Ion diffusion retarded by diverging chemical susceptibility.

For first-order phase transitions, the second derivatives of Gibbs free energy (specific heat and compressibility) diverge at the transition point, resulting in an effect known as super-elasticity along the pressure axis, or super-thermicity along the temperature axis. Here we report a chemical analogy of these singularity effects along the atomic doping axis, where the second derivative of Gibbs free energy (chemical susceptibility) diverges at the transition point, leading to an anomalously high energy barrier for dopant diffusion in co-existing phases, an effect we coin as super-susceptibility. The effect is realized in hydrogen diffusion in vanadium dioxide (VO) with a metal-insulator transition (MIT).

Millimeter-Sized KMnF:Si, NH Red-Luminescent Crystals with High Absorption Efficiency (AE of 93.5%) and External Quantum Efficiency (EQE of 68.9%) Grown by Cooling-Induced Crystallization.

Luminescent bulk crystals exhibit fewer grain boundaries and defects compared with conventional microsized powdery ones. Herein, targeting Mn-activated fluoride crystals with a sharp line-type red luminescence spectrum, we propose a new cooling-induced crystallization method to grow the fluoride crystals. By this new method, we successfully grew millimeter-sized KMnF:Si, NH crystals, featuring an AE (absorption efficiency) of 93.

Immobilization of Oxyanions on the Reconstructed Heterostructure Evolved from a Bimetallic Oxysulfide for the Promotion of Oxygen Evolution Reaction.

Efficient and durable oxygen evolution reaction (OER) requires the electrocatalyst to bear abundant active sites, optimized electronic structure as well as robust component and mechanical stability. Herein, a bimetallic lanthanum-nickel oxysulfide with rich oxygen vacancies based on the LaOS prototype is fabricated as a binder-free precatalyst for alkaline OER. The combination of advanced in situ and ex situ characterizations with theoretical calculation uncovers the synergistic effect among La, Ni, O, and S species during OER, which assures the adsorption and stabilization of the oxyanion [Formula: see text] onto the surface of the deeply reconstructed porous heterostructure composed of confining NiOOH nanodomains by La(OH) barrier.

A study of the Rashba effect in two-dimensional ternary compounds ABC monolayers (A = Sb, Bi; B = Se, Te; C = Br; I).

The structure and electronic and spintronic properties of two-dimensional (2D) ternary compounds ABC (A = Sb, Bi; B = Se, Te; C = Br; I) monolayers are investigated using the first-principles method. The ABC monolayers possess typical Janus structures with a considerable potential gradient normal to the surface, inducing intrinsic Rashba spin splitting (RSS) at the conduction band minimum near the point. Among them, the splitting strength of the BiSeI monolayer is the largest and its Rashba coefficient can reach 1.

The Ultrahigh Adsorption Capacity and Excellent Photocatalytic Degradation Activity of Mesoporous CuO with Novel Architecture.

In this paper, mesoporous CuO with a novel architecture was synthesized through a conventional hydrothermal approach followed by a facile sintering procedure. HR-TEM analysis found that mesoporous CuO with an interconnected pore structure has exposed high-energy crystal planes of (002) and (200). Theoretical calculations indicated that the high-energy crystal planes have superior adsorption capacity for H ions, which is critical for the excellent adsorption and remarkable photocatalytic activity of the anionic dye.

Reviving Oxygen Evolution Electrocatalysis of Bulk La-Ni Intermetallics via Gaseous Hydrogen Engineering.

A hydrogen processing strategy is developed to enable bulk LaNi to attain high activity and long-term stability toward the electrocatalytic oxygen evolution reaction (OER). By a combination of in situ Raman and quasi in situ X-ray absorption (XAS) spectra, secondary-electron-excited scanning transmission electron microscopy (STEM) patterns as well as the Rietveld method and density functional theory (DFT) calculations, it is discovered that hydrogen-induced lattice distortion, grain refinement, and particle cracks dictate the effective reconstruction of the LaNi surface into a porous hetero-nanoarchitecture composed of uniformly confined active γ-NiOOH nanocrystals by La(OH) layer in the alkaline OER process. This significantly optimizes the charge transfer, structural integrity, active-site exposure, and adsorption energy toward the reaction intermediates.

Charge-Polarized Selenium Vacancy in Nickel Diselenide Enabling Efficient and Stable Electrocatalytic Conversion of Oxygen to Hydrogen Peroxide.

