ACS Applied Nano Materials最新文献

In this work, we report the development of the α-MnO₂/Cu-MOF nanocomposite, a metal-oxide-functionalized metal–organic framework composite material. Initially, α-MnO₂ nanorods were synthesized via a solvothermal approach, which acted as the nucleation center for the synthesis of Cu-MOF directly on its surface to attain the nanocomposite material. The as-synthesized material was characterized by various techniques such as FT-IR, PXRD, TGA, FESEM, EDX, ICP-OES, HRTEM, XPS, and BET analysis. The nanocomposite was used as a catalytic system for the Suzuki–Miyaura cross-coupling reaction of aryl boronic acids with different aryl halides under relaxed reaction conditions in an aqueous medium to produce corresponding biphenyl derivatives in good to excellent yields. The α-MnO₂/Cu-MOF nanocomposite-catalyzed reaction process has several noteworthy features, such as low catalyst loading, excellent yield of biaryl moieties, broad substrate scope including challenging halides like aryl chlorides and aryl fluorides, shorter reaction time, and green reaction medium (H₂O). This work also highlights the enhanced thermal and chemical stability of the nanocomposite as compared to its individual components, which clearly demonstrates the synergistic interaction of the NPs and the MOF. This work provides a heterogeneous, durable, and highly efficient catalyst that is pertinent for organic transformations.

Increasing use of Ti-based blood-interfacing medical devices, along with the rising incidence of postimplant infections and thrombosis, necessitates the development of hemophobic surfaces that reduce thrombosis while offering enhanced antibacterial activity and low protein adsorption. Herein, this study aims to develop a carbon nanofiber-coated Ti6Al4V surface utilizing metal catalysts Ti, Cu, Ag, and Zn. CNF grown with Ag, Ti, Zn, and Cu catalysts resulted in a high degree of graphitization (I_D/I_G), i.e., 0.71, 0.67, 0.63, and 0.58, which is attributed to their associated sp² hybridization resulting strong water and blood repellence (contact angles >129°). Ti-CNF, Cu-CNF, Ag-CNF, and Zn-CNF showed higher release of their respective ions (83, 94, 96, and 92 ppb, respectively) compared to uncoated Ti6Al4V (26 ppb), due to sputtering of the metal catalysts. Ti-CNF, Cu-CNF, Ag-CNF, and Zn-CNF exhibited increased contact angles of 135°, 148°, 129°, and 144°, respectively, relative to uncoated Ti6Al4V, indicating enhanced surface hydrophobicity, attributed to air pocket formation. Despite comparable ion release among the coatings, Ag-CNF and Zn-CNF exhibited the highest antibacterial activity against E. coli (40 and 44%) and S. aureus (27 and 38%), respectively, which is attributed to the strong intrinsic antimicrobial effects of Ag⁺ and Zn²⁺ ions. Additionally, surface characteristics played an important role: the reduced contact angle of Ag-CNF promotes greater bacterial interaction and ion-mediated cell damage, while an increased hydrophobicity of Cu-CNF and Zn-CNF also contributed to their antibacterial activity by limiting bacterial adhesion and survival compared to Ti-CNF. Furthermore, the CNF-coated surfaces showed reduced protein adsorption and lower hemolysis, indicating improved hemocompatibility. Zn-CNF exhibited the highest cell density, showing a 4-fold (507 cell/mm²) increase compared to that of uncoated Ti6Al4V. Importantly, none of the CNF-coated surfaces exhibited cytotoxic effects. CNF-grown Ti6Al4V surfaces with selected catalysts produced multifunctional coatings with enhanced antibacterial performance and blood compatibility, highlighting their potential for blood interface medical devices.

