achieved a quantitative yield (96%) with excellent enantioselectivity (up to 99%) within 12 h. Furthermore, the thermosensitive poly(N-isopropylacrylamide, NIPAAm) block enabled facile catalyst recovery through temperature-induced precipitation above its lower critical solution temperature (LCST). This work presents an efficient and recyclable biomimetic catalytic system, offering a novel strategy for designing sustainable chiral catalysts for green organic synthesis. Full article

Copper (Cu), silver (Ag), and copper–silver (Cu–Ag) powders were synthesized using ultrasonic spray pyrolysis (USP) combined with hydrogen-assisted reduction in order to examine how key processing parameters influence particle characteristics. The effects of reduction temperature, gas atmosphere, and precursor molar ratio on particle morphology, size distribution, and elemental composition were systematically investigated. Aqueous precursor solutions of copper nitrate trihydrate and silver nitrate were atomized in a USP reactor and thermally treated under hydrogen-containing or argon atmospheres at temperatures between 500 and 700 °C. The resulting powders were characterized by scanning electron microscopy (SEM), particle size analysis using ImageJ, and energy-dispersive X-ray spectroscopy (EDS). The results showed that both temperature and gas atmosphere strongly affected particle formation. Hydrogen-assisted synthesis promoted efficient reduction and high metal purity but was associated with increased particle coalescence, whereas argon atmospheres yielded finer and more uniform particles through thermally driven decomposition. In the case of Cu–Ag powders, the precursor molar ratio played a decisive role in particle stability. A 1:1 Cu:Ag ratio produced uniform particles with reduced susceptibility to surface oxidation, while Ag-rich compositions (1:3 Cu:Ag) showed increased agglomeration and partial oxidation after synthesis. Overall, this study demonstrates that careful adjustment of gas atmosphere, synthesis temperature, and precursor composition enables control over the morphology and compositional stability of Cu, Ag, and Cu–Ag powders produced by USP. These findings provide practical guidance for the scalable preparation of mono- and bimetallic metal powders for applications in electronics, catalysis, and energy-related technologies. Full article

The synthesis, in particular the industrial production, of pharmaceuticals requires a broad arsenal of synthetic reactions capable of selectively forming specific structural motifs and assembling smaller building blocks into complex molecules. The Chan–Evans–Lam cross-coupling reaction, which forms a bond between a N-nucleophile and an aryl group from a boronic acid, catalysed by copper salts, is a typical example of this synthetic route. Considering the toxicity of copper and the stringent regulatory limits for its residues in final pharmaceutical products, a heterogeneous catalytic approach offers a viable alternative for this transformation. In this work, we present a simply and reproducibly synthesized catalyst based on copper nanoparticles supported on reduced graphene oxide (Cu-rGO), with high efficiency in a model Chan–Lam reaction involving benzimidazole and aniline derivatives with substituted boronic acids. Full article

Hydrogen peroxide (H₂O₂) is a key oxidant for green chemical processes, yet its catalytic utilization and activation efficiency remain limited by material instability and uncontrolled radical release. Here, we report a dual-functional, hollow conductive polymer nanostructure that enables selective modulation of H₂O₂ reactivity through interfacial physicochemical design. Hollow polypyrrole nanospheres functionalized with carboxyl groups (PPy@PyCOOH) were synthesized via a one-step Fe²⁺/H₂O₂ oxidative copolymerization route, in which H₂O₂ simultaneously served as oxidant, template, and reactant. The resulting structure exhibits enhanced hydrophilicity, rapid redox degradability (>80% optical loss in 60 min (82.5 ± 4.1%, 95% CI: 82.5 ± 10.2%), 10 mM H₂O₂, pH 6.5), and strong electronic coupling to reactive oxygen intermediates. Subsequent tannic acid–copper (TA–Cu) coordination produced a conformal metal–polyphenol network that introduces a controllable Fenton-like catalytic interface, achieving a 50% increase in ROS yield (1.52 ± 0.08-fold vs. control, 95% CI: 1.52 ± 0.20-fold) while maintaining stable photothermal conversion under repeated NIR cycles. Mechanistic analysis reveals that interfacial TA–Cu complexes regulate charge delocalization and proton–electron transfer at the polymer–solution boundary, balancing redox catalysis with energy dissipation. This work establishes a sustainable platform for H₂O₂-driven redox and photo-thermal coupling, integrating conductive polymer chemistry with eco-friendly catalytic pathways. Full article

