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The design of efficient and robust non-precious metal electrocatalysts towards oxygen evolution reaction (OER) is of great value for developing green energy technologies. The in-situ formed high-valence (oxy)hydroxides species during the reconstruction process of pre-catalysts are recognized as the real contributing sites for OER. However, pre-catalysts generally undergo a slow and inadequate self-reconstruction. Herein, we reported a PO43− optimized CoFe-based OER catalysts with amorphous structure, which enables a fast and deep reconstruction during the OER process. The amorphous structure induced by ligands PO43− is prone to evolution and further form active species for OER. The electron interaction between metal sites can be modulated by electron-rich PO43−, which promotes generation of high active CoOOH. Simultaneously, the etching of PO43− from the pre-catalysts during the catalytic process is in favor of accelerating the self-reconstruction. As a result, as-prepared pre-catalyst can generate high active CoOOH at a low potential of 1.4 V and achieve an in-depth reconstructed nanosheet structure with abundant OER active sites. Our work provides a promising design of pre-catalysts for realizing efficient catalysis of water oxidation.

In this research, a novel Ni-Co-metallic glass composite was fabricated and the effect of the co-deposition of Ni60Cr10Ta10P16B4 amorphous metallic glass powder (MGP) on the morphology and electrocatalytic properties of Ni–Co coatings was evaluated. The process was initiated by producing Ni60Cr10Ta10P16B4 via mechanical alloying of elemental powders using a planetary ball mill. Then, Ni–Co nanocomposite coatings were deposited on a copper substrate by the addition of different amounts of MGP via the electrodeposition method in a Watts bath. Then, the microstructure and chemical composition of the deposits were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) successively. The electrocatalytic performance of the coatings was evaluated in a methanol-containing alkaline (1 M NaOH) solution through cyclic voltammetry (CV). The enhancement of the electrocatalytic activity of Ni–Co coating through the co-deposition of MGP was observed. It was also concluded that the electrocatalytic properties of composite coatings are optimized when 7.5 g L−1 of MGP is added to the electroplating bath. Moreover, MGP was demonstrated to have altered the microstructure and the content of Co besides enhancing the roughness and specific surface of coatings.

Biopolymer electrolytes based on iota-carrageenan (I-carrageenan) with sodium trifluoromethanesulfonate (NaTf) were prepared by way of the conventional solution-casting technique. The biopolymer I-carrageenan was fixed as 1 g, and the concentration of NaTf was varied from 0.1 to 0.5 wt% in steps of 0.1 wt%. Distilled water was used as a solvent. Alternating current (AC) impedance measurements were carried out in the frequency window of 42 Hz–1 MHz. The same measurements were also carried out at different temperatures for all the prepared biopolymer samples. A maximum ionic conductivity of 2.6771 × 10−5 S/cm was obtained for the 0.3 wt% NaTf-added I-carrageenan system at room temperature. The temperature-dependent conductivity plot of the polymer electrolyte seemed to obey the Arrhenius relation. A low activation energy of 0.021 eV was observed for the sample with the highest ionic conductivity. From AC impedance data, dielectric parameters were obtained. The magnitude of the dielectric constant was found to increase with the increase in temperature. A low relaxation time was observed for the sample that possesses the maximum ionic conductivity.

In the present work, samples of barium borate glasses containing different molar ratios of ZnO were prepared using the conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the studied materials. Structural analysis using FT-Infrared confirmed the incorporation of the Zn atom in the glass matrix as a ZnO4 unit and the existence of ZnO in the tetrahedral interstitial sites. TEM images for the studied materials show that the average particle size is about 20 nm and the ZnO4 structural units reside in the glass matrix with high homogeneity. Density and molar volume studies manifested an increase in the density as the amount of ZnO increases and a subsequent decrease in the molar volume. UV absorption studies showed a blue shift in the absorption peak from 343 nm to 315 nm. Additionally, an observed reversible behavior around 338 nm divides the absorption range into high energy and low energy regions. In the high energy region, both absorbance, absorption coefficient, and refractive index increased with ZnO content increment. In the low energy region, this behavior was reversed, and the calculated values of the refractive index agreed with the measured ones in this region. Studies of optical dielectric parameters showed a Debye-type relaxation process in which increasing the ZnO content shortens the sample relaxation time. Our results, collectively, suggest the studied materials for several optoelectronic device applications such as high-energy optical filters, optical switches, and frequency converters.

In harsh environments, Fe-based amorphous coatings can provide effective protection for equipment. A method of thickness measurement of thin layer and quality evaluation based on high-frequency water-immersion ultrasonic testing and imaging is proposed here. In this paper, because of the interface echoes of the micron-scale coating in the aliasing of ultrasonic testing signals, wavepacket decomposition and extraction technology proposed according to the matching pursuit theory is used to separate the interface echoes. After using the narrow pulse replacement method, the coating structure imaged is reconstructed. The decomposed interface echoes will not be mixed again, thus reflecting the coating thickness information more accurately. Consequently it can be used to evaluate the coating quality. Finally, the experimental results show that the coating structure image can be reconstructed after the high-frequency water-immersion ultrasonic scanning signals are processed with the above method. The relative error of the coating thickness detection is only 3.13% compared with the scanning electron microscope (SEM) results. At the same time, the coating spraying quality can be evaluated effectively through the imaged results.