The electrocatalytic nitrate reduction reaction (NO₃RR) has emerged as a promising strategy for ammonia (NH₃) synthesis under ambient conditions. However, the sluggish anodic oxygen evolution reaction (OER) not only significantly restricts the overall efficiency of the NO₃RR process, but also inevitably wastes electrical energy. In this study, we synthesized a series of CuCo layered double hydroxide (LDH) nanosheets by adjusting the Cu/Co ratio, which demonstrate enhanced electrocatalytic activity for the NO₃RR at the cathode and organic pollution degradation at the anode. Specifically, Cu₂Co₁-LDH nanosheets exhibit an exceptional NH₃ yield of 0.32 mmol h^–1 cm^–2 and a high Faradaic efficiency (FE) of 82.24% at −1.0 V vs reversible hydrogen electrode (RHE). Meanwhile, the optimized Cu₄Co₁-LDH nanosheets achieve highly efficient 2,4-dichlorophenol (2,4-DCP) oxidation reaction (DOR) at 1.9 V vs RHE, which is 1.5 times higher than that of the Cu₁Co₁-LDH. Ultimately, the Cu₂Co₁-LDH cathode and Cu₄Co₁-LDH anode were coupled to form an asymmetric NO₃RR||DOR bifunctional system that maintains a high NH₃ yield and 2,4-DCP degradation at a current density of 10 mA cm^–2 under a cell voltage of 1.89 V, 230 mV lower than that of the NO₃RR||OER arrangement. A series of electrochemical tests reveal that the excellent electrocatalytic performance of the CuCo-LDH nanosheets stems from the bimetallic synergy and layered nanostructure, which effectively inhibit the competing reactions and enhance the charge-transfer efficiency. This study demonstrates an effective design for bifunctional nanocatalysts to address the kinetic sluggishness in the NO₃RR and a strategy for asymmetric coupling with the degradation of organic pollutants.

The transformation of solar energy into chemical energy represents a sustainable approach to transitioning from fossil fuels to renewable energy. Photocatalysis using nanostructures offers a clean and efficient method for storing solar energy in chemical fuels that can be readily transported and used when needed. Among solar energy conversion methods, localized surface plasmon resonance (LSPR)-enhanced photocatalysis is particularly promising as it enables the harnessing of energy across the entire solar spectrum, including the near-infrared region. The key mechanism behind the enhanced photoactivity of plasmonic nanostructures is the LSPR-induced hot-carrier transfer. While significant advancements have been made in plasmonic photocatalysis driven by hot-electron transfer, systems based on hot-hole transfer remain underdeveloped despite their importance. This review highlights recent developments and discoveries related to LSPR-induced hot-hole transfer in plasmonic metal nanocrystals and plasmonic semiconductor nanostructures with a focus on their applications in photocatalysis. Additionally, emerging plasmonic nanomaterials are discussed, providing insight into the potential for utilizing LSPR-induced hot-holes in advanced photocatalytic systems. The physical principles governing LSPR in both metals and semiconductors are first introduced, followed by a discussion of the ultrafast charge dynamics of LSPR-induced hot-carriers. Representative plasmonic photocatalytic systems, including metal–semiconductor heterojunctions, molecule-functionalized plasmonic metals, and self-doped plasmonic semiconductors, are reviewed to illustrate the direct involvement of hot-holes in photocatalytic reactions. In addition, emerging plasmonic nanomaterials and strategies of maneuvering hot-hole dynamics are highlighted as a forward-looking perspective for leveraging the oxidative power of hot-holes in next-generation plasmonic systems for efficient and tunable solar-to-fuel energy conversion.

