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A novel strategy is proposed in this work to accelerate proton-coupled electron transfer via phase-engineered amorphous/crystalline interface for advancing overall water splitting. [Display omitted] • Co/Co 2 C crystals have been assembled on amorphous N, S co-doped porous carbon through hydrothermal and calcination process. • The stable biphase structure and amorphous/crystalline interface enhances the conductivity and intrinsic activity. • The adsorption ability of water molecules and intermediates is improved significantly. • This work has pioneered the crystalline/amorphous phase in electrocatalysts and provided new insights into phase engineering. Traditional phase engineering enhances conductivity or activity by fully converting electrocatalytic materials into either a crystalline or an amorphous state, but this approach often faces limitations. Thus, a practical solution entails balancing the dynamic attributes of both phases to maximize an electrocatalyst's functionality is urgently needed. Herein, in this work, Co/Co 2 C crystals have been assembled on the amorphous N, S co-doped porous carbon (NSPC) through hydrothermal and calcination processes. The stable biphase structure and amorphous/crystalline (A/C) interface enhance conductivity and intrinsic activity. Moreover, the adsorption ability of water molecules and intermediates is improved significantly attributed to the rich oxygen-containing groups, unsaturated bonds, and defect sites of NSPC, which accelerates proton-coupled electron transfer (PCET) and overall water splitting. Consequently, A/C-Co/Co 2 C/NSPC (Co/Co 2 C/NSPC with amorphous/crystalline interface) exhibits outstanding behavior for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), requiring the overpotential of 240.0 mV and 70.0 mV to achieve 10 mA cm−2. Moreover, an electrolyzer assembled by A/C-Co/Co 2 C/NSPC-3 (anode) and A/C-Co/Co 2 C/NSPC-2 (cathode) demonstrates a low drive voltage of 1.54 V during overall water splitting process. Overall, this work has pioneered the coexistence of crystalline/amorphous phases in electrocatalysts and provided new insights into phase engineering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystalline Ni(OH) 2 /Amorphous NiMoS electrocatalyst were designed and synthesized by two-step hydrothermal process. • The as-obtained material shows excellent hydrogen evolution over all pH ranges. • The synergistic mechanism and the role of crystalline Ni(OH) 2 and amorphous NiMoS was elucidated. Designing and fabricating efficient electrocatalysts is a practical step toward the commercial application of the efficient hydrogen evolution reaction (HER) over all pH ranges. Herein, novel Ti@Ni(OH) 2 -NiMoS heterostructure with interface between crystalline Ni(OH) 2 and amorphous NiMoS was rationally designed and fabricated on Ti mesh (denoted as Ti@Ni(OH) 2 -NiMoS). Acid etching and calcination experiments helped in accurate elucidation of the synergistic mechanism as well as the vital role on crystalline Ni(OH) 2 and amorphous NiMoS. In acidic solutions, the HER performance of Ti@Ni(OH) 2 -NiMoS was mainly attributed to the amorphous NiMoS. In neutral, alkaline, and natural seawater solutions, the HER performance was mainly determined by the synergistic interface behaviors between the Ni(OH) 2 and NiMoS. The crystalline Ni(OH) 2 accelerated water dissociation kinetics, while the amorphous NiMoS provided abundant active sites and allowed for fast electron transfer rates. To deliver current densities of 10 mA·cm−2 in acidic, neutral, alkaline, and natural seawater solutions, the Ti@Ni(OH) 2 -NiMoS required overpotentials of 138, 198, 180 and 371 mV, respectively. This paper provides general guidelines for designing efficient electrocatalyst with crystalline/amorphous interfaces for efficient hydrogen evolution over all-pH ranges. [ABSTRACT FROM AUTHOR]

