Search Results (135)

Electrolysis of seawater is considered a green route for hydrogen generation; however, its practical application is limited by strong electrode corrosion and slow OER kinetics in chloride-rich media. Herein, we report a crystal-facet engineering strategy to construct nickel hydroxide with a parallel array structure on nickel foil (denoted as Ni(OH)₂/NFPA, where NFPA represents nickel foil with parallel array) via a facile two-step etching-hydrothermal method. Structural characterization confirms the formation of high-index Ni(220) surfaces and well-aligned hydroxide nanostripes, which promote more favorable bubble–electrode interactions and contribute to improved interfacial stability. Owing to its characteristic parallel array configuration, Ni(OH)₂/NFPA exhibits outstanding OER performance in alkaline electrolyte, delivering a low overpotential of 256 mV at 10 mA·cm⁻² together with a Tafel slope as small as 74.9 mV·dec⁻¹, surpassing commercial RuO₂ and disordered Ni(OH)₂ nanosheets. The optimized electrode also delivers remarkable durability, maintaining stable operation for 48 h at 100 mA·cm⁻² even under harsh alkaline seawater conditions at 80 °C. Bubble dynamics analysis reveals that the ordered array morphology produces a superaerophobic surface, enabling rapid detachment of oxygen bubbles and ensuring efficient mass transport. This study highlights facet-controlled construction of parallel nanoarrays as a promising approach to improve catalytic efficiency, corrosion resistance, and bubble management in seawater electrolysis, offering useful implications for the rational design of high-performance electrodes for practical hydrogen production. Full article

Graphitic nanomaterials have emerged as foundational components in nanoscience owing to their exceptional electrical, mechanical, and chemical properties, which can be tuned by controlling dimensionality and structural order. From zero-dimensional (0D) quantum dots, carbon nano-onions, and nanodiamonds to one-dimensional (1D) nanoribbons, two-dimensional (2D) nanowalls, and three-dimensional (3D) graphene foams, these architectures underpin advancements in catalysis, energy storage, sensing, and electronic technologies. Among various synthesis routes, chemical vapor deposition (CVD) provides unmatched versatility, enabling atomic-level control over carbon supply, substrate interactions, and plasma activation to produce well defined graphitic structures directly on functional supports. This review presents a comprehensive, dimension-resolved overview of CVD-derived graphitic nanomaterials, examining how process parameters such as precursor chemistry, temperature, hydrogen etching, and template design govern nucleation, crystallinity, and morphological evolution across 0D to 3D hierarchies. Comparative analyses of Raman, XPS, and XRD data are integrated to relate structural features with growth mechanisms and functional performance. By connecting mechanistic principles across dimensional scales, this review establishes a unified framework for understanding and optimizing CVD synthesis of graphitic nanostructures. It concludes by outlining a path forward for improving how CVD-grown carbon nanomaterials are made, monitored, and integrated into real devices so these can move from lab-scale experiments to practical, scalable technologies. Full article

The fabrication of semiconductor devices with three-dimensional architectures imposes unprecedented demands on advanced plasma dry etching processes. These include the simultaneous requirements of high throughput, high material selectivity, and precise profile control. In conventional reactive ion etching (RIE), fluorocarbon plasma provides both accelerated ion species and reactive neutrals that etch the feature front, while the CF_x radicals promote polymerization that protects sidewalls and enhance selectivity to the amorphous carbon layer (ACL) mask. In this work, we present computational results on the role of CF₄ addition to hydrogen fluoride (HF) plasma for next-generation RIE, specifically cryogenic etching. Simulations were performed by varying the CF₄ concentration in the HF plasma to evaluate its influence on ion densities, neutral species concentration, and electron density. The results show that the densities of CF_x (x = 1–3) ions and radicals increase significantly with CF₄ addition (up to 20%), while the overall plasma density and the excited HF species remain nearly unchanged. The results of plasma density and atomic fluorine density are consistent with the experimental observations of the HF/CF₄ plasma using an absorption probe and the actimetry method. It was verified that the gas-phase reaction model proposed in this study can accurately reproduce the plasma characteristics of the HF/CF₄ system. The coupling of HF-based etchants with CF_x radicals enables polymerization that preserves SiO₂ etching throughput while significantly enhancing etch selectivity against the ACL mask from 1.86 to 5.07, with only a small fraction (~10%) of fluorocarbon gas added. The plasma simulation provides new insights into enhancing the etching performance of HF-based cryogenic plasma etching by controlling the CF₂ radicals and HF reactants through the addition of fluorocarbon gases. Full article

