Advanced Materials Interfaces最新文献

Enhancing NH₃ as a carbon-free energy carrier of H₂ and next-generation fuel is a promising approach for a sustainable society. Chemically storing NH₃ molecules in crystal structures offers better selectivity and reusability than storage in traditional porous materials based on physicochemical adsorption; however, designing materials that can be reversibly stored in structural gaps is still a significant challenge. Herein, the use of NH₄ZnPO₄, which is previously used as a fertilizer, is proposed as an NH₃ uptake material through a chemical storage mechanism. The NH₄ZnPO₄ particles synthesized by a wet mechanochemical method with monoclinic and hexagonal crystal structures can incorporate NH₃ molecules and directly transform them into NH₄Zn(NH₃)PO₄ without producing byproducts. The chemical storage mechanism depends on the particle morphology; therefore, the uptake amount per surface area surpasses that of porous materials. NH₄ZnPO₄ exhibited excellent cycling performance due to its reusability, which is regenerated by releasing NH₃ from NH₄Zn(NH₃)PO₄ when heated in air at ≈100 °C. Taking inspiration from previously used and familiar fertilizers further extends this new area of innovative materials that can be used for the reversible storage of low-molecular-weight gases.

High-quantity single-crystal silicon carbide (SiC) is widely used in power electronics due to its excellent breakdown electric field strength and high thermal conductivity. However, back grinding during the chip fabrication generally results in ≈70% of single-crystal SiC being wasted, leading to the high cost of SiC chips. In order to improve the utilization, single-crystal SiC on polycrystal SiC (SoP-SiC) is bonded. The challenge to achieve excellent bonding interfaces for such a system is the heterogeneous surface of polycrystals in which those grains with different orientations usually have different physical and chemical properties, making it difficult to achieve sufficiently smooth surfaces for bonding. Here, ion beam etching (IBE) is employed to activate the surface of polycrystal and single-crystal SiC and achieve high bonding strength (up to ≈20 MPa) after annealing in the atmosphere. Sub-nanometer-scale electron microscopy and energy spectroscopy analysis showing the IBE method can effectively inhibit the formation of silicon oxide at the bonding interface, which is expected to reduce the interface thermal resistance according to the phonon spectrum analysis. This study provides a novel method to fabricate single-polycrystal SiC junctions with high bonding strength and high thermal conductivity, which is valuable for the SiC industry.

Biphasic environments can enable successful chemical reactions where any single solvent results in poor substrate solubility or poor catalyst reactivity. For screening biphasic reactions at high throughput, a platform based on microfluidic double emulsions can use widely available FACS (Fluorescence Activated Cell Sorting) machines to screen millions of picoliter reactors in a few hours. However, encapsulating biphasic reactions within double emulsions to form FACS-sortable droplet picoreactors requires optimized solvent phases and surfactants to produce triple emulsion droplets that are stable over multi-hour assays and compatible with desired reaction conditions. This work demonstrates such FACS-sortable triple emulsion picoreactors with a fluorocarbon shell and biphasic octanol-in-water core. First, surfactants are screened to stabilize octanol-in-water emulsions for the picoreactor core. With these optimized conditions, stable triple emulsion picoreactors (>70% of droplets survived to 24 hr), produced protein in the biphasic core via cell-free protein synthesis are generated, and sorted these triple emulsions based on fluorescence using a commercial FACS sorter at >100 Hz with 75–80% of droplets recovered. Finally, an in-droplet lipase assay with a fluorogenic resorufin substrate that partitions into octanol is demonstrated. These triple emulsion picoreactors have the potential for future screening bead-encoded catalyst libraries, including enzymes such as lipases for biofuel production.

