Search Results (567)

The catalytic hydrogenation of carbon dioxide (CO₂) represents a transformative approach for reducing greenhouse gas emissions while producing sustainable fuels and chemicals, with ethanol being particularly promising due to its compatibility with existing energy infrastructure. Despite significant progress in converting CO₂ to C₁ products (e.g., methane, methanol), selective synthesis of C₂₊ compounds like ethanol remains challenging because of competing reaction pathways and byproduct formation. Recent advances in thermo-catalytic CO₂ hydrogenation have explored diverse catalyst systems including noble metals (Rh, Pd, Au, Ir, Pt) and non-noble metals (Co, Cu, Fe), supported on zeolites, metal oxides, perovskites, silica, metal–organic frameworks, and carbon-based materials. These studies reveal that catalytic performance hinges on the synergistic effects of multimetallic sites, tailored support properties and controlled reaction micro-environments to optimize CO₂ activation, controlled hydrogenation and C−C coupling. Mechanistic insights highlight the critical balance between CO₂ reduction steps and selective C−C bond formation, supported by thermodynamic analysis, advanced characterization techniques and theoretical calculations. However, challenges persist, such as low ethanol yields and undesired byproducts, necessitating innovative catalyst designs and optimized reactor configurations. Future efforts must integrate computational modeling, in situ/operando studies, and renewable hydrogen sources to advance scalable and economically viable processes. This review consolidates key findings, proposes potential reaction mechanisms, and outlines strategies for designing high-efficiency catalysts, ultimately providing reference for industrial application of CO₂-to-ethanol technologies. Full article

The bioinspired superhydrophobic surfaces have demonstrated many fascinating performances in fields such as self-cleaning, anti-corrosion, anti-icing, energy-harvesting devices, and antibacterial coatings. However, developing a low-cost, feasible, and scalable production approach to fabricate robust superhydrophobic surfaces has remained one of the main challenges in the past decades. In this paper, we propose an uncommon method for the fabrication of a durable superhydrophobic coating on the surface of the glass slide (GS). By utilizing the screen printing method and high-temperature curing, the epoxy resin grid (ERG) coating was uniformly and densely loaded on the surface of GS (ERG@GS). Subsequently, the hydrophobic silica (H-SiO₂) was deposited on the surface of ERG@GS by the impregnation method, thereby obtaining a superhydrophobic surface (H-SiO₂@ERG@GS). It is demonstrated that the micro-grooves in ERG can provide a large specific surface area for the deposition of low surface energy materials, while the micro-columns can offer excellent protection for the superhydrophobic coating when it is subjected to mechanical wear. It is important to note that micro-columns, micro-grooves, and nano H-SiO₂ jointly form the micro–nano structure, providing a uniform and robust rough structure for the superhydrophobic surface. Therefore, the combination of a micro–nano rough structure, low surface energy material, and air cushion effect endow the material with excellent durability and superhydrophobic property. The results show that H-SiO₂@ERG@GS possesses excellent self-cleaning property, mechanical durability, and chemical stability, indicating that this preparation method of the robust superhydrophobic coating has significant practical application value. Full article

The structural dependence of self-propelled motion in micro/nanomotors is essential for effectively predicting and controlling their dynamic behaviors. In this study, platinum–silica (Pt-SiO₂) micromotors, with structures ranging from spherical Janus to dimer configurations, are fabricated through conventional template-assisted deposition, followed by annealing. These structures are used to investigate how geometry influences motion. Our results demonstrate that the architecture of the Pt-SiO₂ micromotor strongly affects its propulsion mode and trajectory in solution. When immersed in a hydrogen peroxide (H₂O₂) solution, spherical Janus Pt-SiO₂ micromotors exhibit quasi-linear motion, driven by the Pt side (Pt pushing). In contrast, dimeric structures and intermediate forms varied from Janus to dimer display quasi-circular trajectories with continuously changing directions, characteristic of Pt-dragging motion. We reveal that these distinct propulsion behaviors stem from differences in the spatial distribution of Pt on the SiO₂ sphere surface. Variations in Pt distribution alter the exposed silica surface area—rich in hydroxyl groups—which modulates the driving force and causes the resultant force acting on the micromotor to deviate from its mass center axis (or the axis connecting the mass centers of the Pt component and silica sphere), thereby inducing circular motion. This study offers a versatile strategy for fabricating Pt-SiO₂ micromotors with tailored structures and advances the fundamental understanding of structure-dependent self-propulsion mechanisms. Full article

