Nanomaterials最新文献

Nitrogen oxides represent a major source of concern related to atmospheric pollution, causing substantial impacts on human health. One innovative approach to reducing these emissions, and a promising alternative to conventional methods using NH₃, is selective catalytic reduction with carbon (SCR-C). The aim of this study is the development of carbon-based catalysts that are active in the reduction of NO. For that, carbon nanotubes were subjected to treatments to modify their surface chemistry, including introducing oxygen and nitrogen groups, as well as potassium (K) and copper (Cu) incorporated as metal phases. In their original form, carbon nanotubes do not exhibit catalytic activity in reducing NO. However, catalytic performance is significantly improved by the addition of surface groups and Cu. Adding K to the support notably contributes to increasing the catalytic performance. N-doped carbon nanotubes impregnated with copper and potassium (CNT_M_BM@5Cu5K) achieved complete NO reduction at 360 °C. In this catalytic system, the formation of CO₂ and N₂ was observed and CO was not identified. Furthermore, although N₂O was detected during the reaction, its amount was very low compared to the N₂ and CO₂ products. The stability of this catalyst was investigated over 87 h continuous test, revealing deactivation after 41 h of reaction.

Despite their excellent mechanical properties, metallic glasses (MGs) are significantly hindered by poor plasticity and toughness, which are essential for structural applications. The brittleness arises from the rapid propagation of shear bands (SBs), leading to strain softening and catastrophic failure. Recent advancements in microstructural engineering, particularly boundary engineering, such as nano-glass, focus on the utilization of heterogeneous structures to promote the proliferation and delocalization of SBs. Various attempts have been made experimentally to address these issues, but with very limited improvement in tensile strength and toughness. Under tensile loading, micro- or nano-pillar samples exhibit strain softening and continue to undergo plastic deformation after reaching yield or peak stress, especially the nano-glass micro-pillar. Reports on tensile strain-hardening in MG micro-pillars are rare. In this finite element simulation study, we optimize appropriate statistical and spatial distributions of free volume within the microsamples. Both the post-yield strength and the mean tangent modulus increase with progressive gradient structural modifications, thereby inducing a transition from strain-softening to strain-hardening behavior, as well as a concurrent transition from plastic fracture to brittle fracture. We systematically investigate the deformation mechanisms and transition mechanisms of fracture modes, which are closely associated with heterogeneous microstructures and their evolution in MGs. These insights into the transition mechanism could significantly facilitate the design and optimization of MGs to achieve enhanced toughness and strain hardening.

High-resolution short-wave infrared (SWIR) imaging requires photodetectors (PDs) with simultaneously low dark current and high responsivity. To achieve this goal, we demonstrate low-defect bulk germanium-on-insulator (bulk-GeOI) PDs designed for enhanced 1550 nm absorption and suppressed dark current via a resonant cavity and low-defect material platform. Devices were fabricated by direct bonding low-defect bulk Ge and thinning it to ~1300 nm, with an intrinsic layer thickness of only 800 nm. This design avoids epitaxial defects to lower intrinsic dark current while forming a resonant cavity for enhanced responsivity at 1550 nm. Precise doping and Al₂O₃/Si₃N₄ bilayer sidewall passivation were employed. From a design perspective, using low-defect bulk Ge minimizes the defects from epitaxial growth and reduces intrinsic dark current, while thinning the Ge layer enhances the resonant cavity effect to improve 1550 nm responsivity. Experimentally, despite the thin absorbing layer, our devices achieved nA-level dark currents (e.g., 18 nA at -1 V for 10 μm devices) alongside high responsivities. Detailed analysis indicates that this dark current is predominantly attributed to surface and sidewall defects from mesa etching, with minimal contribution from low-defect bulk material defects, validating the effectiveness of the bulk-Ge approach in suppressing intrinsic bulk leakage. Optically, the devices achieved high responsivities of 0.85 A/W (1310 nm) and 0.72 A/W (1550 nm), corresponding to external quantum efficiencies of 80.6% and 57.7%, respectively. This work establishes the bulk-GeOI platform as a promising path toward high-performance SWIR PDs, successfully decoupling high responsivity from bulk leakage and paving the way for future gains through refined surface and interface engineering.

