ACS Applied Nano Materials最新文献

The emergence of eutectic gallium–indium (EGaIn) liquid metal (LM) alloys as a soft multifunctional nanofiller presents an opportunity for the fabrication of hydrogel-based strain sensors with advanced multifunctional properties. However, developing a facile and efficient approach to synthesize nanocomposite conductive hydrogels that exhibit excellent stretchability, conductivity, self-adhesion, and antibacterial properties remains a significant challenge. In this study, we introduce a semi-interpenetrating network design strategy to synthesize a high-performance nanocomposite hydrogel [liquid metal/silver nanowires/sodium lignosulfonate/polyacrylamide] [LM/AgNWs/SL/pAM] (LASM). This hydrogel consists of a single polyacrylamide (pAM) network combined with a semi-interpenetrating network formed by silver nanowires (AgNWs) and LM nanoparticles. The semi-interpenetrating network is primarily cross-linked through hydrogen bonds, electrostatic interactions, and metal coordination. The resulting conductive hydrogels demonstrate superior stretchable properties (tensile stress: 120.28 kPa; tensile strain: 373.15%), impressive conductivity (0.64 S/m), high antifatigue performance, self-adhesive characteristics (Ti: 25.40 kPa; Al: 20.66 kPa), and notable antibacterial activity, all achieved through the construction of a hybrid chemical and physical cross-linking network. Leveraging these attributes, the nanocomposite hydrogel was assembled into a flexible sensor capable of distinguishing an extensive range of human movements, from large scale motions to subtle joint bending with remarkable stability and sensitivity. Furthermore, the LASM strain sensor can function as an adaptable writing keyboard that accurately recognizes English letters (“a”, “p”, “e”, “L,” and “HUT”) in real time when written on its surface. This multifunctional 3D nanocomposite conductive hydrogel holds great potential for applications in wearable electronics.

Rhenium disulfide (ReS₂), a two-dimensional (2D) semiconductor, exhibits unique anisotropic properties rarely found in other 2D materials. This study investigates the alignment characteristics of nematic liquid crystals on ReS₂ nanosheet using optical texture analysis, transmission measurements, and Raman scattering techniques. For the $\overrightarrow{b}\text{and}\overrightarrow{c}$, crystal basis vectors of ReS₂, the director (${\hat{n}}_0$) aligned along the easy axis satisfies equations, ${\hat{n}}_0·(\overrightarrow{c}\times \overrightarrow{b})>0$ and ${\hat{n}}_0·\overrightarrow{b}=\left|\overrightarrow{b}\right|\cos \left(\theta \right)$ > 0 with θ = 15°. Both polar and azimuthal anchoring strengths were found to be very weak, with extrapolation lengths on the order of several micrometers. Additionally, the orientation of the ReS₂ nanosheets suspended in the nematic liquid crystal is effectively controlled through electric field application and director manipulation. The ability to control the orientation of ReS₂ nanosheets through several methods suggests that the anisotropic properties of ReS₂ can be effectively tuned to different values for switching applications. This capability opens up possibilities for leveraging the unique directional characteristics of ReS₂ in devices that require precise orientation-dependent control.

In this study, we demonstrate the tunability of hybrid graphene oxide/reduced graphene oxide/titania nanocrystal (GO/rGO/TNC) films for resistive humidity sensing through photocatalytic reduction. Using a layer-by-layer spin-coating (LbL-SC) technique, we fabricate GO/TNC nanofilms with titania nanorods (TNRs) or nanoplates (TNPs) on various substrates, achieving high uniformity and precise control over the film thickness (15–150 nm). We investigate the evolution of the electrical, optical, and structural properties of these films, modulated by the photocatalytic activity of TNCs under UV exposure (254 nm) while varying the illumination time, TNC type, and film thickness. The inclusion of TNCs enhances the films’ conductivity by several orders of magnitude compared to pure GO films under UV illumination and enables precise adjustment of the GO/rGO and (GO/rGO)/TNC ratios. This approach is used for tuning the sensitivity, response time, and response polarity of (GO/rGO)/TNC resistors on flexible substrates to changes in relative humidity (RH). TNP-based films demonstrate superior performance, achieving sensitivities of up to 2.2 and response times as short as 1 s over a broad range of RH levels (∼35 to 85% and ∼1 to 80%). Depending on the composition and RH level, the sensors exhibit both positive and negative resistive responses to increasing humidity. Gravimetric analyses show that films with varying GO/rGO ratios exhibit the same change in water mass uptake, indicating that the differences in resistive behavior are driven by UV-induced alterations in their chemical and electrical properties. Finally, we propose the use of these sensors to detect body-related humidity fluctuations, demonstrating their suitability for wearable electronics. Our results highlight the potential applicability of (GO/rGO)/TNC nanocomposites as highly customizable humidity sensors.

