Materials Advances最新文献

This research focuses on the development of titania coatings containing calcium, phosphorus, and silver, prepared using the sol–gel method and applied via dip-coating technique for use in biomedical implants. These coatings were evaluated for their adhesion, bioactivity, antibacterial properties, and cytocompatibility. The titanium substrates underwent mechanical grinding or blasting with Al₂O₃ particles, or chemical etching with hydrofluoric acid before coating application. Adhesion was assessed using a tape test, revealing that all coatings adhered well to the substrates. Antibacterial activity against Escherichia coli was evaluated after 4 and 24 hours, demonstrating significant antibacterial effects. Bioactivity was tested in simulated body fluid (SBF) over 20 days, showing promising results. Cytotoxicity was assessed using L929, U-2 OS, and hFOB 1.19 cell lines, confirming the biocompatibility of the coatings. These findings suggest that sol–gel prepared coatings can significantly enhance the functional properties of titanium-based biomaterials for biomedical applications.

Nesquehonite (MgCO₃·3H₂O) is of interest as a carbon sink for mineral carbonation as its formation is kinetically favored at ambient temperatures and pressures and offers the highest CO₂ : MgO ratio compared to most other hydrated magnesium carbonates (HMCs). However, the phase tends to convert to more stable HMCs depending on the environment and time leading to long-term instability. Here, we report a successful attempt to stabilize nesquehonite using a phosphate-based pH 7 buffer, while controlling the equilibrium of aqueous carbonate species did not stabilize the phase. Phosphate interacts with nesquehonite to form a Mg-phosphate phase on nesquehonite's surface. We suggest that a protective layer is formed, which prevents further transformation of nesquehonite.

The electrochemical supercapacitor has been shown to be a reliable and innovative type of energy storage technology over the years. Recent research has shown that CoWO₄ is a potential material for supercapacitor applications because of its unique characteristics, which make it suitable for energy storage. CoWO₄ nanostructures are synthesized using a low-temperature hydrothermal method followed by calcination at 300 °C for 2 h. The powder was characterized through XRD with Rietveld refinement, FE-SEM, TEM, Raman spectroscopy, FTIR, XPS, BET and electrochemical techniques. XRD analysis revealed a monoclinic crystal framework of CoWO₄ with a space group of P2/c. FE-SEM and TEM results are in good agreement with each other and reveal elongated oval-shaped nanostructures of CoWO₄. BET analysis indicates the mesoporosity in the nanostructures, which helps in the increased active sites for an efficient supercapacitor application. XPS results confirm the presence of a Co²⁺ oxidation state in the CoWO₄ nanostructure. The electrochemical characterizations were carried out using a three-electrode system. The CoWO₄ electrode indicates a high specific capacitance of 235 F g⁻¹ at 10 mV s⁻¹ in 6 M KOH electrolyte between −0.15 V to 0.45 V potential window and retains 93.25% capacitance even after 10 000 cycles. Additionally, an asymmetric supercapacitor is assembled using the CoWO₄ and activated carbon as the positive and negative electrodes, respectively, achieving a maximum energy density of 51.8 W h kg⁻¹ and an excellent capacity retention of 96.43% after 10 000 cycles at 3 A g⁻¹. This work will be helpful in the development of high-capacitive, durable, and safe supercapacitor devices for future energy needs.