Yttrium aluminum garnet (YAG) with cerium admixture (Ce:YAG) was plasma sprayed using two different devices – gas-stabilized plasma (GSP) torch and water-stabilized plasma (WSP) torch. Coatings on stainless steel as well as self-standing plates were produced. Besides microstructure and crystallographic characterizations, dielectric tests were performed on these coatings. They included capacitance (i.e. relative permittivity), loss tangent and volume resistivity measurements. After spraying, the YAG crystal phase was preserved without any decomposition, but an amorphous fraction was detected in the as-sprayed coatings deposited by both processes. The dielectric behavior of the coatings was influenced by imperfections like splat boundaries, pores and thin cracks. The Ce:YAG samples were successfully plasma sprayed by both spray techniques. Selected aspects of wear were measured and compared with a single-crystal. The dielectric properties are comparable with the single-crystal and highly promising, particularly the loss tangent with values so low that they were not found in any other as-sprayed ceramic coating.

Ferrite Cobalt (CoFe2O4) is a recognized attractive material with normal implementation and normal size of polarization. It has unmistakable substance security and motorized hardness. It is an eager promoter for the strategy of tactile gadgets and actuators, as an authoritative fixing, attractive medication gadgets electrical and having a broad scope of researching in materialistic innovation or science for mechanical uses and applications. These nanoparticles cobalt and ferrite on an ensnared viably handled on surrounding temperature by a basic process of co-precipitation. This precious stone structures and architecture of image was controlled through X-ray diffraction and SEM. The range of XRD affirms that composite nano-particles were shaped by ideal structure of spinel. This normal pace of precious stones was controlled through methods for Modified Scherer (54 nm) and Williamson-Hall (49 nm) techniques. A SEM view demonstrated nanoparticles CoFe2O4 being assembled in close-by structures. This visual and bond highlights was depicted by FTIR and UV–Vis Spectrum. As the temperature of the production rises, so does the magnetics period for the NPs and the magnetization of the concentration improves monotonously from 2.6 μB to 16 μB plus from 37 to 66 emu/g. According to the actions of both SPM and attendance of a dead layer (surface amorphous shell layer), which systemically decreases as the synthesis temperature increases, the optimum curve-appropriate of M-H statistics is due to the reduced particle/particle interaction.

The development of greatly stable and cost-effective electrocatalysts for urea electro-oxidation reactions (UERs) is urgent and challenging for promoting urea removal in the wastewater and advanced energy conversion devices. We demonstrated that nickel-iron borate (NiFe-B) electrocatalysts supported on carbon paper (CP) for UERs through a one-pot solvothermal method. NiFe-B electrocatalysts were obtained with numerous Ni/Fe molar ratios in the precursors, and the physicochemical features of the NiFe-B were examined by X-ray diffraction, scanning and transmission electron microscope, and X-ray photoelectron spectroscopy. The optimized NiFe-B/CP exhibited a low onset potential (Eonset = 0.287 V vs. SCE) with a Tafel slope of 27.9 mV/dec on CP, demonstrating much greater performance UERs. Furthermore, the NiFe-B/CP catalysts have shown a superior activity for the UERs in alkaline solution and exhibit more than two-fold enhancement in activity than Ni-B. Facile, cost-effective fabrication and highly efficient urea oxidation create the NiFe-B electrodes as attractive materials for UERs.

Revealing the active species of the catalyst is conducive to the design of more efficient catalyst. Herein, we tried to demonstrate the roles of amorphous and crystalline structures on CePO4 catalyst during selective catalytic reduction (SCR) of NOx by NH3. Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO4. Both amorphous and crystalline CePO4 species on CePO-X samples can provide acid sites for NH3 adsorption, but the former can provide more acid sites. The superior redox property of surface amorphous CePO4 species contributes to its high NH3-SCR activity at low temperature, but it also leads to the decrease of high temperature (>350 °C) NH3-SCR activity due to the oxidation of NH3. In contrast, crystalline CePO4 species shows high activity only at high temperature because of its poor redox property. Therefore, it can be inferred that amorphous and crystalline structures on CePO4 catalyst can be the efficient active species of NH3-SCR at low and high temperature, respectively.

