Advanced Materials Interfaces最新文献

Polymer-ceramic composite (PCC) coatings combine functionality with mechanical robustness and flexibility, which is attractive for barrier coatings, membranes, or flexible electronics. Their fabrication is challenging, as conventional ceramic thin film methods make use of polymer-incompatible high-temperature sintering. Powder aerosol deposition (PAD) offers a solvent- and sinter-free avenue toward PCCs. An unresolved key question is how the preparation route of the composite powders dictates the PAD film formation and microstructure. To address this, we investigated PAD deposition of the system polystyrene (PS)-titanium dioxide (TiO₂). PS particles synthesized via emulsion polymerization are combined with TiO₂ particles either through dry mixing, yielding inhomogeneous powders, or through ultrasound-assisted slurry-mixing to form homogeneous powders. When deposited on polycarbonate and steel, these powders produce fundamentally different microstructures, with organized, multilayer-like films emerging from the inhomogeneous powders, and isotropic films from the homogeneous ones. These structural differences correlate with variations in crystallite size revealed by X-ray diffraction, which provided new insights into the role of internal shock absorption of the polymeric component during PAD impact. By employing a sacrificial layer, we obtained free-standing PAD-processed PCC films, which enable accurate compositional determination by thermogravimetric analysis. The fabrication of a 100 cm² flexible coating on a PET film illustrates the scalability and potential for barrier and membrane applications. This work provides a transferable blueprint for designing hybrid thin films by PAD with tunable properties, thus bridging between polymer and ceramic processing.

This work presents a scalable, bottom-up approach for doping quantum confined, 1D lepidocrocite (1DL) titanate nanofilaments (NFs) with transition metal (TM) cations Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, and Cu²⁺ to enhance their photo- and electrocatalytic properties. Here we react titanium oxysulfate with tetramethylammonium hydroxide at 80°C for 12 h at one atmosphere. By incorporating metal salts during synthesis, uniform doping within the 1DL backbone is achieved. The resulting TM-doped 1DL NFs all exhibit lower bandgap energies, E_g, than the undoped samples (3.89 eV); some by as much as 0.8 eV for Mn²⁺ at 1 mol% doping, extending optical absorption into the visible region. X-ray diffraction, scanning electron microscopy, UV–Vis spectroscopy, inductively coupled plasma analysis, and X-ray photoelectron spectroscopy confirm the successful doping and structural integrity of our materials. The photocatalytic performance of the 1 mol% doped NFs is significantly enhanced, with a 95% degradation of rhodamine 6G dye under visible light in just 30 min, compared to only 65% degradation for the undoped 1DL NFs. In electrocatalysis, the Ni-doped 1DL NFs show superior oxygen evolution reaction (OER) activity, with an overpotential of 319 mV at 10 mA cm⁻², which is lower than the 383 mV for undoped 1DL NFs. The Ni-doped 1DL also has the lowest Tafel slope of 145 mV/dec at 1 mol% doping and 143 mV/dec at 5 mol%, compared to 204 mV/dec for the undoped 1DLs, indicating faster reaction kinetics. The Ni-doped NFs also exhibit excellent stability, maintaining a constant potential at 10 mA cm⁻² for > 50 h. Adding methanol to all colloidal suspensions results in their gelation within seconds. These findings highlight the potential of TM doping as an effective strategy to optimize 1DL's electronic and photochemical catalytic properties.

Plasmonic semiconductors have attracted extensive interest in optoelectronics and photocatalysis due to their broadened absorption spectral range, hot-electron injection, and near-field enhancement. Among various plasmonic semiconductors, WO_3-x allows high concentrations of oxygen vacancies (O_V) and pronounced localized surface plasmon resonance (LSPR) effects, enabling continuous tuning of optical and electronic properties. However, the LSPR effect in WO_3-x depends critically on O_V concentration and their stability. Herein, a surface reconstruction approach (structural rearrangement forming a dense surface layer with altered stoichiometry) was employed to synthesize WO_3-x nanosheets consisting of an inner layer with rich O_V concentration and a dense WO₃ surface passivation layer, which suppresses O_V healing and thereby allows stable O_V concentration during exposure in ambient atmosphere conditions or photocatalytic reactions. The as-synthesized plasmonic WO_3-x semiconductor exhibits enhanced LSPR effect due to the formation of a dense WO₃ passivation layer on the surface, which significantly improves the efficiency and stability of photocatalytic degradation of methyl orange under visible-near-infrared light illumination. This study provides a novel approach to improve the O_V stability in plasmonic WO_3-x semiconductors, offering important insights for stabilizing O_V concentrations in various plasmonic semiconductors. This advancement facilitates the application of plasmonic semiconductors in fields such as photocatalysis and nano-optoelectronics.

