• The microstructure and passivation behavior of high-entropy alloys are investigated • Polarization studies revealed corrosion characteristics under applied potential • Dynamic electrochemical impedance spectroscopy demonstrated passivation behavior • High-entropy alloy exhibited accelerated corrosion at potential exceeding -0.186 V • Alloying elements, mainly of Cr and Mn, contributed to the passive characteristics High-entropy alloys (HEAs), which consist of multiple elements with equiatomic concentrations and a single FCC crystal structure, have garnered attention compared to conventional metals and alloys due to their superior performance and enhanced corrosion resistance. The presence of multiple elements substantially influences the corrosion characteristics and significantly affects the formation of the passive layer in the corrosive atmosphere. In the present work, polarization studies were performed to understand the corrosion characteristics of the alloy, and electrochemical impedance spectroscopy (EIS) with varying applied potentials, derived from the polarization curve, called dynamic EIS (DEIS), was used to elucidate the passivation characteristics of the wrought Cantor high-entropy alloy. The polarization and DEIS results, along with equivalent circuit curve-fitting analysis of the Cantor high-entropy alloy, revealed variations in capacitive loop diameters and charge transfer resistance corresponding to passivation characteristics until the applied potential reached -0.266 V vs SCE, after which breakdown occurred with transpassive characteristics when the applied potential exceeded -0.206 V vs SCE. The presence of alloying elements played a crucial role in the formation and breakdown of the passive layer. This phenomenon has been extensively investigated through morphological and X-ray photoelectron spectroscopy studies.

Abstract Laser patterning to fabricate micro/nanoscale structures attracts enormous attention as they find many functional applications owing to their controllable structure and unique properties. The present work proposes a unique solution‐based method to fabricate laser‐induced periodic surface structure (LIPSS) patterns on a thin film of Titanium (IV) butoxide and Ag organometallic (OM) solution‐coated glass substrates with near infra‐red (NIR) nanosecond (ns) laser. The formation of periodic patterns has been confirmed, the thin film solution concentration affects the LIPSS pattern thickness and a continuous pattern is achieved with the diluted solution. Parametric studies demonstrate that the LIPSS patterns could be achieved with optimal solution dilution, laser fluence, scan speed, and pulse duration. A high power and faster scan speed result in discontinued, and defective patterns. The photothermal process such as material reorganization followed by electromagnetic absorption that takes place during laser patterning is mainly responsible for the fabrication of controlled structures. LIPSS patterned surfaces exhibit iridescent surface coloration while illuminated with white light, and the color spectrum from red to blue is distinguished. LIPSS patterned substrates serve as mold and structures are transferrable to the poly dimethyl siloxane (PDMS) film and exhibit iridescent structural coloration like LIPSS patterned substrates.

Plasmonic color printing has received significant attention owing to its advantages such as nonfading and nontoxic color expression, without necessitating the use of chemical dyes. Recently, color generation from laser-induced plasmonic nanostructures has been extensively explored because of its simplicity, cost-effectiveness, and large-scale processability. However, these methods usually utilize a top-down method that causes unexpected background colors. Here, we proposed a novel method of plasmonic color printing via a bottom-up type laser-induced photomodification process. In the proposed method, selective silver nanoparticles (Ag NPs) structure could be fabricated on a transparent substrate through a unique organometallic solution-based laser patterning process. A set of color palettes was formed on the basis of different processing parameters such as laser fluence, scanning speed, and baking time. This color change was verified by finite-difference time-domain (FDTD) simulations via monitoring the spectral peak shift of the localized surface plasmon resonance (LSPR) at Ag NPs. It was also confirmed that the colors can be fabricated at a relatively high scanning speed (≥10 mm/s) on a large substrate (>300 mm 2 ). Since semitransparent color images can be patterned on various transparent substrates, this process will broaden the application range of laser-induced plasmonic color generation.