Silicon (Si) is regarded as the potential anode for lithium-ion batteries (LIBs), due to the remarkable theoretical specific capacity and low voltage plateau. However, the rapid capacity decay resulting from volume variation and slow electron/ion transportation of Si limit its practical application. Here, matryoshka-type carbon-stabilized hollow silicon spheres (Si/C/Si/C) are synthesized by an aluminothermic reduction and calcination process. The Si/C/Si/C anode materials prepared at 500 °C (Si/C/Si/C-500) exhibit unique structures, in which amorphous region and porous structure are preserved in the Si layers. The anode based on Si/C/Si/C-500 displays an initial specific capacity of 2792 mAh/g at a current density of 100 mA/g. At 1000 mA/g, this anode retains a reversible capacity of 1673 mAh/g, 86.9% of the initial capacity after 200 cycles. Such synthetic strategy can be employed to fabricate other high-capacity anode materials with large volume variation during charge/discharge process

In this work, the microstructure of titania coating fabricated on the surface of hydrostatically extruded titanium grade 4 with the use of the micro-arc oxidation method was studied. The surface topography and microstructure investigations performed with atomic force microscopy and scanning and transmission electron microscopy revealed that, by using an Na2HPO4 electrolyte, a well-adherent porous coating is produced on the top surface and side walls of the extruded rod. The distribution of chemical elements was analyzed by using energy dispersive X-ray spectroscopy. The chemical elements dissolved in the electrolyte i.e. (Na, P and O) incorporated into the coating. Sodium locates preferentially in the outer part of the coating, while phosphorus and oxygen are distributed throughout the whole coating. The most relevant finding shows that a grain refinement caused by a hydrostatic extrusion provoked an increase in density of high-angle grain boundaries (HAGB), which in turn secured the formation of a continuous amorphous layer close to the substrate. The presence of this layer compensates for the effect of anisotropic substrate, producing a comparable and homogenous microstructure with a large number of micropores.

The selection and development of cathode of alkaline zinc batteries (AZBs) is still hindered and often leads to poor rate capability and short cycle life. Here, amorphous hollow nickel-cobalt-based sulfides nanocages with nanosheet arrays (AM-NCS) are designed and constructed with ZIF-67 as the self-template to exchange with Ni2+ and S2− by using a two-step ion exchange method. The synthesized AM-NCS possess the high specific capacity (160 mAh/g at 2 A/g), and the assembled battery has excellent rate performance (146 mAh/g reversible capacity at 5 A/g). The assembled device has excellent rate performance (155 mAh/g at 2 A/g) and long cycling stability (7000 cycles, 62.5% of initial capacity). The excellent electrochemical properties of the electrode materials are mainly attributed to the unique structure, in particular, polyhedron structure with hollow structure can improve the cyclic stability, and the amorphous structure can expose more reactive sites on the surfaces of nickel, cobalt and sulfur. This work provides a new strategy for the design and fabrication of high performance cathode materials for AZBs.

Effective strategies to improve the tarnishing resistance of the 18 K (karat) gold-based bulk glass-forming composition Au49Ag5.5Pd2.3Cu26.9Si16.3 were recently found, with the addition of Ga at the expense of Cu and a sufficient reduction of Si. However, the modification of the alloy is accompanied by a reduction of the glass-forming ability (GFA) from 5 to 2 mm in terms of the critical casting thickness, and eventually collapses for Ga contents higher than about 9 at%. In this work, thermodynamic and kinetic studies of the newly discovered 18 K Au-Ag-Pd-Cu-Ga-Si system shed light on the reason for the loss in GFA with increasing Ga content. Investigations of the liquid kinetics in terms of viscosity and transition time, assessed by three-point beam bending and the Tg-shift method, reveal an unexpected change of the fragility to stronger liquid kinetics with increasing Ga concentration, which is usually attributed to an increase in the GFA. Thermodynamic considerations based on specific heat capacity measurements reveal, in contrast, an ascending driving force for crystallization with an increasing Ga-content, accountable for the drop in GFA. Therefore, a Ga-rich melt beyond the threshold concentration of 9 at% is not desirable for the production of bulk metallic glasses (BMGs) from the liquid state. With the intention to outrun this barrier, while preserving the amorphous structure, Ga-ion implantation with a liquid metal focused ion beam source is used as a post-processing routine for a cast Ga-containing 18 K Au-BMG. Hence, the thermodynamic borderline concentration is successfully crossed with additional tremendous improvement of the tarnishing resistance in the Ga-enriched areas.

International audience; The amorphous structure of bulk metallic glasses results in outstanding properties, which are able to outshine the properties of common metallic biomaterials. In particular, Ti-based bulk metallic glasses are interesting candidates for the use as biomaterial or as structural material in lightweight applications. However, the usage of known Ti-based bulk metallic glasses with casting thicknesses of several millimeters is strongly limited due to the large content of rare, expensive and harmful elements. In this work, we design Ni-free Ti-based bulk metallic glasses with a low Cu-content, being suitable for the application as biomaterial. On the basis of the binary Ti-Ni system, novel glass forming alloys are developed by the addition of sulfur. In order to increase the glass forming ability and to reduce the Ni-content, Ti was substituted with Zr and Ni with Cu. Finally, it is possible to produce synchrotron X-ray amorphous samples with a diameter of 3 mm for the Ni-free alloy Ti40Zr35Cu17S8. Furthermore, it is shown that industrial grade raw materials can be used for the synthesis of amorphous samples of this alloy without diminishing the glass forming ability or the mechanical properties. Characterization by mechanical and electrochemical tests proves the superiority of the novel alloys over commercial amorphous and crystalline alloys. All in all, a new class of Ni-free Ti-based bulk metallic glasses with unprecedented properties is developed, being highly attractive for a widespread use.