We investigate the spatiotemporal response of asymmetric polymer networks fabricated by frontal photopolymerization (FPP), a directional solidification process characterized by the emergence of conversion gradients and traveling waves, previously shown to support origami assembly. Employing a model system of UV cross-linking poly(ethylene glycol) diacrylate, we examine the frontal network conversion, the chemical exchanges during solvent development, and ensuing removal during drying. We find that the coupling of diffusion-evaporation and swelling-shrinkage processes gives rise to the formation of asymmetric ‘skin’ layers resulting in dynamic curvature fluctuations in otherwise planar beams, even in the absence of spatial patterning employed in FPP origami. Building on these findings, we demonstrate the fabrication of autonomous bistable switches and self-propulsion via a snapping instability that harness the environmental response of such ubiquitous asymmetric polymer networks.

Lubricating greases play a vital role in reducing friction and wear under dynamic loading, but their performance is often limited by poor dispersion and compatibility of nano-additives. In this study, graphene-coated titanium dioxide (TiO₂@G) hybrids were synthesized via carbothermal treatment and incorporated at 0.5 wt% in lithium grease, alongside pristine graphene, TiO₂, and their physical mixture for comparison. Tribological and thermal behavior were evaluated using ASTM-standard testing, profilometry, transmission electron microscopy and Hamrock–Dowson line-contact film-thickness modeling. The TiO₂@G-800 hybrid demonstrated an 85.7% reduction in wear scar diameter, a 22.0% decrease in operating temperature and a modest increase in calculated film thickness (∼1.5%) relative to the control. Lubrication regime analysis based on Stribeck and Tallian parameter (λ) confirmed mixed lubrication across all samples, with slightly higher λ ratios for TiO₂@G-800 and graphene, consistent with improved film retention and wear protection. The superior performance of TiO₂@G is attributed to its engineered core–shell morphology, wherein the graphene sheath improves interfacial lubricity and thermal conductivity while the TiO₂ core provides structural reinforcement. These findings highlight nanoscale interface engineering as a promising approach for developing next-generation high-performance greases with applications in energy, transportation and advanced manufacturing.

Efficient fog harvesting strategies have attracted increasing attention for addressing global water scarcity. In this study, a bio-inspired slippery surface was engineered by combining hydrophilic–hydrophobic patterning and lubricant infusion based on hydrophobic undecylenic-modified microcrystalline cellulose (UMCC) nanoparticles. The UMCC nanoparticles were synthesized using a dialysis–spraying process, followed by UV-assisted patterning of the hydrophilic domains and infusion with a perfluoropolyether lubricant to create a stable, directionally modified slippery interface. The pristine nanoparticle surface exhibited strong adhesion and high contact-angle hysteresis, which severely hindered droplet removal. However, after lubricant infusion, the contact angle hysteresis was dramatically reduced, enabling rapid droplet mobility, similar to that of Nepenthes pitcher plants. The resulting surface exhibited excellent chemical and environmental stabilities over a wide pH range. Notably, the moderately hydrophilic amino-patterned surface enhanced droplet nucleation, coalescence, and directional removal, achieving an exceptional fog-harvesting rate of 532.8 ± 85.1 mg/(h·cm²), surpassing the performance of all unmodified controls. This study established a simple and sustainable platform for next-generation bio-inspired fog-harvesting and water-management technologies.