In semiconductor manufacturing, fluorinated gases such as CHF₃ and CH₂F₂ are widely used as process gases for plasma etching and cleaning. However, their decomposition within the plasma environment leads to the formation of secondary fluorinated by-products with high global warming potential (GWP). Understanding how plasma intensity affects the generation characteristics of these by-products under realistic process conditions is essential for developing country-specific emission factors and improving inventory accuracy. This study analyzes the by-product formation behavior of CHF₃ and CH₂F₂ under three plasma power conditions (500 W, 600 W, and 700 W), based on process data representative of domestic semiconductor facilities. The quantitative analysis revealed distinct reaction trends between the two gas systems. In the CHF₃ process, a reaction-pathway bifurcation was observed at 700 W, where the formation of high-GWP perfluorocarbons (PFCs, e.g., CF₄, C₂F₆) decreased, while the production of low-GWP fluorinated compounds such as C₄F₆ increased, resulting in an overall 18% reduction in CO₂eq. emissions. Conversely, CH₂F₂ showed a continuous increase in fluoromethane (CH₃F) generation with higher plasma power due to the higher hydrogen content in its molecular structure, leading to an 18.4% net reduction in total GWP emissions. These results provide scientific evidence for understanding the relationship between plasma intensity and by-product formation in fluorinated gas systems under conditions relevant to the Korean semiconductor industry, and offer a foundation for improving national F-gas emission factor development. Full article

To address the challenges of low solar energy utilization efficiency and rapid recombination of photogenerated charge carriers in photocatalytic hydrogen evolution, this study successfully constructed a composite photocatalyst of ZnIn₂S₄ (ZIS) supported on N-doped hollow carbon spheres (N-HCS), denoted as ZIS/N-HCS, via a combination of template etching and in situ growth strategies. Characterization results demonstrate that this hollow structure possesses a high specific surface area (48.41 m²/g) and a narrowed bandgap (2.41 eV), achieve broad-spectrum light absorption, thereby enabling the catalyst to generate a local hot spot temperature of 136 °C under AM1.5G conditions. The optimized ZIS/N-HCS-0.30 sample exhibited a significantly enhanced photocurrent response (8.26 μA cm⁻²) and improved charge separation efficiency. When evaluated at a set solution temperature of 20 °C, the material exhibited a photocatalytic hydrogen evolution rate of 17.03 mmol g⁻¹·h⁻¹, which is 7.06 times higher than that of pure ZIS. Furthermore, it demonstrated excellent cycling stability. This work elucidates the synergistic role of the hollow photothermal structure in enhancing solar energy utilization and catalytic reaction kinetics, providing a new strategy for designing efficient solar-driven hydrogen production systems. Full article

