ACS Applied Nano Materials最新文献

Flexible and wearable hybrid nanogenerators offer a sustainable alternative to conventional power sources by efficiently converting biomechanical energy into electrical energy, particularly for self-powered sensing applications. Herein, we report a hybrid piezoelectric–triboelectric nanogenerator (PTENG), fabricated for human physiological monitoring and energy harvesting. The device integrates a PAN/MXene/PDA composite as a piezoelectric layer and PDMS as a tribonegative layer, fabricated via solution casting, featuring copper electrodes, and encapsulated in polyimide tape to ensure durability. Electrical measurements of the nanogenerator demonstrated that the PTENG achieved a peak-to-peak voltage (Vpp) of 40 V with a power density of 4000 μW/m² at 100 MΩ load resistance and exhibited long-term stability over 20,000 cycles without significant performance degradation. Furthermore, the fabricated PTENG exhibited a fast response time of 3.75 ms and effectively responded to various mechanical stimuli, including human joint movements and vehicular forces. These results demonstrate the potential of the developed PTENG for applications in biomedical monitoring systems, wearable electronics, smart infrastructure, and Internet of Medical Things (IoMT) systems.

Effective ultrafast signal control in integrated photonics requires high optical nonlinearities, making the integration of nonlinear nanomaterials such as graphene a promising strategy. However, conventional graphene transfer approaches face critical limitations in integration to devices with complex surface morphologies, leading to the damage to the nanomaterial quality and consequent degradation of device nonlinearity. We demonstrate the direct integration of graphene onto a lensed optical fiber (LOF) that can be employed as a nonlinear optical interface between fiber links and integrated photonic platforms. Our atomic carbon spraying (ACS) process enables the direct synthesis of a homogeneous graphene layer on the convex surface of an LOF with a tip radius of only a few micrometers while preserving its intact nonlinear optical properties. Systematic analysis confirms the high crystallinity of the synthesized graphene, and its nonlinear response is validated through the realization of a passive mode-locked fiber laser in which graphene functions as a saturable absorber. The resulting ultrashort pulses exhibit a duration of 460 fs at a center wavelength of 1562.5 nm. We expect that the ACS process provides an elegant and robust solution for graphene incorporation into future integrated photonics devices for nonlinearity-enhanced ultrafast signal processing.

In light of recent progress in semiconductor technology, ongoing efforts are directed toward achieving further reductions in the feature sizes of nanoscale semiconductor interconnects in semiconductor devices. The pursuit of improving area selective deposition (ASD) methods has led researchers to explore surface modifications, using surface inhibitors as a tool to optimize ASD techniques for precise nanopatterning. Utilizing precursor inhibitor (PI) in ASD is a promising substitute for self-assembled monolayer (SAMs), owing to its broad material selection and superior process compatibility for fabricating nanostructured semiconductor devices. In this study, CoCp₂ PI was utilized, and a preliminary surface treatment approach, involving exposure to ammonia plasma before the exposure of CoCp₂, was carried out to increase the inhibitor’s adsorption, potentially improving the blocking efficiency of atomic layer deposition (ALD) of nanometer-thick dielectric and metallic films. Substrates of inhibited copper with ammonia plasma pretreatment exhibited superior selectivity, approximating 100% after 10 cycles of HfO₂ ALD and 100 cycles of Ru ALD, compared to inhibited substrates without pretreatment. The pretreatment creates surface sites that are more reactive toward CoCp₂ than the naturally occurring hydroxyl-terminated surface, leading to a more uniform and effective blocking layer that impedes ALD nucleation on the Cu surface more effectively than on the SiO₂ surface. These results align cohesively with theoretical studies, suggesting that the study of PI, coupled with enhanced selectivity through NH₃ plasma pretreatment, could pave the way for groundbreaking research in nanoscale semiconductor manufacturing.

MBene is a type of 2D metal boride compound that has drawn broad attention in the past decade. In this study, MoAlB was partially etched into a mixture of MoBene (Mo-based MBene) and Mo₂AlB₂. The performance in metal adsorption of the product was investigated. The large surface area (40 times higher than that of the MoAlB precursor) and −OH-functionalized surface enable MoBene/Mo₂AlB₂ to have excellent adsorption efficiency and capacity for Cu²⁺ and Pb²⁺ ions. An adsorption of 89.1 mg/g (93.7% of 1.5 mM CuCl₂ solution) and 121.2 mg/g (39.2% of 1.5 mM PbCl₂ solution) for Cu²⁺ and Pb²⁺, respectively, was observed after 15 min of contact time. The effects of the pH, contact time, adsorbent load, and initial solution concentration on adsorption capacity were investigated. The maximum adsorption capacities of Cu²⁺ and Pb²⁺ were 233.4 and 308.6 mg/g, respectively. Target metals can be observed on the adsorbent surface under SEM. The maximum adsorption of Cu²⁺ and Pb²⁺ is 140 times and 3 times higher than that of commercial activated carbon, showcasing the ability of MoBene/Mo₂AlB₂ to remove heavy metals from aqueous solutions.

