Dual-layer Structure Research Articles

Multifunctional daytime radiative cooler resistant to UV aging

Passive radiative cooling presents a promising approach to mitigate global warming and reduce energy consumption. Existing coolers, however, face challenges in practical prolonged adoption due to their unappealing design, susceptibility to environmental pollutants, as well as degradation of polymers by ultraviolet (UV) irradiation from sunlight. This study introduces a multifunctional daytime radiative cooler (MDRC) with a dual-layered structure, combining practical functionality with aesthetic value. Its base layer consists of an Ag–TiO2–Ag thin film stack, imparting vibrant cyan, magenta, and yellow colors, even maintaining visually appealing from various incident angles, up to 75°, to ensure consistent color display. The top layer, comprising S–SiO2 nanospheres with UV resistance rather than polymers, not only forms a superhydrophobic surface with a contact angle of 155.502°, enhancing the self-cleaning capability of the MDRC against contamination and dust, but also renders the MDRC with extraordinary anti-aging capacity. Outdoor experiments has shown that the MDRC maintains operation at temperatures above ambient under direct solar irradiation, achieving a substantial temperature reduction of 6.82 °C compared to the same colored commercial coating. After three months of outdoor exposure, the MDRC demonstrated minimal degradation in performance, with decreases of only 0.29 °C during the day and 0.12 °C at night, underscoring its superior UV-resistant aging properties. This MDRC represents a robust solution for diverse durable outdoor raidative cooling applications, advancing toward real-world utilization.

Influence of pH on passivation of mild steel in simulated concrete pore solution: Electrochemical, ToF-SIMS and ReaxFF study

The passivation evolution of mild steels in simulated concrete pore solutions with varying pH were systematically investigated in present study. Based on electrochemical, time-of-flight secondary ion mass spectrometry, and ReaxFF molecular dynamics simulation, a plausible model with high logical coherence and theoretical soundness was proposed to elucidate the underlying passivation mechanism. The results depict that the steels within concrete pore solution with high pH facilitates quick and compact film formation, leading to superior passivation performance. Spontaneously-induced passive film of mild steel demonstrates a dual-layer structure composed of an inner layer rich in Fe(II) and an outer layer rich in Fe(III).

Antibacterial Janus cellulose/MXene paper with exceptional salt rejection for sustainable and durable solar-driven desalination

The scarcity of freshwater resources and increasing demand for drinking water have driven the development of durable and sustainable desalination technologies. Although MXene composites have shown promise due to their excellent photothermal conversion and high thermal conductivity, their high hydrophilicity often leads to salt precipitation and low durability. In this study, we present a novel Cellulose (CF)/MXene paper with a Janus hydrophobic/hydrophilic configuration for long-term and efficient solar-driven desalination. The paper features a dual-layer structure, with the upper hydrophobic layer composed of CF/MXene paper exhibiting convexness to serve as a photothermal layer with exceptional salt rejection properties. Simultaneously, the bottom porous layer made of CF acts as an efficient thermal insulation. This unique design effectively minimizes heat loss and facilitates efficient water transportation. The Janus CF/MXene paper demonstrates a high evaporation rate of 1.11 kg m−2h−1 and solar thermal conversion efficiency of 82.52 % under 1 sun irradiation. Importantly, even after 2500 h of operation in a simulated seawater environment, the paper maintains a stable evaporation rate without significant salt deposition and biodegradation due to an antibacterial rate exceeding 90 %. These findings highlight the potential of the Janus CF/MXene paper for scalable manufacturing and practical applications in solar-driven desalination.