• The microstructure and passivation behavior of high-entropy alloys are investigated • Polarization studies revealed corrosion characteristics under applied potential • Dynamic electrochemical impedance spectroscopy demonstrated passivation behavior • High-entropy alloy exhibited accelerated corrosion at potential exceeding -0.186 V • Alloying elements, mainly of Cr and Mn, contributed to the passive characteristics High-entropy alloys (HEAs), which consist of multiple elements with equiatomic concentrations and a single FCC crystal structure, have garnered attention compared to conventional metals and alloys due to their superior performance and enhanced corrosion resistance. The presence of multiple elements substantially influences the corrosion characteristics and significantly affects the formation of the passive layer in the corrosive atmosphere. In the present work, polarization studies were performed to understand the corrosion characteristics of the alloy, and electrochemical impedance spectroscopy (EIS) with varying applied potentials, derived from the polarization curve, called dynamic EIS (DEIS), was used to elucidate the passivation characteristics of the wrought Cantor high-entropy alloy. The polarization and DEIS results, along with equivalent circuit curve-fitting analysis of the Cantor high-entropy alloy, revealed variations in capacitive loop diameters and charge transfer resistance corresponding to passivation characteristics until the applied potential reached -0.266 V vs SCE, after which breakdown occurred with transpassive characteristics when the applied potential exceeded -0.206 V vs SCE. The presence of alloying elements played a crucial role in the formation and breakdown of the passive layer. This phenomenon has been extensively investigated through morphological and X-ray photoelectron spectroscopy studies.

Abstract Laser patterning to fabricate micro/nanoscale structures attracts enormous attention as they find many functional applications owing to their controllable structure and unique properties. The present work proposes a unique solution‐based method to fabricate laser‐induced periodic surface structure (LIPSS) patterns on a thin film of Titanium (IV) butoxide and Ag organometallic (OM) solution‐coated glass substrates with near infra‐red (NIR) nanosecond (ns) laser. The formation of periodic patterns has been confirmed, the thin film solution concentration affects the LIPSS pattern thickness and a continuous pattern is achieved with the diluted solution. Parametric studies demonstrate that the LIPSS patterns could be achieved with optimal solution dilution, laser fluence, scan speed, and pulse duration. A high power and faster scan speed result in discontinued, and defective patterns. The photothermal process such as material reorganization followed by electromagnetic absorption that takes place during laser patterning is mainly responsible for the fabrication of controlled structures. LIPSS patterned surfaces exhibit iridescent surface coloration while illuminated with white light, and the color spectrum from red to blue is distinguished. LIPSS patterned substrates serve as mold and structures are transferrable to the poly dimethyl siloxane (PDMS) film and exhibit iridescent structural coloration like LIPSS patterned substrates.

Plasmonic color printing has received significant attention owing to its advantages such as nonfading and nontoxic color expression, without necessitating the use of chemical dyes. Recently, color generation from laser-induced plasmonic nanostructures has been extensively explored because of its simplicity, cost-effectiveness, and large-scale processability. However, these methods usually utilize a top-down method that causes unexpected background colors. Here, we proposed a novel method of plasmonic color printing via a bottom-up type laser-induced photomodification process. In the proposed method, selective silver nanoparticles (Ag NPs) structure could be fabricated on a transparent substrate through a unique organometallic solution-based laser patterning process. A set of color palettes was formed on the basis of different processing parameters such as laser fluence, scanning speed, and baking time. This color change was verified by finite-difference time-domain (FDTD) simulations via monitoring the spectral peak shift of the localized surface plasmon resonance (LSPR) at Ag NPs. It was also confirmed that the colors can be fabricated at a relatively high scanning speed (≥10 mm/s) on a large substrate (>300 mm 2 ). Since semitransparent color images can be patterned on various transparent substrates, this process will broaden the application range of laser-induced plasmonic color generation.

Metal microhoneycomb structures have received considerable attention as a type of interaction-efficient functional devices owing to their unique morphology and material properties. Microhoneycomb structures are mainly fabricated using the well-known breath-figure method. However, additional post-treatments are required to produce a metal structure because it is a polymer-based process, and this necessitates expensive, complex, and multi-step fabrication processes. Therefore, a simple, low-cost metal honeycomb fabrication process is necessary. In this paper, the laser patterning of an organometallic solution to produce silver microhoneycomb (Ag microhoneycomb) structures is proposed. Various phenomena such as rapid organic evaporation, silver nanoparticle solidification, and material reorganization from Marangoni flow are found to enable patterning-induced microhoneycomb formation. Parametric studies demonstrate that the pore size can be easily controlled through simple laser parameter changes. In addition, cyclic voltammetry and electrochemical impedance spectroscopy studies confirm the potential electrochemical applications of the Ag microhoneycomb structures based on the variation of electrochemical redox behavior depending on the pore size. Owing to the excellent advantages of one-step laser patterning without any templates, the proposed process will likely promote the practical use of the metal microhoneycomb structures.