Two-dimensional (2D) layered transition metal dichalcogenides have garnered significant attention for their potential in advanced applications of electronics and energy conversion technologies. As a prototypical member of the 2D materials family, vanadium disulfide (VS₂) distinguishes itself through its great mechanical strength, tunable electronic characteristics, intriguing magnetic properties, and exceptional electrochemical performance. However, the synthesis of high-quality VS₂ films is severely hampered by its thermodynamic instability and the tendency to form polymorphs. In this work, we present clean and efficient low-pressure chemical vapor deposition for the growth of large-scale H-phase VS₂ monolayers on sapphire substrates. By regulating the ratio of precursors, controlling the growth temperature and optimizing the position of substrates, the production of polymorphs is effectively suppressed, resulting in improved quality of VS₂ films. Electrochemical measurements reveal that the VS₂ monolayers exhibit superior electrocatalytic performance for hydrogen evolution reaction compared to monolayer molybdenum disulfide (MoS₂). This work provides a significant advancement in the scalable production of monolayer VS₂ and its potential applications in clean energy technologies.

Quantum dot (QD) filters, characterized by miniaturization, customizability, and low-cost advantages, have emerged as dispersive components in the development of microhyperspectral cameras. In this research, InP QDs were encapsulated with a ZnS single-shell and a ZnSe/ZnS double-shell to synthesize InP@ZnS and InP@ZnSe/ZnS core–shell quantum dots (CSQDs). InP@ZnSe/ZnS CSQDs exhibited enhanced oxidation resistance, spectral stability, a high extinction coefficient, and good filtering performance. By optimizing the precursor ratio, precise control over the size and size distribution of InP CSQDs was achieved, enabling exceptional tunability of their filtering spectra. Moreover, the surface modification of InP@ZnSe/ZnS CSQDs with N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) ligands effectively quenched their photoluminescence properties without sacrificing filtering performance. The structural and optical properties were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV–vis spectrophotometry, revealing critical structure–property correlations. The nontoxic colloidal QD filter arrays based on InP@ZnSe/ZnS-TMPD CSQDs demonstrated dual functional advantages: precise spectral tunability over the 400–800 nm range, and complete short-wavelength cutoff with 86% high-efficiency transmission in the long-wavelength region, with a spectral transition steepness of 1.18%/nm. First-principles calculations revealed that ZnSe middle shell improved the light absorption of InP CSQDs. The underlying mechanisms responsible for the good filtering capabilities, oxidation resistance, spectral stability, and broad spectral tunability of InP@ZnSe/ZnS CSQDs were systematically investigated in this study, and these findings may facilitate the practical application of QD-based microspectrometers.

The utilization of solar energy for pollutants removal is of critical importance for future society developments. In this paper, photocatalysts (Mo-ZIS/STO) compositing Mo-modified ZnIn₂S₄ (ZIS) nanosheets with SrTiO₃ (STO) nanorods are prepared by electrostatic spinning. Mo dopant in S-scheme heterojunction widens the available spectral range and enhanced interfacial electric field effect (IEF), Mo_0.05-ZIS/STO catalyst achieved 73.1% formaldehyde removal within 1 h. The intermediates produced during the removal of formaldehyde were characterized using in-situ DRIFTS. This work offers a perspective on the construction of photocatalytic field with metal doping and S-scheme heterojunctions, with the aim of enhancing photocatalytic performance.

Designed electrode materials within controllable morphology are significant for the improvement of supercapacitor performance. This paper introduces CuCo₂O₄ nanomaterials with four distinct morphologies of needle, block, rod, and tube, prepared via a one-step hydrothermal process within annealing on nickel foam (NF). The ammonium halides in this synthesis were thoroughly investigated. As a three-electrode system, CuCo₂O₄ shows a high performance (942 F g^–1@1 A g^–1) and holds 87.5% of its initial capacitance (following 10k charge/discharge cycles at 20 A g^–1), indicating its potential for the applied supercapacitor. Based on these results, the CuCo₂O₄ block material and activated carbon (AC) are used as the positive/negative electrode for the fabricated asymmetric supercapacitor. This device achieves a superior performance (46.65 Wh kg^–1@800 W kg^–1) and shows an excellent cycle stability (10k cycles) of 89.2%. This is due to its extensive specific surface and porous structure, which help facilitate ion diffusion and reversible redox reactions through abundant channels and active sites created. This paper provides insights into the controlled preparation of electrode materials with specific morphologies.