Performance of a combined battery thermal management system with dual-layer phase change materials and air cooling technologies

Lithium-ion batteries are increasingly applied in electric vehicles, energy storage and more. In order to ensure its stable operation under different ambient temperature, an innovative battery thermal management system (BTMS) based on phase change material (PCM) has the dual-layer PCMs arrangement is proposed in this research. To prove the effectiveness of this structure, the temperature variation of lithium-ion battery 18,650 with single PCM and dual-layer PCMs arrangement is calculated and compared by numerical simulation. The findings reveal that the dual-layer PCMs arrangement proposed in this paper has better environmental adaptability at different ambient temperatures (Tamb). When the Tamb is 20 °C and the discharge rate increases from 1C to 5C, the maximum temperature (Tmax) of the battery under the dual-layer PCMs arrangement is 25.33 °C, 30.80 °C, 33.58 °C, 35.80 °C, 39.07 °C, respectively. And in response to the high ambient temperature and high discharge rate, the dual-layer PCMs layout is combined with air cooling to form a hybrid BTMS. The results show that Tmax of the hybrid BTMS is reduced by 21.5 % compared with the PCM-based BTMS when the Tamb is 40 °C and the discharge rate is 3C. The proposed hybrid BTMS with dual-layer PCMs structure controls the Tmax of the battery pack well and the temperature uniformity is also maintained within acceptable level, which has great application potential in battery thermal management.

Hyperbranched aromatic poly(amidoamine) mediated interfacial polymerization for high-performance thin film composite membranes

The escalating global demand for clean water has driven a growing interest in developing thin-film composite (TFC) membranes with high permeability and selectivity for wastewater treatment and desalination processes. Engineering polymer materials with precisely tunable properties for selective molecular separation remains a challenging step toward achieving this goal. Herein, we have fabricated a highly permselective asymmetric polyamide nanofilm with a dual-layer structure in which the bottom layer is a porous hyperbranched aromatic polyamide (HBPA) interlayer, and the top layer is a dense polyamide layer with a nanostrip structure. The HBPA porous layer was covalently assembled in situ via oxidative coupling reaction with ammonium persulfate on a polysulfone (PSF) substrate. The hydrophilic porous HBPA interlayer forms nanosized cavities that may enhance the storage and confine amine monomer diffusion, leading to the construction of a striped pattern PA nanofilm. The resulting asymmetric PA membrane exhibits excellent water permeability of 18.39 ± 1 L m−2 h−1 bar−1 (3.98 times that of control membranes) and improved divalent salt (Na2SO4) rejection (≥98 %), surpassing most of the commercial and reported nanofiltration membranes. The HBPA-regulated interfacial polymerization provides a groundbreaking framework for developing high-performance membranes for precisely controlled nanofiltration.

Comparison of the polluted dust plume and natural dust air mass in a spring dust event in Beijing 2023

The occurrence of extreme weather events is becoming more frequent due to global climate change. A long-lasting dust outbreak in the spring of 2023 was triggered by Mongolia cyclones and cold fronts in the dust source areas. In this study, we illustrate the spatial distribution, the transport path of the dust and its influence on the air quality of downstream cities utilizing ground-based and space-borne measurements. Results indicate a more complicated pollution, coexisting of polluted dust stage S1 and pure dust stage S2. In S1, the aerosol was characterized by a dual-layer vertical structure—high extinction coefficient of nearly 1.0 km−1 with a low particle depolarized ratio (PDR) of < 0.1 under 500 m, and a small extinction coefficient of 0.3 km−1 with a high PDR of 0.15 above 500 m. Then the intrusion of the Mongolian cyclone carried new dust plumes on 10 March, suggesting the onset of pure dust period S2. The source transition was also confirmed by the MODIS, CALIPSO and Hysplit observations. The pure Asian dust evolved rapidly with one thickening layer and distributed homogeneously in the boundary layer. The PDR increased significantly to the peak of 0.35 and resulted in the peak PM10 value of > 1300 µg/m3. PM10 positively correlated with trace gases in S1 while varying inversely with the pollution gases in S2. The results help to shed light on the classification of different types of dust and also be useful in developing an effective strategy to forecast air pollution in downstream areas.

