Search Results (875)

In this study, B₄C nanoparticles were incorporated into AA2024, one of the aluminum alloys with superior mechanical and wear properties, with the aim of further enhancing its mechanical, tribological, and corrosion performance. The nanocomposites were produced using mechanical milling followed by powder metallurgy techniques. The effects of nano-sized B₄C additions on powder characteristics, microstructure, and physical, mechanical, tribological, and corrosion properties were systematically investigated through microhardness, density, SEM, XRD, bulk hardness, wear, and corrosion tests. B₄C was added at weight fractions of 0–2 wt.%, and all samples were mechanically milled for 8 h. The results revealed a gradual reduction in powder particle size and a corresponding increase in particle microhardness with increasing B₄C content. The sample reinforced with 2 wt.% nano-B₄C exhibited an approximately 80% increase in hardness and around a 55% improvement in tensile strength compared to the unreinforced alloy. Wear resistance was significantly enhanced, showing up to an 8-fold improvement under a 5 N load and a 6-fold improvement under a 25 N load. Furthermore, corrosion resistance nearly doubled with the addition of B₄C nanoparticles. Full article

Pt-rare earth metal (Pt-RE) alloys are considered to be one of the most promising electrocatalysts for producing oxygen reduction reactions (ORRs) due to their compressively strained Pt overlayer and their exceptional negative-alloy formation energies, which result in excellent activity and stability. However, there are still great challenges in the chemical synthesis of Pt-RE nanoalloys. Herein, we report a simple method employing the nanopores of porous carbon as nanoreactors to synthesize a Pt₅La nanoalloy. The Pt₅La alloy nanoparticles are embedded in porous carbon (Pt₅La@C) with a particle size of around 1–3 nm and also exhibit a very narrow size distribution because of the confined-space effect. The as-prepared Pt₅La@C nanoalloy exhibits highly efficient ORR performance with a half-wave potential of 0.912 V in 0.1 M HClO₄, which is 56 mV higher than that of a commercial Pt/C catalyst. Moreover, it achieves an improved intrinsic activity of 0.69 mA cm⁻² and, a mass activity of 0.42 A mg_Pt⁻¹ at 0.90 V. In addition, it also delivers a very stable lifespan performance, with negligible decay in half-wave potential after accelerated stress testing for 10,000 cycles. This work also provides a new method for the development of promising Pt-RE nanoalloys with ultrasmall nanoparticles with a very narrow size distribution for various efficient energy-conversion devices. Full article

Hard anodic oxide coatings on aluminium have long been used to enhance surface functionality. However, increasing industrial demands are driving the need for coatings with superior hardness, wear resistance, corrosion resistance and self-lubricating properties. Due to their porous structure, anodic oxide coatings can be modified by incorporating various nanoparticles. The properties of the modified coatings depend on both the type of nanoparticles used and the method employed to incorporate them. In this study, anodic oxide coatings were produced using direct and duplex methods on a semi-industrial scale to enable process control and potential industrial implementation. The coatings were modified with hard (Al₂O₃) and soft (CaCO₃, PTFE) nanoparticles in order to customise their functional properties. Their microstructure and chemical composition were characterised by SEM and TEM. Their microhardness, abrasion resistance and electrochemical behaviour were also evaluated. Among the tested production methods and methods for modifying nanoparticles, the duplex process incorporating Al₂O₃ particles proved to be the most promising. Its optimisation resulted in coatings with a microhardness of 430 HV0.05 and a mass loss of 9.4 mg after the Taber abrasion test, demonstrating the potential of this approach for industrial applications. Full article

