Unique magnetic transition process demonstrating the effectiveness of bond percolation theory in a quantum magnet.

Like the crystallization of water to ice, magnetic transition occurs at a critical temperature after the slowing down of dynamically fluctuating short-range correlated spins. Here, we report a unique type of magnetic transition characterized by a linear increase in the volume fraction of unconventional static short-range-ordered spin clusters, which triggered a transition into a long-range order at a threshold fraction perfectly matching the bond percolation theory in a new quantum antiferromagnet of pseudo-trigonal Cu(OH)Cl. Static short-range order appeared in its Kagome lattice plane below ca.

p-Orbital Ferromagnetism Arising from Unconventional O Ionic State in a New Semiconductor SrAlO with Insufficiently Bonded Oxygen.

Oxygen in solids usually exists in an O ionic state. As a result, it loses its magnetic nature of a single atom, wherein two unpaired electrons exist in its outer 2p orbitals. Here, it is shown that an unconventional stable ionic state of O is realized in a new semiconductor material SrAlO, leading to an intrinsic p-orbital ferromagnetism stable until ≈900 K.

Improving the Cyclic Reversibility of Layered Li-Rich Cathodes by Combining Oxygen Vacancies and Surface Fluorination.

Layered-type Li-rich cathode materials have attracted significant attention for next-generation Li-ion batteries, but the advantage of their high capacity is eclipsed by their poor reversibility upon cycling. Irreversible oxygen redox activity and surface degradation have been deemed as the root cause and direct cause for their poor performance, respectively. We attempted to suppress surface degradation by inserting fluoride ions up to some depth on the surface.

Investigating Degradation Mechanisms in PtCo Alloy Catalysts: The Role of Co Content and a Pt-Rich Shell Using High-Energy Resolution Fluorescence Detection X-ray Absorption Spectroscopy.

Low Pt-based alloy catalysts are regarded as an efficient strategy in achieving high activity for the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells (PEMFCs). However, the desired durability for the low Pt-based catalysts, such as the PtCo catalyst, has still been considered a great challenge for PEMFCs. In this study, we investigate sub-2.

Mechanisms of point defect formation and ionic conduction in divalent cation-doped lanthanum oxybromide: first-principles and experimental study.

The ionic conduction mechanism in M-doped (M: Mg, Ca, Zn, and Sr) lanthanum oxybromide (LaOBr) was investigated theoretically and experimentally. Formation energy calculations of point defects revealed that Br ion vacancies and substitutional M ions were the major point defects in M-doped LaOBr, while Br ion vacancies and antisite O ions at Br sites were the major defect types in pure LaOBr. In the relaxed point defect models, doped Mg and Zn ions were displaced from the initial positions of the La ions, and this was experimentally supported by crystal structural analysis.

Protection Against Absorption Passivation on Platinum by a Nitrogen-Doped Carbon Shell for Enhanced Oxygen Reduction Reaction.

In polymer electrolyte type fuel cells, the platinum-based catalysts are applied for the oxygen reduction reaction. However, the specific adsorption from the sulfo group in perfluorosulfonic acid ionomers has been considered to passivate the active sites of the platinum. Herein, we present platinum catalysts covered by an ultrathin two-dimensional nitrogen-doped carbon shell (CN) layer to protect the platinum from the specific adsorption of perfluorosulfonic acid ionomers.

Unique Li deposition behavior in LiPS solid electrolyte observed X-ray computed tomography.

The problem of lithium dendrites must be addressed for practical lithium metal all-solid-state batteries. Herein, three-dimensional morphological changes within LiPS electrolyte away from the anode were observed using X-ray computed tomography. We revealed that the electronic conduction of decomposition and the electrolyte/void interface cause the lithium deposition within the LiPS.

Stacking Order Induced Anion Redox Regulation for Layer-Structured Na Li Mn Cu O Cathode Materials.

Stacking order plays a key role in defining the electrochemical behavior and structural stability of layer-structured cathode materials. However, the detailed effects of stacking order on anionic redox in layer-structured cathode materials have not been investigated specifically and are still unrevealed. Herein, two layered cathodes with the same chemical formula but different stacking orders: P2-Na Li Mn Cu O (P2-LMC) and P3-Na Li Mn Cu O (P3-LMC) are compared.

Formed Heterostructure Interface and Well-Tuned Electronic Structure Ensuring Long Cycle Stability for 4.9 V High-Voltage Li-Rich Layered Oxide Cathodes.