The ever-increasing demands for modern energy storage applications drive the search for novel anode materials of lithium (Li)-ion batteries (LIBs) with high storage capacity and long cycle life, to outperform the conventional LIBs anode materials. Hence, we report amorphous ternary phosphorus chalcogenide (a-P4SSe2) as an anode material with high performance for LIBs. Synthesized via the mechanochemistry method, the a-P4SSe2 compound is endowed with amorphous feature and offers excellent cycling stability (over 1500 mA h g−1 capacity after 425 cycles at 0.3 A g−1), owing to the advantages of isotropic nature and synergistic effect of multielement forming Li-ion conductors during battery operation. Furthermore, as confirmed by ex situ X-ray diffraction (XRD) and transmission electron microscope (TEM), the a-P4SSe2 anode material has a reversible and multistage Li-storage mechanism, which is extremely beneficial to long cycle life for batteries. Moreover, the autogenous intermediate electrochemical products with fast ionic conductivity can facilitate Li-ion diffusion effectively. Thus, the a-P4SSe2 electrode delivers excellent rate capability (730 mA h g−1 capacity at 3 A g−1). Through in situ electrochemical impedance spectra (EIS) measurements, it can be revealed that the resistances of charge transfer (Rct) and solid electrolyte interphase (RSEI) decrease along with the formation of Li-ion conductors whilst the ohmic resistance (RΩ) remains unchanged during the whole electrochemical process, thus resulting in rapid reaction kinetics and stable electrode to obtain excellent rate performance and cycling ability for LIBs. Moreover, the formation mechanism and electrochemical superiority of the a-P4SSe2 phase, and its expansion to P4S3−xSex (x = 0, 1, 2, 3) family can prove its significance for LIBs.

Aqueous rechargeable magnesium ion batteries (ARMBs) have obtained more attention due to the two-electrons transfer nature, low cost and safety. However, the scarcity of cathode materials seriously hinders the development of ARMBs because of the unfavorable strong interaction between Mg2+ and cathode material. Herein, we choose a pre-treated spinel Mn3O4 cathode for aqueous Mg2+ storage. The pre-treatment in Na2SO4 solution induces the grain refinement decorated with tortuous amorphous ion diffusion channels, facilitating the production of electrochemical reaction active sites and the diffusion of Mg2+, respectively, which achieve a (sub-)surface pseudocapacitance reaction between Mn (II) and Mn (III). As a result, the pre-treated Mn3O4 cathode exhibits a package of optimal performances, i.e., a capacity of 98.9 mAh g−1 and a high capacity retention rate of 99.4% after 2000 cycles. To the best of our knowledge, our work not only provides a new reaction mechanism of spinel Mn3O4 in aqueous batteries system, but also affords a high cycle stability electrode material for rechargeable Mg2+ energy storage.

Structure, magnetic properties and ductile of melt-spun Fe83-xSi4B13-yCyCux (x = 0–1.7; y = 0–8) alloys were investigated. The addition of 1.7 at.% Cu in a Fe83Si4B13 amorphous alloy generates abundant α-Fe crystals by providing nucleation sites, and further C doping promotes the growth of the crystals by suitable turning amorphous-forming ability, hence they increase saturation magnetic flux density (Bs) and slightly worse magnetic softness of the as-spun alloys. The as-spun Fe81.3Si4B7C6Cu1.7 alloy possesses a combined structure of a fully amorphous layer in wheel side surface and predominating nanocrystalline structure with gradually enlarged α-Fe crystal, whose average size and volume fraction are determined as about 12 nm and 32%, respectively, therefore superior soft magnetic properties and ductile with a high Bs of 1.74 T, coercivity (Hc) of 32.7 A/m, effective permeability (μe, at 1 kHz) of 3200 and high relatively strain at fracture (ef) of 3.61% can be achieved directly in this alloy by only using melt-spinning. The annealing at 578 K releases internal stress, promotes the growth of the α-Fe crystals and remains the amorphous layer of the Fe81.3Si4B7C6Cu1.7 alloy, then improves the soft magnetic properties and maintains the superior ductile with increasing the Bs and μe to 1.80 T and 14,100, respectively, lowering the Hc to 9.4 A/m and slightly reducing the ef to 2.39%. The combination of superior soft magnetic properties and ductile and simplified synthesis process entitles the Fe-Si-B-C Cu nanocrystalline alloys great potentials in high performance electromagnetic applications.

