Design Of Materials Research Articles

Structural Engineering of Metal‐Organic Frameworks for Efficient CO2 Reduction Reaction

AbstractMetal‐organic framework (MOF) materials have attracted much attention due to their diverse topological structures, excellent adsorption capacity, and unique physicochemical properties, which hold great promise in catalytic CO2 reduction reaction (CO2RR). However, the original MOFs materials have disadvantages such as poor electrical conductivity, high diffusion barrier and limited accessible catalytic sites, which seriously limit their application in CO2RR. Therefore, many structural engineering strategies have been used to improve the CO2RR performance of the MOFs materials. In this review, we mainly review the four main structure engineering strategies, i. e. crystal engineering, 2D engineering, heterostructure engineering and MOF derivatives engineering, in enhancing the catalytic CO2RR performance of the MOFs. We hope that this review will not only provide insights for the rational design of efficient MOFs materials for the CO2RR, but also stimulate more research work in this field.

Crystal plane orientation-dependent surface atom diffusion in sub-10-nm Au nanocrystals.

Surface atom diffusion is a ubiquitous phenomenon in nanostructured metals with ultrahigh surface-to-volume ratios. However, the fundamental atomic mechanism of surface atom diffusion remains elusive. Here, we report in situ atomic-scale observations of surface pressure-driven atom diffusion in gold nanocrystals at room temperature using high-resolution transmission electron microscopy with a high-speed detection camera. The topmost layer of atoms on (001) plane initially diffuse in a column-by-column manner. As diffusion proceeds, the remaining atomic columns collectively inject into adjacent underlayer, accompanied by nucleation of a surface dislocation. In comparison, atoms on (111) plane directly diffuse to the base without collective injection. Quantitative calculations indicate that these crystal plane orientation-dependent atom diffusion behaviors contribute to the larger diffusion coefficient of (111) plane compared to (001) plane in addition to the effect of diffusion activation energy. Our findings provide valuable insights into atomic mechanisms of diffusion-dominant morphology evolution of nanostructured metals and guide the design of nanostructured materials with enhanced structural stability.

Glass Disorder Modulated Luminescence in Zero-Dimensional Antimony-Chloride Coplanar Dimers for Optical Anti-counterfeiting.

Zero-dimensional metal halides have received wide attention due to their structural diversity, strong quantum confinement, and associated excellent photoluminescence properties. A reversible and tunable luminescence would be desirable for applications such as anti-counterfeiting, information encryption, and artificial intelligence. Yet, these materials are underexplored, with little known about their luminescence tuning mechanisms. Here we report a pyramidal coplanar dimer, (TBA)Sb2Cl7 (TBA = tetrabutylammonium), showing broadband emission wavelength tuning (585-650 nm) by simple thermal treatment. We attribute the broad color change to structural disorder induced by varying the heat treatment temperatures. Increasing the heating temperature transitions the material from long-range ordered crystalline phase to highly disordered glassy phase. The latter exhibits stronger electron-phonon coupling, enhancing the self-trapped exciton emission efficiency. The work provides a new material platform for manifold optical anti-counterfeiting applications and sheds light on the emission color tuning mechanisms for further design of stimuli-responsive materials.

Interfacial Design of Particulate Photocatalyst Materials for Green Hydrogen Production.

Green hydrogen production using particulate photocatalyst materials has attracted much attention in recent years because this process could potentially lead to inexpensive and scalable solar-to-chemical energy conversion systems. Although the development of efficient particulate photocatalysts enabling one-step overall water splitting (OWS) with solar-to-hydrogen efficiencies in excess of 10% remains challenging, promising photocatalyst candidates exhibiting OWS activity have been demonstrated. This review provides a comprehensive introduction to the solar-to-hydrogen energy conversion process of semiconductor photocatalyst materials and highlights recent advances in photocatalytic OWS via both one-step and two-step photoexcitation processes. The review also covers recent developments in the photocatalytic OWS of SrTiO3, including the establishment of large-scale photocatalytic systems, interfacial design using cocatalysts to enhance water splitting activity, and its photoelectrochemical (PEC) properties at the electrified solid/liquid interface. In addition, there is a special focus on visible-light-absorbing oxynitride and oxysulfide particulate photocatalysts with absorption edges near 600 nm. Methods for photocatalyst preparation and surface modification, as well as PEC properties, are also discussed. The semiconductor properties of particulate photocatalysts obtained from photoelectroanalytical evaluations using particulate photoelectrodes are evaluated. This review is intended to provide guidelines for the future development of particulate photocatalysts capable of efficient and stable OWS.

