Materials最新文献

The construction of heterostructures has been recognized as an effective strategy for enhancing material activity and stability. Herein, a ternary heterojunction FeSe₂-BiSe₂-CoSe₂ was synthesized via a hydrothermal selenidation reaction. The significant electronegativity difference between Bi and Fe/Co triggers charge transfer within the FeSe₂-BiSe₂-CoSe₂ lattice. Furthermore, the abundant pore structure of FeSe₂-BiSe₂-CoSe₂ provides efficient pathways for electron diffusion, significantly enhancing the HER catalytic kinetics. Results demonstrate that FeSe₂-BiSe₂-CoSe₂ exhibits outstanding HER activity in both acidic and alkaline media. In 0.5 M H₂SO₄, it exhibits an overpotential of only 44 mV with a Tafel slope of 108 mV dec^-1. In 1 M KOH, the corresponding overpotential is 188 mV, with a Tafel slope of 45 mV dec^-1 at 10 mA cm^-2. This study constructs electron-rich active sites through electronic structure regulation, providing valuable insights for designing low-cost, high-performance transition metal selenide HER catalysts.

A new method of in situ hydrothermal reduction of graphene oxide (GO) to reduced graphene oxide (rGO) in polymer bulk was developed, which involves heating GO/polyacrylonitrile (PAN) composite membranes (0.5; 1.0; 2.0% w/w of GO/PAN) in the presence of water vapor at a temperature of 120 °C and a pressure of 0.2 MPa. As a result of this process, membranes containing rGO were obtained, as confirmed by FTIR, Raman, WAXS and TGA studies. The composite membranes obtained after hydrothermal reduction of GO to rGO (B60, C60, D60) were substantially different from the initial membranes containing unreduced GO (B0, C0, D0). The hydrothermal reduction process clearly influenced the physicochemical properties (reduction of apparent density, water sorption, and increase in the contact angle) and transport properties of the B60, C60, and D60 membranes (decrease in water flux by ~104 [dm³/m² × h] and even ~348 [dm³/m² × h] compared to the initial membranes).

Recycling wastewater from washing concrete trucks in concrete production addresses both economic and sustainability needs. In the present article, wastewater from washing concrete trucks was added to cement pastes made with two different types of cement for comparison. OPC type CEM I 42.5 was compared to pozzolanic cement type CEM IV/B (P-W) 32.5 in terms of hydration behavior and compressive strength development. The hydration of ordinary Portland cement (CEM I 42.5) was accelerated, while the hydration of pozzolanic cement (CEM IV 32.5) showed a relatively lower total normalized heat. Cement pastes were produced from both cement types, and compressive strength, thermal analysis, and setting time tests were performed for their characterization. The early-age kinetics and compressive strength development of CEM I 42.5 pastes indicate that hydration with wastewater leads to a slight increase in compressive strength. Test concrete prepared with pozzolanic cement (CEM IV 32.5) exhibited increased capillary voids, which contributed to less favorable mechanical and durability performance. Compared to the reference concrete, compressive strength was reduced by 7% at 28 days. Wastewater utilization increased the initial absorption rate by approximately 20%, but the calculated chloride content at the exposed concrete surface decreased after the addition of wastewater compared to the control mix. The carbonation depth of concrete with wastewater increased by 1-2 mm, with an uneven penetration zone, but the compressive strength after carbonation increased. Overall, the type of cement used appears to significantly influence the performance of concrete prepared with wastewater. For wastewater collected from sedimentation tanks, replacing fresh water at a 100% rate and using it with pozzolanic cement to produce concrete, it seems that the mechanical properties and durability are only slightly affected.