The Ni 11 (HPO 3) 8 (OH) 3 /Mn 3 O 4 (named as NiPi/Mn 3 O 4) composite with crystalline/amorphous interface was prepared by electrochemical activation, which exhibited high activity and well stability toward hydrogen evolution reaction. The design of electrocatalysts with cost-efficient, highly-efficient and stable for hydrogen evolution reaction (HER) is significant to alleviate energy crisis in the future. Herein, we prepared the Ni 11 (HPO 3) 8 (OH) 3 /Mn 3 O 4 (named as NiPi/Mn 3 O 4) composite with crystalline/amorphous interface by electrochemical activation based on Ni 3 P/MnOOH precursor. The precursor was synthesized by two-step method that firstly electrodeposited on nickel foam and then used anodic oxidation under the applied voltage. The XPS analysis manifested that NiPi/Mn 3 O 4 had a strong interface coupling between Ni 11 (HPO 3) 8 (OH) 3 and Mn 3 O 4 contributed to fast kinetics of hydrogen evolution reaction. The morphology of the nanowires and nanoparticles were provided lager contact area between catalyst and electrolyte. Meanwhile, the obvious interface between crystalline and amorphous also resulted in NiPi/Mn 3 O 4 heterostructureted material with faster electron transport and superior stability. Owing to these characteristics, the NiPi/Mn 3 O 4 displays amazing HER activity with low overpotential of 84 mV at 100 mA cm−2 and a long-term stability of over 100 h at 200 mA cm−2 in 1.0 M NaOH solution. The surprising activity of NiPi/Mn 3 O 4 is better than that of most reported catalysts, similar to the state-of-the-art Pt/C. [ABSTRACT FROM AUTHOR]

• Triple-hierarchical nanoporous structure with superlarge ECSA. • Pt-like electrocatalytic activity towards HER and HzOR in alkaline solutions. • Synergistical regulation between the crystalline and amorphous interfaces. Replacing kinetically sluggish oxygen evolution reaction (OER) with hydrazine oxidation (HzOR) is an effective strategy for water electrolysis to achieve sustainable hydrogen production. Here we report triple-hierarchical nanoporous Ni(Cu)@NiFeP onto nickel foam (NM) as a bifunctional electrocatalyst for HER and HzOR. The as-prepared catalyst with a 54-fold increased electrochemical active surface area (ECSA) presents remarkable HzOR activity, requiring a potential of 6 mV to achieve 10 mA cm−2 in 1 M KOH, which is comparable to commercial Pt/C. Assembling in an electrolyzer for HER and HzOR, the Ni(Cu)@NiFeP/NM cell requires a cell voltage of 0.491 V to offer 100 mA cm−2, far lower than that of overall water splitting. The superior catalytic performance is ascribed to the synergistic effect from crystalline Ni(Cu) alloy and amorphous NiFe P-derivatives, as well as structural advantages of the unique 3D hierarchical porous nanostructures. The study also presents a strategy for accurate design and construction of multiple hierarchy of nanomaterials for energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

Nanomaterials are exerting a pull on deal with biological and pharmaceutical applications. Biomedical grade of zirconia reveals potential mechanical features of oxide ceramics. In this study, antimicrobial activity and anti-tooth decay applications of the synthesized NPs of ZrO 2 were determined. The as-prepared ZrO 2 NPs were characterized by UV–vis spectroscopy, FTIR and XRD, which determined the formation of ZrO 2 NPs and their crystalline nature. SEM analysis further revealed spherical shaped NPs and TEM analysis determined the size of the particles in the range of 15–21 nm, respectively. The antimicrobial activity of different concentrations of the synthesized ZrO 2 NPs was examined against gram positive bacteria ( Bacillus subtilis and Staphylococcus aureus ), gram negative bacteria ( Escherichia coli and Pseudomonas aeruginosa ), respectively. The synthesized ZrO 2 NPs displayed a better inhibitory action against Pseudomonas aeruginosa (inhibition zone size of 20 mm) at the concentration of 100 μg/ml compared to other bacteria due to the negatively charged P. aeruginosa cell wall readily attracting positively charged ZrO 2 NPs and thereby inhibiting microbial actions. Moreover, the concentration of ZrO 2 NPs was directly proportional to their inhibitory actions against the tested microorganisms. Finally, the preventive role of ZrO 2 NPs in a tooth decay pathway has been elucidated. Hence, it could be concluded that the as-prepared ZrO 2 NPs possess viable biomedical applications. [ABSTRACT FROM AUTHOR]

