Nanoscale Structures Research Articles

Diatom-induced impact on shear strength characteristics of fine-grained soils

Diatomaceous soils, composed of diatom microfossils with biological origins, have geotechnical properties that are fundamentally different from those of conventional non-diatomaceous fine-grained soils. Despite their high fines content, diatomaceous soils typically exhibit remarkably high shear resistance, approaching that of sandy soils. However, the exact role that diatoms play in controlling the mechanical properties of fine-grained soils and the underlying mechanisms remain unclear. In light of this, the shear strength response of diatomaceous soils was systematically investigated using consolidated undrained triaxial compression tests on diatom–kaolin mixtures (DKMs) with various diatom contents and overconsolidation ratios. The micro- and nano-scale structures of the soil samples were characterized in detail using scanning electron microscope (SEM) and atomic force microscope (AFM) to interpret the abnormal shear strength parameters of diatomaceous soils. The results indicated that the presence of diatoms could contribute to significantly higher strength, e.g. the friction angle of DKMs was improved by 72.7% to 37° and the value of undrained shear strength tripled with diatom content increasing from 20% to 100%. Such significant improvement in soil strength with diatom inclusion could be attribute to the hard siliceous skeleton of diatoms and the interlocking between particles with rough surfaces, which were quantitatively analyzed by the surface roughness parameters with AFM. Furthermore, a conceptual model established based on the macro-mechanical tests and microscopic observations portrays a microstructural evolution of soils with increasing diatoms. The microstructure of soils was gradually transformed from the matrix-type to the skeletal one, resulting in a continual augmentation in shear strength through mutual interactions between diatom microfossils. This paper provides new insights into the multi-scale structural properties of diatoms and significantly advances our understanding of the mechanical behavior of diatomaceous soils.

Fabrication of Superhydrophobic Nanostructures on Glass Surfaces Using Hydrogen Fluoride Gas.

Water-repellent glass surfaces have become increasingly important to ensure clear visibility in outdoor cameras, sensors, and automotive windows. In this study, we investigated a process for the formation of nanoscale structures on a glass surface using chemical reactions with hydrogen fluoride gas. Using this approach, nanostructures with superhydrophobicity, superhydrophilicity, and antireflective properties were formed on glass surfaces with minimal processing time. This mask-free method, working at atmospheric pressure, can be efficiently integrated within the float process, a mainstream manufacturing technique for flat glass, to introduce nanostructures onto the glass surface. Notably, after treatment with (1-H, 1-H, 2-H, 2-H-tridecafluorooctyl)trimethoxysilane (FAS-13), a typical hydrophobic agent, the resulting surface exhibited a maximum water contact angle of 162°. Owing to its low reflectivity and superhydrophobicity, this surface is anticipated to find applications in not only the design of architectural window glass and vehicle windows but also the development of solar panels and sensor cover glass for autonomous vehicles.

Phase Electronic Structure Tuning via Pt, P-Doped Ni4Mo-Implanted Ti4O7 for Highly Efficient Water Splitting and Mg/Seawater Batteries.

Fine-tuning nanoscale structures, morphologies, and electronic states are crucial for creating efficient water-splitting electrocatalysts. In this study, a method for electronic structure engineering to enhance overall water splitting in a corrosion-resistant electrocatalyst matrix by integrating Pt, P dual-doped Ni4Mo electrocatalysts onto a Ti4O7 nanorod grown on carbon cloth (Pt, P-Ni4Mo-Ti4O7/CC) is introduced. By optimizing platinum and phosphorus concentrations to 1.18% and 2.42%, respectively, low overpotentials are achieved remarkably: 24mV at 10mA cm-2 for the hydrogen evolution reaction and 290mV at 20mA cm-2 for the oxygen evolution reaction in 1.0m KOH. These values approach or surpass those of benchmark Pt-C and IrO2 catalysts. Additionally, the Pt, P-Ni4Mo-Ti4O7/CC bifunctional electrocatalyst displays low cell potentials across various mediums, maintaining excellent current retention (96% stability after 40 h in mimic seawater at 20mA cm-2) and demonstrating strong corrosion resistance and suitability for seawater electrolysis. As a cathode in magnesium/seawater batteries, it achieves a power density of 7.2mW cm-2 and maintains stability for 100 h. Density functional theory simulations confirm that P, Pt doping-assisted electronic structure modifications augment electrical conductivity and active sites in the hybrid electrocatalysts.