Synthesizing metal nanoshells with well-defined surfaces is a persistent challenge, as conventional methods often require harsh reductants or structure-directing surfactants that contaminate the final product. Here, we report a general, long-chain surfactant-free strategy that utilizes plasmon-induced hot carriers to synthesize a diverse array of metal nanoshells (Au, Ag, Pt, Pd, and Cu) on mesoporous silica supports. The process is initiated by a photocatalyst of high-density, sub-5 nm Au nanoparticles that efficiently generate hot carriers under mild green light illumination. The key innovation is the introduction of molecular hydrogen (H₂), which creates a powerful reduction pathway. Our results strongly suggest this occurs through the activation of H₂ by plasmon-generated hot electrons. This H₂-assisted method dramatically accelerates deposition kinetics and overcomes thermodynamic barriers, enabling the formation of uniform nanoshells of Pt and Pd, and even Cu, which is otherwise inaccessible. Mechanistic studies confirm the enhancement is a true hot-carrier-mediated effect, distinct from bulk photothermal heating.

Detection of low-concentration and diluted target analytes within specific hotspot regions is essential for ultrasensitive surface-enhanced Raman spectroscopy (SERS) analysis. However, achieving high reproducibility and sensitivity for SERS substrates remains a significant challenge. In this study, we present the fabrication of Ag nanoparticles (AgNPs) assemblies on a cylindrical plasmonic copper (Cu) rod substrate, using a drop-casting method to construct colloidal-based droplet-SERS platforms. Systematic optimization of droplet volume, analyte-to-nanoparticle ratio, and reaction conditions revealed the ideal parameters for performance enhancement. The cylindrical substrate exhibits sufficient hydrophobicity, confining the analyte to the tip of the SERS surface and preventing aqueous sample spreading, a common limitation in conventional substrates. This design enabled the analysis of samples as small as 4 μL, without requiring a drying step. Additionally, aligning the cylindrical substrates into a 3D-printed holder facilitated the production of an array for high-throughput analysis of aqueous samples. This strategy demonstrated outstanding SERS performance, with a relative standard deviation of 8.6% and substrate reusability. Under optimized conditions, Rhodamine B, a carcinogenic dye, was detected at a low threshold of 10^–9 M (1 nM) in aqueous and real-world samples, including cotton candy without spiking. This application highlights the potential of this method for food safety analysis by addressing critical concerns regarding toxic contaminants, particularly those that pose health risks to children, who are the primary consumers of these products.

Graphene demonstrates enormous potential for lightweight electronic and conducting applications due to its exceptional physical properties. Liquid exfoliation of graphite to graphene is scalable and economical, which provides a significant advantage to the development of layered material manufacturing. However, minimizing the energy budget to transform colloidal dispersions into a thin-film form with enhanced electrical conduction is the key for reducing the cost of production of graphene thin films. This study explores annealing of the thin films using photon sources including ultraviolet, focused solar, infrared radiation, and matter-based techniques to control the morphology and electrical resistance of the self-assembled graphene (SAG) nanosheet networks. The SAG films are characterized by Raman spectroscopy, electron microscopy, and current–voltage characteristics before and after the annealing. We found that, after 10 min of treatment, the Raman defect ratio (I_D/I_G) of focused solar radiation (FSR) annealed SAG films decreased by 65% compared to conventional resistive annealing. The electrical resistance of SAG films is reduced from 40 to 5 kΩ after the treatment. The balance between heating from photons and radiation pressure effectively reduces the intersheet resistance and improves the electrical conduction of graphene networks. The experiments confirm that photon-assisted irradiation improves the electrical property of self-assembled thin films of graphene nanosheets by aligning the nanosheets in-plane with minimal energy input. The photon-assisted thermal treatment is a practical and scalable way to improve the performance of graphene-based thin films for lightweight and electrically conducting channel applications such as flexible electronics and thin-film EMI shielding.