ABSTRACT Conventional laser irradiation of polyimide (PI) films for flexible electrode fabrication is limited by uncontrolled ablation, compromising structural precision and functional integration. Here, a spatially confined, low‐energy laser‐induced direct‐write strategy is reported that enables precise control over carbonization and nanomaterial integration in flexible carbon‐based electrodes. In the proposed sandwich configuration, a PI film is confined between two glass substrates during nanosecond (ns) laser irradiation, governing localized heat absorption and diffusion to achieve controlled graphitization with minimal structural damage. The confinement architecture further facilitates the laser‐induced reduction of a copper (Cu) metal–organic framework (Cu‐MOF) precursor, thereby enabling selective in situ incorporation of electroactive Cu nanoparticles directly into the carbon matrix. Optimization of the confinement geometry and laser parameters yields electrodes comprising highly graphitized, sheet‐like carbon structures with uniformly dispersed spherical Cu nanoparticles, improving both electrical conductivity and surface catalytic activity. The fabricated flexible electrodes are used as nonenzymatic glucose sensors, achieving a wide linear detection range (from 0.25 µ m to 10 m m ), a sensitivity of 2586.1 µA m m −1 cm −2 (0–1 m m ), and a detection limit of 2.72 µ m . Stable electrochemical performance is retained for the fabricated electrodes under repeated mechanical deformation, validating the robustness of this laser‐processing strategy for sensing applications.

Pulsed laser ablation (PLA) of silver nanowire (AgNW) films has been a promising method for fabricating patterned transparent conductive layers on flexible and stretchable substrates due to its advantages, including pattern flexibility, atmospheric and room-temperature processing, and fast and low-cost processing. However, despite the benefits of the PLA, its generally unclear surface quality has prevented its application in industrial manufacturing fields, as it typically uses light sources with wavelengths exceeding several hundred nanometers, which can induce unintended damage due to their high power. We investigate the degradation of transparency caused by redeposited silver nanoparticles (AgNPs) on the ultraviolet (UV) laser-ablated regions of the AgNW films, where the tendency differs primarily with the laser irradiation energy, as the laser fluence mainly affects the surface finish in the bulk PLA process. Transparency degradations were dominantly observed at the intermediate laser irradiation energies. In contrast, the non-ablated NWs and fully ablated NWs, with no degradation, were observed at low and high laser energies, respectively. These results indicate that PLA of AgNWs using high laser fluence is preferred for complete ablation; however, substrate damage remains a concern. Here, we demonstrate ultrasonic (US) vibration-assisted PLA of the AgNW film in liquid, enabling a wide energy-processing window by minimizing the redeposited AgNPs at intermediate laser energies. US vibration-induced cavitation in the liquid layer is expected to enhance the dispersion of AgNPs in the liquid, resulting in improved transmittance of the ablated regions compared to the atmospheric environment. The wide energy-processing window in the PLA of AgNWs provides a reliable fabrication method for achieving damage-free patterns of AgNW films for flexible and stretchable optoelectronic devices in manufacturing fields.

Due to their structural properties, nanopatterns are actively used in various fields. In the semiconductor industry, the importance of analyzing the uniformity of nanopatterns is becoming increasingly important. New analysis methods are needed. The elliptical Fourier descriptor (EFD) method can quantify the shape information into frequency components by Fourier transforming contours. In this study, shape analysis of nanopatterns was performed using EFD. Nanopatterns with a period of about 400 nm were formed using laser interference lithography. EFD coefficients were then compared. Results of the analysis showed that the variation between coefficients of poorly shaped patterns was larger than that of normal patterns, confirming the possibility of quantitative comparison. However, further research is needed to establish a clear correlation between coefficient changes and quality changes. In the absence of a standard for geometrical changes in nanopatterns, it is expected that EFD can be applied as a methodology to provide new quantitative indicators.

Plasmonic color printing, which uses surface plasmon resonance through metal nanostructures, has received much attention for its advantages, such as no bleaching or toxic chemicals, over dye-based techniques. In particular, laser-based processes are being actively researched due to their simplicity and ability to cover a large surface area. Through a photoreduction reaction, a metal structure can be formed by irradiating a light source using electron activation. This bottom-up method offers the advantages of no background color and a large color span. In this study, plasmonic color printing was implemented by forming a zinc oxide (ZnO) layer through ultraviolet light-induced photoreduction of silver. Silver nanostructures of various sizes were formed depending on the light focus, and the reflectance peak shift determined the color. Offering the advantages of low cost and simple setup, this process is expected to be applicable to plasmonic color printing in practice.