Rational design of a double-layer Janus solid electrolyte for high voltage lithium metal battery

Interfacial side reaction is a major problem faced by solid state electrolyte (SSE), especially the oxidation reaction between high-voltage cathode materials and SSE. Herein, a double-layer PVCA-ETPTA|LAGP-PPC Janus solid electrolyte (JSE) with ultra-high interfacial stability is successfully designed. An oxidation tolerant cross-linked poly (Vinylene Carbonate) (PVCA)-Ethoxylated trimethylolpropane triacrylate (ETPTA) electrolyte is used on the cathode side, resulting in a stable interfacial layer under high-voltage. To enhance the stability of SSE|Li interface, a protective Li1.5Al0.5Ge1.5P3O12 (LAGP)-Poly (propylene carbonate) (PPC) layer is adhered to Li metal. The obtained dual-layer structure shows great thermal stability with an electrochemical stable window of 0–4.5 V. Moreover, the PVCA-ETPTA layer fabricated by in-situ polymerization helps building an integrated structure, which can significantly reduce the interfacial resistance. The ionic conductivity of LP|PE can reach 1.2 × 10−4 S cm−1 at 55 °C. As a consequence, the assembled NCM622|LP|PE|Li solid state cell shows exceptional electrochemical performance, with 70 % cycle retention for 100 cycles at 0.2 C.

Fixed/Preassigned-time synchronization of quaternion-valued BAM neural networks: An event-based non-separation control method

Quaternions provide expressive power beyond real numbers, allowing neural networks to capture and process correlations and patterns in data with greater complexity. Besides, event-triggering mechanism has significant advantages in reducing redundant data transmission and control costs, since the sampling instant is determined by preset trigger conditions. Based on these fact, this article investigates the fixed-time and preassigned-time synchronization of quaternion-valued Bidirectional Associative Memory (BAM) neural networks via event-triggered control. Firstly, based on a dual-layer network structure with different number of nodes, a type of BAM neural network with generalized time-varying delays is established in the quaternion domain. Secondly, four kinds of Zeno-free dynamic event-triggered control mechanisms are designed, and the trigger condition can be dynamically adjusted according to the changing requirements. In the framework of non-separation analysis, the synchronization the controlled network can be guaranteed within a fixed time, and the upper bound of the setting time is provided explicitly. Furthermore, to better meet practical needs, the above event-triggered mechanism and the criteria are extended to the PAT synchronization. Two illustrate examples are presented at last to validate the developed event-triggered mechanism and synchronization results.

Dual-layer capacitance-loaded thin-film lithium niobate electro-optic modulator with high modulation efficiency

Thin film lithium niobate (TFLN) modulators with low driving voltage and high bandwidth are desirable for fiber-optic communication. Enhancing the modulation efficiency of TFLN modulators can reduce the device length while maintaining a low driving voltage, leading to more dies per wafer and subsequently lower fabrication cost. However, waveguide loss induced by metal absorption limits the electrodes spacing, thereby constraining the modulation efficiency. Here, we propose a novel dual-layer capacitance-loaded electrode structure to improves the modulation efficiency while maintaining a low absorption loss. We experimentally demonstrate a C-band (1550 nm) modulator featuring a half-wave voltage of 3.2 V, a modulation length of 5 mm, and a 3-dB bandwidth over 67 GHz.

Design of an ultra-wideband and switchable VO2-based microwave absorber

We propose a design of an ultra-wideband microwave metamaterial absorber using Vanadium dioxide (VO2) based on a dual-layer structure. The ultra-wideband absorption performance of the proposed structure can switch by using the phase transition of VO2. When the VO2 is in the insulator state, the proposed absorber achieves an ultra-wideband absorption response in the range of 3.7–22.5 GHz with an absorptivity higher than 0.9 and a relative bandwidth of 143.5% at normal incidence, which covers the entire bands from the C to Ku. The designed absorber is polarization insensitive and wide incident angle stable for both transverse electric (TE) and transverse magnetic (TM) modes. Owing to the outstanding merits of absorption performance and frequency-tunable capability, our design structure can be suitable for many promising applications in the microwave range, such as smart radar, camouflage and stealth radome technology.