Background and Objectives: Peri-implantitis is a biologically driven complication that jeopardizes dental implant longevity. While chemical decontamination is frequently employed as an adjunct to mechanical debridement, its impact on implant surface integrity and cellular compatibility remains insufficiently defined. This study aimed to evaluate the effects of several chemical agents used in peri-implantitis treatment on the surface morphology and potential biocompatibility of titanium dental implants. Materials and Methods: Twenty-five Ti6Al4V implants were exposed to one of the following agents: saline solution, 3% hydrogen peroxide, 40% citric acid, 17% EDTA, and a mixture (1:1) of citric (2%) and phosphoric (1N) acids. This in vitro study employed a 7-day immersion protocol to accentuate surface effects under controlled laboratory conditions, acknowledging that clinical exposures are substantially shorter. Surface topography was evaluated by Atomic Force Microscopy, while cellular response and corrosion products were assessed using Scanning Electron Microscopy. Surface roughness parameters were statistically analyzed. Results: Hydrogen peroxide induced selective corrosion of the β phase and formed a compact passivation layer that supported mesenchymal stem cell adhesion. Citric acid etched grain boundaries, producing localized roughness that also permitted cell proliferation. EDTA caused advanced grain dissolution and debris accumulation, increasing surface roughness but impairing cellular adhesion. The citric–phosphoric acid mixture led to the highest roughness values and visible corrosion debris. In all cases, macrostructural integrity of the implants was preserved. Conclusions: Chemical agents used in peri-implantitis treatment induce distinct surface alterations on titanium implants. Controlled use of hydrogen peroxide and citric acid may enhance surface biocompatibility, while aggressive protocols such as EDTA and acid combinations require caution due to their adverse effects on surface morphology and cellular response. These findings may inform the development of optimized decontamination protocols for clinical management of peri-implantitis. Full article

The starting material for this research was a metal–ceramic nanocomposite containing nanocrystalline iron with an average nanocrystallite size equal to 23 nm (based on X-Ray Diffraction; a specific surface area of 9 m²/g by the BET method) and a nanocrystallite size distribution standard deviation σ = 15 nm, promoted with hardly reducible oxides (Al₂O₃, CaO, K₂O in total, max. 10 wt%), obtained by melting magnetite with promoter oxides at 1600 °C and reducing the resulting alloy with hydrogen at 500 °C. This material was then oxidized in a controlled manner with water vapor at 425 or 500 °C to achieve different oxidation degrees. Metallic iron remaining in the samples after the oxidizing step was removed by two-stage acid etching. Promoters introduced into the melt ensured the stability of the nanocomposite structure at elevated temperatures. After etching, the iron oxide was reduced with hydrogen at 375 or 500 °C. A series of nanocrystalline iron samples with different nanocrystallite sizes (in the range from 18 to 35 nm; specific surface areas decreased from 32 to 16 m²/g with increasing nanocrystallite size) and a narrowed nanocrystallite size distribution standard deviation σ = 3–5 nm was synthesized, which was then tested in the process of nitriding (at 375 and 500 °C), carburizing (400–550 °C), and oxidation (at 425 and 500 °C). The progress and rate of these reactions were measured in a differential tubular reactor with thermogravimetric measurement of mass changes in the solid sample and catharometric measurement of hydrogen concentration in the gas phase. The scalability of the proposed method was also investigated by conducting measurements on 1, 10, and 100 g samples. The effect of nanocrystallite size on the chemical properties of the tested samples was observed. The nanocomposite samples containing the smallest iron nanocrystallite sizes were found to be the most active in the nitriding reaction and catalytic decomposition of ammonia. All the tested modified samples were at least several times more active in the decomposition of ammonia than the unmodified sample. The practical effect of our work is the presentation and use of a new, more precise method for obtaining nanocrystallites of specific sizes. Full article

The formation of atomically flat Si(111)–H surfaces was critical for molecular electronics, nanoscale device fabrication, and surface chemistry studies. We systematically investigated how initial oxide composition and dissolved oxygen affected terrace-formation kinetics during ammonium fluoride (NH₄F) etching. N-type Si(111) was cleaned with either oxygen plasma or piranha solution to generate, respectively, a more uniform versus a chemically heterogeneous oxide, and then etched in NH₄F containing 0–5% (w/v) ammonium sulfite (AS) as an oxygen scavenger. AFM acquired every 2 min over 20 min revealed that plasma-pretreated surfaces reached atomically flat terraces earlier and more reproducibly than piranha-pretreated surfaces. Increasing AS concentration suppressed oxygen-induced etch pits and promoted the earlier appearance of large, well-ordered terraces, whereas prolonged etching led to roughening. XPS and ATR-FTIR corroborated differences in the starting oxides and confirmed post-etch H-termination. Collectively, the results indicated that oxide uniformity together with oxygen scavenging correlated with faster attainment and greater persistence of low-roughness terraces, providing a practical framework for reproducibly preparing hydrogen-terminated Si(111)–H surfaces. Full article