The emulsification of a molten fusible metal alloy in a liquid epoxy matrix with its subsequent curing is a novel way to create a highly concentrated phase-change material. However, numerous challenges have arisen. The high interfacial tension between the molten metal and epoxy resin and the difference in their viscosities hinder the stretching and breaking of metal droplets during stirring. Further, the high density of metal droplets and lack of suitable surfactants lead to their rapid coalescence and sedimentation in the non-cross-linked resin. Finally, the high differences in the thermal expansion coefficients of the metal alloy and cross-linked epoxy polymer may cause cracking of the resulting phase-change material. This work overcomes the above problems by using nanosilica-induced physical gelation to thicken the epoxy medium containing Wood’s metal, stabilize their interfacial boundary, and immobilize the molten metal droplets through the creation of a gel-like network with a yield stress. In turn, the yield stress and the subsequent low-temperature curing with diethylenetriamine prevent delamination and cracking, while the transformation of the epoxy resin as a physical gel into a cross-linked polymer gel ensures form stability. The stabilization mechanism is shown to combine Pickering-like interfacial anchoring of hydrophilic silica at the metal/epoxy boundary with bulk gelation of the epoxy phase, enabling high metal loadings. As a result, epoxy shape-stable phase-change materials containing up to 80 wt% of Wood’s metal were produced. Wood’s metal forms fine dispersed droplets in epoxy medium with an average size of 2–5 µm, which can store thermal energy with an efficiency of up to 120.8 J/cm³. Wood’s metal plasticizes the epoxy matrix and decreases its glass transition temperature because of interactions with the epoxy resin and its hardener. However, the reinforcing effect of the metal particles compensates for this adverse effect, increasing Young’s modulus of the cured phase-change system up to 825 MPa. These form-stable, high-energy-density composites are promising for thermal energy storage in building envelopes, radiation-protective shielding, or industrial heat management systems where leakage-free operation and mechanical integrity are critical. Full article

Ni-based catalysts have been extensively investigated for lignin hydrogenation; however, they often exhibit limited phenol selectivity and poor catalytic stability. To address these challenges, we introduced Cu as a promoter, resulting in the development of NiCu/ZSM-5 catalysts with significantly enhanced phenol selectivity and durability. Characterization studies revealed that Cu species form an alloy structure with Ni, which effectively suppresses the sintering of Ni nanoparticles during the catalytic process, thereby maintaining consistent performance over multiple reaction cycles. Furthermore, the Cu-Ni alloy demonstrated improved hydrogen activation capability while reducing overall H₂ uptake, leading to a marked increase in phenol selectivity compared to the Cu-free Ni/ZSM-5 catalyst. As a result, the Ni₁Cu₁/ZSM-5 (Ni/Cu molar ratio = 1:1) catalyst achieved a lignin conversion of 69.8% and a phenol selectivity of 84.4%, with negligible performance degradation over 8 cycles. The strategy presented in this work may offer an effective approach for enhancing the performance of industrial catalysts in lignin upgrading processes. Full article

Nanoparticle-mediated photothermal conversion exploits the unique light-to-heat transduction properties of engineered nanomaterials to address challenges in energy, water, and healthcare. This review first examines fundamental mechanisms—localized surface plasmon resonance (LSPR) in plasmonic metals and broadband interband transitions in semiconductors—demonstrating how tailored nanoparticle compositions can achieve >96% absorption across 250–2500 nm and photothermal efficiencies exceeding 98% under one-sun illumination (1000 W·m⁻², AM 1.5G). Next, we highlight advances in solar steam generation and desalination: floating photothermal receivers on carbonized wood or hydrogels reach >95% efficiency in solar-to-vapor conversion and >2 kg·m⁻²·h⁻¹ evaporation rates; three-dimensional architectures recapture diffuse flux and ambient heat; and full-spectrum nanofluids (LaB₆, Au colloids) extend photothermal harvesting into portable, scalable designs. We then survey photothermal-enhanced thermal energy storage: metal-oxide–paraffin composites, core–shell phase-change material (PCM) nanocapsules, and MXene– polyethylene glycol—PEG—aerogels deliver >85% solar charging efficiencies, reduce supercooling, and improve thermal conductivity. In biomedicine, gold nanoshells, nanorods, and transition-metal dichalcogenide (TMDC) nanosheets enable deep-tissue photothermal therapy (PTT) with imaging guidance, achieving >94% tumor ablation in preclinical and pilot clinical studies. Multifunctional constructs combine PTT with chemotherapy, immunotherapy, or gene regulation, yielding synergistic tumor eradication and durable immune responses. Finally, we explore emerging opto-thermal nanobiosystems—light-triggered gene silencing in microalgae and poly(N-isopropylacrylamide) (PNIPAM)–gold nanoparticle (AuNP) membranes for microfluidic photothermal filtration and control—demonstrating how nanoscale heating enables remote, reversible biological and fluidic functions. We conclude by discussing challenges in scalable nanoparticle synthesis, stability, and integration, and outline future directions: multicomponent high-entropy alloys, modular photothermal–PCM devices, and opto-thermal control in synthetic biology. These interdisciplinary innovations promise sustainable solutions for global energy, water, and healthcare demands. Full article

