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We investigated the growth and electronic properties of Co-phthalocyanine (CoPc) molecule deposited on iron film with different structures (pseudomorph-fcc and bcc) and on iron nanowires by scanning tunnelling microscopy and X-ray absorption spectroscopy (XAS). CoPc molecules self-assemble in a two-dimensional (2D) arrangement with the molecular plane parallel to the iron surfaces, and the local order is lost after the first layer. The molecule ferromagnet interaction causes the broadening of Co and N unoccupied molecular states as well as different electronic distribution of N states as a function of the atomic structure of iron surface. The ferromagnetic coupling between the molecule and the iron film is dominated by the electronic interaction between Co and the first Fe layer. CoPc 2D arrangement turns into 1D by using as a template the iron nanowire grown on a facet surface of oxidized Cu(332) surface. CoPc molecules interact weakly with the iron nanowires manifesting a substantial Co 3d(z) spectral feature in XAS spectrum and the possibility of a magnetic interaction between Co moment and iron nanowires. Both CoPc 2D and 1D arrangements can open up new interesting scenarios to tune the magnetic properties of hybrid interfaces involving metallorganic molecules.

Silicon-based nanosheets (SNS) were synthesised via a mild (60 °C) and time-saving (8 h) modified topochemical method. Then, Cu3(BTC)2 and SNS@Cu3(BTC)2 were successfully synthesised by microwave irradiation, and their characteristics and hydrogen storage performance were analysed by multiple techniques. The accordion-like SNS exhibited void spaces, a unique low buckled structure, and ultrathin, almost transparent, loosely stacked layers with a high specific surface area (362 m2/g). After in-situ synthesis with Cu3(BTC)2, the SNS compound achieved a high specific surface area (1526 m2/g), outstanding hydrogen storage performance (5.6 wt%), and a desirable hydrogen diffusion coefficient (10−7). Thus, SNS doping improved the hydrogen storage performance of Cu3(BTC)2 by 64% through electron transfer reactions with Cu enabled by the unique composite nanostructure of SNS@Cu3(BTC)2. This study presents a promising method of synthesising SNS and porous composite materials for hydrogen storage.

This investigation aims to study a novel biologically derived coating applied on Ti alloy substrates. Obtained from a low-cost fish bone resource, a nanocrystalline hydroxyapatite has been synthesized and converted to an organic suspension. Coating was then manufactured by a high-velocity suspension flame spray process. The microstructure, phase composition, coating thickness, and roughness of hydroxyapatite (HA)-coated samples were studied. The results indicated the presence of both hydroxyapatite and β-tricalcium phosphate phases and the final coating layer was uniform and dense. In vitro bioactivity and biodegradability of the HA/Ti composite samples were estimated by immersion in simulated body fluid. Remarkable reductions in Ca2+ and PO43- ion concentrations were observed as well as low weight loss percentage and a slight variation in the pH value, indicating the generation of an apatite layer on the surface of all studied samples. Scanning electron microscopy, energy-dispersive x-ray analysis, and inductively coupled plasma–optical emission spectrometry confirm these results. Thus biological derived HA coatings are a promising candidate to enhance bioactivity and biodegradability of bone implants. To demonstrate feasibility on commercial medical components, a medical screw was coated and evaluated., Science & Technology Development Fund (STDF), Projekt DEAL

In this study, anode supported micro-tubular solid oxide fuel cells (SOFCs) are fabricated by extrusion method and the effects of powder size, thickness and sintering temperature of the anode functional layer (AFL) on the electrochemical performance is experimentally investigated. For this purpose, four different commercial NiO powders are tested as initial powder for the fabrication of the anode functional layer. The thickness of AFL is also considered by varying the number of coatings. After deciding the optimum initial NiO powder size used in AFL and AFL thickness, the effect of pre-sintering temperature is examined. The performance tests are performed at an operating temperature of 800 °C under hydrogen and air. The microstructures of the samples are also investigated by a scanning electron microscope. The best peak power density is obtained as ∼0.5 W/cm2 from the cell having a single layer anode functional layer pre-sintered at 1250 °C prepared by NiO powders with 4 m2/g surface area.

Half-metallic Heusler alloys typically have in-plane magnetic anisotropy, which can be converted to perpendicular by attaching MgO or heavy metal, e.g., Pt, layers as similarly applied for conventional ferromagnets. Recently we have found body-centered cubic (bcc) seed layers, e.g., V and W, to induce perpendicular anisotropy in Heusler-alloy films above, however, they show small giant magnetoresistive (GMR) ratios in spin-valve structures to date. This is partially because of the large resistivity of the seed layer and the nonmagnetic layer in the spin-valve. In this study, we have systematically investigated nonmagnetic overlayers and have found that a Ag layer best maintains the perpendicular anisotropy. The corresponding GMR devices have then been fabricated and characterized, achieving the GMR ratio of ~0.03% at room temperature. Such bcc seed layers can offer an alternative method for perpendicularly magnetized GMR junctions for applications.