Observations of polar mesospheric clouds have revealed the presence of solid ice particles in the upper mesosphere at high latitudes; however, their formation mechanism remains uncertain. In this study, we investigated the formation process of ice particles through nucleation from small amounts of water vapor at low temperatures. Previous studies that used classical nucleation theory have shown that amorphous solid water particles can nucleate homogeneously at conditions that are present in the mesosphere. However, the rate predictions for water in classical nucleation theory disagree with experimental measurements by several orders of magnitude. We adopted a semi-phenomenological model for the nucleation process, which corrects the evaluation of the molecular cluster formation energy using the second virial coefficient, which agrees with both experiments and molecular dynamics simulations. To calculate the nucleation process, we applied atmospheric conditions for the temperature, pressure, numerical density of dust grains, and cooling rate. The results indicate that homogeneous water nucleation is extremely unlikely to occur in the mesosphere, while heterogeneous nucleation occurs effectively. Dust grains generated by meteor ablation can serve as nuclei for heterogeneous nucleation. We also showed that the ice can form directly in a crystalline state, rather than an amorphous state.

The so-called BGMS10, a bioactive glass containing 10 mol.% SrO and 10 mol.% MgO, displays a low inclination to crystallize, as confirmed by its high activation energy (538.9 kJ/mol). Such peculiar aspect and the beneficial use of SPS allow for the obtainment of 99.7 % dense and fully amorphous products at 750 °C. The incipient crystallization in the glass is observed when temperature is increased to 850 °C, while 95 wt. % crystallized ceramics are produced at 950 °C. Main crystalline phases are α- and β-CaSiO3, with grain size of 89 and 97 nm, respectively. Glass crystallization is accompanied by Young’s modulus increase from 90.92 to 98.38 GPa. On the other hand, partially crystallized samples (850 °C) exhibit higher Vickers hardness (718.8) compared to fully crystallized ones (619.8), which show lower density (98.6%). In-vitro tests in SBF indicate that the silica-gel film preceding apatite nucleation is mostly formed on the amorphous substrate region.

A novel Ni30Cr25Al15Co15Mo5Ti5Y5 high-entropy alloy (HEA) coating was irradiated to optimize its internal structure via laser after supersonic particle deposition (SPD). Owing to the high energy density of the laser and large temperature gradient, the crystallization process of the molecules and atoms in the coating was restrained and supercooling occurred. Experimental results showed that a considerable number of nano-crystal grains precipitated and amorphous structures were formed because of the random orientation of the crystals. The baseline of differential scanning calorimetry scans obtained for the coating started to shift at the Tg of 939.37 ℃ and a step was observed. Multiple dispersion peaks and lattice fringes indicated that the nucleation of the irradiated laser-induced topology optimized (LTO) coating was incomplete. The laser-induced topology optimizing treatment led to quasi-isotropy in the SPD coating. Furthermore, the LTO coating exhibited a residual stress of 18.4 MPa, stress-strain response, and fatigue limit of 265 MPa. Hence, the LTO coating exhibited higher performance than the unirradiated SPD coating. The Nyquist and Bode electrochemical impedance spectra of the LTO coating, including two relaxation processes, indicated that the corrosion process steadily recovered to the equilibrium state. This implies that the uniform oxidation passivation layer on the surface of the LTO coating insulated the material from the corrosive medium, protecting the substrate from further corrosion, thus enhancing the structural security of the material for use in super-intense laser facility applications.

Gel polymer electrolytes (GPEs) are one of the promising candidates for high-energy-density quasi-solid-state lithium metal batteries (QSSLMBs), for their high ionic conductivity and excellent interfacial compatibility. The comprehension of dynamic evolution and structure-reactivity correlation at the GPE/Li interface becomes significant. Here, in situ electrochemical atomic force microscopy (EC-AFM) provides insights into the LiNO3-regulated micromechanism of the Li plating/stripping behavior upon cycles in GPE-based LMBs at nanoscale. The additive LiNO3 induces the formation of amorphous nitride SEI film and facilitates the Li+ ion diffusion. It stabilizes a compatible interface and regulates the Li nucleation/growth at steady kinetics. The deposited Li is in the shape of chunks and tightly compact. The Li dissolution shows favorable reversibility, which guarantees the cycling performance of LMBs. In situ AFM monitoring provides a deep understanding into the dynamic evolution of Li deposition/dissolution and the interphasial properties of tunable SEI film, regulating the rational design of electrolyte and interfacial establishment for GPE-based QSSLMBs.

