ACS Applied Nano Materials最新文献

In this work, we report the rational design of Cu@ZnO nanocatalysts (NCs) via a robust one-pot, two-step synthesis. The resulting NCs display two distinct morphologies, cubes and spheres, with tunable ZnO coverage. By precisely adjusting key synthesis parameters, controlled ZnO domain formation was achieved on Cu seeds of varying crystallinity and shape. Structural and chemical characterization provide insights into the ZnO nucleation process, which is influenced by the crystallinity of the Cu seeds. In addition, the presence of oxidized copper species (Cu₂O and CuO) at the Cu–ZnO interface is consistently observed, indicating their involvement in ZnO domain formation and interfacial structuring. The catalytic performance of these nanostructures was evaluated in CO₂ hydrogenation to methanol under high-pressure conditions (31 bar). The results reveal clear correlations between catalyst morphology, Cu–ZnO interfacial density, and catalytic performance. In particular, catalysts consisting of Cu nanoparticles exposing (100) facets and higher interfacial densities are associated with enhanced methanol yield and reduced byproduct formation. This work establishes a versatile synthetic platform that not only provides high-quality nanocatalysts with tunable interfaces but also offers fundamental insights into structure–activity relationships in CO₂ hydrogenation to methanol.

The recovery performance of carbon nanotube (CNT)–graphene foam composites (CGFCs) plays a crucial role in flexible device applications, but the microscopic mechanisms governing the performance are not fully understood. To uncover the underlying mechanisms, coarse-grained molecular dynamics simulations were carried out on CGFCs with pure graphene foam (GrF) as a reference. By analyzing the distribution and evolution of deformation energy in graphene and CNTs at an applied strain of 0.5 under both tension and compression, the deformation mechanisms of recovery are revealed, and the corresponding effects of cross-linking density and maximum applied strain are also investigated. Compared to pure GrF, CGFCs demonstrate lower residual plastic strain after both tensile loading–unloading and compressive loading–unloading processes due to the role of CNTs in restricting irreversible microstructural deformations in graphene; during tension, CNTs bridge adjacent graphene sheets and inhibit their separation, while during compression, CNTs constrain the sliding and rotation of graphene. Consequently, the external work is primarily stored as deformation energy─mainly CNT stretching and graphene bending─which is released upon unloading, resulting in reduced residual plastic strain. In contrast, pure GrF dissipates energy through irreversible microstructural rearrangements, such as separation, sliding, and rotation of graphene, leading to greater residual plastic strain. The suppressive effect of CNTs relies on the presence of CNT–graphene (CG) bonds; consequently, the recovery performance of CGFCs improves with increasing CG bond density. Furthermore, residual strain increases with greater maximum applied strain, indicating that irreversible microstructural rearrangements become more pronounced as the maximum applied strain increases. The study clarifies the recovery mechanisms of CGFCs and informs the design of nanocomposites with enhanced elasticity for flexible applications.

Chiral vanadium oxide nanoparticles (V₂O₃ NPs) with different chiroptical signals were successfully prepared by employing tartaric acid, malic acid, and penicillamine as chirality-inducing agents. These chiral nanoparticles show sensitivity to pH values as they could express various optical transition modes such as charge transfer, d–d transitions, and surface plasmon resonance due to their rich electronic states, leading to tunable chiral optical activities in the UV–visible range. The different colors of V₂O₃ NPs with varied ligands at different pH values indicate the configuration variation of the chiral ligands as revealed by UV–visible absorption spectroscopy and circular dichroism (CD) characterizations. In addition, the as-synthesized chiral V₂O₃ NPs exhibit suitable properties for use as biomolecular probes and exhibit a limit of detection (LOD) of 3.185 μM for H₂O₂ sensing, indicating that chiral V₂O₃ NPs could provide a highly sensitive and real-time sensing scheme, which may provide a useful strategy for the development of chiral materials in the areas of chiroptics and biosensors.