In this study, the effect of the addition of vanadium (V) on the densification, microstructure, and wear behavior of borosintered powder metallurgy steels was investigated. Ball-milled powders containing 0, 1, 5 and 10 wt.% V were cold-compacted under 200 MPa pressure and then subjected to borosintering at 1100°C for 2 h in ambient air. The characterization of the boride layers formed after borosintering was conducted by scanning electron microscopy, X-ray diffraction, microhardness tests, nanoindentation, surface roughness measurements, and ball-on-disk-type wear tests. Wear testing was carried out under 10 N load for a total sliding distance of 250 m in ambient air and in a 3.5% sodium chloride (NaCl) solution. While the thickness of the boride layer decreased with increasing V content, its hardness and modulus of elasticity also increased, owing to the formation of additional vanadium boride (VB) and vanadium carbide (V2C) phases. Wear resistance increased with increasing V content, and the samples tested in 3.5% NaCl displayed lower coefficients of friction and higher wear resistance compared to the samples tested in ambient air. Reduced wear in 3.5% NaCl was attributed to the cooling and lubricant effects provided by the 3.5% NaCl solution.

A new analytical model for the calculation of the shielding effectiveness of multilayer infinite metal meshes is proposed. This model is based on the previously developed one for single- and double-layer metal shielding grids. It enables accurate and fast calculations of the shielding effectiveness of multilayer metal meshes with different air interlayers in a wide frequency range. The proposed model considers the ratio of the wire diameter to the aperture size and the layer interspacing. The model is validated by comparison of the results of calculations with the HFSS simulation results. The model validity in a wide frequency range as well as its calculation speed far bigger than that for HFSS is demonstrated. The results of calculations show that the shielding effectiveness of metal meshes can be effectively improved by increasing the distance between the mesh layers and the ratio of the wire diameter to the aperture size.

This article presents an ultracompact bandpass filter (BPF) realized by slow wave substrate integrated groove gap waveguide (SW-SIGGW). The SW-SIGGW is composed of two layers of the dielectric substrate, in which periodic mushroom-type electromagnetic band-gap (EBG) unit cells are employed as packaging structures. The gap layer is realized by the upper substrate, and the via-patch mushrooms are designed on the lower substrate. Due to the slow wave structure in the form of periodical metallic via-holes designed on the lower substrate, the guided wavelength is reduced by about 52.8% compared with normal SIGGW. A dual-band resonator and a cascaded second-order BPF are designed based on SW-SIGGW. Compared with the conventional second-order SIGGW BPF, the proposed SW-SIGGW BPF achieves a 62.6% reduction in the area. By adopting vertical stacking technology, the area of the SW-SIGGW BPF is further miniaturized. The final area of the stacked SW-SIGGW BPF is only 18.7% of the conventional filter based on normal SIGGW without slow wave and stacked structure, which is very competitive for the room-limited applications. A prototype of the stacked SW-SIGGW BPF with 5.4% and 7.4% fractional bandwidths at 11.8 and 18 GHz is fabricated and measured. A good agreement between the measured and simulated results verifies the validity of the miniaturized design of SW-SIGGW BPF.

In this letter, a compact bandpass filtering power divider with tunable bandwidth based on spoof surface plasmon polaritons (SSPPs) and substrate integrated waveguide (SIW) is proposed. The hybrid-SIW-SSPP structure shows good potential to expand the scope of bandwidth control of the device. The bandwidth can be designed in a wide range by simply optimizing its dimensions or loading interdigital structures (ISs). Defected ground structure (DGS) is also introduced on the bottom layer to further improve the out-of-band suppression. And good isolation can be obtained via additional resistors welded across the SSPP slot. A prototype loaded with dumbbell-shape DGS and two resistors is fabricated with an overall size of 45 mm x 18 mm x 0.5 mm. Both $S_{21}$ and $S_{31}$ are around -3.8 dB within the whole X-band. The simulated and measured results agree with each other well.

The commercialization of Solid oxide fuel cells (SOFCs) has always been limited by the poor catalytic activity and the severe degradation of cathode in the intermediate and low operating temperature. Here we report a Gd0.8Ce0.2O1.9−δ (GDC) coated La0.8Sr0.2Co0.2Fe0.8O3-δ (LSCF) composite cathode material, which can significantly improve the electrochemical performance and durability of LSCF cathode. The effects of different GDC coating thickness on the electrochemical performance and long-term working stability of LSCF cathode are investigated, and the optimal coating thickness is established. The polarization impedance of GDC coated LSCF (LSCF@GDC) cathode with 9 nm of GDC coating is 0.08 Ω cm2 at 800 °C, which is only one quarter of that of the raw LSCF cathode, and the degradation rate of constant current polarization with 100 mA cm−2 is only 0.42%/100 h at 700 °C, which is far less than that of the raw LSCF cathode. The X-ray photoelectron spectroscopy (XPS) results show that the degree of Sr segregation decreases with the increase of the thickness of the coated GDC layer. The potential LSCF@GDC composite material is expected to increase the operability of SOFCs and accelerate its commercialization.