Vacancy engineering is deemed as one of the powerful protocols to tune the catalytic activity of electrocatalysts. Herein, Se-vacancy with charge polarization is created in the NiSe structure (NiSe -V ) via a sequential phase conversion strategy. By a combined analysis of the Rietveld method, transient photovoltage spectra (TPV), in situ Raman and density functional theory (DFT) calculation, it is unequivocally discovered that the presence of charge-polarized Se-vacancy is beneficial for stabilizing the structure, decreasing the electron transfer kinetics, as well as optimizing the free adsorption energy of reaction intermediate during two-electron oxygen reduction reaction (2e ORR).

Ultrahigh thermoelectric performance of Janus α-STe and α-SeTe monolayers.

Janus α-STe and α-SeTe monolayers are investigated systematically using first-principles calculations combined with semiclassical Boltzmann transport theory. Janus α-STe and α-SeTe monolayers are indirect semiconductors with band gaps of 1.20 and 0.

Enhanced Pd/a-WO /VO Hydrogen Gas Sensor Based on VO Phase Transition Layer.

The utilization of clean hydrogen energy is becoming more feasible for the sustainable development of this society. Considering the safety issues in the hydrogen production, storage, and utilization, a sensitive hydrogen sensor for reliable detection is essential and highly important. Though various gas sensor devices are developed based on tin oxide, tungsten trioxide, or other oxides, the relatively high working temperature, unsatisfactory response time, and detection limitation still affect the extensive applications.

Multi-shaped strain soliton networks and moiré-potential-modulated band edge states in twisted bilayer SiC.

Tuning the interlayer twist angle provides a new degree of freedom to exploit the potentially excellent properties of two dimensional layered materials. Here we investigate the structural and electronic properties of twisted bilayer SiC under a series of twist angles using first principle calculations. The interplay of interlayer van der Waals interactions and intralayer strain induces dramatic in-plane and out-of-plane displacements.

A comparative study of condyle position in temporomandibular disorder patients with chewing side preference using cone-beam computed tomography.

Background: Chewing side preference (CSP) could cause structural and morphological changes of temporomandibular joint (TMJ) and has been suggested as one aetiology of temporomandibular disorders (TMDs), but the condylar position in TMD patients with CSP is unknown.

Objective: To compare the condylar position in the TMD patients with and without CSP.

Methods: Ninety TMD patients with unilateral symptom (69 with CSP and 21 without CSP) and 20 asymptomatic participants received cone-beam computed tomography.

Cone-beam computed tomographic assessment of the inclination of the articular eminence in patients with temporomandibular disorders and chewing side preference.

Background: Chewing side preference (CSP) has been proposed as one etiology of temporomandibular disorders (TMDs) as it can induce the structural changes of the temporomandibular joint. But its association with the inclination of the articular eminence (IAE) is unknown. This study aimed to compare IAE between patients with CSP and without CSP.

BaTiF:Mn Red Phosphor: Synthesis of Single Crystals at Room Temperature and the High Hydrolysis-Resistant Property.

Due to the low solubility of BaF, the BaTiF:Mn phosphor for whitelight-emitting diodes application has been generally synthesized by the hydrothermal route, during which process the valence of the manganese dopant is difficult to be controlled as tetravalent. In this paper, a new synthesis method that proceeded at room temperature was reported. This method uses BaTiOF as the precursor and allows for the control of the phase transformation rate from BaTiOF to BaTiF in the KMnF/HF acid solution.

High temperature induced S vacancies in natural molybdenite for robust electrocatalytic nitrogen reduction.

Defect engineering is an important strategy to regulate electronic structure of electrocatalysts for electrochemical N fixation, aiming at improving the electron state density and enhancing the adsorption and activation of inert N. In this paper, a high-temperature strategy to anneal the natural molybdenite under Ar atmosphere was developed, and the as-obtained molybdenite with S vacancies boosted a high activity for N reduction reaction. In 0.

Microsized Red Luminescent MgAlO:Mn Single-Crystal Phosphor Grown in Molten Salt for White LEDs.

A single-crystalline defect-less phosphor is desired for efficient luminescence of the therein doped optical activators. In this paper, microsized MgAlO:Mn single-crystal phosphors with bright red luminescence were grown in molten LiCl salt at 950 °C, for application in blue LED pumped white lighting. By comparing the phosphor formation from various Mg- and Al-bearing sources, both the template-formation and the dissolution-diffusion processes were evidenced to account for the formation of the microsized MgAlO:Mn crystallites.

Hot-Electron-Induced Photothermal Catalysis for Energy-Dependent Molecular Oxygen Activation.