The combination of a strongly resonant optical metasurface (MS) with a MoS₂/WSe₂ heterobilayer is proposed for efficient free-space lasing enabled by the enhanced coupling between the optical and matter (exciton) states. The MS comprises silicon-rich nitride meta-atoms periodically arrayed in a subdiffractive lattice and overlaid with MoS₂/WSe₂, which provides an optically pumped gain around 1130 nm. Light emission is enabled by exploiting a quasi-bound state in the continuum in the form of a perturbed vertical magnetic dipole resonance. Following a meticulous design process guided by full-wave simulations and multipole expansion analysis, an ultralow lasing threshold of ∼6 kW/cm² is achieved. Moreover, the thermal stability of the lasing structure is examined through heat-transfer simulations; stable operation with pump power densities up to a few MW/cm² (3 orders of magnitude above the threshold) is predicted. These results demonstrate that MoS₂/WSe₂-based MS lasers can exhibit robust operation, paving the way for highly performing ultrathin light-emitting surfaces. The lasing response is rigorously assessed through a highly efficient temporal coupled-mode theory framework, verified by time-domain FEM simulations showing excellent agreement. Thus, an efficient and accurate approach to design and study MS lasers with arbitrary geometries and surface or bulk gain media is introduced, exhibiting significant advantages over cumbersome full-wave simulations.

Plasmonic nanostructures provide a versatile platform for modulating nanoscale energy transfer processes. Herein, we report a magnetoplasmonic nanofluid comprising core–shell MnFe₂O₄@Fe₃O₄ nanocubes and gold nanorods that exhibits significantly enhanced magnetic hyperthermia performance under kHz-range alternating magnetic fields. A marked increase in heating efficiency, up to 50% higher specific absorption rate (SAR) compared to the ferrite-only control samples, was observed when the plasmon resonance of the Au nanorods aligned with near-infrared optical transitions of the ferrite nanocubes. This enhancement is attributed to the polariton-like hybridization phenomenon in the near field. Such findings open potential avenues for engineering multifunctional nanomaterials for targeted cancer therapy and theragnostic applications.

Metal-mediated modulation of fluorescence provides a powerful route for developing highly selective fluorescent sensors. In this study, fluorescent polytannic acid nanoparticles (PTA Nps) were synthesized for phosphate detection, with and without metal-ion mediation. The nanoparticles exhibited a pronounced ratiometric fluorescence change (∼3.2-fold) in response to pyrophosphate (PPi), displaying excellent selectivity over other analytes and achieving a low detection limit of 3.93 μM. Mechanistic investigations indicated that PPi triggers deprotonation of phenolic −OH groups and forms hydrogen-bonding interactions with the PTA NPs. Additionally, the nanoparticles showed significant fluorescence quenching, ∼15.5-fold with Fe³⁺ and ∼2.5-fold with Cu²⁺ ions in aqueous medium. This quenching is attributed to the higher complexation affinity and binding constant for Fe³⁺ (∼48,310 M^–1), compared to Cu²⁺ (∼3460 M^–1). XPS, FT-IR, and EPR analyses confirmed metal–nanoparticle complexation as the mechanism underlying these responses. Upon PPi addition, Fe³⁺-incorporated nanoparticles displayed a turn-on fluorescence response (∼6.5-fold), while Cu²⁺-incorporated nanoparticles underwent further fluorescence quenching (∼2.0-fold) selectively in the presence of monohydrogen phosphate (HPO₄^2–). Mechanistic studies revealed that PPi removes the Fe³⁺ complex from the nanoparticle surface, enabling fluorescence recovery, whereas the formation of a ternary Cu²⁺-HPO₄^2– complex induces additional quenching. The sensor system demonstrated practical applicability by successfully detecting PPi in real samples, including tap water, wastewater, and soil extracts. Furthermore, a paper-based sensing platform was developed, enabling rapid and convenient on-site PPi detection and underscoring the potential of PTA NPs for environmental monitoring and diagnostic applications.

