Advanced Materials Interfaces最新文献

To study the antibacterial efficacy of metallic Ag nanoparticle/titania (Ag-NP)/TiO₂ composite thin films against Escherichia coli (ATCC 25922), COMP-Ag_n with various amounts of Ag (10 mol% ≤ n ≤ 80 mol%) are fabricated on a quartz glass substrate at 600 °C using the molecular precursor method. The films are characterized by X-ray diffraction, X-ray photoelectron, scanning electron microscopy, transmission electron microscopy, photoluminescence, and UVvis techniques. The analysis reveals that the films are composed of metallic Ag-NPs embedded in a mixture of anatase and rutile matrix, with a volumetric fraction of Ag ranging from 0.18 to 0.68. The antibacterial activity of the TiO₂ thin film and COMP-Ag_n are determined by disk diffusion and viable cell count methods. Neither pure TiO₂ nor pure Ag films exhibit any discernible antibacterial under dark and visible light. The antibacterial of Ag content in composite films is observed to persist for a maximum increase of 70%. The model is proposed on the basis of photoexcited electron transfer from Ag NPs to the TiO₂ conduction band of COMP-Ag_n, which clarifies the main factors affecting the photoresponse and the excellent response to visible light via surface plasmon resonance.

Since the first isolation of graphene, the importance of van der Waals (vdW) interactions has become increasingly recognized in the burgeoning field of layered materials. In this work, infrared nanoimaging techniques and theoretical modeling are used to unravel the critical role played by interfacial vdW interactions in governing the stability of violet phosphorus (VP)—a recently rediscovered wide bandgap p-type semiconductor—when exfoliated on different substrates. It is demonstrated that vdW interactions with the underlying substrate can have a profound influence on the stability of exfoliated VP flakes and investigate how these interactions are affected by flake thickness, substrate properties (e.g., substrate hydrophilicity, surface roughness), and the exfoliation process. These findings highlight the key role played by interfacial vdW interactions in governing the stability and physical properties of layered materials, and can be used to guide substrate selection in the preparation and study of this important class of materials.

For the prosthetic retina, a device replacing dysfunctional cones and rods, with the ability to mimic the spectral response properties of these photoreceptors and provide electrical stimulation signals to activate residual visual pathways, can relay sufficient data to the brain for interpretation as color vision. Organic semiconductors including conjugated polymers with four different bandgaps providing wavelength-specific electrical responses are ideal candidates for potential full-color vision restoration. Here, conjugated polymer photocapacitor devices immersed in electrolyte are demonstrated to elicit a photovoltage measured by a Ag/AgCl electrode 100 microns from the device of ≈−40 mV for 15–39 µW mm⁻² of incident light power density at three wavelengths: 405 nm for blue photoreceptor candidate material, 534 nm for green, 634 nm for red. Photoresponse is substantially improved by introducing polymer donor/acceptor molecules bulk heterojunctions. Devices with bulk heterojunction configurations achieved at least −70 mV for green candidates with the highest at −200 mV for red cone candidates. These findings highlight the potential for organic materials to bridge the gap toward natural vision restoration for retinal dystrophic conditions such as age-related macular degeneration, Stargardt disease, or retinitis pigmentosa and contribute to the ongoing advancements in visual prosthetic devices.

Mesoporous materials find widespread applications due to their high specific surface area, contributing to enhanced performance. Scanning electron microscopy (SEM) observation of mesoporous materials provides valuable insights into their mesostructures. However, direct observation of the outermost surfaces, which often dictate material properties, remains challenging, especially for highly insulating and fragile compounds. In this study, utilizing SEM observation with ultra-low-voltage acceleration directed by Gemini column is proposed to achieve direct surface imaging of mesoporous organic materials with highly insulating and fragile characteristics. By observing mesostructured polymers obtained through a soft-templating method without washing, stuffed pores are identified allowing the differentiation of micelle templates and polymer walls. Moreover, leveraging SEM measurements, a polymerization mechanism is proposed for dopamine on the polymer micelles adhered to the graphene oxide nanosheets. These findings demonstrate the potential of SEM measurements with ultra-low accelerating voltage in facilitating surface observations of polymer-derived nanomaterials characterized by high insulating properties and a fragile framework.

The development of deposition processes for metal carbide thin films is rapidly advancing, driven by their potential for applications including catalysis, batteries, and semiconductor devices. Within this landscape, atomic layer deposition (ALD) offers exceptional conformality, uniformity, and thickness control on spatially complex structures. This paper presents a comprehensive study on the thermal ALD of MoC_x with MoCl₅ and 1,4-bis(trimethylgermyl)-1,4-dihydropyrazine [(Me₃Ge)₂DHP] as precursors, focusing on the functional properties and characterization of the films. The depositions are conducted at 200–300 °C and very smooth films with RMS Rq ≈0.3–0.6 nm on Si, TiN, and HfO₂ substrates are obtained. The process has a high growth rate of 1.5 Å cycle⁻¹ and the films appear to be continuous already after 5 cycles. The films are conductive even at thicknesses below 5 nm, and films above 18 nm exhibit superconductivity up to 4.4 K. In lieu of suitable references, Raman modes for molybdenum carbides and nitrides are calculated and X-ray diffraction and X-ray photoelectron spectroscopy are used for phase analysis.

