Advanced Materials Interfaces最新文献

Slippery Superhydrophobic Surfaces

Linear polydimethylsiloxane (PDMS)-functionalized carbon nanotubes (CNTs) incorporated into an epoxy-silicone matrix create durable superhydrophobic coatings with enhanced water repellency and droplet rebound, surpassing conventional alkyl functionalization. Electro- and photothermal actions can restore water repellency and mitigate icing. More details can be found in the Research Article by Jia Min Chin and co-workers (DOI: 10.1002/admi.202500706).

We present a combination of µLaue X-ray diffraction and X-ray excited optical luminescence (XEOL) techniques to map local strain, orientation, and light emission in metalorganic vapor phase epitaxy (MOVPE) core–shell InGaN/GaN multiple quantum wells (MQW) wires dispersed on silicon substrates. The components of the deviatoric strain tensor averaged along the beam footprint were quantified with a measurement precision better than 9 × 10⁻⁵ and an accuracy of approximately 4 × 10⁻⁴. This measurement quality is achieved by carefully calibrating the analysis chain with a Ge crystal and verifying it with measurements of the unstrained Si substrate reference. The µLaue mapping of the components of the deviatoric strain confirms the high crystal quality and the impact of the MQW shell grown only in the upper part of the GaN core, as evidenced by the local variations of the full width at half maximum of the diffraction peaks and of the lattice rotation tensor. The two deviatoric tensors of the GaN core and InGaN/GaN shell can be measured independently and are in quantitative agreement with 3D finite element method (FEM) simulations. The structural information is correlated with XEOL measurements, whose spectral analysis reveals the main contributions to light emission: the major UV-blue MQW emission from the m-plane at the top of the wires, with a gradient varying from 406 nm at the top of the MQW to 397 nm at the bottom, with a secondary emission of a semipolar r-plane facet at ∼470 nm; the near-band-edge GaN signal at ∼363 nm; and the usual yellow defect-band luminescence, centered at 560 nm. The paper also highlights the potential of these techniques to obtain statistics on semiconductor heterostructures and their automation capabilities for measurements and analysis.

The development of materials with improved performance and stability relies on the analysis of local compositional inhomogeneities, which may occur at various stages from synthesis to application. This type of analysis benefits from rapid methods that provide high lateral and depth resolution, alongside broad elemental sensitivity. The latter is of paramount importance when considering devices such as lithium-ion batteries and solid oxide cells, whose operating principle depends on the transfer and accumulation of light elements. In this work, we validate glow discharge optical emission spectroscopy (GDOES) as an alternative to state-of-the-art techniques for the chemical analysis of complex oxides. We consider several systems of technological interest for materials used in energy storage and conversion-related applications, namely highly complex perovskite oxide thin films with formula ABO₃ (A = La, Sr, and B = Fe, Co, Mn) and single-phase SrFeO_3-δ (SFO). Quantitative, depth-resolved elemental maps of B-site cations in combinatorial films are generated and benchmarked against state-of-the-art methods. Additionally, an oxygen quantification was achieved on films subjected to different post-annealing treatments. This work demonstrates the potential of GDOES for fast analysis of complex oxide films and heterostructures, enabling both laterally and nanoscale depth-resolved elemental analysis, including difficult-to-quantify light elements.

VO₂ exhibits thermochromic properties with a metal-to-insulator transition occurring at 68°C. VO₂ thin films were deposited by RF magnetron sputtering on Al-doped ZnO coated fused silica with Al₂O₃, TiO₂, and WO₃ as interface layers with the aim of controlling the transition temperature. Annealing under nitrogen atmosphere was employed to promote diffusion or doping from the interface layer into the VO₂ films. The results show that matching between crystalline structures and high oxygen flows during deposition resulted in a higher degree of doping or diffusion of the interface layer into the VO₂. Consequently, oxygen flow rate tuning during the VO₂ deposition on top of a WO₃ interface layer, followed by annealing enabled a decrease of the metal-to-insulator temperature from 68°C to 55°C.

LaTiO₂N (LTON) is a very attractive visible light responsive semiconductor for the fabrication of photoanodes for H₂ production by solar`ting. To design a feasible process, the other half of the water splitting reaction, the oxygen evolution reaction (OER), must be realized, and it is crucial to pair the photoanodes with appropriate OER catalysts such as nonstoichiometric nickel oxide (NiO_x). The application of NiO_x interfacial layers to LTON thin film photoanodes significantly enhances photocurrent performance by improving charge extraction and minimizing recombination. This work demonstrates that NiO_x functions as both a charge-selective layer and a recombination barrier, achieving record photocurrents for sub-50 nm LTON films in alkaline and sulfite-buffered electrolytes. Time-resolved and electrochemical analyses reveal that these improvements stem from effective Fermi-level de-pinning, bulk-to-surface charge transport enhancement, and the presence of scavengeable long-lived charges. These findings underscore the potential of NiO_x as a highly effective interfacial layer for solar water splitting utilizing LTON, a superior oxynitride.