A novel nano-heterojunction photocatalysts of CdS/MoS2 with appropriate interfacial contact was successfully obtained by the facile two-step hydrothermal synthesis. The MoS2 ultrathin layer was well combined with CdS nanosheets and formed the interaction, which facilitated the transfer and separation of charges. The CdS/MoS2 15 wt% possessed much higher H2 evolution photocatalytic performance (35.24 mmol h−1 g−1), exhibiting an 85.95 times enhancement as compared to that of pure CdS (0.41 mmol h−1 g−1). Moreover, the photochemical stability of CdS/MoS2 heterojunctions was excellent, which showed no significant decrease in activity after four cycles of experiments. The finding provides a novel method to integrate the structure of MoS2 with CdS, which exhibits great potential in solar energy conversion.

The constraint effect with material parameters mismatch between every parts of planar solid oxide fuel cell (SOFC) plays an important role in the operation life. In this study, the mismatch effect of material creep strength coefficient on creep damage and failure probability of planar SOFC was investigated by finite element method. The results show that the maximum equivalent creep strain and failure probability of SOFC are located in the outer corner of sealant layer. With the increase of the creep strength coefficient of the sealant layer, the maximum creep damage, damage area and failure probability of the sealant layer all increase gradually. The creep strength coefficient of the sealant layer is suggested to be smaller than that of the frame material, which will improve service life of SOFC.

Radiation-induced graft polymerization is introduced to effectively fabricate proton exchange membrane based on 12.5 μm fluorinated ethylene propylene (FEP) film. The graft side chains penetrate FEP film and distribute inside the bulk matrix evenly. The membranes exhibit hydrophilic/hydrophobic microphase-separated morphology as well as good thermal stability. The influences of irradiation parameters on the membrane property are investigated and the resulting membranes (named FEP-g-PSSA) exhibit excellent physicochemical properties. Membrane with 27.48% degree of graft and 130.1 mS cm−1 proton conductivity is employed for fuel cell performance measurement. Under optimized operate conditions (80 °C, 75% relative humidity), the power density could reach up to 0.896 W cm−2, inspiring for fuel cell application. The mass-transport-controlled polarization of membrane electrode assembly (MEA) based on FEP-g-PSSA membrane is higher than Nafion® 211 within the whole current density range and the gap is widening with increasing current density. At 2.0 A cm−2, the mass transfer polarization of FEP-g-PSSA reaches up to 0.204 V, far higher than Nafion® 211 (0.084 V). By promoting the compatibility between the ionomer in the catalyst layer and FEP-g-PSSA membrane and optimizing the membrane/catalyst layer/gas diffusion layer interfaces, the fuel cell performance could be significantly enhanced, making the FEP-g-PSSA membranes promising in fuel cell application.

Interface recombination is one of the factors limiting the performance of Cu(In,Ga)Se_2 (CIGS). Especially in the absence of band grading at the front and rear surface, interface passivation approaches become important to improve device performance. The integration of an oxide layer as passivation layer at the front surface of the CIGS requires meticulous considerations in order not to impact the further steps of the solar cell production. In this article, a novel approach is reported to try to tackle the problem of interface recombination at the front surface of CIGS without affecting further solar cell production steps. In this approach, an Al_2O_3/HfO_2 multi-stack layer with contact openings is applied. NaCl template patterning with preliminarily selected parameters was used to create a homogeneous pattern of contact opening on the CIGS surface and allow the current flow in the device. After the removal of the NaCl islands, the holes in the multi-stack (openings) were visualized by scanning electron microscopy. In addition, energy-dispersive X-ray spectroscopy (EDS) was performed before and after chemical bath deposition of the buffer layer. The EDS result confirmed that the undesired etching of the Al_2O_3 layer during buffer layer deposition was prevented by using a thin HfO_2 layer. Solar cells were produced by using preliminarily selected parameters for the multi-stack design. As a result, without having a significant negative impact on the solar cell parameters, a device design was achieved which is almost comparable with the reference device. In addition, options for future improvement and development are discussed. European Union's H2020 Research and Innovation Program [715027]

Resistive type superconducting fault current limiter (R-SFCL), based on REBCO coated conductor, is of great help to enhance the safety and stability of power system. When the fault current appears, the current is transferred from the superconducting layer to the metal layers with large resistance in the REBCO coated conductor, so as to limit the current. However, the interface resistance affects the current distribution between different metal layers. What's more, the inhomogeneity effect of REBCO coated conductor has great influence on the quench characteristics of R-SFCL. In this work, the current transfer model of REBCO coated conductor is established, and the influence of interface resistance on current distribution is analyzed. The inhomogeneity effect of resistivity parameters and critical current of REBCO coated conductor is analyzed. One non-inductive bifilar coil is fabricated for DC impulse current test, and the influence of inhomogeneity effect of REBCO coated conductor on quench characteristics is verified.

The open-circuit voltage (V $_\text{oc}$ ) of CdTe-based photovoltaics may be limited by carrier recombination at interfaces (front or back) or in the absorber layer. Reduction in recombination of a given dominant mechanisms can lead to improved device performance if the remaining mechanisms turn on in a narrow bias range just below the open circuit voltage. In this article, we demonstrate enhanced performance by incorporating solution-processed Cu $_\text{x}$ AlO $_\text{y}$ to form a back-buffer layer in CdSe/CdTe devices. Outstanding minority carrier lifetimes of 656 and 4.2 ns were measured with glass side and film side illumination for device stacks processed with Cu $_\text{x}$ AlO $_\text{y}$ . Devices demonstrated efficiencies of up to 17.4% with V $_\text{oc}$ of 859 mV, FF of 75.6% and J $_\text{sc}$ of 26.9 mAcm−2 while the efficiency of the reference device without the back-buffer layer was 16.5% with V $_\text{oc}$ of 839 mV, FF of 70.6%, and J $_\text{sc}$ of 27.9 mAcm−2.

