Materials Research Bulletin最新文献

Mechanoluminescence (ML) exhibits distinctive mechano-optical response characteristics, rendering it promising for various applications. This study presents a porous ML elastomer capable of high intensity luminescence and extended sensitive dimension, which is prepared by molding the composite of luminescent particles (ZnS:Cu) and polydimethylsiloxane (PDMS) within a structured-porous template. With quantitative measurements and simulations, the enhanced luminescence can be attributed to the effect of stress concentration and the enhancement of contact electrification induced by the pore structure. Compared to the dense structure, the luminescence of the porous structure is greatly enhanced (more than 10 times!) and sensitive to compressing, which can promisingly expand ML applications from unidirectional stretching (2D) to three-dimensional (3D).

A single-step solvothermal method has been employed to synthesize MnFe₂O₄ composite nanoparticles where graphene sheets were incorporated into spherical MnFe₂O₄ nanoparticles of size ∼57 nm. The synthesized MnFe₂O₄/reduced graphene oxide (rGO) composite exhibits enhanced electrochemical properties due to its improved porosity, surface area, and conductivity. FTIR, Raman, and XPS studies confirmed the effective reduction of GO and the successful formation of MnFe₂O₄/rGO composite. When employed as an electrochemical cell electrode, the MnFe₂O₄/rGO composite showed an enhanced specific capacitance of 253 F g⁻¹, as opposed to 133 F g⁻¹ for the bare nanoparticles. The composite attains significantly improved energy density of 76.06 Wh kg⁻¹ and power density of 7.49 kW kg⁻¹ at current density of 10 A g⁻¹. The unification of 2D graphene and MnFe₂O₄ nanoparticles yields enhanced electrochemical performance and an outstanding 96 % cyclic stability (after 5000 cycles), which offers a viable approach for developing better supercapacitor electrode materials in the future.

The multi-interface contacted S-scheme photocatalyst was used for CO₂ reduction in this research. A hybrid nanostructures catalyst was constructed using g-C₃N₄ nanosheet, oxidized CeO₂ nanoparticles, and biochar (BIO, cattail-derived). The g-C₃N₄-BIO/CeO₂ catalyst exhibited high selectivity (> 95 %) in converting CO₂ to CO in a gas-solid-liquid phase CO₂ reduction system. Theoretical and experimental evidence suggests that the multi-interface and interfacial internal electric field (IEF) play a crucial role in enhancing electron transfer and redox ability in CO₂ reduction processes. Ce⁴⁺ species in CeO₂ have the capability to donate two electrons, facilitating the two-electron reduction process involved in the transformation of CO₂ to CO. Additionally, Ce⁴⁺ in CeO₂ acted as an electron trapping agent and could be reduced to Ce³⁺ ion after trapping electrons, which facilitated the separation process of photogenerated carriers inside CeO₂. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrated that COOH* intermediate played a key role as the rate determining step in the overall CO₂ photoreduction to CO. This investigation will contribute to the development and application of new and environmentally friendly BIO-based S-scheme photocatalysts.

A new type of solid polymer electrolytes (SPEs) for zinc-ion batteries was fabricated by combining liquid crystalline elastomer (LCE) with glycerol. LCEs were selected for their flexibility and low transition temperatures. However, these materials exhibit a degree of crystallinity at ambient temperatures, limiting high ionic conductivity. Glycerol was introduced as both an antinucleating agent and plasticiser to reduce crystallinity and increase flexibility of this system. As a result, adding 15 wt% glycerol enhanced the ionic conductivity to 1.87 × 10⁻⁵ S cm⁻¹ while maintaining stable charge-discharge cycles for 200 hrs. Besides, this modification reduced the nematic-isotropic transition temperature and storage modulus from 78 °C to 66 °C and 4.7 MPa to 0.6 MPa, respectively. Furthermore, these materials indicated excellent shape fixity and shape recovery of 98.3 % and 99.6 %. The successful fabrication of this LCE/glycerol system highlights its potential for developing shape memory SPE materials tailored for Zn-ion battery applications.

A novel 2D layered nanocomposite was synthesized by in situ polymerization by incorporating aniline into the HLaNb₂O₇ host matrix. This innovative nanocomposite uniquely combines the electroactive properties of polyaniline with the structural stability and ion-exchange capabilities of lanthanum niobate, resulting in a material with superior electrochemical performance. Characterization of the composites was performed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Electrochemical assays revealed that the PANI/LaNb₂O₇ nanocomposite modified glassy carbon electrode could concurrently detect dopamine and uric acid, respectively. The detection limits were determined to be 0.04 μM for DA and 0.61 μM for UA. The enhanced sensitivity, selectivity, and stability of this nanocomposite make it a promising candidate for advanced electrochemical sensors, particularly in biomedical applications where precise detection of biomolecules is crucial.