The growing concern over implant-associated infections motivates the development of novel antibacterial coatings for medical devices as an effective strategy in reducing the occurrence of IAI. Polyelectrolyte multilayers (PEMs) incorporating metal/metal oxide nanoparticles (NPs) as antimicrobial components receive special attention for their ability to coat diverse surface types and low potential to induce antimicrobial resistance. This study investigates the potential of poly(amino acid) multilayers consisting of poly-L-lysine and poly-L-glutamic acid with embedded silver (PEMAg) or copper oxide (PEMCuO) deposited on titanium surfaces for the coating of medical surfaces. The results of the quartz crystal microbalance with dissipation, scanning electron microscopy, and electron dispersive spectroscopy show that both types of NPs are successfully incorporated in the PEM and deposited over the entire coated surface. The incorporation of NPs in PEM prevents the burst release. The viability of MG-63 cells is higher than 70% on all investigated PEMs, confirming their biocompatibility. PEMCuO shows better biofilm prevention compared to PEMAg, entirely preventing Pseudomonas aeruginosa biofilm and allowing the formation of only weak Staphylococcus aureus biofilm. The results obtained confirm the high potential of poly(amino acids) multilayers with embedded metal/metal oxide NPs as biocompatible antimicrobial coatings for medical devices.

The selective influence of elastic strain on the formation of oxygen deficiencies in (001)-, (110)-, and (111)- epitaxial Hf_0.5Zr_0.5O₂ films grown by using atomic layer deposition is reported. Optical spectroscopy, conducted using UV–vis spectroscopic ellipsometry on these Hf_0.5Zr_0.5O₂ films grown on yttria-stabilized zirconia substrates, revealed a dominant shallow trap level in the (111)-oriented Hf_0.5Zr_0.5O₂ film. X-ray photoemission spectroscopy demonstrated that the strong oxygen deficiency is preferred in the (111)-oriented Hf_0.5Zr_0.5O₂ film. Density functional theory calculations of oxygen vacancy formation energy also showed a pronounced preference for oxygen deficiencies in the (111) orientation. This selective formation of oxygen vacancies in the (111)-oriented Hf_0.5Zr_0.5O₂ film suggests that the latent phenomena associated with oxygen defects in functional Hf_0.5Zr_0.5O₂ films are partly attributed to the directional strain in the (111) orientation.

Photoswitchable Wettability

The spiropyran-containing porous surfaces with a certain roughness range demonstrate a photoswitchable wetting properties upon UV exposure due to the ring-opening reaction of spiropyran resulting in a higher dipole moment. Condensate droplets on UV-switched regions coalesce faster, lower number of droplets as well as larger merged droplets form on the surface as the surface is less hydrophobic. More details can be found in article 2400396 by Dorothea Helmer and co-workers.

Mesoporous Metal Oxide Films

In article 2400215, Peter Möller-Buschbaum and co-workers show the systematical development of mesoporous metal oxide films with tailored structures, offering strong potential for high-performance industrial applications such as photovoltaics and photocatalysis. Key factors such as material mass, acid concentration, precursor ratio, and calcination are highlighted to emphasize their impact on film morphology.

Commonly used antifouling coatings rely on the continuous release of biocidal ingredients and are becoming increasingly restricted by legislation. The resulting demand for nonbiocidal technologies involves the search for alternative ingredients and in particular enzymes have received increasing attention. While screening of the antifouling activity of active compounds in solution is well established, the analysis of their activity and in particular anti-biofouling activity when embedded into a coating and even more so in an activated leachate layer is very demanding. Among the challenges is the even distribution throughout the coating and retention of the enzymatic activity. Here a water-based HEMA-methacrylate polymer matrix is presented that aims to mimic the leachate layer and to incorporate active compounds. This technology is used to incorporate several hydrolytically active enzymes-cellulase, protease, and lipase-in a grafting-through approach. After immersion, the enzymes are released in a controlled way during several days. The enzyme-loaded polymer films reduced the attachment of fouling organisms through a combination of their hydrophilic nature and activity of the enzymes. The active contribution of the enzymes became visible in a significant suppression of the accumulation of diatoms and green algal spores compared to the enzyme-free and heat-denatured control coatings.