This review examines hydrogenated amorphous carbon coatings with silicon and oxygen (a-C:H:SiOx), and focuses on synthesis methods, along with coatings structural characteristics, and multifunctional properties. The incorporation of silicon into diamond-like carbon matrix significantly reduces internal stress, enhances thermal stability and mechanical performance. Adding SiOx allows depositing thicker and better-adhered coatings. Various plasma-assisted chemical vapor deposition techniques, including direct current, radio frequency, hot filament plasma-enhanced chemical vapor deposition, and closed drift ion beam sources are evaluated for their effects on coatings morphology, phase composition, and functional behavior. Tribological properties of a-C:H:SiOx coatings with lower friction coefficient and reduced wear rate are discussed from the SiOx concentration and deposition parameters perspective. Anti-corrosion performance is substantially improved with SiOx concentration, attributed to decreased porosity and enhanced surface wear resistance. Optical studies demonstrate tunable refractive index and high transparency across the visible and infrared spectra. These properties make a-C:H:SiOx coatings promising candidates for protective and anti-reflective applications on various substrates, including stainless steel, silicon and germanium. This review highlights how the combined effects of SiOx concentration and deposition process optimization affect the properties and performance of a-C:H:SiOx coatings, advancing their applications in industrial, biomedical, and optical fields.
Synthetic diamond, prized for its exceptional thermal conductivity, is a leading candidate for thermal management. In practice, it is integrated with semiconductor or metal substrates to create efficient heat-dissipation pathways, making the thermal conductance of the bonding interface critical in modern electronics. In this review, recent advances in bonding technology and thermal conductance of synthetic diamond have been summarized and elucidated to reveal the underlying mechanisms that influence its interfacial thermal conductivity. Firstly, the structural and thermal properties of diamond are summarized; then, the applications of existing theoretical models for thermal conductance of synthetic diamond and other materials are discussed; thirdly, the interfacial microstructures between synthetic diamond and typical semiconductors such as Si, GaN, and β-Ga2O3 are examined in order to bridge the relationship between integration process and the interfacial thermal conductance of diamond-based components; finally, the formation of interfacial carbides on synthetic diamond has been reviewed in an attempt to achieve a deep understanding on the bonding microstructure and the interfacial thermal conductance of synthetic diamond. Thus, this review aims to link the integration processes, the interfacial microstructure, and interfacial thermal conductance, and hence point out the future directions and challenges in diamond interfacial thermal transport regulation.
Tin dioxide is a semiconductor, valued for its unique combination of electrical, optical, chemical, and magnetic properties, including superior electrochemical stability, durability, and high electrical conductivity. These attributes support a wide range of applications and have driven extensive research into the development of advanced SnO2-based materials. Among the various methods used to synthesize tin dioxide layers, electrodeposition has attracted particular attention due to its simplicity, cost-effectiveness, and scalability. However, to date, no comprehensive review has systematically examined the electrochemical deposition conditions of SnO2, which are reported in the literature in diverse and often inconsistent forms. Furthermore, a systematic analysis of the thermodynamic and kinetic principles underlying this process remains almost lacking. Accordingly, this review surveys recent advances in the electrodeposition of nanostructured tin dioxide and provides a critical, integrative analysis aimed at clarifying unresolved mechanistic issues and addressing longstanding challenges in the field. The first section outlines the fundamental principles governing SnO2 electrodeposition, with emphasis on the underlying mechanisms that remain incompletely understood. The next sections examine the influence of deposition parameters on the morphology, composition, and functional properties of the resulting oxide layers. The paper concludes with representative examples demonstrating the diverse applications of electrodeposited SnO2.
Small-molecule adsorption dominates many interfacial processes such as solid–gas heterogeneous catalysis, electrochemistry, and corrosion, with the interfacial binding strength, the adsorption energy, controlled by the electronic and geometric properties of both molecules and substrates. In past years, numerous physical models and descriptors have been proposed to determine the adsorption energy. These models offer valuable insights into the trends of adsorption energy from different perspectives. Understanding the differences and intrinsic connections among these models is conducive to developing new, universally applicable, and effective descriptors for adsorption energies. We systematically review and compare the potential descriptors of adsorption energies across transition metals, alloys, and oxide systems, focusing on the underlying physical pictures. By elaborating on the physical correlations among these descriptors, we show that the electronic descriptor ψ of the analytic-parameter model (APM), based on the intrinsic properties of the surface atoms—the valence electron number Sv and the electronegativity χ, provides a promising way for the quantitative description of the adsorption energy. More importantly, APM greatly enhances the practicality of previous models by simplifying the complex physical picture into easily accessible parameters.