The utilization of hybrid plasmonic metal/semiconductor materials for surface-enhanced Raman scattering (SERS) has emerged as a promising approach towards the development of advanced SERS substrates in terms of sensitivity, uniformity, stability, and reusability, based on the synergy of the powerful electromagnetic mechanism with the chemical amplification and functionality of semiconductor supports. In this work, co-assembled WO₃/TiO₂ inverse opal films were utilized as photonic crystal scaffolds of plasmonic Ag nanoparticles in order to optimally combine plasmonic, charge transfer and slow photon effects for ultrasensitive, recyclable SERS sensing. Compositional and photonic band gap engineering of the Ag-decorated WO₃/TiO₂ photonic crystal substrates provided insight to the interplay of plasmonic enhancement assisted by slow light propagation in the inverse opal structure and charge transfer between the analyte and the heterostructured substrate. Highly sensitive detection of 4-mercaptobenzoic acid as a non-resonant analyte was achieved down to 10⁻¹³ M for the optimal Ag–WO₃/TiO₂ substrate with good uniformity and excellent recyclability due to its enhanced photocatalytic self-cleaning capacity. Comparative performance tests along with photoelectrochemical evaluation showed a significant contribution of cascade electron transfer from plasmonic Ag to the staggered WO₃/TiO₂ heterojunctions and the analyte, providing an additional charge transfer pathway to promote the substrate-to-molecule interaction for the design of efficient and versatile metal/metal oxide SERS platforms.

In this research, the impact of the mesoporous graphitic carbon nitride–papain–nickel (mpg-C₃N₄@Pa@Ni) nanocomposite in the reduction of hazardous nitroaromatic derivatives was investigated under solvent-less and solvent-free conditions. The mpg-C₃N₄@Pa@Ni composite was synthesized in four steps; synthesizing bulk and mesoporous g-C₃N₄, and functionalization with 1,3-dibromopropane, papain, and Ni nanoparticles. Papain was found to be a suitable composite material due to its ability to form covalent and coordination bonds with the substrate and Ni. Several solvent-free and solvent-less methods, including using mortar and pestle, ball mill, microwave, and magnetic stirrer, were employed to investigate the reduction of nitroaromatic compounds due to their fast, simple, and economical green nature. The synthesized nanocomposite demonstrated high efficiency rates in reducing toxic nitroaromatic compounds ranging from 80–98.6%. Structural confirmation of the mpg-C₃N₄@Pa@Ni nanocomposite was carried out using various techniques such as Fourier-Transform Infrared spectroscopy (FT-IR), N₂ adsorption analysis (BET), Field Emission Scanning Electron Microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray Diffraction spectroscopy (XRD), and Thermogravimetric Analysis (TGA). Furthermore, the mpg-C₃N₄@Pa@Ni nanocomposite showed promising recoverability without significant decreases in efficiency for up to eight cycles, indicating its potential as a sustainable and efficient catalyst. The synthesis of mpg-C₃N₄@Pa@Ni nanocomposite and its efficient performance in reducing hazardous nitroaromatic compounds pave the way for a sustainable and environmentally friendly alternative to traditional methods.

The achievement of lithium ion batteries (LiBs) with improved electrochemical performance requires advances in the synthesis of cathode materials with controlled composition and properties. In particular, NMC core–shell materials formed by a Ni-rich core and a Mn-rich shell are recently gaining interest as they allow the achievement of increased energy density and high discharge capacity values. In order to overcome some of the limitations of these NMC compounds and broaden their applicability, controlled synthesis and detailed analysis of their properties are required. In this work, NMC in the form of core and core–shell microparticles have been synthesized by an oxalate-assisted co-precipitation synthesis method which allows control of the final composition. The morphology, crystalline structure and composition of the particles have been investigated as a function of the synthesis parameters and the presence of the Mn-rich shell, by means of diverse microscopy and spectroscopy techniques. Additionally, in situ SEM and XPS measurements allow analysis of the NMC particles in variable operation environments. Aspects such as the cationic mixing in the NMC compound or the formation of a rock-salt phase as the annealing temperature increases are discussed. Finally, preliminary electrochemical tests have been performed using NMC particles as cathodes in LiBs.

Understanding the mechanism of the oxygen exchange rate between the gas-phase and the oxide surface is essential to utilize electrochemical transport of oxygen in ceria-based materials for sustainable technologies. This contribution applies pulse isotope exchange (PIE) to investigate the oxygen exchange mechanism on La₂Ce₂O₇ and 5% Pr-substituted La₂Ce₂O₇. The oxygen exchange kinetics is rate-limited by the dissociation of adsorbed molecular oxygen. Pr substitution increases the surface kinetics, presumably due to an increased concentration of electronic defects that enhances charge transfer of electronic defects at the surface. Humidity decreases the exchange rate due to the selective dissociative adsorption of water molecules into surface oxygen vacancies, forming hydroxide defects. This effect diminishes with increasing temperature due to the exothermic nature of hydration.

