No abstract

The advantages of ionic conductors have attracted great interest worldwide because they can fit the requirements that standard electrical conductors struggle to meet. Yttria-stabilized zirconia (YSZ) is the most common ionic conductor for various practical applications. In this study, in order to bring ionic conductors into the field of soft technology, transparent YSZ films with superior mechanical flexibility were epitaxially grown on a muscovite substrate by pulsed-laser deposition. The epitaxial relationship between YSZ and muscovite has been well established, indicating a high-crystallinity thin film. The heterostructure of YSZ/ muscovite exhibits excellent ionic conductivity with great mechanical flexibility. The smallest bending radius of this heterostructure that can be achieved is ∼10 mm with excellent mechanical cyclabilty (>800 cycles) and stability (>10 5 s), serving as a new platform to fabricate highly flexible ionic conductors.

Herein, a facile and rapid surface-plasma-induced method was adopted for the one-pot synthesis of a 2D/0D/2D hybrid nanostructure consisting of N,S co-doped carbon dots (NSCD) intercalated few-layer MoS2/graphene nanosheets (MoS2/G) as an excellent catalyst for the hydrogen evolution reaction (HER). In this process, bulk MoS2 and graphite foil served as the sources of MoS2 and graphene nanosheets, respectively, while glucose and thiourea served as the source of NSCD. The sturdy integration of 0D NSCD and 2D MoS2/G in a well-constructed ternary composite provided a huge number of edge active sites with tunable and extraordinary physicochemical properties for electron transport, facilitating HER performance. The optimal NSCD@MoS2/G exhibited a superior catalytic activity toward HER with a low onset potential (37 mV), an overpotential of 98 mV at 10 mA cm–2, and a Tafel slope as small as 53 mV dec–1, which were better than other 2D electrocatalysts. The increase in double-layer capacitance for NSCD@MoS2/G (12.2 mF cm–2), which was 2-fold of the MoS2/G sample, is strong evidence of the large catalytic edge sites and electrical coupling in the NSCD@MoS2/G ternary system. Moreover, the strong bonding and interaction between NSCD and MoS2/G nanosheets enabled outstanding long-term stability and structural integrity, displaying 95 and 90% activity retention at 10 and 50 mA cm–2 after 48 h i–t test, respectively. This approach paves the way to efficient syntheses of 2D/0D/2D heterostructures with great potential for various energy-related applications.

Purpose: Determine the state of stress-strain, formation and development cracks, three-layer beam diagrams of load-compression stress, load-tension stress, load-vertical displacement relationships with a change in concrete grade. Design/methodology/approach: This paper presents the results of an ANSYS numerical simulation analysis involving stress-strain state and cracking of the steel fiber concrete layers of three-layer reinforced concrete beams with the upper and lower layers. With a cross-section of 150x300 mm, a total span of 2200 mm and an effective length of 2000 mm, the middle is a normal concrete layer. Under two-point loads, all the beam samples were tested. The research simulated three-layer concrete beams in different layers of beams with a change in concrete grade, and compared with and without the use of steel fibers in layers of concrete beams, including the nonlinearity of the material considered. Findings: A diagram of the formation and development of cracks in three-layer concrete beams has been constructed by the study results, determining the load at which the concrete beams begin to crack, the load at which the concrete beams are damaged. In the middle of three-layer steel fiber reinforced concrete beams, load-compression stress, loadtension stress, load-vertical displacement relationships are established. Study results show that these three-layer concrete beams appear to crack earlier than in other cases in cases 2 and 3, but the beam bearing capacity is damaged at 67 kN, the earliest in case 3. And case 6 at 116 kN is the latest. The effects of case 1 and case 3 are small compared with and without the use of steel fibers in cases, while the effects of case 5 and case 6 are very high. Research limitations/implications: The research focuses only on the change of concrete grade in the layers, but the input parameters affecting three-layer steel fiber concrete beams have not been researched, such as the number of tensile steel bars, tensile steel bar diameter, steel fiber content in concrete, thickness variation in three-layer concrete beam layers, etc. Practical implications: Provides a result of experimental study and ANSYS numerical simulation in multi-layer steel fiber concrete beams. Originality/value: The analysis of multi-layered steel fiber concrete beams using experimental and simulation methods shows that other parameters influencing the beams will continue to analysis the working stages of three-layer beams.

Plasma nitridation of an amorphous SiO2 layer on Si (110) substrate can form well-aligned α-Si3N4 crystallites in fibrous morphology. Nitriding is performed at a temperature in the range of 800–1000 °C by using microwave plasma with a gas mixture of N2 and H2. Raman spectroscopy shows the characteristics of an α-Si3N4 phase without other crystalline nitrides. As shown by scanning electron microscopy, the formed α-Si3N4 microfibers on the Si substrate can be in a dense and straight array nearly along with Si <11¯0>, and can have a length over 2 mm with a diameter in the range of 5–10 μm. Structural characterization of scanning transmission electron microscopy in cross section view reveals that the elongated α-Si3N4 crystallites are formed on the surface of the nitrided SiO2/Si (110) substrate without any interlayers between Si3N4 and Si, and the longitudinal direction of α-Si3N4 appears mainly along <112¯0>, which is approximately parallel to Si <11¯0>.