The rational design of highly efficient, economical and environment-friendly electrocatalysts is currently an important goal of research on renewable energy conversion and storage. Herein, a facile metod was developed to construct two-dimensional composites, which consist of exfoliated CoPS3 nanosheets grafted onto defective N-doped carbon (DNC) derived from spent tea leaves. The CoPS3@DNC composites demonstrate remarkable oxygen evolution reaction (OER) performance in an alkaline medium, with an overpotential of 297 mV at 10 mA cm− 2 and a small Tafel slope of 51.8 mV dec−1, which is better than that of commercial IrO2 catalysts. Our experimental evidence reveals that the enhanced OER performance of this hybrid catalyst can be attributed to the interfacial effect of exfoliated CoPS3 and N-doped carbon defects (electron transfer from the CoPS3 layer to DNC). This work suggests a promising interface engineering technique for developing highly efficient and non-precious OER catalysts based on layered transition-metal trichalcogenides.

In this work, coupling effects of water content, temperature, oxygen density, and polytetrafluoroethylene (PTFE) loading on oxygen transport through an ionomer thin film on a platinum surface in a catalyst layer of a proton exchange membrane (PEM) fuel cell are investigated using molecular dynamics approach. Taguchi orthogonal algorithm is employed to comprehensively analyze the coupling effects in a limited number of cases. It is found that the effect of operation temperature is the weakest among the four factors, which has the smallest effect index 14.4. Coupling effects including the PTFE loadings on the oxygen transfer through the ionomer thin film is uncovered. Less PTFE loadings should be beneficial for the oxygen transfer. The chemical potential gradient is considered as the major driven force for the oxygen transport through the ionomer thin film, and oxygen density is the dominating factor, significantly affecting the chemical potential in the thin film.

The cathode activity in a solid oxide fuel cell can be promoted by introducing various catalysts to reduce its polarization resistance towards oxygen reduction, and thus improve cell performance. In this work, the La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode surface is modified by the infiltration of Pr6O11 and the power density at 0.8 V and 750 °C is improved by 21%. Moreover, by replacing the traditional barrier layer Gd0.2Ce0.8O1.9 with mixed conducting Pr0.1Gd0.1Ce0.8O1.9 (PGCO), the power density increases by 38%. The ohmic resistance is dramatically reduced by applying the PGCO interlayer. The distribution of relaxation time was used to analyze the mechanism for which the polarization resistance was decreased, attributing to the mixed conduction nature in PrOx. An increase of power density, ∼0.358 W/cm2 (71%) at 0.8 V, is achieved with the implementation of both surface modification and buffer layer engineering.

Coulomb explosion, characterized by coulomb repulsion between the particles with the same charge on the surface of a material, has been used to realize exquisite nano-manipulation, however, researchers usually only found one aspect of application of Coulomb explosion when they utilized it. Herein, we successfully design a “metal@insulator” based Coulomb explosion process through irradiating oxidized Topological Crystalline Insulator SnTe under electron beam. The occurrence of Coulomb explosion mainly due to the oxide encapsulated SnTe retained the metallic surface state, which not only can be positively charged, but also can realize charge accumulation through the shield effect of the insulate oxide layer. By changing experimental conditions and carefully studying various experimental phenomena, we conclude six aspects of application, namely speculating the metallic surface state of oxide-encapsulated SnTe, controllable fabricating nanoplates, observing the PVD (Physical Vapor Deposition) process under low temperature, rapid coating film, unraveling the oriented attachment and self-recrystallization of larger nanocrystals and fabricating hollow structure. Our findings are important for utilizing of Coulomb explosion as well as other EBI techniques to conduct nano-manipulation.

This study presents a detailed review on the ultrathin catalyst layer (UTCL) design strategy for high-performance proton exchange membrane fuel cell (PEMFC). Specifically, the motivation towards the further reduced Pt loadings by applying the UTCL electrode design is firstly introduced from both the historical and mechanism deductions. Then, the recent developments on the UTCL designs belonging to different classifications are summarized with their respective merits. In particular, the critical issues remained on these ultra-thin, low Pt-loaded electrodes are proposed with alternative solutions. Finally, the whole review is concluded with the perspectives on the possible future directions settling the remaining challenges.

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We report the design and development of vertical 1.5 kV GaN p–n diodes that consists of an 8 μm drift layer and a thin p-GaN/p+-GaN layer grown by metal–organic chemical vapor deposition (MOCVD) on a hydride vapor phase epitaxy (HVPE) synthesized GaN substrate. The drift layer has a low doping concentration of ∼9 × 1015 cm−3 and electron mobility ~ 1200 cm2/Vs at room temperature. The fabricated devices with an optimized guard ring design as edge termination exhibit a breakdown voltage of > 1.5 kV with specific on-resistance of ~ 1.5 mΩ cm2. The breakdown efficiency of these diodes is over 72% when compared to ideal analytical calculations and over 90% with respect to numerical simulations. Temperature-dependent measurements show that the devices have a positive temperature coefficient suggesting the avalanche breakdown mechanism. These results suggest that these MOCVD grown vertical GaN-on-GaN (HVPE) p–n diodes are promising for low-mid range voltage power switching applications.