All Solid Photonic Crystal Fiber Enabled by 3D Printing Fiber Technology for Sensing of Multiple Parameters

AbstractUsing the flexibility and diversity of material and structure designs possible with 3D printing fiber technology, an all‐solid photonic crystal fiber (PCF) is fabricated using borate (B2O3) doping. The geometry, material, and optical properties of this 3D printed PCF are characterized and analyzed using optical microscopy, scanning electron microscopy (SEM), fiber index profilometry, and Fourier transform infrared (FTIR) microscopy. Analysis demonstrates that B2O3 doped in fabricated PCF has experienced evaporation leading to mass loss during drawing. In addition, there is no observable difference between the structure of substrate silica (SiO2) and the SiO2 nanoparticles. However, microdomain differences may explain enhanced reflectance. Furthermore, a Mach–Zehnder interferometer (MZI) sensor is constructed with this 3D printed solid PCF and applied to temperature, refractive index, tensile force, and bending sensing. The specially designed 3D printed PCF has maximum temperature sensitivity up to Δλ/ΔT ≈0.075 nm °C−1. When immersed in 76.34 wt.% glycerol‐water solution, the sensitivity can be further improved. These results demonstrate that 3D printing fiber technology enables the custom fabrication of highly sensitive optical fiber sensors, increasing opportunities for the development of diverse and flexible sensors and devices for future internet‐of‐things (IoT) applications.

Estimation of optimal process parameters for minimum wear in the application of SiC/RHA reinforced Al7075 hybrid composites using ANN, ANFIS, and GA

Increasing demand for high-performance materials has led to the exploration of composite materials for enhanced mechanical properties. In this study, a composite of silicon carbide particulate and rice husk ash (RHA) in varying proportions was utilized to reinforce an aluminum alloy (Al7075) hybrid composite fabricated through the stir casting technique. Microstructure examination via an optical microscope ensured the homogeneous distribution of reinforced particles. Wear was evaluated using a pin-on-disc apparatus, considering material factors (% of SiC and % of RHA) and mechanical wear factors (load applied, speed of rotation, and sliding distance). Experimental data were used to develop artificial neural network and adaptive neural fuzzy inference system models, which demonstrated high predictive accuracy. An objective function, formulated to minimize wear via regression analysis, guided the application of a genetic algorithm to determine optimal process parameters. The optimal combination, resulting in a minimum wear of 34.5 µm, comprised 12% SiC, 7% RHA, a sliding speed of 1.9 m/s, an applied load of 11.5 N, and a sliding distance of 715 mm. This study concludes with recommendations for further research and implications for composite material design and optimization.

Domain Switching Characteristics in Ga-Doped HfO2 Ferroelectric Thin Films with Low Coercive Field.

The gallium-doped hafnium oxide (Ga-HfO2) films with different Ga doping concentrations were prepared by adjusting the HfO2/Ga2O3 atomic layer deposition cycle ratio for high-speed and low-voltage operation in HfO2-based ferroelectric memory. The Ga-HfO2 ferroelectric films reveal a finely modulated coercive field (Ec) from 1.1 (HfO2/Ga2O3 = 32:1) to an exceptionally low 0.6 MV/cm (HfO2/Ga2O3 = 11:1). This modulation arises from the competition between domain nucleation and propagation speed during polarization switching, influenced by the intrinsic domain density and phase dispersion in the film with specific Ga doping concentrations. Higher Ec samples exhibit a nucleation-dominant switching mechanism, while lower Ec samples undergo a transition from a nucleation-dominant to a propagation-dominant reversal mechanism as the electric field increases. This work introduces Ga as a viable dopant for low Ec and offers insights into material design strategies for HfO2-based ferroelectric memory applications.

