Journal of Materials Science最新文献

It is an innovative issue to degrade the organic pollutants in sea water by using ocean energy. The triboelectric nanogenerator (TENG) provides an ideal way to perform the idea. However, the output power of TENG is still insufficient for electrocatalytic degradation. In the paper, the mace-like core–shell Cu₂WS₄@ZnO heterojunction was prepared by a simple hydrothermal method. After mixed with PVDF and injected into the Ni(OH)₂/Ni foam with nano-needle array, the Cu₂WS₄@ZnO-PVDF/Ni(OH)₂ positive triboelectric layer with interspersed Ni foam electrode was formed. Then it was used to assemble the TENG with the negative triboelectric layer of nylon film on Cu sheet electrode. Obviously, the interspersed electrode and the inner embedded nano-needle array greatly increase the electrode area and decrease the effective dielectric thickness, the Cu₂WS₄@ZnO heterojunction induces obvious space-charge polarization and further increases the dielectric constant. All these innovative measures increase the instantaneous V_OC from 27.4 to 516.2 V, and the instantaneous J_SC from 0.23 to 0.82 mA/m². Then, the generated charges by TENG were successfully applied to degrade the typical dye polymers into harmless small molecules.

TP321 austenitic stainless steel exhibits excellent strength, toughness, and high-temperature corrosion resistance, making it a preferred material for critical components in high-temperature environments, particularly within the nuclear industry. When a nuclear power plant is operated in a high-temperature environment, its critical components are subjected to creep-fatigue interaction. In order to study the creep-fatigue performance of TP321 austenitic stainless steel at high temperatures, creep-fatigue tests are conducted and combine with microstructure inspection to analyze the effects of temperature, holding time and strain amplitude on the deformation and damage behavior of TP321 austenitic stainless steel. Then, three different life prediction models are used to predict the life of the creep-fatigue tests. The results show that increasing the test temperature, holding time and strain amplitude decreases the creep-fatigue life of the material. A tendency for cracks and cavities to promote each other’s expansion is observed, which is an important reason for the decrease in creep-fatigue life. Of the three life prediction models, the modified strain energy density (MSEDE) exhaustion model gives the most accurate lifespan prediction.

Lightweight and flexible materials with high dielectric constant and low dielectric loss are highly desirable for capacitor energy storage applications. In this study, a new class of microencapsulated graphene-reinforced silicone elastomer foam composite with excellent dielectric properties is presented. The silicone elastomer/graphene composite was prepared through foaming. The interfacial compatibility between silicone elastomer and graphene was enhanced by microencapsulated graphene, with graphene as the core and MF as the shell, through in-situ grafting reactions. The best microencapsulated graphene with a “salt-like” substance was achieved at a dispersing power of 840 W, a ratio of graphene to emulsifier of 1:100, and a mass ratio of graphene to wall material MF of 1:10. The silicone elastomer foam composite with optimized microencapsulated graphene content displays a dielectric constant of 27.26 @1000 Hz ~ 10 MHz with a significantly improved dielectric loss of @1000 Hz ~ 10 MHz, which is 2.45 times greater than the dielectric constant of graphene/silicone elastomer composite. This performance originates from the synergistic effect of micropore and microencapsulated. This interaction reaches its peak when the content of microencapsulated graphene is increased to 2.0 wt%, resulting in a dielectric constant of 48.26. The optimization of high-electric-constant foam composite will have far-reaching impacts on the sustainable energy and will be an important research topic in the near future.

Polyvinyl chloride (PVC) gel actuator is an ideal actuator choice for soft robotics, wearable devices, and human–computer interaction because of its excellent performances under electrical stimulation, such as low driving voltage, large deformation, and asymmetric deformation. These excellent performances originate from the enrichment layer in PVC gel formed by the migration of plasticizers and charge transfer. The intermolecular interactions between plasticizers and PVC molecular chains are crucial in plasticizers migration, but the effect of these factors on actuator’s performance is still unclear. In this study, the effects of types of plasticizes with varying molecular volumes on the actuation performance of PVC gel actuators were systematically investigated using experiments and simulations. The network structure of PVC gels typically consists of a primary network formed by physical entanglements and microcrystals and a secondary network constructed by intermolecular interactions between primary network and plasticizers, including hydrogen bonds and van der Waals forces. The experimental and simulation results indicate that intermolecular interactions significantly influence the migration rate of plasticizers within the PVC gel. The PVC gel actuators prepared with large-volume plasticizers containing a benzene ring structure exhibit the strongest intermolecular interactions. When subjected to an applied stimulus voltage of 800 V, the actuator made with benzene-ring-based plasticizers achieves a maximum displacement of only 23%, along with a relatively longer response time compared to the gel incorporating linear plasticizers. These results provide valuable insights into the relationship between the internal structure and actuation performance of PVC gels for their potential applications in robotic devices and medical assistive equipment.