Portuguese ceramic tile (azulejo) production has evolved significantly since its beginnings in the 16th century. While historic tiles reflect well-established traditional techniques and styles, modern and contemporary works began to explore new aesthetic and material possibilities, introducing textures, surface effects, and experimental approaches that challenge conventional conservation methods. This study examines a contemporary Portuguese tile panel dated from 1987, featuring decorative effect glazes with crater and crazing textures, which were characterized and reproduced. Analytical techniques, including optical microscopy, micro-X-ray fluorescence spectrometry, and Raman spectroscopy in microscopic mode, were employed to characterize material composition and formation mechanisms. Results showed that the crater-effect glazes were achieved with a silica-rich glaze recipe with MnO₂ and ZrO₂. The crazing effect developed in regions where unmelted crystalline silica induced internal stresses within a lead-silicate glaze, contributing to localized degradation. Experimental reproductions of the glazes, guided by analytical data, were conducted to better understand their formation and inform conservation strategies. The results provide essential insights for the technical assessment, documentation, and preservation of contemporary ceramic artworks featuring decorative effect glazes and contribute to the broader field of cultural heritage conservation. Full article

The main goal of the research was to determine whether it was possible to reduce the cement content in mortar without compromising strength parameters. This is crucial for reducing the carbon footprint associated with cement production. In this article, the authors presented the results of research evaluating the effect of selected mineral additives on the strength properties of standard mortar after 7, 28, and 56 days of curing. The analysis of the effect of mineral additives was performed for CEM II and CEM III cements and seven selected mineral additives: white microsilica, Mikrosill+ microsilica, limestone powder, glass powder, glass granulate, and basalt powder. The study considered the use of mineral additives at 10% and 20% by weight of cement as a substitute. During the analysis of the test results, it was observed that the use of white microsilica and Mikrosill+ at 10% and 20% increased strength by approximately 50% compared to the reference samples. Importantly, strength was 50% higher with a 20% reduction in cement content. A positive effect of additives on strength parameters was observed only for CEMII cement. In the case of CEMIII cement, mineral additives reduce compressive strength. Full article

Currently, in hydrotechnical engineering, such as oil and gas platform construction, floating docks, and other floating structures, the need to develop new lightweight composite building materials is becoming an important problem. Expanded clay concrete (ECC) is the most common lightweight concrete option for floating structures. The aim of this study is to develop effective composite ECC with improved properties and a coefficient of structural quality (CCQ). To improve the properties of ECC, the following formulation and technological techniques were additionally applied: reinforcement of lightweight expanded clay aggregate by pre-treatment in cement paste (CP-LECA) with the addition of microsilica (MS) and dispersed reinforcement with basalt fiber (BF). An experimental study examined the effect of the proposed formulation and technological techniques on the density and cone slump of fresh ECC and the density, compressive and flexural strength, and water absorption of hardened ECC. A SEM analysis was conducted. The optimal parameters for LECA pretreatment were determined. These parameters are achieved by treating LECA grains in a cement paste with 10% MS and using dispersed reinforcement parameters of 0.75% BF. The best combination of CP-LECA10MS-0.75BF provides increases in compressive and flexural strength of up to 50% and 61.7%, respectively, and a reduction in water absorption of up to 32.8%. The CCQ increases to 44.4%. If the ECC meets the design requirements, it can be used in hydraulic engineering for floating structures. Full article