Because the amorphous/amorphous nano-laminates could enhance significantly the mechanical properties of the amorphous materials, they have been widely studied as a new group of structural materials. In this study, the nano-scratch performance of the Cu80Zr20/Cu20Zr80 (A/B-type) and the Cu20Zr80/Cu80Zr20 (B/A-type) amorphous/amorphous nano-laminates was evaluated by molecular dynamics simulation. Their dependences on the type of indenter, layer thickness, stacking mode and scratch depth were systematically analyzed. There is a significant size effect for the tribological properties of amorphous/amorphous nanolaminates that the friction force of the A/B-type increases with the increase of layer thickness, but the friction force of the B/A-type decreases as the layer thickness increase. The interface has an obvious obstruction effect on the shear deformation and reduces the plastic affected region below the scratched groove. Particularly, the contact environment of the indenter bottom has an important influence on the normal force, so it's not that the deeper the depth, the greater the normal force. Hence it should not be ignored when evaluating the tribological properties of the amorphous/amorphous nano-laminates. This work can deepen the understanding of hetero-interface on the deformation mechanism during nano-scratch, and help to design amorphous nano-laminates with tailored tribological performance for practical applications.

Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for wastewater remediation. Herein, we report a new type of amorphous catalyst Fe41Co7Cr15Mo14C15B6Y2 hollow balls. Results demonstrate that the catalyst can still completely decolorized the 20 mg/L methylene blue (MB) solution after reused for 50 times under conditions of pH = 5, catalyst content 0.5 g/L, and temperature 80 °C. The catalyst is easily broken during degradation, so the inner surface also provides additional active sites. The Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy hollow balls were characterized by EDS, SEM and XPS, respectively. The elements in the catalytic system have a synergistic catalytic effect. Redox cycle Fe2+/Fe3+, Co2+/Co3+ and Mo4+/Mo6+ promote mutual conversion and accelerate the catalytic process of their reaction with H2O2, forming a self-stable redox cycle process. Among them, Fe2+ promotes the conversion of Co3+ to Co2+, and Mo4+ promotes the conversion of Fe3+ to Fe2+, mainly Fe2+ and Co2+ react with H2O2 to generate •OH. Mo and Cr element form MoO2 and Cr2O3 plasma compounds on the surface, which act as a protective film to make the catalyst more stable and repeated use more frequently.

Magnetic refrigeration (MR) by utilizing the magnetocaloric (MC) effect is recognized as one of the most potential promising solid state environmentally friendly and high efficiency alternative method to the well-used state-of-the-art gas compression cooling technique. In this work, a systematic investigation of quinary equi-atomic rare-earths (RE) based Er20Ho20Gd20Ni20Co20 high-entropy (HE) amorphous alloy in terms of the microstructure, magnetic and magnetocaloric (MC) properties have been reported. The Er20Ho20Gd20Ni20Co20 exhibits promising glass forming ability with an undercooled liquid region of 72 K. Excellent cryogenic MC performances can be found in wide temperature from ∼25 and ∼75 K, close to H2 and N2 liquefaction, respectively. Apart from the largest magnetic entropy change (-ΔSM) reaches 17.84 J/(kg K) with 0-7 T magnetic field change, corresponding refrigerant capacity (RC) attains a giant value of 1030 J/kg. The promising cryogenic MC performances together with the unique HE amorphous characterizations make the quinary Er20Ho20Gd20Ni20Co20 HE amorphous alloy attractive for cryogenic MR applications.

Adsorption is a simple and efficient phosphorus removal method used to control the eutrophication of water bodies. A simple and gentle atmospheric pressure hydrothermal method by adjusting the dosage of ammonium chloride and sodium hydroxide was used to synthesize amorphous, monoclinic, and tetragonal zirconia nano-powders with high specific surface areas (383.91 m2/g, 330.01 m2/g, and 234.36 m2/g) and particle size of about 40 nm for phosphate adsorption. When pH = 6.3, the phosphate adsorption capacity of the amorphous monoclinic phase and the tetragonal phase respectively reached 102.58 mg P/g, 68.11 mg P/g, and 37.25 mg P/g and the adsorption process of the three crystal forms of zirconia powders conformed to the Langmuir adsorption model. In the first 2 min of rapid adsorption, amorphous zirconia completed 76.23% of the adsorption process and the monoclinic phase also completed more than 60%. The adsorption process of the three crystal forms of zirconia was completed within 240 min and conformed to the pseudo-second-order kinetic model. Their adsorption characteristics of the three crystal forms of zirconia decreased with the increase in pH. While the pH was above than the isoelectric point of the solution, the adsorption capacity was significantly reduced. The large specific surface area and high hydroxyl content of the zirconia nano-powder made a great contribution to the adsorption process.