Van der Waals (vdW) complexes, surfaces and interfaces are a current ‘hot-topic’ in surface science. Their importance for surfaces, layered structures and interfaces stems from weak interlayer binding which allows strain to be applied relatively easily, particularly when compared to more rigid covalently bound systems, and used to tune the behaviour and properties of the material. Most ab-initio studies of extended vdW systems focus on the geometric (layering) and electronic properties, including fundamental quantities like the work function. Far fewer investigations highlight the thermal properties of these layers, including in many cases even the most basic phonon characterization.In this article the utility of dynamical studies of layered and interfacial vdW systems will be highlighted. The weak coupling between the layers of a vdW interface enables efficient coupling between modes; however, ‘veering’, the effects of the orientation of subsequent layers and strain engineering can limit the redistribution of vibrational energy. This article will discuss some case studies of these effects and discuss their limitations; in particular, examples involving graphene, black phosphorus and hBN will be included together with a discussion of systematic design strategies which have been currently seen to optimize thermal energy transfer in these materials.
Laser Surface Texturing (LST) is a precise and versatile method for modifying the surface of materials to improve their functional properties in various industrial applications. This review highlights the most important achievements of LST, focusing on its ability to tailor surface properties such as wettability, mechanical properties, corrosion resistance, and biocompatibility. The main results show that LST is a sustainable and effective alternative to traditional surface modification methods, reducing the need for chemical treatment and excess material use. The review also describes the transformative potential of LST for future innovations in materials science and engineering, while pointing out current limitations and areas for further research.
Recent progress in the investigation of the role of charge on semiconductor surfaces has been reviewed. The review begins with contributions to the calculations and data analysis. This new procedure includes the application of the Laplace correction method in ab initio calculations. The new analysis incorporates the projected density of states (PDOS) and Crystal Orbital Hamilton Population (COHP) and averaging of the electric potential to derive its smoothed long-range variation in space, parallel to plots of real-space band profiles. These methods include the discovery of spurious Coulomb interactions between the separated subsystems, which have different Fermi levels. The ab initio use of a single Fermi level may cause incorrect electron redistribution, an artificial charge of the separated subsystems, and spurious interactions. The quantum nature of the charge influence on semiconductor surfaces stems from the delocalization of electrons, which leads to the emergence of an external surface dipole, which is important for determining the workfunction and plays a role in the proposed thermalization of the adsorbate via electron tunnelling. The kinetic energy loss of the adsorbate (i.e., its thermalization) occurs via the tunnelling of electrons into the solid interior owing to the strong external dipole electric field. The other charge-related quantum effect is related to the known subsurface dipole charge layer. New simulations of the variation of the electric potential within a slab model show the band bending at the semiconductor surfaces that induces the Surface States Stark Effect (SSSE) and misrepresents the surface band diagrams. This underlines the role of pinning the Fermi level and its connection to subsurface dipoles. The charge balance determines the occupation of the surface states and the symmetry and periodicity of surface reconstructions. The occupation of the surface states may be changed by adsorption, both by the new donated electrons and by the emergence of new quantum states. As their numbers could be different, this leads to a jump in the Fermi level pinning and adsorption energy at selected critical coverages. Thus, the Fermi level becomes free, subsurface dipoles disappear, and bands become flat. The adsorption energy jump may reach several electronvolts, which may change the adsorbate equilibrium vapor pressure by several orders of magnitude. Such a flat-band state is likely to occur during the growth of crystals that fall within such pressure intervals. Additionally, quantum effects may include resonant bonding involving several states, which leads to fractional occupation. The existence of resonant states resolves the existing inconsistencies between bonding and lattice symmetry in nitrides. This effect is observed not only at the stability points but also at the activated complex position in the diffusion jumps. Additionally, the effects include the quantum state energy increase during the jump, shifting them to the vicinity of the Fermi level or even above. According to quantum statistics, the state occupation is reduced, which affects the energy barrier for diffusion. Thus, these results demonstrate the role of quantum effects in the charge control of semiconductor surfaces.