Chiral monomer template for designing Low-Driving-Field blue phase liquid crystals

Blue phase liquid crystals (BPLC) are known to be useful for various non-trivial applications due to their nanoscale self-assembled cubic crystalline structures. Even though the BPLC exhibits an efficient optically isotropic phase due to the double helical confinement of liquid crystal (LC) molecules within a few hundred-nanometer range, this hinders the orientation of LC molecules along the applied field direction. Consequently, the BPLC demands larger driving fields to operate, degrading the device’s performance in real-world applications. In this context, we provide a chiral monomer template for BPLC that decreases the driving field by 52 % while the electro-optical responses remain unaffected. Furthermore, our approach provides higher thermal stability, with a broader BPLC phase range (42 °C), including near ambient temperature. As this approach potentially overcomes the fundamental challenges of BPLC, the proposed system could be useful for next-generation display devices.

Imaging of Isolated Exosomes by Correlative Microscopy.

Correlative microscopy is a sophisticated imaging technique that combines optical and electron microscopes, with the most common approach being the integration of light microscopy and electron microscopy, known as correlative light and electron microscopy (CLEM). While CLEM provides a comprehensive view of biological samples, it presents a significant challenge in sample preparation due to the distinct processes involved in each technique. Striking a balance between these methods is crucial. Despite numerous approaches, achieving seamless imaging with CLEM remains a complex task. Exosomes, nanovesicles ranging from 30 to 150 nm in size, are enclosed by a lipid bilayer and released by various cell types. Visualizing exosomes poses difficulties due to their small size and minimal electric charge. However, imaging exosomes at high resolution offers a direct method to understand their morphology and functions. In this study, we evaluated exosome imaging with CLEM using a combination of confocal, transmission electron microscope, and scanning electron microscope (SEM). In addition, we conducted a comparative analysis of these two techniques, evaluating their suitability and efficiency in imaging nanoscale structures. In this study, we found that confocal-SEM correlation is more applicable for imaging exosomes. Moreover, we observed that exosomes were found in clusters in confocal-SEM correlation.

Engineered Bacterial Biomimetic Vesicles Reprogram Tumor-Associated Macrophages and Remodel Tumor Microenvironment to Promote Innate and Adaptive Antitumor Immune Responses.

Tumor-associated macrophages (TAMs) are among the most abundant infiltrating leukocytes in the tumor microenvironment (TME). Reprogramming TAMs from protumor M2 to antitumor M1 phenotype is a promising strategy for remodeling the TME and promoting antitumor immunity; however, the development of an efficient strategy remains challenging. Here, a genetically modified bacterial biomimetic vesicle (BBV) with IFN-γ exposed on the surface in a nanoassembling membrane pore structure was constructed. The engineered IFN-γ BBV featured a nanoscale structure of protein and lipid vesicle, the existence of rich pattern-associated molecular patterns (PAMPs), and the costimulation of introduced IFN-γ molecules. In vitro, IFN-γ BBV reprogrammed M2 macrophages to M1, possibly through NF-κB and JAK-STAT signaling pathways, releasing nitric oxide (NO) and inflammatory cytokines IL-1β, IL-6, and TNF-α and increasing the expression of IL-12 and iNOS. In tumor-bearing mice, IFN-γ BBV demonstrated a targeted enrichment in tumors and successfully reprogrammed TAMs into the M1 phenotype; notably, the response of antigen-specific cytotoxic T lymphocyte (CTL) in TME was promoted while the immunosuppressive myeloid-derived suppressor cell (MDSC) was suppressed. The tumor growth was found to be significantly inhibited in both a TC-1 tumor and a CT26 tumor. It was indicated that the antitumor effects of IFN-γ BBV were macrophage-dependent. Further, the modulation of TME by IFN-γ BBV produced synergistic effects against tumor growth and metastasis with an immune checkpoint inhibitor in an orthotopic 4T1 breast cancer model which was insensitive to anti-PD-1 mAb alone. In conclusion, IFN-γ-modified BBV demonstrated a strong capability of efficiently targeting tumor and tuning a cold tumor hot through reprogramming TAMs, providing a potent approach for tumor immunotherapy.

Characterization of Surface Modifications in Oxygen Plasma-Treated Teflon AF1600.