Hot electrons activate reactants and reduce the activation energy barrier (E ) of a reaction through electron donation. However, a comprehensive understanding of the intrinsic driving force of this electron-donating effect is lacking, let alone the precise manipulation of electron donation processes. Herein, the essential and promotional role of hot electron energy on the electron-donating effect was elucidated using molecular oxygen activation (MOA) as a model reaction.

Magnetism arising from Mexican-hat-like band dispersion in the WSe/SnS heterostructure interlayer strain.

Mexican-hat-like band dispersion is extremely critical to the realization of hole-doping-induced magnetism in monolayer metal monochalcogenides. However, it is absent from transition-metal dichalcogenides (TMDCs), i.e.

Tunable Hydrogen Doping of Metal Oxide Semiconductors with Acid-Metal Treatment at Ambient Conditions.

Hydrogen doping of metal oxide semiconductors is promising for manipulation of their properties toward various applications. Yet it is quite challenging because it requires harsh reaction conditions and expensive metal catalysts. Meanwhile, acids as a cheap source of protons have long been unappreciated.

Tuning Phase Transitions in Metal Oxides by Hydrogen Doping: A First-Principles Study.

Optimizing physical or chemical properties via electronic phase transitions is important for developing high-performance semiconductor materials. Using first-principles calculations, we established hydrogen doping (H-doping) as an alternative strategy for modulating phase transitions in metal oxide semiconductors. We found that H-doping can induce an insulator-to-metal phase transition in rutile TiO or wurtzite ZnO, a metal-to-insulator phase transition in rutile VO, and sequential insulator-metal-insulator phase transitions in SnO.

Electron-Proton Co-doping-Induced Metal-Insulator Transition in VO Film via Surface Self-Assembled l-Ascorbic Acid Molecules.

Charge doping is an effective way to induce the metal-insulator transition (MIT) in correlated materials for many important utilizations, which is however practically limited by problem of low stability. An electron-proton co-doping mechanism is used to achieve pronounced phase modulation of monoclinic vanadium dioxide (VO ) at room temperature. Using l-ascorbic acid (AA) solution to treat VO , the ionized AA species donate electrons to the adsorbed VO surface.

Gate-controlled VO phase transition for high-performance smart windows.

Vanadium dioxide (VO) is a promising material for developing energy-saving "smart windows," owing to its infrared thermochromism induced by metal-insulator transition (MIT). However, its practical application is greatly limited by its relatively high critical temperature (~68°C), low luminous transmittance (<60%), and poor solar energy regulation ability (<15%). Here, we developed a reversible and nonvolatile electric field control of the MIT of a monoclinic VO film.

Dynamic Electronic Doping for Correlated Oxides by a Triboelectric Nanogenerator.

The metal-insulator transition of vanadium dioxide (VO ) is exceptionally sensitive to charge density and electron orbital occupancy. Thus three-terminal field-effect transistors with VO channels are widely adopted to control the phase transition by external gating voltage. However, current leakage, electrical breakdown, or interfacial electrochemical reactions may be inevitable if conventional solid dielectrics or ionic-liquid layers are used, which possibly induce Joule heating or doping in the VO layer and make the voltage-controlled phase transition more complex.

Coupled ultrasonication-milling synthesis of hierarchically porous carbon for high-performance supercapacitor.

Activated carbon (AC) based supercapacitors exhibit intrinsic advantages in energy storage. Traditional two-step synthesis (carbonization and activation) of AC faces difficulties in precisely regulating its pore-size distribution and thoroughly removing residual impurities like silicon oxide. This paper reports a novel coupled ultrasonication-milling (CUM) process for the preparation of hierarchically porous carbon (HPC) using corn cobs as the carbon resource.

Non-catalytic hydrogenation of VO in acid solution.

Hydrogenation is an effective way to tune the property of metal oxides. It can conventionally be performed by doping hydrogen into solid materials with noble-metal catalysis, high-temperature/pressure annealing treatment, or high-energy proton implantation in vacuum condition. Acid solution naturally provides a rich proton source, but it should cause corrosion rather than hydrogenation to metal oxides.

Synthesis of TiO@g-CN core-shell nanorod arrays with Z-scheme enhanced photocatalytic activity under visible light.

Novel rutile TiO@g-CN core-shell photocatalysts were synthesized by a facile saturated aqueous solution method. The composites were further characterized by using X-ray diffraction (XRD), high-resolution transmission microscopy (HRTEM), UV-visible light diffusion reflectance spectrometry (DRS), X-ray photoelectron spectroscopy (XPS) and so on. The results indicated that an ultrathin layer of g-CN was in-situ fabricated over the surface of rutile TiO nanorod.