Alkaline earth metal substitutional doped C20: a density functional study

Exploring the structure and electronic properties has become a very interesting subject for nanomaterial application in many fields. This study presents a comprehensive density functional theory exploration of structure and electronic properties of alkaline earth metal (Be, Mg, and Ca) substitutional doped C20 fullerene. The study shows that MC19 (M = Be, Mg, and Ca) cage has elongated M–C bond lengths and expanded C–M–C bond angles. The Be in BeC19 gains a modest charge, while Mg in MgC19 and Ca in CaC19 donate charge. The most amazing result is that MC19 has very large energy gap, which indicates their higher stabilities than C60, and further proved by the larger hardness of MC19 than that of C20. Importantly, the physical interaction mechanism between M and the cage are different for three MC19 structures, which can be proved by the frontier orbital wavefunction and total density of states. The chemical potential values of C20 are larger than that of MC19, indicating their weaker ability to contain electrons and higher activity. Our research will provide the groundwork for rational design and application of such materials in electronic devices and nanotechnology fields. Highlights Substitutioonal doping of Be(Mg, Ca) brings remarkable influence on the geometric structure of C20. The MC19(M = Be, Mg, and Ca) has higher stability than C20. It is evident MC19(M = Be, Mg, and Ca) clusters have none magnetic moment. The chemical potential values of C20 are higher than those of MC19(M = Be, Mg, and Ca). Our research will provide the groundwork for rational design and application of such materials in electronic devices and nanotechnology fields.

Advanced Insights on MXenes: Categories, Properties, Synthesis, and Applications in Alkali Metal Ion Batteries.

The development and optimization of promising anode material for next-generation alkali metal ion batteries are significant for clean energy evolution. 2D MXenes have drawn extensive attention in electrochemical energy storage applications, due to their multiple advantages including excellent conductivity, robust mechanical properties, hydrophilicity of its functional terminations, and outstanding electrochemical storage capability. In this review, the categories, properties, and synthesis methods of MXenes are first outlined. Furthermore, the latest research and progress of MXenes and their composites in alkali metal ion storage are also summarized comprehensively. A special emphasis is placed on MXenes and their hybrids, ranging from material design and fabrication to fundamental understanding of the alkali ion storage mechanisms to battery performance optimization strategies. Lastly, the challenges and personal perspectives of the future research of MXenes and their composites for energy storage are presented.

Aggregation-Induced Emission (AIE) in Polymers: Effect of Polymer size on the Fluorescence of Low Molecular Weight PEG and PPG.

Aggregation-induced emission (AIE) is a fascinating phenomenon where specific molecules exhibit enhanced fluorescence upon aggregation. This unique property has revolutionized the design and development of new fluorescent materials for different applications, from biosensors and organic light-emitting diodes (OLEDs) to biomedical imaging and diagnostics. Researchers are creating sensitive and selective sensing platforms, opening new avenues in material science and engineering by harnessing the potential of AIE. To expand the knowledge in this field, this study explored the aggregation-induced emission (AIE) properties of two polymers, namely polyethylene glycol (PEG) and polypropylene glycol (PPG) of low molecular weight (MW) using fluorescence spectroscopy and absorbance (UV). PEG-300 and PPG-725 were the most fluorescent polymers at UV of the ten investigated. Interestingly, AIE did not correlate linearly with molecular weight (MW), and monobutyl ether substitution in PEG with a similar MW substantially altered its AIE. Furthermore, fluorescence precisely quantified low polymer concentrations in water, and non-aqueous solvents suppressed AIE, suggesting potential for AIE manipulation. These findings enhance our understanding of AIE in polymers, fostering the development of novel materials for applications such as biosensors.

Cu nanoparticle geometry as the key to bicolor behavior in Oregon sunstones — an application of LSPR theory in nanomineralogy

Abstract The coloration mechanism of Oregon sunstone is a classic and controversial topic in mineralogy because of the unique co-existence of anisotropic (green-red) and isotropic (red) color zones within single feldspar crystals. After nearly 50 years of research, no models proposed to date have satisfactorily accounted for all observed optical phenomena. Here we present high-resolution transmission electron microscopy analyses of samples prepared by focused ion beam extraction along specific crystal directions. In both the anisotropic and the isotropic color zones, we observed Cu nanoparticles (NPs) included within plagioclase but with different geometries. In the isotropic (red) zone, NPs were randomly distributed nano-spheres or nano-ellipsoids (8.7-12 nm in diameter) with an aspect ratio of 1-1.3. In contrast, in dichroic (green/red) zones, NPs were directionally-aligned nano-rods (8.5-21 nm along the long axis) with an aspect ratio of ~2.5. We applied localized surface plasmon resonance (LSPR) theory to simulate absorption spectra, and we developed a model to explain the observed optical properties. LA-ICP-MS and polarized UV-Vis spectroscopy were also performed to confirm our conclusions. This study systematically reveals the existence and optical influence of variably shaped metal-NP inclusions in feldspar crystals. Furthermore, it demonstrates the necessity of including LSPR in the canon of mineral coloration mechanisms. Cu-NP-bearing labradorite has been shown to exhibit third-order non-linear optical properties, and approaches that incorporate NP shapes as well as sizes will assist in the design of NP-embedded optical materials with tailored optical behaviors.