We explore the surface properties of Teflon AF1600 films treated by oxygen plasma with various procedure parameters. Contact angle (CA) measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron microscopy (XPS) are employed to investigate the wetting behavior, surface topography, and chemical composition, respectively. While the etched thickness reveals a linear relationship to the applied plasma energy, the surface presents various wetting properties and topographies depending on the plasma energy: low advancing and zero receding CA (1 kJ), super high advancing and zero receding CA (2-3 kJ), and super high advancing and high receding CA (≥4.5 kJ) for the wetting behaviors; pillar-like (≤6 kJ) and fiber-like (>6 kJ) nanoscaled structures for the topographies. The results of XPS analysis reveal slight changes in the presence of O- and F-components (<4%) after oxygen plasma treatment. Furthermore, we discuss the applicability of the Wenzel and Cassie-Baxter equations and employ the Friction-Adsorption (FA) model, where no wetting state and structure-related parameters are needed, to describe the CAs on the plasma-treated surfaces. Additionally, we conduct electrowetting experiments on the treated surfaces and find that the experimental results of the advancing CA are in good agreement with the predictions of the FA model.

Passivating Blunt‐Ended Helices to Control Monodispersity and Multi‐Subunit Assembly of DNA Origami Structures

Deoxyribonucleic acid (DNA) origami enables the synthesis of bespoke nanoscale structures suitable for diverse applications. Effective design requires preventing uncontrolled aggregation, while still facilitating directed multi‐subunit assembly. Uncontrolled aggregation is often caused by base‐stacking interactions between arrays of blunt‐ended helices, a problem which is typically mitigated by incorporating disordered single‐stranded DNA (ssDNA) (like scaffold loops or poly‐thymine brushes) at the end of double‐stranded DNA (dsDNA) helices. Such disordered regions are ubiquitous in DNA origami structures yet their optimal design requirements in various chemical environments remains unclear. This study systematically investigates scaffold loops and poly‐nucleotide brushes for aggregation prevention and control of multi‐subunit assembly, examining length, sequence, and MgCl2 concentration dependencies. Additionally, a novel strategy is introduced using orthogonal double‐stranded DNA helices to create a steric shield against base stacking. The results reveal key considerations. Poly‐thymine brushes excel in achieving monodispersity across diverse conditions whereas scaffold loops aid directed multi‐subunit assembly. Orthogonal DNA helices remove the need for disordered regions altogether, preventing aggregation over a broad range of MgCl2 concentrations and facilitating controlled multi‐subunit assembly. This study expands the toolbox for DNA origami design and enables a more informed approach for achieving control of monodispersity and multi‐subunit assembly in DNA origami structures.

Resolving Multi-Asperity Contacts at the Nanoscale through Super-Resolution Fluorescence Imaging.

Contact mechanics, spanning nanometer to tectonic scales, faces long-standing challenges arising from multiscale random roughness, which hinders experimental validation of theories. Understanding multi-asperity rough contacts is vital for addressing catastrophic consequences of these contacts failing such as earthquakes and for diverse technological applications. To visualize such contacts, we introduce a super-resolution microscopy method utilizing spontaneous millisecond ON/OFF fluorescence blinking of contact-sensitive molecular rotor molecules immobilized on a glass coverslip. This technique achieves ∼55 nm lateral imaging resolution for rough poly(methyl methacrylate) and glass spheres on glass contacts. For soft polymer spheres due to large plastic deformation, the resolution improvement does not significantly affect the area of real contact. However, for hard glass spheres, the real contact area is found to be 2.4 times smaller than that found by diffraction-limited imaging. This study highlights, through direct visualization, the impact of material stiffness on the nanoscale structure within the area of real contact.

Free vibration characteristics of elastic foundation-supported porous functionally graded nanoplates using Rayleigh-Ritz approach