Under the conditions of low-temperature plasma, this work proposes a new controllable express method for transformation of nano-sized Bi films into semiconducting Bi2O3 films in a modified plasma microreactor with GaAs photosensitive plate. The transformation mechanism of Bi films depends on the current density, charge transferred, and exposure time. From the mechanism of formation of Bi2O3 semiconductor film, we have established: 1) that this is a surface process that moves deeper into the Bi film when the operation parameters change; 2) the band gap value of the Bi2O3 semiconductor film obtained from Tauc’s plot is Eg ≈ 3 eV; 3) that this process is provided by the combined kinetic energy of electrons and oxygen ions.
The deposition of functional coatings by Physical Vapor Deposition (PVD) on open-cell 3D foams represents a burgeoning area within material science, especially for electrochemical applications. Due to the novelty of this field and the unique geometry of the foams, the use of PVD on these substrates is a breakthrough innovation for functional material development. However, several challenges remain, e.g. understanding film growth mechanisms on foams, their impact on electrochemical processes, and optimizing the performance of coated foams across various applications through an understanding of the electrochemical phenomena occurring inside and on the surface of the coated foams. This review provides the first thorough overview of the current state-of-the-art in this area and suggests innovative solutions to the challenges encountered. It reports the various properties of films on foams reported in literature, compares the electrochemical performance of PVD-coated foams for Oxygen Evolution Reaction (OER)/Hydrogen Evolution Reaction (HER) catalysis, and energy storage applications, and discusses the mechanisms that explain their performance. Additionally, the review offers an analysis of existing research and introduces a novel numerical methodology, integrating Direct Simulation Monte Carlo (DSMC), Particle-in-Cell Monte Carlo (PICMC), and kinetic Monte Carlo (kMC) techniques to facilitate the characterization of coatings within the foams.
As a prominent connection technique in modern industry, adhesive technology provides advantages unattainable by conventional methods. It is widely applied in diverse industries, including electronics, medical devices, automotive, and aerospace. Laser surface texturing facilitates the high-precision fabrication of micro/nano-scale surface features, enabling simultaneous control over surface morphology, roughness, and contact angle, thereby enhancing adhesive joint strength. This review focuses on the interfacial bonding strength enhancement achieved via laser texturing technology. We systematically analyze the laser sources, operational classifications, and underlying material interaction mechanisms of laser texturing. Incorporating biomimetic science, this review synthesizes recent advances in texture-induced interface regulation and bonding reinforcement mechanisms. Finally, we discuss the persisting challenges and emerging research directions in laser-texturing-enabled bonding strength improvement.
The growing global demand for energy has positioned photoelectrochemical water splitting as a highly promising method for producing gaseous hydrogen. For this process to be sufficiently effective, the use of semiconductor electrodes with specific properties is required. Among the already proposed semiconductors for this purpose, iron oxides are particularly promising. Therefore, this review paper aims to discuss recent advancements in the fabrication of nanostructured iron oxides through an anodic oxidation of metallic iron and, above all, the possibilities of utilizing these materials in photoelectrochemical systems. The first part of the paper discusses the procedure of Fe anodization with particular emphasis on the correlation between synthesis conditions and the morphology, composition, and properties of the obtained oxide layers. The most important part of the paper is a detailed discussion of the applications of anodically generated iron oxides in photoelectrochemical systems. Strategies for modifying Fe2O3 layers to enhance their photoelectrochemical properties have also been presented. Finally, examples of other applications of anodic iron oxides, as well as challenges and perspectives of the anodic oxidation method, were described.