Thermodynamic descriptions of the CaO–Al2O3 and CaO–Al2O3–SiO2 systems over the whole composition and temperature ranges

AbstractThe CaO–Al2O3–SiO2 system is a fundamental system in aluminosilicate materials, and its thermodynamic description provides key information for ceramic design, cement production, slag tapping, and geological prediction. However, the existing thermodynamic calculations for the CaO–Al2O3 system show inaccurate heats of formation for the compounds and consequently a decomposition of the CA2 (CaO⋅2Al2O3) phase at a low temperature. Besides, the solid solutions in anorthite and cristobalite have never been considered in the previous thermodynamic assessments for the CaO–Al2O3–SiO2 system. Therefore, thermodynamic reassessments of the CaO–Al2O3 and CaO–Al2O3–SiO2 systems are carried out in the present work using the CALculation of PHAse Diagram method, considering the solid solution in anorthite and cristobalite for the first time. The anorthite and cristobalite phases are modeled based on the individual mechanism of solid solution, with the anorthite described by (Ca+2, Va)1(Al+3, Si+4)2(Si+4)2(O−2)8 and the cristobalite described by (Va, Ca+2)1(Si+4, Al+3)2(O−2)4. The present assessment solves the above issues and provides consistent thermodynamic descriptions for the liquid and solid phases. Based on the established thermodynamic database, a Scheil solidification simulation is carried out for a cement clinker and the variations of mass fractions of the phases as well as the composition of liquid during Scheil cooling are calculated. The present work guides the design of relevant materials and lays an essential foundation for the establishment of the thermodynamic database of multicomponent aluminosilicate materials.

New materials and complications of prostheses in humans: situation in Spain.

Prostheses or implantable medical devices (IMDs) are parts made of natural or artificial materials intended to replace a body structure and therefore must be well tolerated by living tissues. The types of IMDs currently available and usable are very varied and capable of replacing almost any human organ. A high but imprecise percentage of Spaniards are carriers of one or more IMDs to which they often owe their quality of life or survival. IMDs are constructed with different types of materials that are often combined in the same prosthesis. These materials must combine harmlessness to human tissues with high wear resistance. Their durability depends on many factors both on the host and the type of prosthesis, but the vast majority last for more than 10-15 years or remain in function for the lifetime of the patient. The most frequently implanted IMDs are placed in the heart or great vessels, joints, dental arches or breast and their most frequent complications are classified as non-infectious, particularly loosening or intolerance, and infectious. Complications, when they occur, lead to a significant increase in morbidity, their repair or replacement multiplies the health care cost and, on occasions, can cause the death of the patient. The fight against IMD complications is currently focused on the design of new materials that are more resistant to wear and infection and the use of antimicrobial substances that are released from these materials. Their production requires multidisciplinary technical teams, but also a willingness on the part of industry and health authorities that is not often found in Spain or in most European nations. Scientific production on prostheses and IMD in Spain is estimated to be less than 2% of the world total, and probably below what corresponds to our level of socio-economic development. The future of IMDs involves, among other factors, examining the potential role of Artificial Intelligence in their design, knowledge of tissue regeneration, greater efficiency in preventing infections and taking alternative treatments beyond antimicrobials, such as phage therapy. For these and other reasons, the Ramón Areces Foundation convened a series of experts in different fields related to prostheses and IMDs who answered and discussed a series of questions previously formulated by the Scientific Council. The following lines are the written testimony of these questions and the answers to them.

Tandem four-component reaction to access fused polycycles exhibiting aggregation-enhanced through-space charge transfer emission.