Milling force is a parameter affecting wood processing quality, tool life, and energy consumption, and its variation is influenced by the multi-factor coupling of cutting parameters and tool geometric factors. This study systematically investigates milling forces during the processing of pine wood (Pinus sylvestris var. mongholica Litv.) using a hybrid modeling approach combining principal component analysis (PCA) and multiple linear regression (MLR). Firstly, PCA was employed to reduce the dimensionality of the tool rake angle (γ), helix angle (λ), cutting depth (h), feed per tooth (U_z), and triaxial milling forces (F_x, F_y, F_z); this eliminated the multicollinearity among variables and extracted the integrated features. Subsequently, an MLR model was constructed using the principal components as independent variables to quantitatively evaluate the contribution of each factor to milling forces. The results support the conclusion that PCA successfully extracted the first four principal components (cumulative variance contribution rate: 92.78%), with PC1 (49.16%) characterizing the comprehensive milling force effect and PC2 (15.03%) primarily reflecting the characteristics of the tool geometric parameters. The established MLR model demonstrated a high significance (R²: F_x = 0.915, F_y = 0.907, F_z = 0.852). The cutting depth exerted a significant positive driving effect on the triaxial milling forces via PC1 (each 1 mm increase in depth increased the PC1 score by 0.64 units, resulting in increases of 27.2%, 26.6%, and 21.8% for F_x, F_y, and F_z, respectively). The helix angle significantly suppressed F_y through PC2 (β = -0.090, p < 0.001), whereas the rake angle exhibited a weak negative effect on F_x via PC3 (β = -0.015). Parameter optimization identified the combination γ = 25°, λ = 30°, h = 0.5 mm, and U_z = 0.1 mm∙z^-1 as optimal, which reduced the triaxial milling forces by 62.3% compared to the experimental maximum. This study provides a theoretical foundation and novel parameter optimization strategy for the efficient, low-damage processing of wood materials.

Furfural extraction oil (FEO) is rich in polycyclic aromatic hydrocarbons (PAHs) and is hard to convert under mild conditions. To address this upgrade challenge, this study proposed a co-aquathermolysis process with corn stalk and a Ni/Mo hydrofining catalyst. Key parameters, including reaction temperature, time, catalyst dosage, and corn stalk dosage, were systematically evaluated for their impact on upgrade performance. Under optimized conditions (oil-to-water mass ratio 2:1, 280 °C, 18 h, 8 wt% catalyst, 8 wt% corn stalk), a viscosity reduction rate of 19.96% was achieved, significantly exceeding the 12.69% rate obtained without corn stalk. Meanwhile, the average molecular weight decreased from 430.0 to 353.3 g·mol^-1 and the aromatic ring index declined from 3.049 to 2.593. The H/C ratio increased to 1.568, and the sulfur content decreased to 0.09210%. ¹H NMR analysis revealed that corn stalk promotes long-chain scission and inhibits aromatic condensation, leading to a reduced aromatic carbon fraction. A detailed hydrocarbon composition analysis corroborated the conversion of tricyclic and tetracyclic aromatic hydrocarbons to monocyclic and bicyclic aromatic hydrocarbons. These findings offer valuable insights for the modification of FEO via aquathermolysis and establish biomass utilization as a practical strategy for FEO upgrades.

Rare-earth fluoride nanocrystals have emerged as promising scintillator materials due to their excellent optical properties, environmental stability, and ease of fabrication into flexible screens. However, their practical application is often hindered by persistent afterglow, a phenomenon caused by deep trap states that capture and slowly release charge carriers after X-ray excitation, which leads to signal overlap and image artifacts in dynamic imaging scenarios. This study addresses this critical challenge by developing Ce³⁺/Tb³⁺ co-doped NaLuF₄ nanoscintillators with suppressed afterglow. By introducing Ce³⁺ions as dopants into the Tb³⁺-activated NaLuF₄ host, we successfully quenched the characteristic long afterglow without compromising the intrinsic radioluminescence efficiency of the Tb³⁺ centers. The optimized nanocrystals were subsequently incorporated into a poly (vinyl alcohol) matrix to fabricate transparent, high-loading composite scintillator films. The resulting films exhibit negligible afterglow, maintain high spatial resolution, and demonstrate excellent radiation stability. This work presents an effective strategy for suppressing afterglow in rare-earth fluoride scintillators through targeted ion doping, which paves the way for their application in real-time, high-quality X-ray imaging technologies such as medical diagnostics and industrial inspection.