This review explores the significance of residual stresses determination in the performance and durability of materials modified by plasma electrolytic oxidation (PEO). The study highlights how residual stresses can critically affect mechanical properties and the fatigue behavior of PEO-coated components, based on different aluminum alloys, where a direct correlation between residual stress levels and fatigue performance has been established. The review also discusses residual stresses and their implications in magnesium and titanium-based materials. In the former, residual stresses have been shown to influence not only mechanical properties but also corrosion resistance, making the materials attractive for lightweight structures and biomedical applications. Overall, the review highlights the potency of the sin2Ψ method using X-ray diffraction for non-destructive measurement of residual stresses in PEO coatings. While this technique has gained popularity due to its relative simplicity, its application can be limited by measurement errors, particularly in multilayered microstructures, typical of PEO-coated samples. Therefore, advancements such as the extended sin2Ψ method, which allows for more localized sampling and analysis, are necessary for a comprehensive understanding of stress distributions. Future research directions are proposed, focusing on enhancing coating functionality and understanding the relationship between residual stresses and material properties across various substrates.
Recent advancements in ultrafast laser systems and high harmonic generation (HHG) techniques have enabled time-resolved photoemission spectroscopy on femtosecond timescales, opening up unprecedented opportunities to explore quantum materials in both time and momentum space. In this review, we present recent representative studies utilizing HHG-laser-based time- and angle resolved photoemission spectroscopy for a variety of quantum materials. We particularly highlight electron–phonon interactions and non-equilibrium dynamics in time and frequency domain, through which rich information about non-equilibrium electron–phonon couplings and related phenomena has been clearly revealed.
Wastewater represents a valuable resource, offering the potential for nutrient recovery that can address the increasing demand for natural resources while fostering a sustainable future. Forward osmosis (FO) membranes stand out as a promising technology for nutrient extraction due to their excellent ability to retain organic matter, their low energy requirements. However, several obstacles hinder the large-scale implementation of FO membranes for nutrient reclamation and enrichment. Overcoming challenges such as insufficient ion selectivity, suboptimal water flux, and a heightened vulnerability to fouling during extended use is essential for improving the performance and feasibility of FO systems. This review aims to provide a comprehensive evaluation of recent advancements in functionalized FO membranes specifically designed for nutrient recovery and enrichment in wastewater treatment. It critically examines the limitations of traditional FO membranes and explores innovative modification strategies, like surface modifications and nanomaterial integrations, that have been developed to enhance membrane performance. In addition, the review incorporates emerging yet underexplored directions, such as the integration of artificial intelligence (AI)-driven membrane design and the application of novel materials like covalent organic frameworks (COFs). By focusing on these aspects, this work offers valuable insights into the advancement of FO membrane technology for sustainable nutrient recovery.
Resolving the early-stage dynamics of exciton formation following non-resonant photoexcitation in time, energy, and momentum is quite challenging due to their inherently fast timescales and the proximity of the excitonic state to the bottom of the conduction band. In this study, by combining time- and angle-resolved photoemission spectroscopy with ab initio numerical simulations, we capture the timing of the early-stage exciton dynamics in energy and momentum, starting from the photoexcited population in the conduction band, progressing through the formation of free excitons, and ultimately leading to their trapping in lattice deformations. The chosen material is bismuth tri-iodide (BiI3), a layered semiconductor with a rich landscape of excitons in the electronic structure both in bulk and in monolayer form. The obtained results, providing a full characterization of the exciton formation, elucidate the early stages of the physical phenomena underlying the operation of the ultrafast semiconductor device.
To address the issue of corrosion damage to copper in printed circuit boards (PCBs), electronic components, and other precision parts, the application of superhydrophobic surface technology is utilized to enhance its corrosion resistance properties. In this study, a superhydrophobic CuO/Cu2O/CuCl composite surface was fabricated via a facile one-step chemical etching and modification process. The surface morphology was tailored by optimizing microstructural roughness, while the effects of etching time, etchant concentration, and modification duration on wettability were systematically investigated. Various characterization technologies, such as SEM, X-ray diffraction, and X-ray photoelectron spectroscopy, were utilized to examine surface morphologies, crystalline phases, chemical composition, and wettability. The engineered surface exhibited exceptional superhydrophobicity, with a contact angle (CA) of 161.4 ± 0.3° and a sliding angle (SA) below 3°. Electrochemical assessments revealed outstanding corrosion inhibition efficiency (99.98 %) in 3.5 wt% NaCl solution, corroborated by post-immersion corrosion morphology analysis. Furthermore, the coating demonstrated robust self-cleaning functionality and sustained superhydrophobicity for over 360 days under ambient conditions, highlighting its potential for real-world applications.