Rapid construction of new fluorescence emitters is essential in advancing synthetic luminescent materials. This study illustrated a piperidine-promoted reaction of chiral dialdehyde with benzoylacetonitrile and malonitrile, leading to the formation of the 6/6/7 fused cyclic product in good yield. The proposed reaction mechanism involves a dual condensation/cyclization process, achieving the formation of up to six bonds for fused polycycles. The single crystal structure analysis revealed that the fused cyclic skeleton contains face-to-face naphthyl and cyanoalkenyl motifs, which act as the electronic donor and acceptor, respectively, potentially resulting in through-space charge transfer (TSCT) emission. While the TSCT emissions were weak in solution, a notable increase in luminescence intensity was observed upon aggregation, indicating bright fluorescent light. A series of theoretical analyses further supported the possibility of spatial electronic communication based on frontier molecular orbitals, the distance of charge transfer, and reduced density gradient analysis. This work not only provides guidance for the one-step synthesis of complex polycycles, but also offers valuable insights into the design of aggregation-enhanced TSCT emission materials.

Impact of a Lightly Branched Star Polyelectrolyte Architecture on Polyelectrolyte Complexes.

The effect of charge density in blocky and statistical linear polyelectrolytes on polyelectrolyte complex (PEC) properties has been studied with the finding that increased charge density in a polyelectrolyte tends to increase the salt resistance and modulus of a PEC across various polyelectrolyte pairs. Here, we demonstrate the ability to orthogonally alter PEC salt resistance while maintaining rheological properties and internal structure by going from linear to lightly branched architectures with similar total degrees of polymerization. Using a model system built around glycidyl methacrylate (GMA) and thiol-epoxy "click" functionalization, we create a library of homologous linear, 4-armed, 6-armed, and 8-armed star polyelectrolytes. The PECs formed from these model polyelectrolyte pairs are then characterized via optical microscopy, rheology, and small-angle X-ray scattering to evaluate their salt resistance, mechanical properties, and internal structure. We argue that our results are due to the difference between linear charge density or charge per unit length along backbone segments for each polyelectrolyte and spatial charge density, the number of charges per unit volume of the polyelectrolyte prior to complexation. Our findings suggest that linear charge density is the dominant factor in determining intermolecular interactions of the complex, leading to identical rheological and structural behavior, whereas the spatial charge density primarily influences the stability of the complexes. These distinct mechanisms for altering various sought-after PEC properties offer greater potential applications in precision design of polyelectrolyte complex materials.

Plasmonic effect of metal nanoparticles on the photocatalytic properties of TiO2/rGO composite

A comparative study of the plasmon effect of Ag and Au nanoparticles on TiO2/rGO nanocomposite was carried out. The synthesis of Au and Ag nanoparticles was carried out by laser ablation. The morphology and structure of the nanocomposites were studied by EDA, HRTEM, XRD and Raman spectroscopy. It was shown that the absorption capacity of the nanocomposite material was increased in the visible range of the spectrum when Ag and Au nanoparticles were added to TiO2/rGO. This leads to an increase in their photocatalytic activity. The photocurrent generated by NC/Au 10−11 films is in 3.8 times and NC/Ag 10−12 is in 2 times higher compared to pure TiO2/rGO film. Similar results were obtained from experimental data on the dyes photodegradation. In the presence of plasmon nanoparticles a significant enhancement in the electrical properties of the TiO2/rGO nanocomposite was recorded. The charge carrier transfer resistance in nanocomposites was decreased by almost ∼7 times for NC/Au,10−11 and ∼4 times for NC/Ag,10−12 films compared to pure TiO2/rGO. In addition, for nanocomposites with Ag or Au nanoparticles, a decrease in the effective electron lifetime was observed. The data obtained allow us to conclude that plasmonic NPs have a synergistic effect in TiO2/rGO nanocomposites, which consists in modifying both their light-harvesting properties and charge-transport characteristics. The results obtained can be used for the design of materials with improved photocatalytic and optoelectronic characteristics.

Designing semiconductor materials and devices in the post-Moore era by tackling computational challenges with data-driven strategies.