Bearings play a vital role in the operation of a two-axis system. Long-term bearing use inevitably produce bubbles and frictional damage. Therefore, the protection of bearings is critical for the stable operation of a two-axis system. In this study, a TiO2 nanofilm is used to physically protect a bearing. The discretization method is used to analyse the cavitation process. Cavitation primarily occurs on the front surface of the pad during bearing operation. A finite element analysis of a bearing pad coated and not coated with TiO2 nanofilms shows that TiO2 nanofilms can effectively absorb the cavitation force exerted on pads, thereby reducing inflicted damage. Moreover, the TiO2 nanofilm reduces the friction coefficient of the pad surface, promoting good bearing capacity of the bearing during rotation. The TiO2 nanofilm serves as a protective layer that improves the anti-wear and bearing performance of a two-axis system.

Due to the compact two-dimensional interlayer pore space and the high density of interlayer molecular adsorption sites, clay minerals are competitive adsorption materials for carbon dioxide capture. We demonstrate that with a decreasing interlayer surface charge in a clay mineral, the adsorption capacity for CO2 increases, while the pressure threshold for adsorption and swelling in response to CO2 decreases. Synthetic nickel-exchanged fluorohectorite was investigated with three different layer charges varying from 0.3 to 0.7 per formula unit of Si4O10F2. We associate the mechanism for the higher CO2 adsorption with more accessible space and adsorption sites for CO2 within the interlayers. The low onset pressure for the lower-charge clay is attributed to weaker cohesion due to the attractive electrostatic forces between the layers. The excess adsorption capacity of the clay is measured to be 8.6, 6.5, and 4.5 wt % for the lowest, intermediate, and highest layer charges, respectively. Upon release of CO2, the highest-layer charge clay retains significantly more CO2. This pressure hysteresis is related to the same cohesion mechanism, where CO2 is first released from the edges of the particles thereby closing exit paths and trapping the molecules in the center of the clay particles.

The thermodynamic properties of few-layer graphene arbitrarily stacked on LiNbO3 crystal were characterized by measuring the parameters of a surface acoustic wave as it passed through the graphene/LiNbO3 interface. The parameters considered included the propagation velocity, frequency, and attenuation. Mono-, bi-, tri-, tetra-, and penta-layer graphene samples were prepared by transferring individual graphene layers onto LiNbO3 crystal surfaces at room temperature. Intra-layer lattice deformation was observed in all five samples. Further inter-layer lattice deformation was confirmed in samples with odd numbers of layers. The inter-layer lattice deformation caused stick–slip friction at the graphene/LiNbO3 interface near the temperature at which the layers were stacked. The thermal expansion coefficient of the deformed few-layer graphene transitioned from positive to negative as the number of layers increased. To explain the experimental results, we proposed a few-layer graphene even–odd layer number stacking order effect. A stable pair-graphene structure formed preferentially in the few-layer graphene. In even-layer graphene, the pair-graphene structure formed directly on the LiNbO3 substrate. Contrasting phenomena were noted with odd-layer graphene. Single-layer graphene was bound to the substrate after the stable pair-graphene structure was formed. The pair-graphene structure affected the stacking order and inter-layer lattice deformation of few-layer graphene substantially.

Amorphous aluminum oxide (alumina) thin films are of interest as inert chemical barriers for various applications. However, the existing literature on the aqueous stability of atomic layer deposited (ALD) amorphous alumina thin films remains incomplete and, in some cases, inconsistent. Because these films have a metastable amorphous structure─which is likely partially hydrated in the as-deposited state─hydration and degradation behavior likely deviate from what is expected for the equilibrium, crystalline Al2O3 phase. Deposition conditions and the aqueous solution composition (ion content) appear to influence the reactivity and stability of amorphous ALD alumina films, but a full understanding of why these alumina films hydrate, solvate, and/or dissolve in near-neutral pH = 7 conditions, for which crystalline Al2O3 is expected to be stable, remains unsolved. In this work, we conduct an extensive X-ray photoelectron spectroscopy investigation of the surface chemistry as a function of water immersion time to reveal the formation of oxyhydroxide (AlOOH), hydroxide (Al(OH)3), and possible carbonate species. We further show that brief postdeposition exposures of these ALD alumina films to an air plasma anneal can significantly enhance the film's stability in near-neutral pH aqueous conditions. The simplicity and effectiveness of this plasma treatment may provide a new alternative to thermal annealing and capping treatments typically used to promote aqueous stability of low-temperature ALD metal oxide barrier layers.