Deep eutectic solvents (DES) have emerged as a versatile and sustainable medium for the green synthesis of nanomaterials, offering a viable alternative to conventional organic solvents and ionic liquids. Nanomaterials can be synthesised in DESs via multiple routes, including chemical reduction, solvothermal, and electrochemical methods. Among the different pathways, this review focuses on the electrochemical synthesis of nanomaterials in DESs, as it offers several advantages: low cost, scalability for large-scale production, and low-temperature processing. The size, shape, and morphology (e.g., nanoparticles, nanoflowers, nanowires) of the resulting nanostructures can be tuned by adjusting the concentration of the electroactive species, the applied potential, the current density, mechanical agitation, and the electrolyte temperature. The use of DES as an electrolytic medium represents an environmentally friendly alternative. From an electrochemical perspective, it exhibits high electrochemical stability, good solubility for a wide range of precursors, and a broad electrochemical window. Furthermore, their low surface tensions promote high nucleation rates, and their high ionic strengths induce structural effects such as templating, capping and stabilisation, that play a crucial role in controlling particle morphology, size distribution and aggregation. Despite significant progress, key challenges persist, including incomplete mechanistic understanding, limited recyclability, and difficulties in scaling up synthesis while maintaining structural precision. This review highlights recent advances in the development of metal, alloy, oxide, and carbon-based composite nanomaterials obtained by electrochemical routes from DESs, along with their applications. Full article

Contaminated water detoxification remains difficult due to the presence of persistent halo-organic contaminants, such as perfluorooctanoic acid (PFOA) and chlorophenols, which are chemically stable and resist conventional purification methods. Functionalized membrane-based separation and decontamination have garnered immense attention in recent years. Commercially available microfiltration membrane (PVDF) and polymeric non-woven fiber filters (glass and composite) are functionalized with poly(methacrylic acid) (PMAA) that shows outstanding pH-responsive performance and tunable water permeability under ambient conditions perfect for environmental applications. Polymer loading based on weight gain measurements on PMAA–microglass composite fibers (137%) and microglass fibers (116%) confirmed their extent of functionalization, which was significantly greater than that of PVDF (25%) due to its widely effective pore diameter. Presence of chemically active hydrogel within PVDF matrix was validated by FTIR (hydroxyl/carbonyl) stretch peak, substantial decrease in contact angle (68.8° ± 0.5° to 30.8° ± 1.9°), and decrease in pure water flux from 509 to 148 LMH/bar. Nanoparticles are generated both in solution and within PVDF using simple redox reactions. This strategy is extended to PVDF-PMAA membranes, which are loaded with Fe/Pd nanoparticles for catalytic conversion of 4-chlorophenol and PFOA, forming Fe/Pd-PVDF-PMAA systems. A total of 0.25 mg/L Fe/Pd nanoparticles synthesized in solution displayed alloy-type structures and demonstrated a strong catalytic performance, achieving complete hydrogenation of 4-chlorophenol to phenol and 67% hydrogenation of PFOA to its reduced form at 22–23 °C with ultrapure hydrogen gas supply at pH 5.7. These results underscore the potential of hybrid polymer–nanoparticle systems as a novel remediation strategy, integrating tunable separation with catalytic degradation to overcome the limitations of conventional water treatment methods. Full article