This work reports the engineering of a visible-light-active type-II heterojunction CoWO₄/WO₃ nanocomposite via a hybrid hydrothermal and mechanical grinding method. Varying the hydrothermally produced CoWO₄-to-WO₃ weight ratio optimized the effective bandgap to 2.5 eV. Mechanical grinding generates intimate interfacial contact by dispersing nanosized CoWO₄ (∼50 nm) over thinned monoclinic WO₃ plates (∼100 nm), as confirmed by HR-TEM and FESEM. The optimized composite containing 42.85 wt % WO₃ (CW3) exhibits a bandgap of 2.51 eV and a negative zeta potential (−26.9 mV), which enhances adsorption of cationic dyes. The composite shows an extended electron–hole recombination lifetime of 30.5 ns, which is 3–6× longer than that of pristine CoWO₄ and WO₃. Under visible-light irradiation (350 W, Xe lamp, λ > 420 nm filter), the composite achieves 98% degradation of methylene blue at pH 14 (40 min) and retains 80% efficiency after 10 reuse cycles. The composite degraded cationic methylene blue, methylene orange, rhodamine B, and some volatile organic chemicals (acetaldehyde) under visible-light energy sources. These results highlight the potential of CoWO₄/WO₃ heterojunctions for photocatalytic applications in environmental remediation.

Hollow Rh nanostructures are highly attractive, owing to their potential to enhance catalytic performance while reducing Rh loading. However, the synthesis of hollow Rh-based nanostructures has achieved fewer successes compared to other noble metals such as Pd, Pt, Ag, and Au, primarily due to the high bond dissociation energy and surface free energy of Rh. In this work, we constructed hollow Rh nanocockleburs (Rh H-NCs) via an improved seeded growth followed by selective etching (SGSE) method. Leveraging the penta-twinned structure of Au nanobipyramids (Au NBPs), we achieved site-selective Rh deposition. Specifically, Rh atoms first nucleated at the high-energy edges and vertices owing to their lower activation barrier and then covered the facets. This process led to the formation of Au@Rh nanocockleburs (Au@Rh NCs) with a porous shell morphology. The surface porosity and shell thickness of the Rh H-NCs could be regulated by varying the amount of the Rh precursor. Our investigation into the selective etching of Au@Rh NCs reveals that the complete removal of the Au core relies on specific reaction conditions (i.e., O₂ atmosphere, high concentration of CTAB, and sufficient H⁺) and the pivotal role of the Rh shell. The improved SGSE method was further demonstrated to be easily extended to other Au nanosystems, yielding various hollow Rh nanostructures, such as cylindrical, cubic, and spherical shapes. Benefiting from the enlarged surface area resulting from their hollow structure, the Rh H-NCs exhibited superior catalytic activity and durability for the hydrogen evolution reaction, surpassing the performance of a commercial Rh/C catalyst. This work not only provides a universal strategy for fabricating various hollow Rh nanostructures with desired shapes but also highlights their significant potential in catalytic applications.

Bacterial outer membrane vesicles (OMVs) have emerged as promising platforms for cancer therapy owing to their intrinsic biological activity and capacity for drug loading. Herein, we developed a multifunctional OMV-based nanoreactor (T-TiCNOMV-GL) for enhanced photodynamic therapy (PDT) against breast cancer by integrating OMV purification, tumor targeting, metabolic depletion, and photodynamically driven self-propulsion. Titanium carbonitride (TiCN) was selected as the photosensitizer because of its strong affinity for OMVs and efficient absorption of near-infrared light, enabling robust photodynamic reactions. To improve tumor specificity, the homing peptide LyP₁ was conjugated to the membrane protein cytolysin A. In addition, self-expressed lactate oxidase and exogenously supplied glucose oxidase were incorporated into the nanoreactor to deplete lactate and glucose within the tumor microenvironment while generating hydrogen peroxide to amplify PDT efficacy. In vitro experiments demonstrated that T-TiCNOMV-GL significantly inhibited the viability, proliferation, migration, and colony-forming ability of 4T1 breast cancer cells. In vivo, treatment markedly suppressed tumor growth and increased serum levels of pro-inflammatory cytokines. Transcriptomic analysis further revealed that, beyond inducing oxidative stress, T-TiCNOMV-GL promotes tumor cell apoptosis through the regulation of immune-related key genes. Collectively, these findings demonstrate the successful construction of a multifunctional OMV-based nanoplatform with enhanced antitumor efficacy, highlighting its potential for breast cancer PDT.