Silica-based multifunctional coatings hold great promise for applications in optical devices, lenses, and solar panels. Herein, we report a facile, low-temperature route to integrate super-hydrophobicity with high transparency and low haze. By precisely controlling particle gradation and applying fluorine passivation, a multi-scale structure with micro-scale uniformity and nano-scale asperity was constructed. This unique architecture, combined with low surface energy, effectively reduces light scattering and enhances air trapping. Consequently, the coated glass achieves a high optical transmittance of 95.24% with a low haze of 0.97%, alongside a water contact angle of 153° and a sliding angle of 3°. The coating also exhibits distinct anti-reflection (an improvement of ~5.0% relative to the bare substrate) and self-cleaning properties. Furthermore, it demonstrates impressive robustness and durability, withstanding extreme conditions including cryogenic temperatures (−50 °C), hygrothermal environments, and long-term outdoor exposure. This work demonstrates the versatile potential of our strategy for fabricating highly transparent and superhydrophobic surfaces. Full article

The development of the ceramic industry requires the creation of new innovative products with improved properties. Given the growing demand for high-quality finishing materials and the limited availability of traditional raw materials, the search for more efficient technologies for porcelain stoneware production is a relevant challenge. The aim of this study was to develop porcelain stoneware with enhanced performance characteristics. The research presents the results of a study aimed at improving the production technology of porcelain stoneware in Kazakhstan using local raw materials and microsilica. The raw materials from the Turkestan region were examined for their suitability for porcelain stoneware production. The influence of technological parameters (firing temperature, particle size) on the properties of porcelain stoneware was studied. New ceramic compositions with various microsilica contents, a by-product of silicon production, were investigated. Different compositions with varying raw material mixtures and microsilica content were prepared and fired at temperatures of 1100, 1150, and 1200 °C. The optimization of process parameters for producing porcelain stoneware in different compositions showed the degree of yield dependence on firing temperature and time as well as the effect of microsilica content. The temperature, time, and visually determined parameters at which different yield values were achieved were highlighted in different colors. The results showed that changes in the mixture composition and sintering temperature affect the quality of ceramic tiles. The final experimental conclusions demonstrated that the production of ceramic tiles containing up to 3% microsilica at a firing temperature of 1200 °C. The addition of microsilica increases the flexural strength of porcelain stoneware to 41 MPa (exceeding the standard), reduces water absorption to 0.023%, increases frost resistance to 107 cycles, and also enhances shrinkage. These findings open new prospects for the development of the domestic ceramic industry, the expansion of the product range, and the resolution of environmental issues. Full article

Metal casting industries generate substantial quantities of spent foundry sand (SFS), a silica- and alumina-rich by-product that remains underutilized, with recycling rates below 30%. This study explores the incorporation of aluminum SFS as a secondary raw material in aluminosilicate refractory castables to promote sustainable waste valorization and circular economy practices. Refractory mixtures were prepared with bauxite, kyanite, calcium aluminate cement, microsilica, and flint clay, where fine flint clay was partially replaced by aluminum SFS at 0, 5, 10, and 15 wt.%. Samples were dried at 120 °C and sintered at 850, 1050, and 1400 °C for 4 h. Bulk density, apparent porosity, cold crushing strength, and modulus of rupture were measured, while phase and microstructural evolution were examined by XRD and SEM. The 5 wt.% SFS-containing castable exhibited comparable strength and density to the reference formulation, attributed to the formation of secondary mullite and anorthite that improved matrix cohesion. Higher SFS contents (10–15 wt.%) increased porosity and reduced strength due to excess SiO₂ and silica polymorphism. These results demonstrate the technical feasibility of using aluminum SFS in refractory castables, contributing to resource conservation, waste reduction, and the development of environmentally sustainable refractory materials for high-temperature applications. Full article