Postoperative infections in orthopedic implants remain a major complication, particularly in open fractures, where early bacterial colonization and the limited bioactivity of titanium alloys hinder osseointegration. This study reports a hierarchical coating synthesized in situ on Ti-407 alloy, integrating bioactive and antibacterial functions. TiO₂ nanotube arrays were formed by anodization and subsequently functionalized by sequential electrodeposition of Ag nanoparticles and doped hydroxyapatite (HA) (Ca, P, Mg, Zn). SEM/EDS confirmed uniform coatings with a Ca/P ratio near stoichiometric HA (1.61). Agar diffusion assays against E. coli ATCC® 25922™ revealed well-defined inhibition zones, confirming the antibacterial efficacy of the coatings. These findings highlight the potential of hierarchical coatings to enhance bone integration while reducing infection risk in orthopedic implants. Full article

This work develops a novel Ni-Co nanoparticles coupled with Ni₃S₂ and Co₉S₈ phases on nickel foam (denoted as Ni-Co NPS@Ni₃S₂/Co₉S₈/NF) hybrid structure material as a bifunctional water electrolysis catalyst. The self-assembly Ni-Co alloy phases enhance electrical conductivity, while the synergistic interactions among the three components (Ni-Co, Ni₃S₂ and Co₉S₈) optimize the lattice parameters and electronic environment for boosting both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The catalyst achieves low overpotentials of 106 mV for HER and 185 mV for OER at 10 mA·cm⁻² in 1M KOH, along with a very low charge-transfer resistance. Density functional theory (DFT) calculations reveal that the multi-component interaction narrows the band gap and optimizes the hydrogen adsorption free energy (ΔG_H*) as well as the adsorption free energies of OER intermediates (ΔG_OH*). This work identifies the hybrid structure as the key to the enhanced activity and offers a promising strategy for designing efficient nickel–cobalt-based electrocatalysts. Full article

Constituent phases and their corresponding phase transformations are important in developing alloys. This study investigates the phase transformations of a Cr₃₉Co₁₈Fe₁₈Ni₁₈Al₇ HEA after annealing at and quenching from 1100 °C, 1200 °C and 1300 °C. The as-quenched alloy exhibits major body-centered cubic (BCC) and minor face-centered cubic (FCC) structures. The volume fraction of the BCC phase progressively increases as the annealing temperature is elevated. Upon cooling, the occurrence of spinodal decomposition in the high-temperature BCC phase leads to the formation of two distinct disordered BCC phases, BCC1 and BCC2, at a high temperature regime. The BCC1 phase acts as the matrix and is lean in Ni and Al concentrations, while the BCC2 phase presents as fine particles and is enriched in Ni and Al. As the temperature decreases, sequential spinodal decompositions occur in both BCC phases, giving rise to other product BCC phases. Upon further cooling, the Ni–Al-enriched BCC phases undergo ordering reactions, transforming into B2 phases. Consequently, the major phases in the matrix and fine particles are BCC and B2, respectively. In addition, the BCC matrix and B2 fine particles also contain B2 and BCC nanoparticles, respectively. The co-clustering and ordering effects of Ni and Al participate in the phase transformations of the as-quenched HEA. Correspondingly, the hardness increases with annealing temperature, which is attributed to the higher BCC phase fraction and the increasing number density of ordered B2 precipitates that collectively strengthen the matrix by impeding dislocation motion. Full article

The aim of this work was high-temperature synthesis of PtPdCoNiCu/C nanoparticles with high-entropy alloy (HEA) structure as catalysts for oxygen reduction reaction. The materials were synthesized using a highly dispersed PtPd/C support, which was impregnated with Cu, Ni, and Co precursors followed by their precipitation with an alkali. Subsequently, the material was subjected to thermal treatment in a tube furnace at 600 °C for 1 h in a stream of argon containing 5% hydrogen. In combination with HRTEM, element mapping and line scan, XRD, and XPS data, these results confirm the successful synthesis of five-component PtPdCoNiCu high-entropy alloy nanoparticles on the surface of the carbon support. The obtained materials are characterized by a high electrochemical surface area of up to 63 m²/g(PGM), as determined by hydrogen adsorption/desorption and CO-stripping, and a high specific oxygen reduction reaction (ORR) activity of approximately 269 A/g(PGM) at 0.9 V vs. RHE. The synthesized material demonstrated outstanding stability, as confirmed by an accelerated stress test of 10,000 cycles. After the test, the electrochemical surface area decreased by only 12%, while the catalytic activity for ORR even increased. The proposed synthetic strategy opens a new pathway for obtaining promising highly stable five-component HEA nanoparticles of various compositions for application in catalysts. Full article