PurposeThe purpose is to explore the free vibration behaviour of elastic foundation-supported porous functionally graded nanoplates using the Rayleigh-Ritz approach. The goal of this study is to gain a better knowledge of the dynamic response of nanoscale structures made of functionally graded materials and porous features. The Rayleigh-Ritz approach is used in this study to generate realistic mathematical models that take elastic foundation support into account. This research can contribute to the design and optimization of advanced nanomaterials with potential applications in engineering and technology by providing insights into the influence of material composition, porosity and foundation support on the vibrational properties of nanoplates.Design/methodology/approachA systematic methodology is proposed to evaluate the free vibration characteristics of elastic foundation-supported porous functionally graded nanoplates using the Rayleigh-Ritz approach. The study began by developing the mathematical model, adding material properties and establishing governing equations using the Rayleigh-Ritz approach. Numerical approaches to solve the problem are used, using finite element methods. The results are compared to current solutions or experimental data to validate the process. The results are also analysed, keeping the influence of factors on vibration characteristics in mind. The findings are summarized and avenues for future research are suggested, ensuring a robust investigation within the constraints.FindingsThe Rayleigh-Ritz technique is used to investigate the free vibration properties of elastic foundation-supported porous functionally graded nanoplates. The findings show that differences in material composition, porosity and foundation support have a significant impact on the vibrational behaviour of nanoplates. The Rayleigh-Ritz approach is good at modelling and predicting these properties. Furthermore, the study emphasizes the possibility of customizing nanoplate qualities to optimize certain vibrational responses, providing useful insights for engineering applications. These findings expand understanding of dynamic behaviours in nanoscale structures, making it easier to build innovative materials with specific features for a wide range of industrial applications.Originality/valueThe novel aspect of this research is the incorporation of elastic foundation support, porous structures and functionally graded materials into the setting of nanoplate free vibrations, utilizing the Rayleigh-Ritz technique. Few research have looked into this complex combo. By tackling complicated interactions, the research pushes boundaries, providing a unique insight into the dynamic behaviour of nanoscale objects. This novel approach allows for a better understanding of the interconnected effects of material composition, porosity and foundation support on free vibrations, paving the way for the development of tailored nanomaterials with specific vibrational properties for advanced engineering and technology applications.

Attosecond electron microscopy by free-electron homodyne detection

Time-resolved electron microscopy aims to track nanoscale excitations and dynamic states of matter at a temporal resolution ultimately reaching the attosecond regime. Periodically time-varying fields in an illuminated specimen cause free-electron inelastic scattering, which enables the spectroscopic imaging of near-field intensities. However, access to the evolution of nanoscale fields and structures within the cycle of light requires sensitivity to the optical phase. Here we introduce free-electron homodyne detection as a universally applicable approach to electron microscopy of phase-resolved optical responses at high spatiotemporal resolution. In this scheme, a phase-controlled reference interaction serves as the local oscillator to extract arbitrary sample-induced modulations of a free-electron wavefunction. We demonstrate this principle through the phase-resolved imaging of plasmonic fields with few-nanometre spatial and sub-cycle temporal resolutions. Due to its sensitivity to both phase- and amplitude-modulated electron beams, free-electron homodyne detection measurements will be able to detect and amplify weak signals stemming from a wide variety of microscopic origins, including linear and nonlinear optical polarizations, atomic and molecular resonances, and attosecond-modulated structure factors.

Morphology Control of Self-Assembled Copper Coordination Polymers for Glucose Assays.

Low-cost analytical assays enable accessible detection of clinically and environmentally important analytes; however, common enzyme-based assays suffer from high production and storage costs. Catalytically active synthetic materials serve as replacements for natural enzymes, but development of cost-effective, highly efficient synthetic strategies remains a challenge. Here, we utilized a facile synthesis for copper bipyridine coordination polymers (CuBpyCPs) and investigated structure-function relationships to achieve optimal catalytic properties for a glucose assay. We demonstrated the manipulation of CuBpyCP morphology, resulting in nanoscale petal-like structures and microscale high-index faceted structures, and identified three pure crystal morphologies exhibiting a comparable catalytic activity (Km = 0.3-0.5 mM) to horseradish peroxidase.

Facilitating excited-state plasmonics and photochemical reaction dynamics

Continuously advancing technologies is crucial to tackling modern challenges such as efficient energy transfer, directing catalytic behavior, and better understanding of microscopic phenomena. At the heart of many of these problems is nanoscale chemistry. In previous decades, the scientific community has made significant progress in nanoscale structures and technologies, especially relating to their interactions with light. Plasmonic nanostructures have been extensively studied over the past decades because of their fascinating properties and vast technological applications. They can confine light into intense local electromagnetic fields, which has been exploited in the fields of spectroscopy, energy harvesting, optoelectronics, chemical sensing, and biomedicine. Recently, however, plasmonic nanostructures have shown great potential to trigger chemical transformations of proximal molecular species via hot carrier and thermally driven processes. In this review, we discuss the basic concepts governing nanoscale light–matter interactions, the immediate phenomena induced by them, and how we can use nanoscale light–matter interactions to our advantage with surface-enhanced spectroscopy techniques and chemical reactions in confined plasmonic environments.