Electrode materials with high electrochemical performance is of great importance for facilitating the practical large-scale application of advanced supercapacitors. In this paper, polyaniline@reduced graphene oxide (PANI@rGO) modified carbon cloth (CC) (ACC-PANI@rGO) was successfully prepared as the electrode for the construction of high-performance flexible solid-state supercapacitors (FSSC). The pristine carbon cloth was doubly activated by Hummers method and electrochemical treatment for the improvement of hydrophilicity and capacitance. Followed by the polymerization of aniline and adsorption and reduction of GO on the surface of treated CC, the flexible ACC-PANI@rGO electrode was obtained. It showed a maximum specific capacitance of 670 F g⁻¹ at a current density of 0.5 A g⁻¹. Further, the rGO layer was used as a protective layer to alleviate the expansion and contraction of PANI during the long-term process, thereby realizing the enhancement of cycling stability of ACC-PANI@rGO. The capacitance retention of ACC-PANI@rGO reached 87.5% of the initial specific capacitance after 6000 cycles at a high current density of 10 A g⁻¹. The synergistic effect of the components enabled the FSSC assembled by two symmetrical ACC-PANI@rGO electrodes to achieve a high energy density of 111.96 µWh cm⁻² at a power density of 0.5 mW cm⁻² Moreover, it retained about 91.2% of the specific capacitance when repeatedly bent to 180° for 500 times, which is promising for the application of flexible energy storage devices.

In light of the mounting environmental challenges, there is a pressing need to investigate the development of a lead-free energy storage solution with excellent energy storage properties. Herein, lead-free dielectric energy storage ceramics, namely (1−x)Bi_0.48Na_0.48Ba_0.04TiO₃₋xLa_1/3NbO₃ (BNBT-LN), are synthesized using a traditional solid-phase method. The incorporation of LN into BNBT ceramics led to the observation of rhombohedral and tetragonal phase transitions at room temperature, while randomly distributed nanodomains were induced. The charge mismatch induced by heterovalent cation doping alters the dielectric anomaly peaks, resulting in the ceramics remaining highly polarized. Furthermore, the enhancement of grain boundary density optimizes the ceramic breakdown electric field. As a result, the 0.91BNBT-0.9LN ceramics obtain excellent energy storage properties (W_rec = 7.7 J cm⁻³, (eta) = 73.8%, E = 560 kV cm⁻¹), along with good frequency stability, temperature stability, and discharge performance. This work proposes a novel strategy to develop environmentally friendly dielectric capacitors with superior energy density.

The importance of hydrogen storage for mobile applications remains a timely subject with respect to a sustainable energy economy. Magnesium is a viable material for hydrogen storage by insertion, because of its low weight, abundance, and non-toxicity. A major obstacle for magnesium hydrides to be used for hydrogen storage is the high temperature for release, making it impracticable. However, nanoscale magnesium shows promising hydrogen desorption temperatures, which is employed in the form of nanoparticles in this work. A palladium “nanoneedle” network was used to speed up hydrogen transport to and from the magnesium nanoparticles in a matter of minutes. By using the optical changes that accompany the presence of hydrogen in magnesium, hydrogen transport was studied. The palladium nanoneedle “highways” improved the (de-) hydrogenation of magnesium nanoparticles by at least a factor two, which could be a template for further improvements in hydrogen storage systems.

Bismuth vanadate (BiVO₄, BVO) is an ideal photoabsorber for the photoelectrocatalytic water splitting, but its performance and photostability limit its commercial application. Therefore, enhancing the catalytic performance and stability becomes an increasingly crucial issue. In this study, we report a composite catalytic material poly (3,4-ethylenedioxythiophene, EDOT) (PEDOT)-modified β-FeOOH nanosheets loading onto the surface of BVO through the hydrolysis of Fe³⁺ in BVO semiconductor film and the catalytic polymerization of EDOT form the conductive polymer. The structure facilitates the catalytic process, and when it is used in photoelectrocatalysis oxygen evolution reaction, it exhibits a photocurrent density of 3.3 mA cm⁻² at 1.23 V versus standard hydrogen electrodes. Mechanistic studies show that the introduction of PEDOT-modified β-FeOOH optimized the electrode/electrolyte contact interface, adjusted the defect state, and provided catalytically active sites during the catalytic process. This study provides a feasible idea for exploring the catalytic mechanism of BVO-based photoelectrode and designing catalysts.

Cold spray additive manufacturing (CSAM) has great industrial potential due to its high deposition rate and the possibility of building metallic alloys and composite parts once the process is conducted in a solid state, preserving many raw materials properties. A material highly studied for CSAM is the Ti6Al4V alloy, which is used in medical implants and aeronautical structural components. It has a matrix of two phases (α + β) with different crystallography arrangements, compact hexagonal, and body-centered cubic, which can tailor the mechanical properties according to its volumetric percentage. To improve CSAM-ed material ductility and strength and homogenize its residual stress, heat treatments (HTs) have been employed. These HTs sinter the deposited particles, enhancing their cohesion and other properties. This study focuses on the effect of the HT parameters on the characteristics of CSAM-ed Ti6Al4V freeform parts. HT reduces the hardness from 385 in as-sprayed condition to around 320 HV_0.3, conserving the porosity close to 4.0%, and increasing the HT temperature from 600 to 1000 °C improved the amount of phase β in the α grains boundaries. The findings of this study will provide valuable insights into the impact of HT on the mechanical properties and microstructure of CSAM-ed components, thereby aiding in the optimization of this manufacturing process for the Ti6Al4V alloy.