Photocatalytic technologies based on silicon (Si-based) nanostructures offer a promising solution for water purification, hydrogen generation, and the conversion of CO₂ into useful chemical compounds. This review systematizes the diversity of modern approaches to the synthesis and modification of Si-based photocatalysts, including chemical deposition, metal-associated etching, hydrothermal methods, and atomic layer deposition. Heterostructures, plasmonic effects, and co-catalysts that enhance photocatalytic activity are considered. Particular attention is drawn to the silicon doping of semiconductors, such as TiO₂ and ZnO, to enhance their optical and electronic properties. The formation of heterostructures and the evaluation of their efficiency were discussed. Despite the high biocompatibility and availability of silicon, its photocorrosion and limited stability require the development of protective coatings and morphology optimization. The application of machine learning for predicting redox potentials and optimizing photocatalyst synthesis could offer new opportunities for increasing their efficiency. The review highlights the potential of Si-based materials for sustainable technologies and provides a roadmap for further research. Full article

Diamond is a promising next-generation semiconductor material, offering a wider band gap, higher electron mobility, and superior thermal conductivity compared with silicon. However, its exceptional hardness makes it challenging to fabricate. In this study, we demonstrate a novel approach to realize material removal on hydrogen-terminated diamond surfaces by atomic force microscope (AFM) tip-based local anodic oxidation. By adjusting both the applied voltage and hydrogen plasma etching parameters, the material is removed over an area larger than the AFM tip size. Notably, the hardness of the material surrounding the removal zone is significantly reduced, enabling it to be scratched with a silicon tip. These findings open a promising pathway for improving the machinability of diamonds in future device applications. Full article

Fast, spark-free detection of hydrogen leaks is indispensable for large-scale hydrogen deployment, yet electronic sensors remain power-intensive and prone to cross-talk. Optical schemes based on surface plasmons enable remote read-out, but single-metal devices offer either weak H2 affinity or poor plasmonic quality. Here we employ full-wave finite-difference time-domain (FDTD) simulations to map the hydrogen response of nanohole arrays (NAs) that can be mass-produced by colloidal lithography. Square lattices of 200 nm holes etched into 100 nm films of Pd, Mg, Ti, V, or Zr expose an intrinsic trade-off: Pd maintains sharp extraordinary optical transmission modes but shifts by only 28 nm upon hydriding, whereas Mg undergoes a large dielectric transition that extinguishes its resonance. Vertical pairing of a hydride-forming layer with a noble metal plasmonic cap overcomes this limitation. A Mg/Pd bilayer preserves all modes and red-shifts by 94 nm, while the predicted optimum Ag (60 nm)/Mg (40 nm) stack delivers a 163 nm shift with an 83 nm linewidth, yielding a figure of merit of 1.96—surpassing the best plasmonic hydrogen sensors reported to date. Continuous-film geometry suppresses mechanical degradation, and the design rules—noble-metal plasmon generator, buried hydride layer, and thickness tuning—are general. This study charts a scalable route to remote, sub-ppm, optical hydrogen sensors compatible with a carbon-neutral energy infrastructure. Full article