Fullerenes were modified into fulleramines by the wet chemical method, and then a CoRu/CNB bimetallic catalyst with defect-rich carbon-coated CoRu alloy and Ru NPs anchored on N- and B-doped carbon, promoting full pH hydrogen evolution, was prepared by condensation reflux and pyrolysis. Structural analysis indicates that the carbon layer endows the catalyst with excellent acid/alkali corrosion resistance, and the defect-rich characteristics expose more active sites. This catalyst only requires overpotentials of 21, 33, and 56 mV to drive HER to a current density of 10 mA cm⁻² in alkaline, acidic, and neutral solutions, featuring a rapid kinetic process and a large electrochemically active surface area. The synergistic effect of CoRu alloy and Ru NPs promotes charge redistribution and accelerates electron transfer, enabling CoRu/CNB to exhibit electrochemical activity and stability far exceeding that of commercial Pt/C in 1 M KOH, 0.5 M H₂SO₄, and 1 M PBS media. Full article

This work reports on the effects of surface pre-treatment and EPD process parameters on the nanomechanical and adhesive performance of chitosan-based composite coatings fabricated on a Ti13Zr13Nb alloy. Three different coating systems were prepared: chitosan–Cu (series A), chitosan–HAp (series B), and HAp–Cu (series C). Coatings were deposited from suspensions at different voltages (10–30 V) and for various times (1–2 min) onto polished, anodized, and laser surface-treated titanium alloy substrates. Microstructural, nanomechanical, and adhesion properties were characterized by means of SEM, nanoindentation, and nanoscratch testing, respectively. Chitosan–Cu coatings exhibited the highest hardness (up to 8.2 GPa) and stiffness due to the homogeneous dispersion of Cu nanoparticles and strong interfacial bonding to the underlying anodized TiO₂ layer. Chitosan–HAp coatings were softer (0.05–0.13 GPa) and highly plastic, particularly after laser surface treatment due to their specific porous, polymer-dominated structure. HAp–Cu coatings exhibited an intermediate mechanical behavior with a hardness between 0.1 GPa and 2.9 GPa and enhanced elastic recovery (Wp/We ≈ 3.5–4.7), particularly for anodized substrates. The nanoscratch test results showed that the HAp–Cu coatings exhibited the highest adhesion Lc (≈150–173 mN), confirming a synergistic effect of hybrid composition and heat treatment on interfacial toughness. The present data demonstrate that the optimization of anodizing and EPD processing parameters allows for the manipulation of the mechanical integrity and adhesion of bioactive chitosan-based coatings for titanium biomedical applications. Full article

This work describes the preparation and characterization of chitosan-based biopolymer coatings containing silver, zinc, and hydroxyapatite nanoparticles deposited on the Ti13Zr13Nb alloy by the EPD method. It was intended to evaluate the influence of surface pretreatments and deposition parameters on the structural, electrochemical, and biological properties of coatings. The morphology and composition were characterized by means of SEM/EDS, AFM, XRD, and FTIR analysis. The obtained results indicated uniform continuous layers with homogeneously distributed nanoparticles and the presence of characteristic functional groups originating from chitosan and hydroxyapatite. Corrosion investigations performed in SBF solution revealed a significant enhancement in corrosion resistance for chitosan/nanoAg/nanoZn/nanoHAp coatings, reflected in a drastic decrease in corrosion current density compared with uncoated Ti13Zr13Nb alloy. The contact angle measurements confirmed their hydrophilic nature, which favors better biointegration ability. Biological tests (MTT and LDH) performed on human osteoblasts (hFOB 1.19) confirmed high biocompatibility (>85% cell viability) in the case of all coatings with the addition of hydroxyapatite, whereas in the case of coatings without HAp, cytotoxicity was observed, probably due to the uncontrolled release of metallic nanoparticles. These findings suggest that the presence of hydroxyapatite in chitosan-based coatings efficiently enhances corrosion protection and cytocompatibility, showing very good prospects for biomedical applications such as the surface modification of titanium implants. Full article