In this work, we systematically explore the structural and electronic attributes of planar two-dimensional (2D) M₃N₂ structures and probe their consequences on thermoelectric applications by solving the Boltzmann transport equation (BTE) within a first-principles formalism. A comprehensive evaluation of their mechanical response confirms the ductile nature of these metal nitrides and demonstrates their mechanical flexibility through computed elastic constants. Both of them feature a direct band gap, and the intrinsic band anisotropy with higher acoustic phonon-limited carrier mobility (10³ cm² V^–1 s^–1) is expected to substantially enhance electronic transport. Inherent morphology in the electronic band structure is further narrated by an analytical tight-binding model. Remarkably, despite containing intrinsically light elements such as Be, Mg, and N, the thermal conductivity of M₃N₂ is substantially lower (2–7 W/m·K) than that of MoS₂. A detailed analysis of the M₃N₂ sheet unveils that their suppressed thermal conductivity stems from the unconventional atomic arrangement combined with the pronounced electronegativity disparity between constituting elements, which collectively induce strong phonon anharmonicity and enhance scattering rates. The room-temperature power factors obtained at optimal doping levels result in a peak thermoelectric figure of merit of 0.86 at 300 K, rising to nearly unity at 700 K. The results obtained in this study not only advance the fundamental understanding of heat transport in low-dimensional materials but also provide an instructive foundation for the rational design and optimization of thermal-functional, high-performance thermoelectric materials.

A BiVO₄/polyaniline derivative interlayer mediated Z-Scheme BiVO₄/MoO₃ (BPM) heterostructure photoanode is rationally designed and fabricated for enhanced photoelectrochemical (PEC) water oxidation. The polyaniline derivative interlayer, formed via annealing polyaniline at 500 °C under Ar, serves as an efficient charge-transfer mediator. Selective Au photodeposition experiments provide direct evidence for the Z-scheme charge transfer pathway, preserving the strong reducibility of BiVO₄ conduction band electrons. The optimized BPM photoanode delivers a photocurrent density of 0.92 mA cm^–2 at 1.23 V vs RHE, which is further boosted to 2.13 mA cm^–2 after Co-Pi cocatalyst modification, 3.9 times higher than that of pristine BiVO₄. Frequency-dependent Mott–Schottky analysis confirms a significantly enhanced effective carrier density and negatively shifted flat-band potential. Moreover, the BPM/Co-Pi photoanode exhibits good stability with ∼85% photocurrent retention after 10 h continuous operation. This work presents a strategy utilizing conductive polymer-derived carbon-rich interlayers to mediate Z-scheme charge transfer, offering a promising route to design high-performance photoanodes for solar fuel production.

In developing countries and rural areas, access to safe drinking water is a pressing issue that necessitates portable treatment solutions. This study describes the development of a portable conductive membrane capable of filtering and inactivating waterborne pathogens, removing lead (Pb (II)), and improving water quality parameters using a low-voltage current. A membrane composed of polyacrylonitrile (PAN) and polyaniline (PANI) integrated with cellulose nanocrystals (CNC) and graphene oxide (GO) nanosheets (PAN@PANI/CNC/GO) was first optimized to determine the optimal GO concentration. The incorporation of these nanomaterials improved the wettability, increased hydraulic conductivity, and enhanced mechanical properties. The PAN@PANI/CNC/GO membrane with 0.5% GO was subsequently reduced using the eco-friendly l-(+)-ascorbic acid (LAA) method, resulting in a PAN@PANI/CNC/rGO membrane with enhanced conductivity. The reduced PAN@PANI/CNC/rGO exhibited an electrical conductivity of 1.83 ± 0.01 S/cm, enabling an efficient electrochemical performance at low voltages. At a voltage of 3 V, the membrane achieved a 7-log reduction of Escherichia coli and Bacillus subtilis. In addition, it effectively reduced nitrate, phosphate, and turbidity concentrations and removed 76% of Pb (II) from real water samples spiked with 0.1 mg/L of Pb (II), confirming its multifunctional removal capability. These results highlight the PAN@PANI/CNC/rGO membrane as a promising point-of-use (POU) nanocomposite material for integrated bacterial inactivation, heavy metal removal, and overall improvement in water quality.

Hydrogen sulfide (H₂S), a volatile sulfur-containing compound, is a key indicator of fish spoilage. However, existing analytical methods often require unstable oxidants or complex instrumentation, limiting their real-time use. Here, we report a smartphone-assisted colorimetric assay using MnO₂/Au/Ag nanoframes (NFs) for sensitive and selective H₂S detection. The hollow Au/Ag scaffold, coated with an amorphous, defect-rich MnO₂ shell, exhibits H₂O₂-independent oxidase-like activity with strong substrate affinity (K_m = 0.086 mM) and high catalytic efficiency. The assay shows a linear range of 2.1–30 μM H₂S, a detection limit of 3.85 μM, excellent selectivity against thiol-type reductants and dimethyl sulfide, good reproducibility (relative standard deviation 3.94%), and stability for up to 4 weeks under refrigeration. Application to fish samples confirmed time-dependent H₂S release, consistent with spoilage levels. This nanozyme-based, smartphone-readable strategy offers a practical approach for on-site freshness monitoring and portable biosensing of volatile biomarkers in food safety.