Ionic transport through porous membranes and porous materials has received enormous attention due to its importance to many applications. An innovative methodology is proposed to study ion diffusion and ion sieving through mesoporous silica membranes (shells). The mobility of fluorescently labeled core particles within a hollow porous shell, filled with an index-matched electrolyte solution, is observed using confocal laser scanning microscopy. The core motion range, i.e., the area explored by the core within the hollow compartment, sensitively changed depending on the local ionic concentration. Monitoring transitions in the core motion range is a practical way to detect which ions can migrate through the shells and on what timescale. For instance, lithium and chloride ions easily diffused through the porous silica shells, resulting in a core motion range that changed relatively quickly upon change of the ion concentrations outside of the shell. However, the motion range changed significantly slower upon changing to a bigger cation (tetraoctylammonium ion). This proof of principle experiment can be explained by the Gibbs-Donnan effect, revealing that the detection of core motion ranges is a good probe to measure both ion diffusion and ion sieving through porous membranes.

Surface decoration of support structures by physical vapor deposition (PVD) of small molecular building blocks offers a versatile platform to realize functional supramolecular nanofibers in a controlled manner and with tailored properties. Here, details on the preparation of surface-decorated polyamide fabrics by PVD using N¹,N³,N⁵-tris[2-(diisopropylamino)-ethyl]-1,3,5-benzenetricarboxamide (1) as a molecular building block are reported. It is shown that a defined morphology with uniform nanofiber length can be achieved, which is controlled by the PVD conditions. The functional periphery of supramolecular nanofibers of 1 allows the immobilization of gold nanoparticles (AuNPs). This results in AuNP-loaded nanostructures with a high surface area, which can be used as a heterogenous catalyst for the reduction of 4-nitrophenol in aqueous media. The surface-decorated support structures with firmly deposited AuNPs also provide the opportunity to conveniently reuse these structures without compromising the catalytic performance. This approach provides fabrication strategies for the controlled surface decoration of macroscopic support structures with small molecular building blocks by PVD with the potential to realize functional robust supramolecular nanofibers for various catalytic or filtration applications.

Surface hydroxyls (OH) are crucial for heterogeneous catalysis in water. However, they are commonly characterized at solid–gas interfaces (e.g., FTIR, XPS, TGA), which may not represent the surface in aqueous environments. Here, the surface OH of five catalytically relevant oxides (Al₂O₃, ZrO₂, TiO₂, Fe₂O₃, Co₃O₄) are quantified by substituting them with F⁻ ions at pH 3–10, where the surface fluoride (F) density is evaluated by XPS using the geometry factor for spherical particles. These results show that the surface F density peaks at around pH 4 across all oxides, but decreases at more basic pH due to increased OH⁻ competition. Generally, oxides more abundant in surface OH can also accommodate more surface F, establishing F⁻ ions as effective probes. While terminal F are likely the preferential substitution product, bridging F also appear to form at lower pH levels. Furthermore, fluoride substitution is applied to a series of Co₃O₄ gradually enriched with defects using pulsed laser defect engineering in liquid (PUDEL). This approach reveals a linear correlation between laser processing and surface OH density, which aligns with a previously observed improvement in OER activity, and is supported by additional DFT calculations here. This work will stimulate further studies adopting fluoride substitution to better understand the relationship between surface chemistry and catalytic processes in aqueous environments.

In this study, the double remnant polarization (2P_r) is enhanced from ≈2 to 25 µC cm⁻² at a low applied voltage of ±2 V (or from 10 to 35 µC cm⁻² at a voltage of ±4 V) by decreasing the WN_x interfacial capping layer (ICL) thickness from 6 to 2 nm in a novel Ru/WN_x ICL/Hf_0.5Zr_0.5O₂(HZO)/TiN structure after annealing at 400 °C in a furnace. This occurs because of the higher orthorhombic (o) plus rhombohedral (r) phases (>70%), which is analyzed by geometrical phase analysis (GPA) of high-resolution transmission electron microscope (HRTEM) images. An optimized 2 nm WN_x ICL memory capacitor shows a low coercive field (E_c) of 1.27 MV cm⁻¹ and long endurance of > 10⁹ cycles (remaining 2P_r value of 13.5 µC cm⁻²) under a low field stress of ±2 MV cm⁻¹ and 0.1 µs hold pulse width (or ≈1.67 MHz). Even this long endurance of > 10⁹ cycles is obtained by applying a higher stress of ±2 MV cm⁻¹, 1 MHz, or 100 kHz. Under ±3 MV cm⁻¹ stress, the mechanism is caused by m-phase growth from both the HZO/TiN bottom electrode (BE) and WN_x ICL/HZO interfaces, which is evidenced by HRTEM images after 2 × 10⁷ cycles for the first time.

Molecular Templates

Harnessing Langmuir-Blodgett nanoarchitectonic tools to create molecular platforms through supramolecular chemistry for orchestrating the arrangement of functional materials on surfaces. More details can be found in article 2301090 by José L. Serrano, Pilar Cea, and co-workers.