The development of heterogeneous catalysts for liquid-phase aerobic oxidation is of great interest. Herein, we report the synthesis of 3D porous graphitic carbon spheres incorporating M_n+1C_n-type MXenes (M = Ti, V, Nb), prepared by delaminating MXene nanosheets in chitosan-based aerogels, followed by pyrolysis. In the case of Nb₂C, a heterojunction with a NaNbO₃ perovskite forms within the carbon matrix, leading to the highest catalytic performance. This 3D Nb₂C/NaNbO₃ structure achieved a 100% yield in the aerobic oxidation of cyclohexanone oxime to cyclohexanone within 6 h, with negligible metal leaching. Structural analysis revealed the partial oxidation of Nb₂C to NaNbO₃ during synthesis, leading to a Nb₂C–NaNbO₃ heterostructure. Control experiments confirmed that this interface is essential for the high activity, as neither Nb₂C nor NaNbO₃ alone on the porous carbon matrix reached a similar performance. Mechanistic studies based on hot filtration tests, quenching experiments, and EPR spectroscopy demonstrated that the reaction involves reactive oxygen species, mainly superoxide and hydroperoxyl radicals, generated and acting on the catalyst surface. This work provides a promising strategy for designing efficient and robust MXene-based catalysts for sustainable oxidation processes.

Materials development through sustainable approaches offers a promising route to address future challenges in the energy and environmental fields. The present work addresses such critical challenges in environmental monitoring through environmental sensing and remediation by developing a sustainable platform based on 3D nanomicro complex composite structures. It includes a facile synthesis of Au nanoparticles (NPs)-decorated 3D ZnO tetrapods (TPs) as an efficient solar-driven photocatalyst and ultrasensitive surface-enhanced Raman scattering (SERS) substrate. 3D TP nanoarchitectures with sharp arms provide efficient charge transport pathways, while Au NPs anchored on ZnO TPs enhance photocatalytic as well as SERS activity by introducing plasmonic features that intensify local electromagnetic field and facilitate stronger light–matter interactions. Various spectroscopic, microscopic, and electrochemical investigations confirm the successful deposition of Au NPs on ZnO TPs along with strong Au-ZnO interfacial coupling resulting in enhanced optoelectronic properties. The ZnO TPs exhibit a wide band gap of 3.11 eV, which is remarkably narrowed to 2.57 eV upon Au deposition, highlighting the profound influence of localized surface plasmon resonance in extending absorption into the visible region. The Au-ZnO 3D nanoarchitecture shows enhanced photocatalytic performance for methylene blue (MB) pollutant with a degradation efficiency of 96% within 60 min under natural sunlight, maintaining a stable recyclability of 88.3% after five cycles of photodegradation. Furthermore, 3D nanoarchitecture shows excellent SERS performance with a high enhancement factor of 1.38 × 10⁵ and limit of detection of an extremely low concentration of 10^–12 M for MB. Interestingly, such investigations have also been extended to other complex organic pollutants (i.e., ciprofloxacin, tetracycline hydrochloride, and phenol) including study of photodegradation byproducts and photocorrosion/stability of photocatalysts. The observed results are attributed to the synergy between plasmonic Au and 3D TP morphology, promoting charge separation, visible-light harvesting, and electromagnetic chemical enhancement, making it a versatile platform for environmental sensing and remediation.

We report the optimized one-pot synthesis of gold nanoparticle/polypyrrole (AuNPs/PPy) nanocomposites via a 2³ factorial design, enabling control of key optical and electrochemical properties. The nanocomposite formulation with the highest performance exhibited a maximum fluorescence intensity of (3.55 ± 0.063) × 10⁶ CPS upon excitation at 350 nm. Nonlinear optical characterization by the Z-scan technique revealed self-defocusing behavior with a negative nonlinear refractive index of −9.6 × 10^–8 cm²/W. Electrochemical impedance spectroscopy confirmed the hybrid’s capacitive and conductive characteristics, with a charge transfer resistance of approximately 81 Ω and a distinct capacitive response in the Bode phase angle. STEM analysis revealed a core–shell nanostructure with an average particle size of 66.4 ± 12.0 nm, consistent with direct measurement. Thermogravimetric analysis confirmed thermal stability, while cytotoxicity assays in four mammalian cell lines revealed no significant toxic effects up to 500 μg/mL, supporting the material’s biocompatibility. These combined features position the AuNPs/PPy nanocomposite as a promising multifunctional platform for integrated optical, electrochemical, and biosensing technologies.