In situ constructing a porous organic component-zincophilic Cu clusters layer on zinc anode for high performance aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) with Zn metal anodes stand out as a promising candidate for large-scale energy storage systems, owing to their high safety, low cost, and environmental friendliness. However, the commercialization of AZIBs is plagued by issues such as Zn dendrite growth and side reactions. Herein, an organic component-Cu metal composite layer is constructed on Zn anode (Org-Cu@Zn) by a novel, one-step and in situ spontaneous displacement reaction. The outer porous organic layer with functional groups may serve as migration sites and transport channels for Zn2+ ions, promoting transfer kinetics. The inner zincophilic Cu clusters layer diminishes the interfacial resistance, facilitating Zn2+ ions diffusion and even Zn deposition. Compared to the bare Zn, the unique dual-layer structure exhibits stronger zincophilicity, smaller interface resistance, lower nucleation energy barrier, and stronger anti-corrosion capability, thus effectively suppressing the Zn dendrite growth and side reactions. Remarkably, the Org-Cu@Zn electrode shows an ultra-long lifespan of 3600 h (1800 cycles) with an average Coulombic efficiency of 99.7 %, realizes long cycling stability over 4300 h (1 mA cm−2) and 1350 h (5 mA cm−2), and assures the stable operation of Org-Cu@Zn||ZVO full cells with coin-type configurations.

Superior anti-oxidation layer induced by PVA-boehmite sol-gel film on AISI304 steel

The superior anti-oxidation layer induced by the PVA-boehmite sol-gel film on the AISI304 steel during the cyclic oxidation is investigated in this work. The moderate PVA addition in the boehmite sol conduces to increase the film thickness and is beneficial to the adhesion between the film and the substrate. The presence of the PVA-boehmite film leads to a significant reduction in mass gain during the high-temperature cyclic oxidation at 800 °C, demonstrating the enhanced oxidation resistance. The generated oxide layer induced by the PVA-boehmite film presents as a thin, compact, and continuous layer without spalling, offering sustainable protection against oxidation etching. The PVA-boehmite film promotes the preferential formation of the corundum (Al, Cr)2O3 phase rather than the detrimental hematite Fe2O3 phase during the oxidation procedure, which facilitates the development of the above compact oxide layer. Finally, the superior anti-oxidation oxide layer is characterized as a novel dual-layer structure: the outer spinel MnCr2O4 layer and the inner corundum (Al, Cr)2O3 layer, effectively delaying the oxidation process.

Design and Tensor Impedance Analysis of 4×4 Isotropic Homogeneous Metasurface-Backed Slotted Dual-Layered Bio-Superstrate-Loaded MPA

A 4×4 Isotropic Homogeneous Metasurface (IHM) backed, rectangular slotted dual-layered triband microstrip patch antenna (MPA) is proposed in this article. A detailed mathematical way to analyze the tensor surface impedance matrix (TSIM) of the proposed 4×4 IHM and slotted patch is demonstrated. The proposed IHM-backed MPA has a triband even-mode resonance at fr0=2.45 GHz, 2fr0=5.4 GHz, and 4fr0=7.7 GHz. A better and more accurate estimation of bio-superstrate loading effect for triband resonance is employed using the human skin (εr=52.79, σs=1.39) and blood (εr=52.8, σs=1.23) layer on the top of dual-layered metasurface-backed slotted MPA. TSIM characterization is observed for both blood- and skin layer-loaded dual-layered metasurface-backed slotted MPA. Chicken breast (εr=55.2, σs=1.49, and tanδ=0.325) with blood (εr=58.2, σs=2.59, and tanδ=0.364) is loaded onto fabricated dual-layered structure to verify numerically modeled estimation. A closed form triband, even-order resonance mode (i.e., fr0, 2fr0, and 4fr0) estimation based on dielectric superstrate thickness (Hs) is numerically established using MATLAB solver. Complete measurement setup with simulated vs. measured results is compared in this article.