In the post-Moore's law era, the progress of electronics relies on discovering superior semiconductor materials and optimizing device fabrication. Computational methods, augmented by emerging data-driven strategies, offer a promising alternative to the traditional trial-and-error approach. In this Perspective, we highlight data-driven computational frameworks for enhancing semiconductor discovery and device development by elaborating on their advances in exploring the materials design space, predicting semiconductor properties and optimizing device fabrication, with a concluding discussion on the challenges and opportunities in these areas.

Mixture composition design of magnesium oxychloride cement-stabilized crushed stone materials applied as a pavement base

Conventional binding materials, such as silicate cement and lime, present high energy consumption, pollution, and carbon emissions. Therefore, we utilize crushed stone as a stabilization material. Magnesium oxychloride cement (MOC) is modified and used as an inorganic admixture owing to its eco-friendly nature and low carbon content. We analysed the control indicators of an integrated design of MOC-stabilized crushed stone by conducting unconfined compressive strength and water-resistance tests. The optimum mixing composition of the MOC-stabilized crushed stone was determined through the response surface methodology. We determined the best approach and dosage for improving the water resistance of MOC-stabilized crushed stone by comparing the effects of four modification methods: fly ash, citric acid + silica fume, phosphoric acid + waterborne polyurethane, and dihydrogen phosphate potassium salt. We also perform a comparison with 5% ordinary silicate cement-stabilized crushed stone. The results indicate that the MOC-stabilized crushed stone exhibits a rapid increase in strength in the early stage, but this rate reduces after 28 days. The mixing design employs the 4-day unconfined compressive strength and 1-day water resistance coefficient as the technical indicators. The best mixing composition includes a 4.27% MOC dosage and a molar ratio of MgO/MgCl2 of 5.85. We use 1% citric acid + 10% silica fume in equal amounts to replace the MOC dopant method for composite modification of the MOC stabilized crushed stone. Consequently, the 1-day water resistance coefficient before water immersion is significantly increased from 0.78 to 0.91 and its 4-day unconfined compressive strength is only reduced by 0.10 MPa. This significantly improves the water resistance of the MOC-stabilized crushed stone and ensures that its strength remains unaffected, which is the optimal modification method. However, this method must ensure that a small amount of citric acid and silica fume are uniformly distributed in the MOC-stabilized crushed stone, which increases the construction difficulty of the road base.

Influences of pretreatment methods on the mechanical and environmental behaviors of PG-GGBS-LM ternary stabilizer.

Phosphogypsum is a kind of acidic industrial byproducts with high content of soluble phosphorus and fluorine pollutants, which requires to be pretreated when used as cementitious material to (partial) replace traditional Portland cement. In this study, five different pretreatment methods were proposed for comparative analysis to examine the pretreatment effect on the mechanical and environmental behaviors of ternary phosphogypsum (PG), ground granulated blast-furnace slag (GGBS), and lime (LM) mixed stabilizer. Series laboratory tests, including unconfined compressive strength (UCS), pH, phosphorus (P)/fluorine (F) leaching, scanning electron microscopy (SEM), and X-ray diffraction (XRD) tests, were conducted to comprehend the macro- and microscopic mechanism. The results show that it is essential to grind raw PG to finer powdered state, so that it reacts more easily and quickly with LM and water. In addition, it was noticed that the UCS and P/F leaching concentration are not only affected by the mixing proportion of the PG-GGBS-LM ternary stabilizer, but also by the curing duration. The UCS increases rapidly from initial curing period and then grows slowly after 28days of curing. From the perspective of strength evolution, mixing proportion of PG: GGBS: LM = 15:80:5 is optimal, but considering the economy and environmental related issues, PG: GGBS: LM = 30:65:5 was regarded as a more attractive choice. The findings can provide a reference for the selection of pretreatment methods and design of PG-based cementitious materials suited for stabilized soils.

Investigation of the magnetic properties of a Borophyne superlattice using the Monte Carlo method

In this study, the effect of different physical parameters on the magnetic properties of a Borophyne superlattice is investigated by means of Monte Carlo simulations. The structure consists of alternating A, B, and C layers, each with a different spin (A = 1, B = 5/2, and C = 2). We plot hysteresis loops for different parameter sets, analyze the total and partial magnetization changes as a function of temperature, and exchange coupling parameters. Our investigations reveal intriguing properties of the magnetic structure that are useful for a better understanding of complex magnetic phenomena and for the design of novel magnetic materials.