Fat analogue emulsions stabilized by peanut protein microgel particles: microscale and nanoscale structure and stabilization process analysis.

Biopolymer-based microgels are being regarded increasingly as promising building blocks in food applications. This study aimed to clarify the evolution process of the network for fat analogue emulsions stabilized by peanut protein isolate (PPI) microgel particles. It also investigated the interfacial structure and characteristics of emulsions (50% oil phase, w/w) stabilized by microgels under different pH conditions. There was an increasing interfacial adsorption capacity for PPI microgels over time (from 85.26% to the maximum of 89.78% at 24 h of storage) due to the aggregation of microgels around droplets and the development of cross-linking microgel chains between adjacent interfaces. The increased β-sheet content (from 35.51% to 41.12%) of adsorbed microgels indicated unfolding and the enhanced aggregation of microgels, which led to stronger droplet interaction. The network evolution observed with different microscopes clarified the transition to a self-supporting emulsion. The uneven adsorption of large microgel aggregates at the oil-water interface promoted larger and deformed droplets, so more fat-like medium internal phase emulsion stabilized by PPI microgel could be obtained by adjusting the microgel pH to 4.5. The interfacial membranes observed by scanning electron microscopy were thicker and coarser at pH 3.0 and 4.5 than those at pH 7.0 and 9.0. The adsorption of PPI microgel aggregates enhanced the structural strength and improved emulsion stability. This work could form a basis for further studies relating physical properties to the design of plant protein-based fat analogues. © 2024 Society of Chemical Industry.

Palmitic acid at high concentration modifies the nanoscale structure of anhydrous milk fat

We performed a nanoscale study based on X-ray scattering to understand the impact of a promotor of crystallization, palmitic acid (PA), at high concentration, on the networks of triacylglycerols (TAGs) in anhydrous milk fat (AMF). Melted blends containing 10 wt% PA were quenched at 25 °C. X-ray scattering data were compared with those obtained for pure AMF, pure PA, and AMF containing 1 wt% PA. While PA at low concentration did not modify the nanostructure of TAG crystals (direct crystallization in the β’-2L form), a high concentration of this promotor favored the formation of polymorphic forms suggesting that PA first crystallizes and then directs crystallization of AMF TAGs towards α and β forms.

Carbon quantum dots with honeycomb structure: a novel synthesis approach utilizing cigarette smoke precursors

This study presents a novel approach to synthesizing honeycomb carbon quantum dots (CQDs) from cigarette smoke by a hydrothermal process. A comprehensive characterization of these CQDs, conducted through high-resolution transmission electron microscopy (HRTEM), showcases their unique honeycomb structure, with an average particle size of 6.3 nm. Photoluminescence (PL) in CQDs is a captivating phenomenon where these nanoscale carbon structures emit strong blue luminescence at 461 nm upon exposure to ultraviolet light, with their excitation peak occurring at 380 nm. Fourier Transform Infrared (FTIR) analysis also identifies specific functional groups within the CQDs, offering valuable insights into the mechanisms governing their photoluminescence. Analysis of excitation spectra indicates the presence of both aromatic C=C bonds at 254 nm and C–O bonds from 280 to 420 nm.

Enhanced interfacial property and thermal conductivity of pitch-based carbon fiber/epoxy composites via three-layer assembly of PDI/GN/PDI interphase

Π-conjugate perylene diimide (PDI)/graphene (GN)/PDI interphase was designed and constructed on pitch-based carbon fiber (PCF) surface by multi-layer assembly, and the interfacial and thermal conductive performances of PCF/Epoxy (EP) composites with PDI, PDI/GN and PDI/GN/PDI interphase were investigated. Flat nanoscale structures with fragmented and wrinkled GN, PDI nanowires were respectively observed on PCF-GN, PCF-PDI/GN and PCF-PDI surface, while three-dimensional oblique cicada-wing nanostructure of three-layer interphase was constructed on PCF-PDI/GN/PDI surface due to the re-assembly of PDI under confinement constraint of GN substrate. Interlayer shear strength and transverse fiber bundle tensile strength of PCF-PDI/GN/PDI/EP composite were 28.4 %, 9.36 %, 12.0 % and 246 %, 85.8 %, 116 % higher than those of PCF-GN/EP, PCF-PDI/GN/EP and PCF-PDI/EP composites, which were attributed to the improvement of interface adhesion and the effectively buffer stress transfer between carbon fiber and resin matrix by introducing three-layer PDI/GN/PDI interphase. Additionally, PCF-PDI/GN/PDI/EP composites showed the highest heat conduction and thermal conductivity, ascribing to the construction of extra conductive paths and the weakening of phonons scattering from three-dimensional (3D) structure of PDI/GN/PDI interphase, which realized the formation of structure-function integration interphase of pitch-based carbon fiber composites.