Water electrolysis represents a promising method for producing hydrogen from renewable sources, yet its efficiency is limited by the high overpotentials and sluggish reaction kinetics of conventional catalysts. Herein, we report the rational design and synthesis of hierarchical nanoarchitectures featuring crystalline–amorphous Mo–Ni₂P/Co₂P heterostructures directly grown on nickel foam (NF). Electrochemical tests reveal exceptional performance: HER overpotentials of 70, 120, and 260 mV at 10, 100, and 300 mA·cm^–2, respectively, which surpass those of most reported transition metal phosphides; and an OER overpotential of only 250 mV at 10 mA·cm^–2. As a bifunctional catalyst in alkaline overall water splitting (OWS), the system maintains a stable operation for 100 h with only a 3.13% decay in voltage. By leveraging a porous Co-MOF as a sacrificial nanoscale template, we engineered abundant defects and macroporous frameworks, which facilitate the in situ formation of high-density crystalline–amorphous nanointerfaces. Concurrently, the multiphase interfaces within these heterostructures and the transition-metal-mediated synergistic effects enhance charge-transfer kinetics. This work contributes fundamental insights and establishes a paradigm for designing nonprecious electrocatalysts through phase engineering.

Transition-metal hydroxides and spinel nickel cobaltite (NiCo₂O₄) nanomaterials are promising for supercapacitors, batteries, fuel cells, electrochemical sensing, and electrocatalysis. Because performance and stability are strongly governed by size and morphology, numerous studies target nanostructure control. Ideally, synthesis should combine (i) operational simplicity, (ii) precise control of shape and size, and (iii) high performance. Here, we report a simple, surfactant-free hydrothermal route that yields highly crystalline, ultrafine hexagonal nanoplates of β-Co(OH)₂, β-Ni(OH)₂, and mixed (Ni,Co)(OH)₂ using only alkaline conditions (no stabilizers or complex reagents). The Ni:Co ratio tunes morphology, size, and interplanar (d-)spacings, while mixed compositions exhibit the characteristic intermediate between the single-component hydroxides. Upon annealing, (Ni,Co)(OH)₂ converts topotactically to NiCo₂O₄, and β-Co(OH)₂ converts to Co₃O₄ while preserving the hexagonal nanoplate morphology and high crystallinity. All products display high morphological uniformity and narrow size distributions, demonstrating the robust control afforded by this minimalist synthesis. As a proof of concept, NiCo₂O₄ and Co₃O₄ nanoplates were evaluated as electrocatalysts for the nitrite reduction reaction, achieving Faradaic efficiencies of 10.0 and 92.5%, respectively, highlighting Co₃O₄ as a particularly effective catalyst for environmentally and energy-relevant applications.

Lithium–sulfur batteries (LSBs) have attracted significant attention as next-generation secondary batteries owing to their outstanding theoretical energy density. Nevertheless, the practical application of sulfur cathodes is hindered by intrinsic challenges, including low electronic conductivity, severe polysulfide shuttle effects, and sluggish redox kinetics, which collectively induce rapid capacity fading and poor rate capability, significantly hindering the progress of LSBs. Bimetallic catalysts have been regarded as promising electrocatalysts for lithium–sulfur batteries due to their ability to chemically interact with polysulfide and promote its kinetic conversion. Composites exhibiting synergistic effects from binary metal nanoparticles typically demonstrate superior catalytic performance compared to conventional single-metal particles. In this work, taking advantage of a bimetallic metal–organic framework (MOF), we synthesized spherical entanglement structures by intertwining iron–nickel alloy particles with carbon nanotubes (FeNi/CNT). This distinctive structural configuration offers a rich diversity of adsorption and catalytic active sites, while the porous carbon architecture further boosts its electrical conductivity. Electrochemical testing of the FeNi/CNT/S cathode showed a first discharge capacity of 963.43 mAh g^–1 at a current density of 0.5C, with a remaining capacity of 464.58 mAh g^–1 following 800 cycles. In brief, FeNi/CNT accelerates the polysulfide conversion and enables the high efficiency of LSBs.