The valorization of dredged sediments represents a major environmental and logistical challenge, particularly in the context of forthcoming regulations restricting their marine disposal. This study investigates the potential of untreated dredged sediments as sustainable raw materials for geopolymer binder development, with the dual objective of sustainable sediment management and reduction in cement-related environmental impact. Dredged sediments from the Grand Port Maritime de Bordeaux (GPMB) were activated with sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃), both alone and in combination, with supplementary aluminosilicate and calcium-rich co-products, to assess their reactivity and effect on binder performance. A multi-scale experimental approach combining mechanical testing, calorimetry, porosity analysis, Scanning Electron Microscopy and Energy-Dispersive Spectroscopy (SEM-EDS), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), and solid-state Nuclear Magnetic Resonance (NMR) was employed to challenge the commonly assumed inert behavior of sediments within geopolymer matrices, to elucidate gel formation mechanisms, and to optimize binder formulation. The results show that untreated sediments actively participate in alkali activation, reaching compressive strengths of up to 5.16 MPa at 90 days without thermal pre-treatment. Calcium-poor systems exhibited progressive long-term strength development associated with the formation of homogeneous aluminosilicate gels and refined microporosity, whereas calcium-rich systems showed higher early age strength but more limited long-term performance, linked to heterogeneous gel coexistence and increased total porosity. These findings provide direct evidence of the intrinsic reactivity of untreated dredged sediments and highlight the critical role of gel chemistry and calcium content in controlling long-term performance. The proposed approach offers a viable pathway for low-impact, on-site sediment valorization in civil engineering applications.

Sheep wool is a low-value agricultural by-product with potential to contribute to more sustainable cementitious materials. This study investigates Segureña sheep wool fibres as reinforcement in cement mortars, comparing washed wool (W) and cement-encapsulated wool (E) at the same oven-dry raw wool dosages (0.5, 1.0, and 3.0 g per batch), and benchmarking against polypropylene (PP) fibres. Flexural and compressive strength were evaluated at 1, 7, and 28 days, whereas apparent density, water absorption, and thermal conductivity were assessed at 28 days. An intermediate dosage (1.0 g per batch) provided the most favourable mechanical response, while the highest dosage (3.0 g per batch) reduced performance, plausibly due to dispersion limitations and void formation. At 28 days, W-1 reached 9.65 ± 0.50 MPa in flexure (very close to PP-1) and 59.70 ± 1.05 MPa in compression, exceeding PP-1 in compression. Wool incorporation also reduced apparent density and yielded an observed reduction in thermal conductivity of up to ~18% at the highest dosage (single specimen per series). Overall, optimally dosed washed wool can deliver competitive mechanical performance while improving thermal behaviour, supporting circular-economy valorisation of waste wool in eco-mortars.

This paper presents an experimental framework that allows damage identification and retrofitting assessment in reinforced concrete (RC) beam with implemented piezoelectric lead zirconate titanate (PZT) sensors embedded into the concrete matrix. The study was conducted with concrete prepared from 30% refuse-derived fuel (RDF) fly ash and 70% cement as part of research on sustainable materials for structural health monitoring (SHM). Electromechanical impedance (EMI) was employed for detecting structural degradation, with progressive damage and evaluation of recovery effects made using root-mean-square deviation (RMSD) and conductance changes. Concrete beam specimens with dimensions of 700 mm × 150 mm × 150 mm and embedded with 10 mm × 10 mm × 0.2 mm PZT sensors were cast and later subjected to three damage stages: concrete chipping (Damage I), 50% steel bar cutting (Damage II), and 100% steel bar cutting (Damage III). Three retrofitting stages were adopted: reinforcement welding (Retrofitting I and II), and concrete patching (Retrofitting III). The results demonstrated that the embedded PZT sensors with EMI and RMSD analytics represent a powerful technique for early damage diagnosis, reserved retrofitting assessment, and proactive infrastructure maintenance. The combination of SHM systems and sustainable retrofitting strategies can be a promising path toward resilient and smart civil infrastructure.

The anaerobic thermal decomposition of plant biomass produces raw materials such as wood charcoal, wood oil, or biogas, which can be used to replace conventional fossil fuels. This enables the development of environmentally friendly alternatives to traditional fuels without the need to develop new technologies, such as engines. The aim of the study was to verify the substances produced during the anaerobic thermal decomposition process of wheat straw. Measurement was carried out by pyrolysis at eight selected temperatures between 350 °C and 1050 °C, with an increase of 100 °C. The analysis was performed on a pyrolyzer coupled to a gas chromatograph (PY/GC-MS). An ANOVA test was used to detect the significance of the results. Based on the ANOVA analysis, the distribution of compound classes in the three temperature regimes was statistically significant. Phenolic compounds reached their highest relative abundance (or relative content) at 650 °C, while PAHs (polycyclic aromatic hydrocarbons) were absent below 550 °C and increased sharply above 850 °C. The results illustrate the thermal decomposition pathway of straw biomass: low-temperature pyrolysis favors the formation of oxygen-rich bio-oils, while higher temperatures increase aromatic condensation and PAH production.