Developing a novel expression for chloride ion concentration threshold in reinforced concrete: Integration of electrochemical analysis and time-dependent modeling

Chloride ion concentration threshold is a crucial parameter for evaluating the durability of reinforced concrete. This study aimed to develop a novel expression method for this threshold by analyzing the open-circuit potential of steel in simulated mortar pore solution across three pH values. Concurrently, the correlation between pitting potential and chloride ion concentration was examined through potentiodynamic polarization testing. Additionally, Mott-Schottky analysis facilitated the investigation of the passivation film structure on the steel under both passivation and depassivation conditions. By integrating the analysis of the open-circuit potential and pitting potential models in the simulated solution, a time-dependent relationship curve between the chloride ion threshold and time was established. The findings reveal that the steel’s passivation film comprises a dual-layer structure, with its corrosion resistance enhancing as the pH value of the simulated mortar pore solution increases. Furthermore, within the simulated mortar pore solution, the chloride ion concentration threshold exhibited a decreasing trend over time, suggesting a minimum threshold value exists. This research provides a significant foundation for forecasting the corrosion state of steel in steel-reinforced engineering projects.

Stable Inverted Perovskite Solar Cells with Efficiency over 23.0% via Dual-Layer SnO2 on Perovskite.

Perovskite solar cells (PSCs) have shown great potential for reducing costs and improving power conversion efficiency (PCE). One effective method to achieve the latter is to use an all-inorganic charge transport layer (ICTL). However, traditional methods for crystallizing inorganic layers often result in the formation of a powder instead of a continuous film. To address this issue, we designed a dual-layer inorganic electron transport layer (IETL). This dual-layer structure consists of a layer of SnO2 nanocrystals (SnO2 NCs) deposited via a solution process and a dense SnO2 layer deposited through atomic layer deposition (ALD SnO2) to fill the cracks and gaps between the SnO2 NCs. PSCs having these dual-layer SnO2 ETLs achieved a high efficiency of 23.0%. This efficiency surpasses the recorded performance of ICTLs deposited on the perovskite. Furthermore, the PCE is comparable to that achieved with a C60 ETL. Moreover, the high-density structure of the ALD SnO2 layer inhibits the vertical migration of ions, resulting in improved thermal stability. After continuous heating at 85 °C in 10% humidity for 1000 h, the PCE of the dual-layer SnO2 structure decreased by 18%, whereas that of the C60/BCP structure decreased by 36%. The integration of dual-layer SnO2 into PSCs represents a significant advancement in achieving high-performance, commercially viable inverted monolithic PSCs or tandem solar cells.

STN localization using local field potentials based on wavelet packet features and stacking ensemble learning

Background:DBS entails the insertion of an electrode into the patient brain, enabling Subthalamic nucleus (STN) stimulation. Accurate delineation of STN borders is a critical but time-consuming task, traditionally reliant on the neurosurgeon experience in deciphering the intricacies of microelectrode recording (MER). While clinical outcomes of MER have been satisfactory, they involve certain risks to patient safety. Recently, there has been a growing interest in exploring the potential of local field potentials (LFP) due to their correlation with the STN motor territory. Method:A novel STN detection system, integrating LFP and wavelet packet transform (WPT) with stacking ensemble learning, is developed. Initial steps involve the inclusion of soft thresholding to increase robustness to LFP variability. Subsequently, non-linear WPT features are extracted. Finally, a unique ensemble model, comprising a dual-layer structure, is developed for STN localization. We harnessed the capabilities of support vector machine, Decision tree and k-Nearest Neighbor in conjunction with long short-term memory (LSTM) network. LSTM is pivotal for assigning adequate weights to every base model. Results:Results reveal that the proposed model achieved a remarkable accuracy and F1-score of 89.49% and 91.63%. Comparison with existing methods:Ensemble model demonstrated superior performance when compared to standalone base models and existing meta techniques. Conclusion:This framework is envisioned to enhance the efficiency of DBS surgery and reduce the reliance on clinician experience for precise STN detection. This achievement is strategically significant to serve as an invaluable tool for refining the electrode trajectory, potentially replacing the current methodology based on MER.