GaN pyramid arrays have been successfully synthesized by selective photo-assisted chemical etching in a K 2 S 2 O 8 /KOH solution. A detailed analysis of time evolution of surface morphology has been conducted, which describes an etching process of GaN pyramids. Room temperature cathodoluminescence images indicate that these pyramids are composed of crystalline GaN surrounding dislocations, which is caused by the greater recombination rate of electrons and holes at dislocation than that of crystalline GaN. The Raman results show a stress relaxation in GaN pyramids compared with unetched GaN. The optical property of both unetched GaN and GaN pyramids has been studied by photoluminescence. The formation mechanism and feature of GaN pyramids are also rationally explained. [ABSTRACT FROM AUTHOR]

Well-crystalline homogeneous α-Fe 2 O 3 nanopeanuts were synthesized, characterized and utilized as an effective photocatalysts for the photocatalytic degradation of toxic and harmful organic dyes, i.e. Congo red (CR), Eosin red (ER) and methylene blue (MB). The nanopeanuts were synthesized by facile one-step hydrothermal process without employing any templates and characterized in detail in terms of their morphological and structural properties. The detailed characterizations confirmed the well-crystallinity, large-scale growth and rhombohedral crystal structure of the synthesized nanopeanuts. Further, the detailed growth processes of prepared nanopeanuts were studied by examining the effects of reaction time, temperature and amounts of hexamethylenetetramine (HMT) on the shapes and sizes of the products. Thus, based on the observed experimental evidences, a possible growth mechanism for the formation of nanopeanuts was also proposed. Finally, the nanopeanuts were used as efficient visible-light driven photocatalyst for the photocatalytic degradation of organic dyes and the observed degradation rates were MB (57%) < ER (63%) < CR (93%) under visible-light irradiation. Interestingly, it was seen that the photocatalytic degradation of nanopeanuts was higher than other α-Fe 2 O 3 nanostructures such as nanospindles and commercial α-Fe 2 O 3 which revealed that the prepared α-Fe 2 O 3 nanopeanuts are excellent visible-light driven photocatalyst for the photocatalytic degradation of harmful and toxic organic dyes. [ABSTRACT FROM AUTHOR]

Abstract: Hierarchically structured CaCO3 films were synthesized at atmospheric conditions (room temperature and 1atm) without the use of templates or amphiphilic molecules in this process. The resulting CaCO3 film was formed by self-organization between Ca(OH)2 and aqueous CO2. The building blocks of the CaCO3 film were thought to be CaCO3 primary nanoparticles that aligned to build higher level structures with greater size, called mesocrystals, depending on the additives. The soluble additives played a key role in the control of the morphology, crystallinity, and polymorphism of the CaCO3 film, and the effects strongly depended on the type of additive and their concentrations. The additives used in this study decreased the crystallinity of CaCO3 (calcite) film in the order of glucose>aspartic acid>serine in a manner inversely proportional to the concentration of the additives. In addition, Mg2+, K+, and Na+ ion additives led to the formation of an aragonite phase, the proportion of which increased with the concentration of ions. The threshold concentrations of these ions for the formation of the aragonite phase in CaCO3 film were found to be in the order of Na+ >K+ >Mg2+. [ABSTRACT FROM AUTHOR]

Abstract: A new photocatalyst, namely single-crystalline Bi5O7NO3 nanofibers, was prepared by a facile hydrothermal method in the presence of Triton X-100 and ammonia. Bi5O7NO3 possessing a crystalline sheet morphology could be dissolved and transformed into nanofibers by controlling the reaction time. Samples were characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy. The Bi5O7NO3 nanofiber growth mechanism is discussed in detail. The band gap energy of the as-prepared Bi5O7NO3 photocatalyst was about 2.70–2.90eV. Results of first-principle density functional theory calculations confirmed that Bi5O7NO3 had a narrow band gap. They revealed that the conduction band bottom was predominantly composed of Bi 6s, Bi 6p, N 2p and O 2p orbitals, while the valence band (VB) top primarily consisted of Bi 6p, Bi 6s and O 2p orbitals. The as-obtained Bi5O7NO3 nanofibers showed good photocatalytic activity and stability for the degradation of Rhodamine B (RhB) under visible light irradiation, which may be ascribed to the highly mobile conduction band (CB) and VB charge carriers. [Copyright &y& Elsevier]