In a functional solar cell device, the morphology of a layer is a key to the performance of Bi-based perovskite solar cells (Bi-PeSCs). Especially, pinholes generated during spin coating degrade the solar cell performance. This paper proposes a method to prepare pinhole-free methylammonium bismuth iodide (MBI) film by multi-step spin coating, with the thickness optimized by changing the layer number between 1 and 12 layers. A strong absorption band is observed at around the wavelength of ~ 500 nm for all the MBI layers. The scanning electron microscopy (SEM) cross-section images visually depict that the MBI layers are free from pinholes at more than 6 layers, and we found that the maximum solar cell performance was reached at 8 layers of MBI with an open-circuit voltage of 0.18V, which is greater than using a single-spin coating. After that, it exhibited a decrease in its performance by increasing the number of MBI layers. The growth model and its mechanism for pinhole-free multi-MBI layers is also discussed. These results suggested an improvement of MBI layer morphology in the development of solar cell devices in the future.

The semiconductor material of ternary alloy of Indium and Aluminum nitride (InxAl1-xN) has interesting properties for potential optoelectronic applications and solar cells as well. In the present research, layers of In0.63Al0.37 N were synthesized using the DC reactive sputtering magnetron technique, on p-type silicon substrates (100), ITO/PET, and ITO/Glass. The reason why an intermediate layer of ITO was placed on the PET and Glass substrates is that possibly in an InAlN thin-layer solar cell, the ITO would fulfill the role of Conductive Transparent Oxide (CTO). This CTO would be located between the window layer and the transparent substrate. On the other hand, in the case of a hetero-union solar cell, InAlN-n would be located on the Si-p material, in order to form the p–n junction. Therefore, the present work allowed us to study subsystems in which the InAlN would be part of the window layer in three different types of solar cells.

The present work is undertaken to highlight a novel in situ process to fabricate SiC/graphite/Al hybrid composite coating by laser direct energy deposition using Al–Si–C powder mixtures. Microstructures of the coatings, mainly the in situ formed reinforcing phases and their interface with the matrix, are comprehensively characterized by scanning electron microscopy, X-ray diffraction, analytical transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that almost all the graphite powders are dissolved in the molten pool during the deposition, except for a few large graphite powders that are only partially dissolved in the Al–Si melt. In the coating with a low content of Si and graphite, i.e., Al–19Si–4C with a C/Si mole ratio of 0.44, needle-like Al4C3 is the sole in situ formed carbide phase. Most of the Al4C3 are uniformly distributed in the Al–Si matrix. Al4C3 is also observed on the surface of partially dissolved graphite powder. In the coating with a high content of Si and graphite, i.e., Al–32Si–11C with a C/Si mole ratio of 0.75, SiC, plate-like Al4SiC4, and dissolved-and-precipitated feather-like graphite are the main in situ formed phases. The size and morphology of SiC are varied depending on the location in the coating. In the upper region of the coating, elongated SiC crystals with a typical length of 10 to 40 µm and a width of 2 to 3 µm are observed. A mixture of elongated SiC and blocky SiC crystals of 9 to 15 µm, together with precipitated feather-like graphite phases, are revealed in the middle region. In the bottom region, fine SiC particles with a size of 2 to 6 µm are formed. Besides, ultra-fine microcrystalline SiC phases are formed on the feather-like graphite, whereas a continuous SiC layer is formed on the surface of partially dissolved graphite powder. Several interfaces interfacial structures between the in situ formed phases and matrix have been identified, i.e., SiC/Al4SiC4/Al, SiC/graphite, SiC/Al4SiC4/graphite, and graphite/Al4SiC4/Al or Si. The thermodynamics and the mechanism for forming in situ carbide, i.e., solution-precipitation mechanism and solid–liquid diffusion-reaction mechanism, are discussed. Based on the experimental and theoretical results, a sequence of the reaction and solidification leading up to the in situ synthesis of SiC/graphite/Al hybrid composite coating is illustrated. The corresponding mechanism for the present process has been proposed.

The paper formulates the nonlinear problem of steady-state heat conduction at the constant electric potential difference on the surfaces of a plane dielectric layer with the temperature-dependent heat conduction coefficient and electrical resistivity. A fixed temperature value is set on one of the layer surfaces, and the convective heat exchange with the ambient medium occurs on the opposite surface. The formulation of the problem is transformed into integral ratios, which allows the calculation of the temperature distribution over the layer thickness, governed both by the monotonic and nonmonotonic function. The quantitative assay of the temperature state of a layer of a polymer dielectric made of amorphous polycarbonate is given as an example, as well as the analysis of nonuniformity of the absolute value of electric field intensity over the thickness of this layer.

The structures of Cr/Be multilayer mirror interfaces are investigated using X-ray reflectometry, diffuse X-ray scattering and atomic force microscopy. The combination of these methods makes it possible to separate the contributions of roughness and interlayer diffusion/intermixing for each sample. In the range of period thicknesses of 2.26–0.8 nm, it is found that the growth roughness of the Cr/Be multilayer mirrors does not depend on the period thickness and is ∼0.2 nm. The separation of roughness and diffuseness allows estimation of layer material intermixing and the resulting drop in the optical contrast, which is from 0.85 to 0.17 in comparison with an ideally sharp structure.