Zinc oxide (ZnO) nanoparticles combined with conducting polymers such as polyaniline (PANI) demonstrate promising potential in flexible ultraviolet (UV) photodetection applications. However, the overall performance of undoped ZnO in photodetectors is often limited by high dark current, low responsivity, and detectivity, attributable to the high density of intrinsic defects and recombination rates. This study was aimed at evaluating the influence of magnesium (Mg) concentration (0.5≤x≤3.0% mol) on the structural and optical properties of 3-aminopropyltriethoxysilane (APTES)-modified ZnO/PANI hybrid matrix for ultraviolet (UV) photodetector applications. The novelty of this work lies in the dual strategy of Mg doping and surface modification intended to tailor the optoelectronic properties of ZnO nanoparticles (NPs). X-ray diffraction analysis confirmed the formation of a single-phase wurtzite ZnO. Photoluminescence measurements revealed a significant increase in photoemission intensity with increasing Mg concentration up to a maximum 2.0% mol. Incorporation of Mg remarkably modified the surface morphology and topography of the ZnO/PANI thin film, demonstrating an increase in both surface area and roughness. The Mg-ZnO/PANI photodetector with 1.0% mol of Mg doping concentration demonstrated excellent performance, with responsivity of 2.34 × 10^-2 A/W and detectivity of 1.56 × 10¹⁰ Jones. The effect of Mg doping concentration on the photoemission and photodetection is discussed in detail.

Cryogenic CMOS technology provides a promising approach to surpass the Boltzmann limit and advance Moore's Law, addressing the increasing demand for high-performance computing. However, at cryogenic temperatures, the subthreshold swing (SS) of the device saturates due to the band-tail effect. This study presents a 3-vertically stacked gate-all-around nanosheet (NS) transistor featuring room-temperature O radical interface passivation. This approach leverages the high reactivity of O radicals to minimize etch-induced damage, passivate interface defects, reduce thermal budget, and ensure uniformity in complex 3D structures. Structural characterization revealed a uniform 0.76-nm-thick interface layer, with a surface roughness of 0.103 nm and an interface trap density of 2.72 × 10¹¹ cm^-2·eV^-1 at 300 K. Thereby, the band-tail-induced SS saturation at cryogenic temperatures is effectively mitigated. Experimental results confirm a lower characteristic temperature T_v for reaching the saturation plateau, and a saturated SS of 15.4 mV/dec at 4.5 K. Furthermore, reducing disorder-induced defects substantially suppresses the band tail state-assisted carrier emission, thereby minimizing subthreshold leakage. This enables the device to achieve an off-state current below 1 pA/μm at a temperature under 77 K, reaching 0.18 pA/μm at 4.5 K. Additionally, a reduction in 25.4% in drain-induced barrier lowering (DIBL), with a 9% boost in transconductance (G_m) peak is achieved at 4.5 K. The enhanced subthreshold switching, reduced leakage, and improved G_m in this interfacial-optimized NS FET strongly supports cryo-CMOS as a viable solution for energy-efficient computing.

CeO₂ particles were synthesized via a hydrothermal method to investigate the influenceof precursor molarity and reaction time on their structural, optical, and adsorption characteristics. Ce(NO₃)₃·6H₂O served as the cerium source, while PVP and Triton X-100acted as surfactants to regulate nucleation and particle growth. XRD and Raman analysesconfirmed the formation of single-phase cubic fluorite CeO₂, whereas FTIR spectra verifiedthe presence of Ce-O bonding. SEM observations revealed that a decreasing precursormolarity led to smaller and more uniform particles, while prolonged reaction times enhanced crystallinity. UV-Vis DRS and XPS analyses indicated that both the band gap(3.06-3.12 eV) and the Ce³⁺/Ce⁴⁺ ratio were governed by oxygen vacancies, demonstrating defect-mediated redox behavior. Adsorption studies using methyl orange (MO) dye followed pseudo-second-order kinetics (R² > 0.99), indicating chemisorption as the dominant mechanism. The CP1-8 sample exhibited the highest dye removal efficiency (87%) under acidic conditions (pH < pHPZC). These findings demonstrate that controlled hydrothermal synthesis enables precise tuning of CeO₂ morphology, defect density, and surface chemistry, yielding efficient adsorbent materials for environmental remediation applications.