An optical levitation system in a vacuum is an efficient system to investigate the dynamics of isolated micro- and nanoparticles. However, the motion and stability of the trapped particles in this system can be affected by the internal temperature, which remains a challenge to measure. Conventional methods are constrained by material specificity or lack the capability for direct temperature measurement. Here, we demonstrate the application of Raman thermometry for non-contact temperature detection of an optically levitated fused silica sphere in vacuum. In addition, the experimental results reveal a linear increase in particle temperature with laser power, consistent with photothermal theory. The integration of Raman thermometry with the optical levitation system enables high-precision thermal sensing at the microscale, offering significant potential for applications in precision metrology and fundamental physics. Full article

The development of oil–water separation materials that combine high separation efficiency, robust mechanical properties, and environmental degradability remains a significant challenge. This study presents a novel degradable and superhydrophobic porous material fabricated via a multi-step process. A porous foam was first synthesized from degradable poly(ε-caprolactone-co-2-ethylhexyl acrylate) using a high internal phase emulsion templating technique. The foam was subsequently modified through in situ silica (SiO₂) deposition via a sol–gel process, followed by grafting with hydrophobic hexadecyltrimethoxysilane (HDTMS) to produce the final oil–water separation porous materials. Various characterization results showed that the optimized material featured a hierarchical pore structure in micro scales and the porosity of the foam remained ~90% even after the 2-step modification. Mechanical tests indicate that the modified material exhibited significantly enhanced compressive strength and the water contact angle measurements revealed a superhydrophobic surface with a value of approximately 156°. The prepared material demonstrated excellent oil/water separation performance with notable absorption capacities ranging from 4.11 to 4.90 g/g for oils with different viscosity. Additionally, the porous material exhibited exceptional cyclic stability, maintaining over 90% absorption capacity after 10 absorption-desorption cycles. Moreover, the prepared material achieved a mass loss of approximately 30% within the first 3 days under alkaline hydrolysis conditions (pH 12, 25 °C), which further escalated to ~70% degradation within four weeks. The current work establishes a feasible strategy for developing sustainable, high-performance oil–water separation materials through rational structural design and surface engineering. Full article

Injection composites based on mineral binders are widely used for soil stabilization, using jet grouting technology to solve various geotechnical problems. Cement, which contains toxic components and worsens the ecology of the environment, is typically the main mineral component used to manufacture injection composites. Reducing cement consumption in the production of building materials is currently of great importance. This study developed highly effective, environmentally friendly injection composites for soil stabilization based on three mineral components: Portland cement, fly ash (FA), and microsilica (MS). FA was introduced into the composites as a partial Portland cement substitute, in amounts ranging from 5 to 50% in 5% increments. The properties of fresh and hardened composites, including the density, flow rate, water separation, compressive strength at 7 and 28 days, and the structure and phase composition of the composites, were studied. The inclusion of FA in the composition of composites contributes to a decrease in density by 16.9%, from 1.89 g/cm³ to 1.57 g/cm³, and cone spread by 9%, from 30.1 cm to 27.4 cm, and an increase in water bleeding by 91.4%, from 3.5% to 6.7%, respectively. Based on the results of the experimental studies, the most effective dosage of FA was determined, which amounted to 20%. An increase in compressive strength was recorded for composites at the age of 7 days of 8.3%, from 33.6 MPa to 36.4 MPa, and for compressive strength at the age of 28 days of 9.4%, from 41.3 MPa to 45.2 MPa, respectively. SEM and XRD analysis results show that including FA and MS promotes the formation of additional calcium hydrosilicates (CSH) and the development of a compact and organized composite structure. The developed composites with FA contents of up to 50% exhibit the required properties and can be used for their intended purpose in real-world construction for soil stabilization. Full article