Carbon aerogels with nanoporous structure are attractive for thermal insulation under extreme conditions, but their practical applications are usually plagued by the inherent brittleness and easy-oxidation characteristic at high temperature. Herein, silica-modified carbon aerogels (SCAs) with extraordinarily high strength are prepared via a facile sol-gel polymerization of phenolic resin and siloxane, followed by ambient pressure drying and carbonization. The resulting SCAs possess medium-high density of ∼ 0.5 g·cm-3 and mesoporous structure with the mean pore size of 33 nm. During carbonization process, the siloxane could be gradually transformed into the amorphous SiO2 particles and crystalline SiC particles, which are coated on the surface of carbon nanoparticle and consequently improve the oxidation-resistance of carbon aerogels. Due to the density-porosity trade-off, the SCAs have high compressive strength of 10.0 MPa and satisfied thermal conductivities of 0.118 W·m-1·K-1 at 25 °C and 0.263 W·m-1·K-1 at 1000 °C. Furthermore, needled carbon fiber-reinforced SCAs (CF-SCAs) with ultrahigh compressive strength of 210.5 MPa are prepared, which exhibit good thermal conductivities of 0.207 W·m-1·K-1 at 25 °C and 0.407 W·m-1·K-1 at 1000 °C. The ultrahigh mechanical strength, good oxidation-resistance, good thermal insulation as well as the facile preparation make the SACs great promising in high-temperature insulations especially under harsh conditions.

In this work, the glass system of 3.95Li2O–9.95Na2O–0.85Al2O3–(100 − x)SiO2–9.25CaO–4.7MgO–3.8ZnO–xCeO2, where x is 0, 2.5, 5.0, 7.5 and 10.0 mol%, was investigated for a potential use in radiation-shielding applications. For this purpose, the newly developed Phy-X/PSD software was utilized to determine the radiation-shielding characteristics in the proposed lithium (Li)–zinc (Zn)–silicate (LZS) glass system. Based on the linear attenuation coefficient (LAC) calculations, the half-value layer (HVL) and the radiation protection efficiency were evaluated for the glass series. Further, some physical properties such as glass density (ρ glass), molar volume (V m), oxygen molar volume and oxygen packing density were estimated, while various optical features such as refractive index (n) and metallization criterion (M) were also assessed. The findings clearly showed that the addition of cerium (IV) oxide (CeO2) in the LZS glass system was a good choice for improving radiation-shielding characteristics – that is, the LAC was efficiently enhanced from 0.145 to 0.166 cm−1 at 1.5 MeV as the concentration of cerium (IV) oxide was increased from 0 to 10 mol%. On the other hand, the HVL decreased from 3.066 to 2.592 cm for LZS0 to LZS4. Moreover, the physical calculations revealed that ρ glass could be increased from 2.8181 to 3.2751 g/cm3 with the addition ratio of cerium (IV) oxide as 0–10 mol%, respectively. More importantly, LZS4, having the highest cerium (IV) oxide content, can compete with commercial radiation-shielding glasses.

The retarded kinetics of oxygen evolution on electrodes is a bottleneck for electrochemical energy conversion and storage systems. NiFe-based electrocatalysts provide a cost-effective choice to confront this challenge. However, there is a lack of facile techniques for depositing compact catalytic films of high coverage and possessing a state-of-the-art performance, which is especially desired in photoelectrochemical (PEC) systems. Herein, we demonstrate a spray pyrolysis (SP) route to address this issue, featuring the kinetic selective preparation towards the desired catalytic-active material. Differing from reported SP protocols which only produce inactive oxides, this approach directly generates a unique composite film consisting of NiFe layered oxyhydroxides and amorphous oxides, exhibiting an overpotential as small as 255 mV (10 mA cm−2) and a turnover frequency of ∼0.4 s−1 per metal atom. By using such a facile protocol, the surface rate-limiting issue of BiVO4 photoanodes can be effectively resolved, resulting in a charge injection efficiency of over 90%. Considering this deposition directly start from simple nitrates but only takes several seconds to complete, we believe it can be developed as a widely applicable and welcomed functionalization technique for diverse electrochemical devices.

In this study, we prepared GdZn2 by mechanical alloying method and measured its magnetization to reveal the magnetic and magnetocaloric properties. For a milling time (MT) ≥ 10 and 20 h, the GdZn2 phase was confirmed by X-ray diffraction measurements. For MT = 40 and 60 h, amorphous like patterns are observed. For MT = 10 and 20 h, magnetization (M) as a function of temperature below 80 K showed ferromagnetic-like increase. The observed values of M are 4.5 μB at 5 K for MT = 10 and 20 h, which is smaller than that of the theoretical expected value of 7 μB. For MT = 40 and 60 h, the long-range ferromagnetic order collapses because there is no spontaneous magnetization. The value of ΔT, where ΔT is the full width at half maximum of the magnetic entropy change (ΔSm (T)), increases significantly for MT ≤ 20 h because of the gradual release of magnetic entropy by the milling effect. Since M decreases with increasing MT, the maximum values of |ΔSm|, the relative cooling power, and the refrigerant capacity also decreases.