3D porous iron (Fe) scaffolds with interconnected open pores are promising candidates for bone repair. However, the bare 3D porous Fe scaffolds lack of antibacterial activity and the ability for cell adhesion. Herein, atomic layer deposition technique was used to deposit nanometer-thick zinc oxide (ZnO) layer onto the skeleton of 3D porous Fe scaffolds with interconnected open pores. The effect of ZnO thin film on the in vitro degradation behavior, antibacterial activity and cytocompatibility of 3D porous Fe scaffolds was systematically evaluated. The results showed that a dense ZnO thin film with a thickness of 76 nm was uniformly deposited on the skeleton of the porous Fe scaffolds. The thickness of ZnO thin film could be easily controlled by the deposition cycles. The deposited ZnO thin film significantly reduced the degradation rate of porous Fe scaffolds and the fabricated ZnO coated porous Fe scaffolds demonstrated strong antibacterial ability against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, while did not significantly affect cytocompatibility and could also promote cell adhesion.

In this paper, A modified one-step method was used to prepare the CH3NH3PbI3 (MAPbI3) perovskite film, and the planar heterojunction perovskite solar cells (PHPSCs) were assembled by optimizing the preparation process of the TiO2 compact layer (c-layer) and perovskite film. A TiO2 c-layer as the electron transfer layers (ETLs) was controlled by the spin coating method with the different TiO2 precursor solution and the number of spin coating. The perovskite layer, as a light absorption layer, was obtained by spin coating on the TiO2 c-layer with MAPbI3 precursor solutions of different mass concentrations. The characterization results show that although the preparation process is different, the surface morphology of TiO2 c-layer and perovskite layer are not very different, but there are some fluctuations in the thickness and internal structure of their films. The planar solar cell devices with c-TiO2/MAPbI3/HTM/Ag structure showed different photoelectric conversion performance. By optimizing the preparation process, the photoelectric conversion efficiency of the assembled solar cell device can reach 12.11% based on a TiO2 c-layer obtained by two-spin coating with 0.1 M precursor solution and the perovskite layer obtained by spin coating with a mass concentration of 45% in MAPbI3 solution.

The combination therapy that combines drug delivery with other treatments (e.g., photothermal therapy) has great advantages in treating tumors. Here, we prepared a promising versatile platform based on gold nanocages (Au NCs) poly (N-isopropylacrylamide) (PNIPAM) entrapped porous silica core−shell nanostructure (Au@SiO2-PNIPAM). This system not only served as a container for therapeutic drugs, but also had high photothermal conversion efficiency. The thermosensitive PNIPAM wrapping around porous silica acted as a gatekeeper to encapsulate the drug molecules within the channels of Au@SiO2-PNIPAM carrier. Under the light irradiation, Au NCs could absorb near-infrared (NIR) light and convert it into heat, which would promote the swelling of PNIPAM layer for releasing drug. The Au@SiO2-PNIPAM displays pH/light-responsive drug release and excellent photothermal-chemical combined therapeutic effect.

Polyformaldehyde (POM) is one of the most commonly used engineering thermoplastics that has been widely used in the industry as well as in our daily life. Compared with other thermoplastics, POM has a relatively high thermal resistance and self-lubricating properties. In this study, the POM was used as the bulk material for microfluidic devices, with the microchannels directly laser ablated on the surface of POM plates. The profile of the microchannels with various CO2 laser energy and scan speed was also studied in detail. To enclose the channel, a layer of adhesive polyester film was attached to the surface of the POM plate to seal the fabricated microchannels, and the bonding strength was enhanced with a further compression procedure and then tested with a burst opening method. With the help of the high thermal resistance of POM, an enhanced oil recovery (EOR) test under high temperature was conducted in this study based on the POM-based microfluidic device to mimic the underground oil recovery process in the porous sandstone structure.

The molecular structure and stacking mode relationship is the core of creating planar layer-stacked materials by crystal engineering. However, it remains highly challenging to clarify the relations...

Two approaches can be taken when designing properties of the native oxide layers formed on Ti-based biomedical materials: (i) changing the chemical composition of the substrate by adding biocompatible, valve alloying elements, and (ii) changing the microstructure of the substrate—especially its level of defectiveness—through large plastic deformation. However, especially in the aggressive fluoridated oral environment, it is still unknown what factor is more effective in terms of enhancing oxide layer protectiveness against biocorrosion: (i) the presence of valve alloying elements, or (ii) a high number of structural defects. To gain knowledge about the separate influence of both of these factors, surface properties were examined for commercially pure Ti and Ti–Nb–Ta–Zr alloy in microcrystalline state as well as after multiple-pass cold rolling, a process that can be readily scaled up to the industrial level. This study showed that while valve-alloying elements and structural defects individually have a beneficial effect on Ti oxide layer properties in fluoridated medium, they not have to act in a synergistic manner. These findings have to be taken into account when designing future Ti-based dental materials together with analyzing their mechanical performance with respect to mechanical strength and elastic properties.