Persistent organic pollutants, such as Rhodamine B (RhB), pose significant environmental and health risks, necessitating the development of advanced oxidation technologies for effective removal. While heterogeneous photo-Fenton catalysts are known for their high degradation efficiency, their practical application is often limited by complex synthesis processes, catalyst detachment, and difficult recovery. This study proposes an innovative laser-induced, one-step synthesis strategy to fabricate metal/carbon nanocomposite catalytic layers directly onto flexible carbon paper. The as-prepared composites exhibit strong interfacial interaction between metal nanoparticles and the carbon matrix, as indicated by XPS analysis, and demonstrate enhanced catalytic activity in the UV/H₂O₂ system. Notably, the integrated composites exhibit exceptional catalytic activity in the UV/H₂O₂ system, achieving complete degradation of a 20 mg/L RhB solution within just 1.5 h. The enhanced performance is attributed to the facilitated Fe³⁺/Fe²⁺ cycling and efficient generation of hydroxyl radicals (·OH), although the underlying charge separation mechanism requires further investigation with techniques such as photoluminescence spectroscopy and transient photocurrent measurements. This work not only demonstrates the high activity and stability of the photo-Fenton catalyst but also provides a green, rapid fabrication approach for the development of efficient and integrable catalytic devices for wastewater treatment.

It is important to be able to detect xylene with high selectivity and low sensor resistance when monitoring indoor and outdoor air quality. In this study, we report the development of Sb-doped SnO₂ hollow spheres synthesized via ultrasonic spray pyrolysis for high-performance xylene detection with significantly reduced sensor resistance. The 2 mol% Sb-doped SnO₂ sensor exhibited a remarkably high response (S_X = 24.0) and selectivity (S_X/S_E = 3.4) toward 5 ppm xylene at 300 °C. Notably, the sensor resistance in air (R_a) was reduced by ~200-fold compared to that of pure SnO₂, reaching a practical level of 38.5 kΩ, which enables cost-effective signal measurement. Furthermore, the 2Sb-SnO₂ sensor demonstrated a low detection limit of 50 ppb and rapid response times (4-5 s). These results suggest that Sb doping is a highly effective strategy for engineering low-resistance and highly selective SnO₂ gas sensors. This study could pave the way for a practical approach to designing xylene detection systems for indoor air monitoring.

In recent years, metal phthalocyanine (MPc)-based sensors have garnered significant interest for applications in environmental monitoring, biomedical diagnostics, and industrial process control, owing to their efficient and cost-effective sensing capabilities. In contrast to conventional inorganic materials, MPcs are a class of small-molecule materials characterized by a stable, π-conjugated macrocyclic framework with a tunable central metal ion. This structural architecture imparts unique physicochemical properties, including high chemical stability, excellent redox activity, structural versatility, considerable dielectric constant and electrical conductivity, along with pronounced optical absorption and excellent environmental stability. By incorporating different metal ions into the macrocyclic core, their functional characteristics can be precisely modulated to achieve high sensitivity and selectivity toward various gas, ion, or biomolecule targets. Leveraging these advantages, MPcs have been extensively utilized in diverse sensing platforms, such as photoelectric, gas, and biosensors. This review outlines recent advances in MPc-based sensor research and provides perspectives on their future development trends.

Seed germination represents the initial stage of the plant life cycle and directly affects subsequent plant establishment. Mold infestation is a major cause of reduced germination rate, yet effective and safe control methods are still lacking. Thus, developing effective strategies to ensure healthy seed germination is of critical importance. This study investigated the effect of priming with silver nanoparticles (AgNPs) on the germination rate of Bupleurum chinense seeds and on mold suppression. Additionally, we aimed to clarify the underlying microbial mechanism through high-throughput sequencing of the internal transcribed spacer (ITS) region. Seeds primed with 15 mg/L AgNPs exhibited a significantly increased germination rate of 71.67% (vs. 58.90% in control) and reduced mold incidence to 16.46% (vs. 31.01%). The ITS sequencing revealed that AgNPs significantly reduced the Shannon index to 3.60 (vs. 4.04) and decreased the abundance of potential pathogens. Co-occurrence network analysis demonstrated that AgNPs simplified the fungal network and reduced the natural connectivity to 22.35 (vs. 39.38). Topological analysis identified five keystone hub genera (e.g., Trichosporon, Podospora), whose suppression indicates their critical roles in network maintenance. This study provides evidence supporting the application of AgNPs in seed germination and offering a foundation for addressing germination challenges in mold-susceptible seeds.