Granite wet edge finishing is widely adopted to improve surface durability and aesthetics while reducing dust dispersion compared to dry processes. However, even under flooded lubrication, fine particles (FP, 0.5–20 µm) and ultrafine particles (UFP, <100 nm) containing crystalline silica are emitted, posing health risks such as silicosis and pulmonary or cardiovascular diseases. This study investigates particle emissions during CNC edge finishing of black (containing 0% quartz) and white granites (containing 41% quartz) using two industrially relevant profile tools: Half-Beveled (HB) and Ogee (OG). A full factorial design evaluated the effects of granite type, tool geometry, abrasive grit size, spindle speed, and feed rate. Particle concentrations were measured with Aerodynamic and Scanning Mobility Particle Sizers. Results show that spindle speed (N) is the dominant factor, explaining up to 92% of variance in emissions, whereas feed rate (V_f) played a minor role. Tool geometry had a pronounced effect on UFP release: sharp-edged geometries (HB) promoted localized micro-fracturing and higher emissions, while curved geometries (OG) distributed stresses and reduced particle detachment. White granite generated higher mass emissions due to its high quartz content, while black granite exhibited more stable emission behavior. These findings highlight the dual necessity of optimizing cutting kinematics and selecting appropriate tool profiles to balance surface quality and occupational health in granite processing. Full article

Autoclaved aerated concrete has been widely used in recent years and has gradually begun to replace classical concrete systems. In this paper, the optimal compositions of D500 and D600 autoclaved aerated concrete, which are widely used as structural and insulation materials with low cement consumption, were determined using mathematical regression models. The data obtained from the experimental results were converted into a dataset in the Matlab program, and optimization was performed to achieve maximum strength and minimum cement consumption. This study identified the stages of the process for developing and adjusting the properties of an efficient autoclaved aerated concrete composition using a cement matrix with the addition of various microfillers. The amount of components and mineral and chemical additives in the composition of autoclaved aerated concrete was optimized. With the application of carbonate filler and microsilica, aerated concrete compositions with an average density of 500 and 600 kg/m³ and a strength of 1.1–2.24 MPa were developed, which correspond to the D500 brand in terms of density and D600 to B1–B2 in terms of strength class. As a result of this study, it was determined that despite a 16.4% decrease in cement consumption when various microfillers were added to the cement matrix, the compressive strength of the D600 brand aerated concrete at 7 days was 1.35 MPa, and at 28 days, it was 2.25 MPa. Since the prepared aerated concrete composition is more efficient than traditional porous concrete, it can be widely used in the production of lightweight structures and insulation blocks. This research supports the Sustainable Development Goals (SDGs), particularly Goal 9 (Industry, Innovation and Infrastructure), Goal 11 (Sustainable Cities and Communities), and Goal 12 (Responsible Consumption and Production), by promoting the development of resource-efficient and environmentally sustainable building materials. Full article

The salt lake and saline–alkali soil regions of high plateaus are characterized by widespread Alkali–silica reactive (ASR) aggregates, which severely threaten the durability of constructed infrastructure, including railways, highways, and buildings. The research systematically investigates the uniaxial compressive mechanical behavior and stress–strain constitutive relationship of high-performance concrete (HPC) with ASR mitigation measures (performance grades C40, C45, C50, and C60) after ten years of immersion in a standard alkali solution. A corresponding three-dimensional random aggregate mesoscopic concrete model was developed, and mesomechanical numerical simulations were performed to explore the failure process, failure patterns, and underlying mesoscopic damage mechanisms of the specimens. Results show that While the uniaxial compressive strength and elastic modulus of HPC show an expected increase with the concrete strength grade following long-term alkali exposure, both properties demonstrate a clear decline as the equivalent alkali content rises. Comparing and analyzing the C50 specimens of different admixtures, it was found that the air-entraining agent provided the most effective ASR suppression and obtained the highest uniaxial compressive strength compared with the rust inhibitor. By normalizing the stress–strain curves, the long-term constitutive behavior of HPC under alkali corrosion was summarized. Furthermore, mesoscopic model visualizations indicate that cracks initially appear in the mortar and gradually propagate inward during loading, leading to compressive failure characterized by diagonal cracks. Tracking the mesoscopic damage patterns within the specimens demonstrates that microcracks originate in the mortar and progressively extend through aggregates, revealing the underlying micro-damage mechanism. By studying the SEM-EDS images, it is found that HPC with a specific mix ratio designed in this paper can effectively inhibit the ASR effect, and it still has good corrosion resistance in long-term alkali immersion. Full article