A novel atomic layer deposition (ALD) process for highly conducting nickel disulfide thin films is introduced. This simple, sustainable and safe deposition process is based on two solid precursors, nickel acetylacetonate (Ni(acac)₂) and elemental sulfur. The process yields single-phase NiS₂ thin films in the deposition temperature range from 220°C to 270°C, with an appreciably high growth rate of ca. 3.42 Å per cycle. The as-deposited films are highly crystalline and chemically homogeneous. Room-temperature electrical conductivity values up to 2.8 × 10³ S/m and optical bandgap values in the range of 0.8–0.9 eV are measured for the films. The distinctly high surface area of the films, caused by flake-like nanostructures, together with the excellent electrical properties makes the present ALD-grown NiS₂ thin films attractive for various electrochemical applications, such as catalysts for hydrogen evolution reaction.

Organic artificial enzymes, renowned for their stability under non-physiological conditions, have recently attracted attention. In this study, we strategically designed small molecular photo-activated oxidase mimics by incorporating halogen atoms onto styrene-based molecular rotors, termed DAPy-X^m series (X = Cl, Br, and I), to leverage the heavy atom effect and amplify the generation of reactive oxygen species (ROS). In addition, incorporation of halogen atoms at the meta-position of 4-methyl-picolinium unit modulates the internal rotational barrier, thereby enhancing the temperature sensitivity of DAPy-X^m series. Among them, DAPy-I^m exhibited a significant enhancement in generating both superoxide anion (O₂^•−) and singlet oxygen (¹O₂) species. Taking advantage of its unique photo-responsive oxidase-like behavior with cold-adapted property, DAPy-I^m is successfully applied to the visible-light driven synthesis of ergosterol peroxide (EP), a bioactive compound with notable anti-tumor and anti-microbial characteristics. Remarkably, the photo-oxidase activity of DAPy-I^m is significantly improved at low temperatures compared to higher-temperature conditions, highlighting the potential of heavy atom-engineered molecular rotors to achieve an exceptionally low-temperature photocatalytic reaction for synthesizing thermo-sensitive products.

Transient electric birefringence measurements are used to show that brookite titania nanorods dispersed in the apolar liquid butylbenzene possess a large permanent dipole moment of 516 debye (rod length: 39 nm, diameter: 4.1 nm). This dipole moment makes the particles highly susceptible to applied electric fields. Isotropic dispersions at high volume fractions of up to 20% nanorods are aligned on a time scale of tens of microseconds at low field strengths. Alignment becomes nearly complete at a field strength of around 10 V/µm. It is shown that the birefringence of these dispersions is large enough that light transmission can be switched on and off in thin film cells of 150 µm thickness. These properties make brookite nanorod dispersions promising as the active material in optoelectronic applications.

Spheroids have emerged as valuable tools in bone tissue engineering, mimicking the cellular interactions in native tissues. However, the application of small and low-cell-number spheroids for simultaneous bone regeneration and vascularization remains underexplored. In this study, small pre-vascularized spheroids (250 cells each) were developed, using human mesenchymal stem cells (hMSCs) or human periosteum-derived stem cells (hPDCs), co-cultured with human umbilical vein endothelial cells (HUVECs). Spheroids were evaluated for stability, osteogenic differentiation, and angiogenic potential. Results indicated that hMSC and hPDC spheroids formed stable structures, while HUVEC monocultures failed to achieve spheroid stability. Co-cultures showed HUVEC localization patterns mimicking native vascular structures. Gene and protein analyses revealed distinct osteogenic potential between hMSC and hPDC spheroids, with the latter demonstrating superior and earlier differentiation. Additionally, vascular endothelial growth factor expression was higher in co-cultures, suggesting enhanced angiogenic potential, particularly in hPDC spheroids. Using small-diameter spheroids addresses limitations of conventional large spheroids, such as necrotic core formation and heterogeneous differentiation. These findings emphasize the promise of pre-vascularized spheroids for scaffold-free and scaffold-based tissue engineering applications. Furthermore, their small size enables the exploration of their potential applications in 3D bioprinting, paving the way for the future development of more biomimetic vascularized bone constructs.