New results about the influence of a small iron borided layer (~ 36 µm) obtained by the powder-pack boriding process (PPBP) and diffusion annealing post-process (DAP) were evaluated. Dry sliding wear tests on PPBP, PPBP + DAP and untreated AISI 1018 steel were performed under the pin-on-disc configuration, and balls of Al2O3 and WC were used as a counterpart at different sliding distances. Also, the contact pressures of the layer/substrate system were evaluated using the finite element model with the aid of the ABAQUS software. The results showed that the Al2O3 ball presented the major coupling (ball-disc), and the PPBP + DAP reduces the specific wear rate around ~ 304 times related to the untreated AISI 1018 steel to 500 m under severe sliding conditions.

Flexible memory devices are promising for information storage and data processing applications in portable, wearable, and smart electronics operating under curved conditions. In this work, we realized high-performance flexible ferroelectric capacitors based on Hf0.5Zr0.5O2 (HZO) thin film by depositing a buffer layer of Al2O3 on polyimide (PI) substrates using atomic layer deposition (ALD). The flexible ferroelectric HZO films exhibit high remnant polarization (Pr) of 21 µC/cm2. Furthermore, deterioration of polarization, retention, and endurance performance was not observed even at a bending radius of 2 mm after 5,000 bending cycles. This work marks a critical step in the development of high-performance flexible HfO2-based ferroelectric memories for next-generation wearable electronic devices.

MgO·Al2O3 spinel particles adhered to MgO refractory become a source of inclusions in stainless steel during the aluminum deoxidation process. In contrast, the MgO·Al2O3 spinel layer formed on MgO refractory can protect it from further dissolution and spalling. Thus, identifying the MgO·Al2O3 spinel particles and layer is critical for locating areas on the refractory that require repair and replacement. In this study, the author demonstrates that the MgO·Al2O3 spinel particles and layer on MgO refractory for aluminum deoxidation process of stainless steel are distinguishable from their luminescence colors in cathodoluminescence (CL) and X-ray excited optical luminescence (XEOL) images at wavelengths of 420 to 680 nm, 650 to 680 nm, and 350 to 1000 nm, respectively. The CL and XEOL images can be acquired within 2 seconds and 1 minutes, respectively. Surface examination of the MgO refractory aids in more precise identification. XEOL imaging, in particular, is promising because it can perform a nondestructive onsite evaluation of the MgO refractory.

In the micro electro mechanical system (MEMS) area, micro metal devices fabricating by the electroplating process were used widely in biology, medicine and optics field. However, due to the oxide layer of the metal substrate surface, the electroplating layer suffers from the poor adhesion. In order to reduce the oxide layer of the metal substrate surface, effects of the ultrasonic assisted electrochemical potential activation method have been investigated originally. The electrochemical test was processed by an electrochemical station. The oxide content of the substrate surface was measured by the X‐ray photoelectron spectroscopy (XPS) method. The experimental results show that, comparing with the ultrasound free one, the ultrasonic assisted electrochemical potential activation method can improve the hydrogen evolution reaction and reduce the metal ion nucleation rate. Then the Cu substrate surface oxide content has been restored. Results of this paper can provide a new ultrasonic electrochemical potential activation method to activate the oxide layer of the substrate surface, as well as to improve the adhesion.

As the most important element in improving the service life of a mechanical system, surface coating materials are of key importance in the development of high-end equipment. To improve the comprehensive properties of the surface coating, the common core-shell structure/Ni60 coating was prepared on the surface of #45 steel by supersonic plasma spraying. The results show that the Ni60 has no layer structure, pores, cracks, and other defects on the surface of the coating. The nanohardness of the NNA(Ni60/Ni (Al) mixture powder), NNM(Ni60/Ni (MoS2) mixture powder), and NNC(Ni60/Ni (C) mixture powder) coatings is 6815 μN, 5750 μN, and 2000 μN. The results show that the wear resistance of the NNA coating is better. In the friction and wear test, the NNA coating mainly shows adhesive wear and abrasive wear, while the NNM and NNC coatings mainly show abrasive wear.

Liquid-infused slippery surfaces have replaced structural superhydrophobic surfaces in a plethora of emerging applications, hallmarked by their favorable self-healing and liquid-repelling characteristics. Their ease of fabrication on different types of materials and increasing demand in various industrial applications have triggered research interests targeted toward developing an environmental-friendly, flexible, and frugal substrate as the underlying structural and functional backbone. Although many expensive polymers such as polytetrafluoroethylene have so far been used for their fabrication, these are constrained by their compromised flexibility and non-ecofriendliness due to the use of fluorine. Here, we explore the development and deployment of a biodegradable, recyclable, flexible, and an economically viable material in the form of a paper matrix for fabricating liquid-infused slippery interfaces for prolonged usage. We show by controlled experiments that a simple silanization followed by an oil infusion protocol imparts an inherent slipperiness (low contact angle hysteresis and low tilting angle for sliding) to the droplet motion on the paper substrate and provides favorable anti-icing characteristics, albeit keeping the paper microstructures unaltered. This ensures concomitant hydrophobicity, water adhesion, and capillarity for low surface tension fluids, such as mustard oil, with an implicit role played by the paper pore size distribution toward retaining a stable layer of the infused oil. With demonstrated supreme anti-icing characteristics, these results open up new possibilities of realizing high-throughput paper-based substrates for a wide variety of applications ranging from biomedical unit operations to droplet-based digital microfluidics.