Synthesis of Porous Carbon Nanomaterials from Vietnamese Coal: Fabrication and Energy Storage Investigations

The choice of precursor and simple synthesis techniques have decisive roles in the viable production and commercialization of carbon products. The intense demand for developing high-purity carbon nanomaterials through inexpensive techniques has promoted the usage of fossil derivatives as a feasible source of carbon. In this study, Vietnamese-coal-derived porous carbon (PC) was used to fabricate coal-derived porous carbon nanomaterials (CDPCs) using the modified Hummers method. The resulting porous carbon nanomaterials achieved a nanoscale structure with an average pore size ranging from 3 to 10 nm. The findings indicate that CDPC exhibits well-developed micropores and mesopores. The presence of macropores and mesopores not only facilitates the complete immersion of the material in the electrolyte but also effectively shortens the ion diffusion pathways. CDPC boasts a high carbon content, constituting 80.88% by weight. Electrochemical impedance spectroscopy (EIS) Nyquist plot of electrodes made from CDPC showed good conductivity value with low charge-transfer resistance. This electrode worked well and stably with capacitance retention of 74.7% after 1000 cycles. The CDPC specific capacitance reached 236 F/g under a current density of 0.1 A using the constant current discharge method and then decreased as the current density increased. Based on the results of the electrochemical properties of the materials, the energy storage capacity of the CDPC material was good and stable. This investigation presents an eco-friendly methodology for the judicious utilization of coal in energy storage applications, specifically as electrodes for supercapacitors and anodes for Li-ion batteries.

In Situ and Operando X-ray Scattering Methods in Electrochemistry and Electrocatalysis.

Electrochemical and electrocatalytic processes are of key importance for the transition to a sustainable energy supply as well as for a wide variety of other technologically relevant fields. Further development of these processes requires in-depth understanding of the atomic, nano, and micro scale structure of the materials and interfaces in electrochemical devices under reaction conditions. We here provide a comprehensive review of in situ and operando studies by X-ray scattering methods, which are powerful and highly versatile tools to provide such understanding. We discuss the application of X-ray scattering to a wide variety of electrochemical systems, ranging from metal and oxide single crystals to nanoparticles and even full devices. We show how structural data on bulk phases, electrode-electrolyte interfaces, and nanoscale morphology can be obtained and describe recent developments that provide highly local information and insight into the composition and electronic structure. These X-ray scattering studies yield insights into the structure in the double layer potential range as well as into the structural evolution during electrocatalytic processes and phase formation reactions, such as nucleation and growth during electrodeposition and dissolution, the formation of passive films, corrosion processes, and the electrochemical intercalation into battery materials.

Microstructure evolution and formation mechanism of interfaces in parallel gap resistance welding of stranded Ag-plated Cu conductor to Ag interconnector

In space flexible solar arrays, stranded Ag-plated Cu conductors and Ag interconnectors are preferred materials for energy transmission. Parallel gap resistance welding is a solderless micro-joining process that favors the reliability of joints between stranded Ag-plated Cu conductors and Ag interconnectors. It was found the interfacial microstructure presented diversity and complexity while mechanical and electrical properties showed unusual nonlinear variations with welding voltage. This study aims to clarify the interfacial microstructure evolution and its effects on the joint properties while elucidating the microstructure formation mechanisms. A shift in the bonding mechanism at interfaces from solid-state diffusion to brazing was found as welding voltage reached a critical value (1.5 V). It eliminated micro gaps and built nano-scale interlocking structures, resulting in substantial improvement in mechanical properties. Increasing the welding voltage from 1.2 V to 1.4 V improved electrical conductivity due to the enlarged bonding area at interfaces. However, high welding voltage (1.6 V) led to degradation in the electrical conductivity of joints due to excessive Ag-Cu solid solution formed at interfaces. The key to fabricating high-strength and high-conductivity joints lies in achieving appropriate interfacial melting while reducing alloying by controlling peak temperature and shortening the duration above the Ag-Cu eutectic point.