Fluorescent color-changing smart materials based on force stimulus have attracted wide attention due to their multifunctional and reversible characteristics, leading to advanced applications. However, it is still challenging to develop high-contrast mechanochromic luminescent molecules and reveal the relationship between their structure and properties. This article illustrates the high-contrast mechanochromic properties of D–A–D type derivatives. Two pyridine-functionalized anthracene derivatives (MTPA and BTPA) both showed significant photoluminescence shift under mechanical force stimulus. It is worth noting that the unilaterally substituted D–A–D anthracene derivative (MTPA) exhibits a significant wavelength shift of 122 nm when ground, and the luminescence color changes from blue to yellow. Moreover, it can recover to the original luminescent color after steaming with water or ethanol. This study not only elucidates the mechanochromic properties of D–A–D type cationic organic small molecules, but also provides a novel design concept for designing high-contrast mechanochromic materials.

To fabricate a selective lead (Pb(II)) ion sensor, a slurry of the synthesized N,N′,N′′,N′′′-tetrasalicylidene-3,3′-diaminobenzidine (TSDB) ligand was deposited on multiwalled carbon nanotubes (MWCNTs)/paraffin graphite electrode (PGE). The ligand (octadentate) was easily synthesized using 3,3′-diaminobenzidine and salicylaldehyde. The TSDB ligand that was synthesized was verified using Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (¹H-NMR) spectroscopy and carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopy. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX) were used to analyze the surface morphology of Pb(II)-TSDB/MWCNTs/PGE, TSDB/MWCNTs/PGE, MWCNTs/PGE, and PGE. TSDB/MWCNTs/PGE, MWCNTs/PGE, and PGE were confirmed for conductivity using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Pb(II) was examined using square wave anodic stripping voltammetry (SWASV) on TSDB/MWCNTs/PGE, MWCNTs/PGE, and PGE. Pb(II) stripping voltammetry was carried out using the TSDB/MWCNTs/PGE at varying concentrations (0.8–222 μg L⁻¹). It was found that the lowest detection limit was 0.15 μg L⁻¹. During sensing performances, the Pb(II) sensor with active TSDB exhibits stability, perfect reproducible results, interference, and stability. Above all, its successive applicability to the detection of squid, cow urine and wheat grain samples was demonstrated. Atomic absorption spectroscopy (AAS) measurements are correlated with those of the real samples.

The use of biomass-derived materials as supports for enzyme immobilization is of interest for developing biocatalytical processes based on renewable resources. Reversible immobilization offers a solution to the problem of enzyme activity loss over time, as it allows for the removal of deactivated enzymes and their replacement with fresh ones using a renewable biopolymer. In this work, β-cyclodextrin-grafted chitosan (Ch-CD) has been prepared and used as support to reversibly immobilized adamantane-modified enzymes via supramolecular host–guest interactions in an environmentally friendly aqueous medium. The prepared Ch-CD beads were characterized by solid-state ¹³C and ¹⁵N CP/MAS (cross-polarization/magic angle spinning) NMR spectroscopy. The performance of three types of enzymes immobilized by this method has been studied: β-galactosidases in the hydrolysis of β-galactopyranosides, one glucose oxidase in the oxidation of glucose, and one peroxidase in the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). A double sequential enzyme reaction catalyzed by immobilized glucose oxidase/peroxidase was performed, showing the possibility to develop a glucose test by means of this sustainable biocatalysis. The reusability of the biocatalytic materials was dependent on the type, source of enzyme and the linker used in the preparation. The enzymes bound to cyclodextrin-grafted chitosan beads were desorbed after washing with a β-CD solution, thus being able to recycle the Ch-CD beads for a new enzyme immobilization.