Metal-organic complexes with multiple metal ions and unsaturated spin structures are intriguing for their potential to tune magnetic properties. We focus on the Cu(II)[12-MCCu(II)N(Shi)-4] metallacrown complex (CuCu4) to show how phase-dependent geometric transformations influence magnetic coupling between copper spins and shape molecular magnetic behavior. To uncover these effects, we investigated the valence band structure of CuCu4 in bulk form and as a monolayer on Au(111). Using ultraviolet photoemission spectroscopy (UPS) and ab-initio calculations, we analyzed the experimental UPS spectra of the bulk state and the CuCu4/Au(111) interface with the total density of states (tDOS) obtained via density functional theory (DFT) approaches. While adsorption causes subtle changes in the tDOS, the exchange coupling constants between copper ion-related spins shift significantly. This leads to a transformation in molecular spin configuration from a low-spin state (S = 1/2) in bulk to a higher-spin state (S = 3/2) upon adsorption on Au(111). Analysis of the spin-resolved tDOS reveals partial spin polarization in the adsorbed state, absent in bulk, while bridging earlier experimental data on bulk and surface-bound CuCu4. This behavior suggests the CuCu4/Au(111) interface as a promising candidate for molecular spintronics, where control over spin states is key.

Macromolecular coatings can establish a broad range of functionalities on medical devices, and examples include increased wettability, lubricity, and anti-biofouling properties. However, even though sterilization is an indispensable procedure for medical devices to be used on patients, the process can come with certain issues. In addition to often not being very sustainable, established sterilization procedures such as autoclaving, gamma irradiation, or ethylene oxide fumigation can either damage sensitive coatings or may produce/leave cytotoxic residues on the treated objects. In this study, we demonstrate how decontaminating sensitive macromolecular coatings with plasma activated water (PAW) or plasma activated saline (PAS) can be a valuable alternative to established sterilization processes. We expose mucin-based macromolecular coatings to a PAW/PAS treatment and show that, when used at a temperature level of 50°C, both activated liquids can successfully sterilize those coatings without compromising their structural integrity and functionality. Furthermore, cytocompatibility tests do not indicate any reason for concern regarding the formation of toxic residues in response to the PAW/PAS treatment. Together, our results suggest that PAW/PAS treatment of sensitive medical devices can be a very promising technique for applications in clinical and private settings.

We report the self-assembly of cobalt mono-oxide (CoO) nanobeads on van der Waals (vdW) surface of electrically conducting platinum ditelluride (PtTe₂) as a catalytic heterostructure for enhanced oxygen evolution reaction (OER). We optimize the crystallinity and surface roughness during the thermally assisted conversion (TAC) of platinum (Pt) thin films to PtTe₂, achieving an atomically flat vdW surface with ultra-low surface energy. On these optimized PtTe₂ templates, Co films are deposited and thermally annealed, allowing residual oxygen in the chamber to oxidize the Co films into CoO. The large surface energy difference between CoO and PtTe₂ drives the self-assembly of CoO into spherical nanobeads that are uniformly distributed over the PtTe₂ surface. Interestingly, chemical interactions at the CoO/PtTe₂ interface across the vdW gap are evidenced by a reduced gap, a low contact angle of CoO nanobeads, and Te diffusion at the CoO/PtTe₂ interface. These interactions enhance OER in the CoO/PtTe₂ heterostructure by improving charge-transfer efficiency between the catalytically active CoO and conducting vdW PtTe₂ support, showing comparable catalytic performance of commercial CoO nanoparticles on glassy carbon. These findings present a new synthesis approach for oxide nanostructures on van der Waals surfaces and open new combinations of heterostructures for energy applications.

Twin-twin boundaries play vital roles in microstructure evolution and tailoring mechanical properties. In this work, the atomic structures of twin-twin boundaries formed by interactions between tensile twin variants sharing the same or different zone axes in a deformed magnesium alloy are investigated. Strain accumulation induced by twin-twin interactions causes the lattice distortion around the intersecting area, which promotes the formation of twin-twin interfaces. The characteristics of twin-twin boundaries significantly depend on the activation of twin variants involved in the interactions. The lattice distortion around the twin-twin boundary region can contribute to the subdivision of coarse grains and suspension of twinning propagation, as well as the absorption of dislocations and nucleation of new grains in the subsequent thermomechanical process.

A scalable method for fabricating multilayer polymer waveguides consisting of up to three layers two of which are prepared using a floating film transfer technique is presented. As an exemplary polymer material, poly(methyl methacrylate) (PMMA) is selected, a widely used material in polymer waveguide technology. To ensure clean delamination of the PMMA films from the carrier substrate, a surface treatment using a PDAC monolayer that significantly reduces interfacial adhesion, allowing fast and reproducible film transfer is utilized. Key parameters such as immersion angle, speed, and mechanical strain are optimized to prevent transfer defects like wrinkling or cracking of the films. Optical waveguides composed of laminated PMMA layers are then characterized via angular-resolved transmission spectroscopy and the results are compared to Rigorous Coupled-Wave Analysis (RCWA) simulations. The stacked waveguides exhibited low extra loss caused by the lamination. Moreover, we demonstrate the fabrication of high-index-contrast OrmoStamp/air grating structures integrated within PMMA waveguides. RCWA simulations and spectroscopic measurements show strong agreement. Therefore, this work establishes floating film transfer as a robust, solvent-free approach for assembling multilayer polymer films, offering design flexibility, compatibility with a wide set of polymer materials, and minimal optical loss.