In the realm of composite solid propellant research, the enhancement of energy performance without altering the underlying formulation holds paramount significance. This investigation employed an in situ displacement technique to establish a highly reactive interface, successfully synthesizing the [nCu+nCo+nFe]/μAl composite material, which considerably augmented the energy performance of RDX/AP. The decomposition pathways of ammonium perchlorate (AP) and RDX were optimized, resulting in a reduction in their thermal decomposition temperatures by 1.3 °C and 22.4 °C, respectively. Simultaneously, the highly reactive interface promoted efficient oxygen transport, thereby facilitating more rapid and complete reactions of aluminum. Moreover, the distinct dual-catalyst efficacy of the composite significantly enhanced the combustion efficiency of the composite energy micro-unit. Consequently, the [nCu+nCo+nFe]/μAl+RDX/AP composite energetic micro-units exhibited a notable decrease in combustion duration (from 1.58 s to 1.07 s) and elevated combustion flame temperatures (ranging from 1712.8 °C to 2205.6 °C) alongside an expanded combustion area, thus underscoring its potential for advanced propulsion applications. Full article

Copper(II) complexes with 2,2′:6′,2″-terpyridines (terpys) are promising candidates for anticancer therapy and catalysis. Their structural and optical properties can be tuned by modifying the terpy backbone, including a substitution at the 4′ position or the replacement of peripheral pyridines with thiazole rings, forming 2,6-bis(thiazol-2-yl)pyridines (dtpys). dtpy-based copper(II) complexes (Cu-dtpys), despite their applicative potential, are barely characterized in the literature. Here, the series of Cu-dtpys (1–13) was synthesised and characterized by FT-IR, HRMS, X-ray diffraction, and UV-Vis spectroscopy. Their structural and optical features were compared to previously studied Cu-dtpys (14–24) and their terpy analogues (Cu-terpy-1 ÷ Cu-terpy-24). The detailed analysis revealed that five-coordinate Cu-dtpys complexes adopt a square pyramidal geometry comparable to that of Cu-terpys complexes but with markedly smaller deviations from the ideal square pyramid. Compared with Cu-terpys, Cu–Cl_apical bonds are shorter, while Cu–N_central bonds are elongated. The Cu-dtpy systems usually present the longest wavelength of the lowest energy absorption band in comparison to Cuterpys. The analysis of the relationship between Hammett’s constant and wavelength of absorption indicates that the most promising from the photophysical point of view are compounds 4–6, 10–13, 16–17, and 22, for which a newly formed intraligand charge transfer band is formed. Full article

The integration of polymer coatings with metal and metal oxide nanoparticles represents a significant advancement in nanotechnology, enhancing the stability, biocompatibility, and functional versatility of these materials. These enhanced properties make polymer-coated nanoparticles key components in a wide range of applications, including biomedicine, catalysis, environmental remediation, electronics, and energy storage. The unique combination of polymeric materials with metal and metal oxide cores results in hybrid structures with superior performance characteristics, making them highly desirable for various technological innovations. Polymer-coated metal and metal oxide nanoparticles can be synthesized through various methods, such as grafting to, grafting from, grafting through, in situ techniques, and layer-by-layer assembly, each offering distinct control over nanoparticle size, shape, and surface functionality. The distinctive contribution of this review lies in its systematic comparison of polymer-coating synthesis approaches for different metal and metal oxide nanoparticles, revealing how variations in polymer architecture and surface chemistry govern their stability, functionality, and application performance. The aim of this paper is to provide a comprehensive overview of the current state of research on polymer-coated nanoparticles, including metals such as gold, silver, copper, platinum, and palladium, as well as metal oxides like iron oxide, titanium dioxide, zinc oxide, and aluminum oxide. This review highlights their design strategies, synthesis methods, characterization approaches, and diverse emerging applications, including biomedicine (e.g., targeted drug delivery, gene delivery, bone tissue regeneration, imaging, antimicrobials, and therapeutic interventions), environmental remediation (e.g., antibacterials and sensors), catalysis, electronics, and energy conversion. Full article