Abstract: In the lens of the eye the ordered arrangement of the major proteins, the crystallins, contributes to lens transparency. Members of the β/γ-crystallin family share common β-sheet rich domains and hydrophobic regions at the monomer–monomer or domain–domain interfaces. Disruption of these interfaces, due to post-translational modifications, such as deamidation, decreases the stability of the crystallins. Previous experiments have failed to define the structural changes associated with this decreased stability. Using hydrogen/deuterium exchange with mass spectrometry (HDMS), deamidation-induced local structural changes in βB2-crystallin were identified. Deamidation was mimicked by replacing glutamines with glutamic acids at homologous residues 70 and 162 in the monomer–monomer interface of the βB2-crystallin dimer. The exchange-in of deuterium was determined from 15 s to 24 h and the global and local changes in solvent accessibility were measured. In the wild type βB2-crystallin (WT), only about 20% of the backbone amide hydrogen was exchanged, suggesting an overall low accessibility of βB2-crystallin in solution. This is consistent with a tightly packed domain structure observed in the crystal structure. Deuterium levels were initially greater in N-terminal domain (N-td) peptides than in homologous peptides in the C-terminal domain (C-td). The more rapid incorporation suggests a greater solvent accessibility of the N-td. In the βB2-crystallin crystal structure, interface Gln are oriented towards their opposite domain. When deamidation was mimicked at Gln70 in the N-td, deuterium levels increased at the interface peptide in the C-td. A similar effect in the N-td was not observed when deamidation was mimicked at the homologous residue, Gln162, in the C-td. This difference in the mutants can be explained by deamidation at Gln70 disrupting the more compact C-td and increasing the solvent accessibility in the C-td interface peptides. When deamidation was mimicked at both interface Gln, deuterium incorporation increased in the C-td, similar to deamidation at Gln70 alone. In addition, deuterium incorporation was decreased in the N-td in an outside loop peptide adjacent to the mutation site. This decreased accessibility may be due to newly exposed charge groups facilitating ionic interactions or to peptides becoming more buried when other regions became more exposed. The highly sensitive HDMS methods used here detected local structural changes in solution that had not been previously identified and provide a mechanism for the associated decrease in stability due to deamidation. Changes in accessibility due to deamidation at the interface led to structural perturbations elsewhere in the protein. The cumulative effects of multiple deamidation sites perturbing the structure both locally and distant from the site of deamidation may contribute to aggregation and precipitation during aging and cataractogenesis in the lens. [Copyright &y& Elsevier]

The dissociation of CO serves both as a model test reaction on single crystals and as a relevant reaction step for industrial methanation. We combined extensive density functional theory calculations, ultra-high vacuum experiments on well-defined single crystals, and catalytic activity measurements on supported catalysts in a study of the dissociation mechanism of CO on Ni surfaces. We found that this process is highly structure-sensitive and also is sensitive to the presence of hydrogen: Under ultra-high vacuum, with no hydrogen present, the dissociation proceeds through a direct route in which only undercoordinated sites (e.g., steps) are active. Under methanation conditions, the dissociation also proceeds most favorably over undercoordinated sites, but through a COH species. [Copyright &y& Elsevier]