Energetic electromagnetic fields produce a variety of elementary excitations in solids that can strongly modify their primary photoemission spectra. Such is the plasmon excitation or pumping mechanism which, although indirect, is very efficient and hence may give rise to formation of plasmonic coherent states. In turn, these states may act as a source or sink of energy and momentum for escaping electrons. Starting from the model Hamiltonian approach we show that prepumped plasmonic bath of coherent states gives rise to ponderomotive potentials and Floquet electronic band structure that support multiple plasmon-induced electron emission or plasmoemission from metals. Theoretical description of multiple plasmoemission requires a nonperturbative approch which is here formulated by applying cumulant expansion and Volkov ansatz to the calculations of electron wavefunctions and emission rates. The calculations are performed in the standard length gauge as well as in the Pauli-transformed velocity gauge for electron-plasmon interaction. The applicability of two nonperturbative approaches to calculation of excitation amplitudes are examined in each gauge. They smoothly interpolate between the fully quantal first order Born approximation and semiclassical multiplasmon-induced electron excitation limit. This is illustrated on the example of plasmoemission from Floquet surface bands on Ag(111) from which this channel of electron yield has been detected. Our calculations indicate that even subsingle mode occupations of plasmonic coherent states can support multiplasmon electron emission from surface bands. A way of calibration of plasmonic coherent states is proposed.
We briefly review a few recent progresses of the ultrafast generation and detection of coherent phonons in various types of quantum materials. Both the shared properties and unique aspects of coherent phonons are addressed, followed by concrete examples, including some recent works from our group. Perspectives on the mechanism of coherent phonons are introduced, along with experimental details, tricks, and innovations. The main focus of this review is to reveal what one can obtain from the studies of coherent phonons, thus guiding the further investigations. Particularly, we show that various interactions among different degrees of freedom can be unveiled, telling the legends of the hidden secrets in many quantum materials. The content is intended to be intriguing to non-ultrafast spectroscopy experts as well.
Macroscopic friction is the result of the interplay of several processes occurring at different scales; an atom-scale description of the tribological interactions is then paramount for the explanation of the elementary phenomena at the basis of such processes, and finds immediate application in technological fields involving nanostructured devices. At the moment, there is no theory which tells us what is the friction coefficient given the atomic description of two surfaces in contact: it is measured experimentally or computationally case by case at specific environmental parameters and chemical composition of the moving surfaces. A general theory describing nanoscale friction is then desirable to reduce human effort, search time and material costs necessary to design new tribological materials with target response. We here provide a selective overview of theoretical and computational models which, from our perspective, may pave the avenue towards a unified theoretical framework of nanofriction. In this respect, we believe that the key aspect is to identify a novel mathematical formulation of friction based on its energetic aspects, i.e. energy dissipation, rather than its dynamical effects, i.e. hindering the relative motion of interacting surfaces. Ultimately, such avenue might lead to a way to predict the value of the friction coefficient of two surfaces in contact from the sole knowledge of the atom types and their arrangement, without the need to measure it in operative conditions: one of the biggest challenges in the field of nanotribology.
Semiconductor interfaces are at the heart of the functionality of many devices for opto-electronic applications. At these interfaces, the importance of ultrafast dynamics – processes that occur on sub-nanosecond timescales – has been long understood. While these ultrafast spectroscopic studies have revealed important information, there remains a rich array of physics that is hidden within sub-micrometer length scales when using spatially-averaged techniques. However, powerful tools that could access material dynamics in semiconductors simultaneously at ultrafast time- and sub-micrometer length scales are challenging to implement. Here, we review recent developments in time-resolved photoemission electron microscopy as a technique to study ultrafast electron dynamics at semiconductor interfaces at the nanoscale. In particular, we review recent work in traditional semiconductor interfaces and heterojunctions, low-dimensional materials, and semiconductors for photovoltaic applications.