Bioinspired melt-blown fiber felt with flame retardancy for efficient oil spill remediation by solar-driven oil evaporation and adsorption

Confronted with rapid-spread river oil leaks and marine oil spills containing toxic and light fractions, conventional emergency response measures often fall short. This study proposes a solar-driven oil evaporation and adsorption (SOEA) strategy that efficiently addresses the challenges posed by toxic and light oils in rivers and oceans. Inspired by the self-protection and anti-fouling effects of fish scales, a photothermal oil-adsorbing felt with a biomimetic scale structure for efficient SEOA is constructed by decorating functional components onto the melt-blown fiber felt using scalable spraying technology. The rational integration of a dual-layer scale structure and functional constituents imparts stable superhydrophobicity, self-cleaning, flame retardancy, enhanced mechanical strength, and a higher oil adsorption capacity. Benefiting from the superior photothermal conversion, the solar-vapor conversion efficiency of the resulting P-EG/MXene@PP reaches 85.6 % under 1 sunlight, with an evaporation rate for light oil of 13.17 kg/m2/h, 8 times higher than natural volatilization. For crude oil floating on water, it achieves a 98 % oil removal efficiency in 6 h, with 41 wt% of the light fraction evaporated. This research provides distinctive insights into solar-driven oil spill remediation behavior and pioneers the SOEA strategy, offering rapid, efficient, and safe solutions for intricate oil spill scenarios.

The Positive impact of biomineralization for marine corrosion protection of AA5083 alloy

This paper investigates, using surface characterisation techniques (SEM, XPS and ToF-SIMS), the impact of marine biological activity on AA5083 corrosion behaviour during seawater immersion. Different solar exposure (light vs. dark) results in distinct marine fouling development, influencing surface modifications. On the dark side, an Al/Mg oxide/hydroxide layer forms, allowing Cl- penetration. Pitting attack is observed after immersion. For the light side, a dual layer structure forms, with a hydrated Mg rich outer layer, showing barrier effect to Cl- penetration. No localized corrosion occurs. A comparison with abiotic conditions demonstrates the corrosion-inhibiting effect of marine biological activity on AA5083.

Nonlinear Neutral Modes in Zero-Mass-Flux Plane Poiseuille-Couette Flow

Summary Plane Poiseuille–Couette flow with zero mean advection velocity, a flow well known to be linearly stable, is analysed at asymptotically large Reynolds number R. A nonlinear neutral mode structure is uncovered which is self-sustained due to the interaction of the viscous wall layers with a predominantly inviscid nonlinear internal critical layer. The O(1) phase speed and wavenumber of the disturbance are computed as functions of the O(R−1/3) wave amplitude, with the formula for the amplitude determined analytically. Two distinct coherent structures are found: one involving a single critical layer and a second with two critical layers. The single critical layer case has a long wavelength/small amplitude limit for which an analytical solution exists, while the dual critical layer structure possesses two solution branches and exists above a threshold amplitude. Both states distort the mean flow by an O(R−1/6) amount, and in the long wavelength limit the distortion becomes comparable in size with the original basic flow. The relevance of this work to the experimental observation of self-sustained states in this flow is discussed.

Stabilizing Solid Electrolyte Interphase on Liquid Metal Via Dynamic Hydrogel-Derived Carbon Framework Encapsulation.

Eutectic gallium-indium liquid metal (EGaIn-LM), with a considerable capacity and unique self-healing properties derived from its intrinsic liquid nature, gains tremendous attention for lithium-ion batteries (LIBs) anode. However, the fluidity of the LM can trigger continuous consumption of the electrolyte, and its liquid-solid transition during the lithiation/de-lithiation process may result in the rupture of the solid electrolyte interface (SEI). Herein, LM is employed as an initiator to in situ assemble the 3D hydrogel for dynamically encapsulating itself; the LM nanoparticles can be homogeneously confined within the hydrogel-derived carbon framework (HDC) after calcination. Such design effectively alleviates the volume expansion of LM and facilitates electron transportation, resulting in a superior rate capability and long-term cyclability. Further, the "dual-layer" SEI structure and its key components, including the robust LiF outer layer and corrosion-resistant and ionic conductive LiGaOx inner layer are revealed, confirming the involvement of LM in the formation of SEI, as well as the important role of carbon framework in reducing interfacial side reactions and SEI decomposition. This work provides a distinct perspective for the formation, structural evolution, and composition of SEI at the liquid/solid interface, and demonstrates an effective strategy to construct a reliable matrix for stabilizing the SEI.