A carbon-supported palladium-containing polysiloxane macrocatalyst (Pd-PDMS) was developed for pharmaceutical-grade cross-coupling reactions. The catalyst demonstrates exceptional year-long stability at room temperature while maintaining full catalytic activity. Pd-PDMS efficiently promotes three pharmaceutically relevant reactions: Suzuki coupling (80% yield), copper-free Sonogashira coupling (90% yield at 55 °C), and Heck coupling (80% yield at 90 °C). The copper-free Sonogashira protocol eliminates toxic copper cocatalysts, phosphine ligands, and organic bases while operating under mild conditions. Most significantly, palladium contamination in products reaches ultra-low levels of 22 ppb (Sonogashira, Suzuki) and 167 ppb (Heck), representing a 60–450-fold improvement over European Medicines Agency requirements (10 ppm). The catalyst exhibits excellent recyclability without activity loss over multiple cycles, with simple washing protocols between uses. Scanning electron microscopy and X-ray photoelectron spectroscopy confirmed uniform Pd-PDMS coating on carbon fibers, while density functional theory calculations revealed specific coordination interactions between the palladium complex and carbon support at 3.26 Å distance. This convergence of pharmaceutical-grade metal contamination control, exceptional stability, and multi-reaction versatility establishes a significant advancement for sustainable cross-coupling catalysis in pharmaceutical applications. Full article

Sulfonyl derivatives are very important compounds as they can be found in sulfones and sulfonamides, two classes of compounds with prominent biological and pharmacological activities. This study explores a copper-catalyzed cascade heterocyclization/sulfonylation reaction for the controlled preparation of sulfonyl oxazinones. Surprisingly, in this work we have isolated a great variety of vinyl sulfones with high selectivity instead of the expected cyclization. These sulfones are obtained by the reaction between N-Boc-allenes and aromatic sodium sulfinates. These results emphasize the reactivity of allenes toward the formation of bis(γ-amino-functionalized vinyl sulfones) in the presence of copper salts under radical conditions. Full article

Tungstophosphoric acid (TPA) has been supported on mesoporous silicas prepared using urea as the pore forming agent. The amount of urea (20, 30, or 40% w/w) influences the silica specific surface area (S_BET), total pore volume (Vp), and average pore diameter (Dp). The materials synthetized using 20% w/w (SiU20) display mainly mesoporous structures, with the highest Vp and Dp values being chosen to be used as TPA support. The SiU20-TPA solids with different TPA loadings (10, 20, or 30% w/w) have been used as supports for chiral copper catalysts with bis(oxazoline) or azabis(oxazoline) ligands. The catalytic efficiency of enantioselective cyclopropanation strongly depends on support morphology and TPA loading. SiU-TPA20 has been shown to be the optimal one. The stability of the complex is also a very important parameter, and the best results are obtained with an excess of chiral ligand to ensure the correct formation of the complex on the solid. In this way, with azabox-Cu/SiU20-TPA20 it is possible to obtain a highly selective (90% ee for the trans-cyclopropanes) and recoverable catalyst. Full article

The design of sustainable nanomaterials for catalysis is a key challenge in green chemistry. Herein, we report the synthesis of halloysite nanotube (Hal)-based nanomaterials selectively functionalized with a bio-inspired polydopamine (PDA) coating, which enables the controlled anchoring of palladium and copper nanoparticles (PdNPs and CuNPs). This mild and ecofriendly strategy yields highly dispersed and ultrasmall (<5 nm) metal nanoparticles without the need for surfactants or harsh reagents. The resulting materials, Hal@PDA/PdNPs and Hal@PDA/CuNPs, were evaluated in two well-established model reactions commonly employed to probe catalytic performance: cinnamaldehyde hydrogenation and 4-nitrophenol reduction. Hal@PDA/PdNPs displayed complete conversion and >90% selectivity toward hydrocinnamaldehyde at low Pd loading (0.8 wt%) and maintained its efficiency over six catalytic cycles (TOF up to 0.1 s⁻¹), while Hal@PDA/CuNPs retained high activity through eight consecutive runs in the reduction of 4-nitrophenol. Hal@PDA/CuNPs proved to be an excellent recyclable catalyst for the reduction of 4-nitrophenol, retaining high activity through eight consecutive runs. Overall, this study introduces a robust and modular approach to fabricating halloysite-based nanocatalysts, demonstrating their potential as green platforms for metal nanoparticle-mediated transformation. Full article