The solution behavior of homologously obtained crystalline surfactant molecular complexes (SMCs) that are generated between quaternary ammonium bromide and several additive materials has shed light on the recognition of fundamentals of solubilization. It has been revealed that the SMCs derived from long-alkyl-chain surfactants are sufficiently dissolved in water through the path of micellar dispersion above the cmc''s of the complex surfactants, whereas the short-chain homologues cannot dissolve in water but dissociate the complexes, resulting in a heterogeneous phase made up of the liberated additives. The fact agrees perfectly with the familiar aspects of solubilization by surfactant; i.e., the longer the alkyl chain of the surfactant becomes, the more effective it is for solubilization. Based on these results, it has been deduced that the possibility for any pair of surfactant and solubilizate (additive) to realize solubilization simply depends on the relative importance of equilibrium of dissociation or association of the SMC species in aqueous medium. [Copyright &y& Elsevier]

We present a coupled atomistic–continuum method for the modeling of defects and interface dynamics in crystalline materials. The method uses atomistic models such as molecular dynamics near defects and interfaces, and continuum models away from defects and interfaces. We propose a new class of matching conditions between the atomistic and the continuum regions. These conditions ensure the accurate passage of large-scale information between the atomistic and the continuum regions and at the same time minimize the reflection of phonons at the atomistic–continuum interface. They can be made adaptive by choosing appropriate weight functions. We present applications to dislocation dynamics, friction between two-dimensional crystal surfaces, and fracture dynamics. We compare results of the coupled method and of the detailed atomistic model. [Copyright &y& Elsevier]

The stability of two rigidly rotating magnetic fluids separated by a cylindrical interface and stressed by a timely oscillating axial magnetic field is investigated. Only axisymmetric disturbances are considered. The interface admits both mass and heat transfer. Weak viscous effects on the interface are taken into account so that their contributions are demonstrated in the boundary conditions. The solution of the boundary value problem leads to a transcendental differential equation. It includes a periodic coefficient together with modified Bessel functions of operators involved as their arguments. In the absence of rotation and under the assumption of small amplitude of the harmonic magnetic field, the characteristic equation is analyzed by means of Whittaker''s perturbation technique to determine the transition curves which separate stable from unstable solutions. While in the presence of rotation, the method of multiple-time scales is adopted to investigate the necessary and sufficient conditions for stability. The analysis results in the resonance cases as well as the nonresonance cases. In order to simplify the analysis, the periodic solutions are only considered. Therefore, stability is discussed through the marginal state. Furthermore, the rotation is considered as small. The analytical results are numerically confirmed. [Copyright &y& Elsevier]

We study the behavior of solutions of the modified Stefan problem in the plane for polygonal interfaces. We are particularly interested in a solution near a singularity of either the loss of a facet or the breaking of a facet. We establish precise regularity results if a facet disappears. We use them to establish the existence of a weak solution with singular data, i.e., when some of the zero-crystalline-curvature facets have zero length. [Copyright &y& Elsevier]

Phase composition and molecular mobility were studied using 1H NMR T 2 relaxometry in isotactic polybutene-1 (iPB-1) with two polymorphs - form I and II crystals. Several types of NMR relaxation methods and data analysis were evaluated for determining the most reliable way for studying physical phases in iPB-1. Three-phase model provided the most appropriate description of the phase composition in iPB-1, i.e., a crystal-amorphous interface separates the crystalline and the amorphous phases. Due to complex molecular mobility in iPB-1, the amount of rigid fraction should be considered as NMR crystallinity number. Two types of chain segments are present in the amorphous phase: (1) chain segments with anisotropic mobility due to chain anchoring to crystals and chain entanglements; and (2) highly mobile chain end segments. The polymorphic phase II to I transition causes significant immobilization of polymer chains in the crystalline and the amorphous phases. Molecular weight of iPB-1 largely influences phase composition and molecular mobility in crystalline and amorphous phases. Image 1 • Phase composition and molecular mobility in isotactic polybutene-1 are studied using 1H NMR T 2 relaxometry. • The three-phase model provides the best description of the phase composition. • Advantages and disadvantages of different types of T 2 relaxation experiments are discussed. • The polymorphic phase II to I transition causes decrease in chain mobility in the crystalline and the amorphous phases. • Molecular weight of iPB-1 largely influences phase composition and molecular mobility in crystalline and amorphous phases. [ABSTRACT FROM AUTHOR]