This study addresses the efficiency and cost challenges of hydrogen evolution reaction (HER) catalysts in the context of carbon neutrality strategies by employing a synergistic approach that combines cation vacancy anchoring and transition metal doping on two-dimensional (2D) MXenes. Using an in situ LiF/HCl etching process, the aluminum layers in Ti₃AlC₂ were precisely removed, resulting in a few-layer Ti₃C₂T_x MXene with an increased interlayer spacing of 12.3 Å. Doping with the transition metals Fe, Co, Ni, and Cu demonstrated that Fe@Ti₃C₂ provided the optimal HER performance, characterized by an overpotential (η₁₀) of 81 mV at 10 mA cm⁻², a low Tafel slope of 33.03 mV dec⁻¹, and the lowest charge transfer resistance (R_ct = 5.6 Ω cm²). Mechanistic investigations revealed that Fe’s 3d⁶ electrons induce an upward shift in the d-band center of MXene, improving hydrogen adsorption free energy and reducing lattice distortion. This research lays a solid foundation for the design of non-precious metal catalysts using MXenes and highlights future avenues in bimetallic synergy and scalability. Full article

This study synthesized boron-doped diamond (BDD) thin films using hot-filament chemical vapor deposition at different carbon-to-hydrogen (C/H) ratios in the range of 0.3–0.9%. The C/H ratio influence, a key parameter controlling the balance between diamond growth and hydrogen-assisted etching, was systematically investigated while maintaining other deposition parameters constant. Microstructural and electrochemical analysis revealed that increasing the C/H ratio from 0.3% to 0.7% led to a reduction in sp2-bonded carbon and enhanced the crystallinity of the diamond films. The improved conductivity under these conditions can be attributed to effective substitutional boron doping. Notably, the film deposited at a C/H ratio of 0.7% exhibited the highest electrical conductivity and the widest electrochemical potential window (2.88 V), thereby indicating excellent electrochemical stability. By contrast, at a C/H ratio of 0.9%, the excessively supplied carbon degraded the film quality and electrical and electrochemical performance, which was owing to the increased formation of sp² carbon. In addition, this led to an elevated background current and a narrowed potential window. These results reveal that precise control of the C/H ratio is critical for optimizing the BDD electrode performance. Therefore, a C/H ratio of 0.7% provides the most favorable conditions for applications in advanced oxidation processes. Full article

The integration of thick homoepitaxial layers on silicon carbide (SiC) substrates is critical for enabling high-voltage power devices, yet it remains challenged by substrate surface quality and wafer geometry evolution. This study investigates the relationship between substrate preparation—particularly chemical mechanical planarization (CMP)—and the impact on wafer bow, total thickness variation (TTV), local thickness variation (LTV), and defect propagation during epitaxial growth. Seven 150 mm, 4° off-axis, prime-grade 4H-SiC substrates from a single ingot were processed under high-volume manufacturing (HVM) conditions and grown with epitaxial layers ranging from 12 μm to 100 μm. Metrology revealed a strong correlation between increasing epitaxial thickness and geometric deformation, especially beyond 31 μm. Despite initial surface scratches from CMP, hydrogen etching and buffer layer deposition significantly mitigated scratch propagation, as confirmed through defect mapping and SEM/FIB analysis. These findings provide a deeper understanding of the substrate-to-epitaxy integration process and offer pathways to improve manufacturability and yield in thick-epilayer SiC device fabrication. Full article

To achieve efficient preparation of microfine tool electrodes with a large aspect ratio, a bipolar pulse vertical liquid membrane electrochemical etching technique was proposed. The difference in current density distribution on the surface of tungsten rods under single-ended and double-ended vertical liquid membrane methods was analyzed using COMSOL software. The effects of negative voltage and pulse width on the distribution of electrolytic products and electrode preparation were investigated. It was found that when a large number of hydrogen bubbles were generated on the surface of the electrode, the electrode lost the protection of the diffusion layer, and the length was drastically shortened. When the pulse width was large, the electrode surface was covered with a coating layer of insoluble electrolysis product, and the shortening of electrode length was suppressed. Subsequently, the effects of forward voltage and bias on electrode preparation were investigated for large pulse widths. The optimal parameters are as follows: electrolyte concentration of 0.5 M, forward voltage of 4 V, negative voltage of −2 V, pulse period of 50 microseconds, and pulse width of 40 microseconds. Finally, the tool electrode with an average diameter of about 23.8 μm and an aspect ratio of 91.2 was prepared. Full article