Flexible supercapacitors (SCs) enduring mechanical deformation without affecting electrochemical performance are crucial in the development of miniature wearable electronics. Integrating shape memory alloys (SMAs) into SC design is one of the promising approaches to enhance their flexibility and durability. The current work is the first-ever approach introducing the interdigitated structure of Nickel–Titanium (NiTi) SMA as the current collector for the shape memory SCs (SMSC). A water-based reduced graphene oxide (rGO) ink is developed using cellulose nanofiber (CNF) as a nanospacer and carboxymethyl cellulose sodium (CMC) as a binder. The finger width of the interdigitated structure (500 μm), screen-printing mesh size (140), and number of printing passes (4) are optimized. The SCs are screen-printed on interdigitated NiTi and Cu current collectors using the rGO/CNF/CMC ink. NiTi SMSC with EMIM BF₄ electrolyte exhibits a high areal capacitance of 52.90 mF cm^–2 at a current density of 0.2 mA cm^–2, and maximum energy density of 29.38 μWh cm^–2 at a power density of 0.2 mW cm^–2. The NiTi SMSC retains 81% of its initial capacitance at 180° static bending and 60% at cyclic bending, with a shape recovery ratio of 97% after 1000 bending cycles, mainly attributed to its superelasticity and high mechanical strength. This study highlights the potential of superelastic NiTi SMA for flexible energy storage devices, offering enhanced durability and performance in applications requiring mechanical resilience.

To suppress the subthreshold swing (SS) and overcome the 60 mV/dec limit, we theoretically propose a strategy using isolated-band semiconductors as the channel. Monolayer LaBr₂ has a unique isolated band around the Fermi level that cuts off the carrier transport of high-energy regions in the off-state while maintaining thermionic emission in the on-state. Even at a supply voltage of 0.50 V, the armchair-oriented LaBr₂ field-effect transistors (FETs) meet the international standards for high-performance and low-power applications by minimizing the gate length to 3 and 4 nm, respectively. Specifically, the 5 nm armchair-oriented LaBr₂ FET brings the SS to 50 mV/dec with a high on-state current of 1057 μA/μm. The zigzag-oriented LaBr₂ FETs can meet high-performance requirements with gate length lowered to 4 nm. The LaBr₂ FETs also exhibit excellent spin filtering and negative differential resistance effects. This finding provides a practical solution for extending Moore’s law to sub-5 nm scales.

MoSe₂ is a promising surface-enhanced Raman spectroscopy (SERS) substrate because of its cost-effectiveness, simple synthesis, exceptional optical properties, high carrier mobility, tunable bandgap, and conducive biocompatibility. In this study, we synthesize MoSe₂ nanoflakes with different morphologies over a large area (centimeter scale) on Mo and Si substrates using the chemical vapor deposition (CVD) technique. These pristine MoSe₂ films are employed as SERS substrates to detect melamine, bilirubin, vitamin B₁₂, and Rhodamine 6G (R6G). Strong vibronic coupling during the charge transfer (CT) process facilitates resonance in photoinduced charge transfer (PICT) to enhance SERS activity. We obtain the excellent detection limits of 10^–9 M for melamine, 10^–10 M for bilirubin, 10^–9 M for vitamin B₁₂, and 10^–11 M for R6G with MoSe₂/Si SERS substrate, while detection limits of 10^–6 M for melamine, 10^–9 M for bilirubin, 10^–8 M for vitamin B₁₂, and 10^–10 M for R6G are observed with MoSe₂/Mo as SERS substrate. We could observe near single molecule detection for R6G (2 and 11 molecules for MoSe₂/Si and MoSe₂/Mo substrates, respectively) and bilirubin (18 molecules for MoSe₂/Si). Quantitative analysis of degree of charge transfer deepens understanding of SERS signal enhancement. As per our knowledge, this is the first demonstration of low-temperature SERS activity on pristine MoSe₂ films, revealing enhanced SERS performance due to synergistic PICT and Fano resonance. The pristine MoSe₂-based SERS substrate offers an in situ, efficient approach for trace detection, with medical and environmental monitoring, food safety, and surface contamination analysis applications.