This study aims at investigating the effect of the substrate material on growth mechanism and also microstructure of Ta2O5 thin films. For this purpose, atomic force microscopy, scanning electron microscopy, and interferometry analyses were implemented to reveal the influence of silicon wafer and amorphous BK7 glass substrates on the nucleation and growth mechanisms of Ta2O5 thin films deposited via the radio frequency magnetron sputtering technique. Results indicated that those films with finer morphologies had relatively higher nucleation densities. Compared with BK7 glass substrate, crystals formed on the silicon wafer were shown to be finer and had lower mean areas in more nucleation sites. Moreover, optical properties and morphological characteristics of the films on the silicon substrates had much more endurance after the annealing treatment. It was observed that shift in the transmission spectra of the deposited films after the treatment was insignificant, implying high packing density of the films. However, a 6-nm shift in the transmission spectra indicated low density and high porosity of the films. Finally, atomic force microscopy analysis along with the light scattering measurements confirmed the formation of a low-roughness film on the silicon wafer substrates.

Multicomponent alloys of Zr50M50, Zr50(M,Ag)50 and Zr50(M,Pd)50 (M = Fe,Co,Ni,Cu) can be melt-spun to obtain amorphous ribbons. The maximum thickness for fully amorphous ribbons varies with composition in the range 34‒53 μm. In contrast, fully amorphous ribbons are not obtainable for binary Zr50Ni50 or ternary Zr50(Ni,Cu)50 alloys. Heating-induced crystallization occurs through: two stages of amorphous [am] →[ am ′ + B2] → [B2 + B33] for Zr50M50; and [am] → [ am ′ + B2] → [B2 + AgZr] for Zr50(M,Ag)50; and a single stage of [am] → [B2] for Zr50(M,Pd)50, while no B2 phase is formed for the binary and ternary Zr50Q50 (Q = Ni or/and Cu) alloys. As-spun amorphous ribbons have good bending plasticity. Remarkably, Zr50M50 ribbons in tension show 0.22‒0.28% plastic elongation and work-hardening (the yield stress is ∼820 MPa, the fracture stress is ∼1200 MPa). When cold-rolled at room temperature to 30% reduction in thickness, Zr50M50 ribbons show 10% increase in hardness, while retaining good bending plasticity. Cold-rolling induces precipitation of spheroidal B2 and irregular B33 particles, while deformation in tension induces B2, B33 and also plate-like monoclinic precipitates. The B2 and B33 particles form by polymorphic transformation, and include a high density of internal defects. This novel deformation-induced precipitation has not been recognized for any Zr50Q50 binary or ternary alloys. The new multicomponent systems are encouraging for future progress as structural amorphous alloys.

Development of electrocatalyst using facile way from non-noble metal compounds with high efficiency for effective water electrolysis is highly demanding for production of hydrogen energy. Nickel based electrocatalysts were currently developed for electrochemical water oxidation in alkaline pH. Herein, amorphous nickel tungstate (NiWO4) was synthesized using the facile successive ionic layer adsorption and reaction method. The films were characterized by X-ray diffraction, Raman spectroscopy, Fourier transfer infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy techniques. The electrochemical analysis showed 315 mV of overpotential at 100 mA cm−2 with lowest Tafel slope of 32 mV dec−1 for oxygen evolution reaction (OER) making films of NiWO4 compatible towards electrocatalysis of water in alkaline media. The chronopotentiometry measurements at 100 mA cm−2 over 24 h showed 97% retention of OER activity. The electrochemical active surface area (ECSA) of NW120 film was 25.5 cm−2.

Powder processing by ball milling is an effective approach for materials engineering. Although various methods for material processing are available, only high-energy shaker/vibratory or planetary mills have been intensively utilized to develop mechanical milling or alloying routes for structural control of MgB2 superconducting materials. Herein, we have attempted structural modification by using a low-rotation shaker, which is categorized as a low-energy and economical mill in terms of industrial applications. The operation speed was kept constant at 40 rpm, which is much lower than typical conditions employed for planetary mills. Instead of adjusting the low rotational speed, the other processing parameters were controlled to enhance the energy transfer from the balls to powders. The applied milling conditions were ultimately found to cause severe plastic deformation of the raw powders. The shape and size changed drastically, depending on the processing time. The morphological variation of the processed powders as precursors for the MgB2 materials influenced the void structure and the composition including amorphous phases. By considering these results, we also elucidated the mechanism underlying the structural changes upon ball milling and their effects on the transport critical current performance. The present approach for powder processing offers potential as an effective milling route for structural modification of superconducting materials.

In this work, we report the resistive switching behavior of an amorphous La2Ti2O7 (LTO) film as sandwiched between two Pt electrodes. The resistive switching is forming-free and highly uniform. Furthermore, it exhibits self-rectifying resistive switching behaviors owing to the Schottky contact and quasi-ohmic contact formed at the top and bottom interfaces, respectively. The mechanism of switching behavior in the device is attributed to the trapping/detrapping-mediated electronic bipolar resistance switching. By fitting the current-voltage characteristics, it indicates the coexistent conduction mechanisms of Schottky emission and space-charge-limited-conduction (SCLC), while the Schottky barrier modified by electron trapping/detrapping plays a dominating role in the resistive switching process.