The Solid-state chemiresistive gas sensing devices are the desirable recruit to detect toxic gases and volatile organic compounds; however, the growth of real-life applications of these sensors is poor due to their drawbacks, including high working temperature, showing poor responses during moderate to high humidity, and poor selectivity towards the gas of interest. In this work, we synthesised zeolitic imidazolate framework (ZIF-71), carbon soot (CNPs) and CNPs@ZIF-71 composite and were successfully characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The ZIF-71, CNPs and CNPs@ZIF-71 composites are used to fabricate the sensors to detect toluene, ethanol, mesitylene, diethyl ether and acetonitrile vapours at room temperature. The ZIF-71 did not respond to any of the tested VOCs at room temperature; however, the CNPs sensor showed some little response to the tested VOCs. However, the linear response was not observed as the analyte concentration increased. However, the CNPs@ZIF-71 showed excellent response and sensitivity towards the toluene vapour and less sensitivity towards mesitylene, diethyl ether, acetonitrile and ethanol vapours. ZIF-71 synergistically improves CNPs sensing performances on toluene vapour detection. The CNPs@ZIF-71 sensor was found to be highly resistive during the detection of toluene vapour. The calculated limit for the detection of toluene vapour on the CNPs@ZIF-71 composite sensor was 518 ppb. In situ, FTIR coupled with LCR meter online analysis was done to study the sensing mechanism, and it was found that toluene vapour detection on sensor 3 undergoes total deep oxidation to form H₂O and CO₂ as by-products.

Numerous studies have been conducted over the past few decades on energy-efficient, sustainable, and cost-effective materials and technologies for consumer electronics. Among such materials, ferrite-based compounds are expected to play a significant role in the miniaturization of circuits. However, densification of such materials is a very challenging problem. The cold sintering process (CSP) has recently been found as an alternative strategy for producing advanced materials, enabling their densification at low temperatures. The present work uses different volume fractions of Y₃Fe₅O₁₂ with EDTA to create a dense composite system. Here, we report the synthesis of composites of the formula (1 –x)Y₃Fe₅O₁₂-xEDTA (x = 0.2, 0.3, 0.4, 0.5) through CSP. These composites possess a permittivity of 6.4–7 combined with a loss tangent of 10^–2. Moreover, for the 0.5 EDTA composite, ε_r of 5.7 and tanδ of 0.01 are obtained at 10 GHz, suggesting the prepared composites' potential for substrate applications.

In the framework of luminescent transition metal ions-doped phosphors for near-infrared (NIR) lighting, Fe³⁺-activated phosphors have been recently demonstrated to be a potential alternative to the most common Cr³⁺ and Ni²⁺-based NIR materials. However, this family of phosphors still suffer from low absorption efficiency and severe thermal quenching. This study investigates the effect of Bi³⁺ ion concentration on the spectroscopic features of Fe³⁺ ions in CaAl₄O₇:Fe³⁺, Bi³⁺ system. The presence of the ¹S₀→¹P₁ transition band in Fe³⁺ PLE spectra indicates the Bi³⁺→Fe³⁺ energy transfer leading to a corresponding increase in luminescence intensity of Fe³⁺ ions by over 30-fold compared to Fe³⁺-singly doped sample. High Bi³⁺ concentrations also quench Bi³⁺ ion luminescence, improving NIR emission purity. Additionally, the presence of Bi³⁺ ions enhances Fe³⁺ ion luminescence stability by delaying the thermal depopulation, as evidenced by a T₅₀ shift from 323 K to 393 K. Overall, co-doping CaAl₄O₇:Fe³⁺ with Bi³⁺ ions expands excitation spectra, boosts luminescence intensity, and enhances the thermal stability.

Silicon has emerged as one of the most promising anode materials for next-generation lithium-ion batteries due to its exceptional specific capacity and abundant resources. However, its widespread application is hindered by structural deformability and low intrinsic conductivity. By strategically integrating a conductive carbon matrix with silicon, it becomes feasible and efficient to enhance the electrical conductivity of silicon and accommodate the stress-induced volume expansion during battery operation. In this study, a series of silicon/graphite/amorphous carbon (Si/G/C) composites were prepared using mechanical milling and carbothermal reduction. The study focused on two main aspects: the effect of the ratio of micro-sized silicon to flake graphite on the properties of the composite and the compatibility of different-scale silicon particles (micro-sized silicon and nano-sized silicon) and different kinds of natural graphite (flake graphite and cryptocrystalline graphite). The results reveal that when micro-sized silicon and flake graphite are combined, the graphite is fragmented more thoroughly, resulting in smoother surfaces and reduced aggregation of secondary particles. The composites with a mass ratio of 7:3 micro-sized silicon to flake graphite have the smallest specific surface area and pore size, homogeneous distribution, and stable structure. This exceptional carbon-to-silicon ratio endows the Si/G/C composite with rapid reaction kinetics, enabling a specific discharge capacity of 854.1 mAh g^-1 after 200 cycles at 1A g^-1. The findings offer valuable insights into the design and optimization of silicon-based anode materials for next-generation lithium-ion batteries.