High-voltage lithium-rich manganese-based layered oxides (LMLOs) are considered as the most competitive cathode materials for next-generation high-energy-density lithium-ion batteries (LIBs). However, LMLOs still suffer from irreversible lattice oxygen release, uncontrollable interface side reactions, and surface structural degradation. Herein, we propose an integration strategy combining La/Al codoping and LiCoPO nanocoating to improve the electrochemical performance of LMLOs comprehensively.

Improvement of Visible-Light H Evolution Activity of Pb Ti O F Photocatalyst by Coloading of Rh and Pd Cocatalysts.

Pb Ti O F modified with various metal cocatalysts was studied as a photocatalyst for visible-light H evolution. Although unmodified Pb Ti O F showed negligible activity, modification of its surface with Rh led to the best observed promotional effect among the Pb Ti O F samples modified with a single metal cocatalyst. The H evolution activity was further enhanced by coloading with Pd; the Rh-Pd/Pb Ti O F photocatalyst showed 3.

Rate-Determining Process at Electrode/Electrolyte Interfaces for All-Solid-State Fluoride-Ion Batteries.

Developing high-performance solid electrolytes that are operable at room temperature is one of the toughest challenges related to all-solid-state fluoride-ion batteries (FIBs). In this study, tetragonal β-PbSnF, a promising solid electrolyte material for mild-temperature applications, was modified through annealing under various atmospheres using thin-film models. The annealed samples exhibited preferential growth and enhanced ionic conductivities.

Impact of the Composition of Alcohol/Water Dispersion on the Proton Transport and Morphology of Cast Perfluorinated Sulfonic Acid Ionomer Thin Films.

The dispersion of perfluorinated sulfonic acid ionomers in catalyst inks is an important factor that controls the performance of catalyst layers in membrane electrode assemblies of polymer electrolyte fuel cells. Herein, the effects of water/alcohol compositions on the morphological properties and proton transport are examined by grazing incidence small-angle X-ray scattering, grazing incidence wide-angle X-ray scattering, and electrochemical impedance spectroscopy. The thin films cast by a high water/alcohol ratio Nafion dispersion have high proton conductivity and well-defined hydrophilic/hydrophobic phase separation, which indicates that the proton conductivity and morphology of the Nafion thin films are strongly influenced by the state of dispersion.

soft X-ray absorption spectroscopic study on microporous carbon-supported sulfur cathodes.

Sulfur is a promising material for next-generation cathodes, owing to its high energy and low cost. However, sulfur cathodes have the disadvantage of serious cyclability issues due to the dissolution of polysulfides that form as intermediate products during discharge/charge cycling. Filling sulfur into the micropores of porous carbon is an effective method to suppress its dissolution.

Synthesis of Sulfide Solid Electrolytes through the Liquid Phase: Optimization of the Preparation Conditions.

All-solid-state lithium batteries using inorganic sulfide solid electrolytes have good safety properties and high rate capabilities as expected for a next-generation battery. Presently, conventional preparation methods such as mechanical milling and/or solid-phase synthesis need a long time to provide a small amount of the product, and they have difficult in supplying a sufficient amount to meet the demand. Hence, liquid-phase synthesis methods have been developed for large-scale synthesis.

Determining Factor on the Polarization Behavior of Magnesium Deposition for Magnesium Battery Anode.

To clarify the origin of the polarization of magnesium deposition/dissolution reactions, we combined electrochemical measurement, soft X-ray absorption spectroscopy ( SXAS), Raman, and density functional theory (DFT) techniques to three different electrolytes: magnesium bis(trifluoromethanesulfonyl)amide (Mg(TFSA))/triglyme, magnesium borohydride (Mg(BH))/tetrahydrofuran (THF), and Mg(TFSA)/2-methyltetrahydrofuran (2-MeTHF). Cyclic voltammetry revealed that magnesium deposition/dissolution reactions occur in Mg(TFSA)/triglyme and Mg(BH)/THF, while the reactions do not occur in Mg(TFSA)/2-MeTHF. Raman spectroscopy shows that the [TFSA] in the Mg(TFSA)/triglyme electrolyte largely does not coordinate to the magnesium ions, while all of the [TFSA] in Mg(TFSA)/2-MeTHF and [BH] in Mg(BH)/THF coordinate to the magnesium ions.

Morphology Changes in Perfluorosulfonated Ionomer from Thickness and Thermal Treatment Conditions.

The morphological changes of Nafion thin films with thicknesses from 10 to 200 nm on Pt substrate with various annealing histories (unannealed to 240 °C) were systematically investigated using grazing incidence small-angle X-ray scattering (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS). The results revealed that the hydrophilic ionic domain and hydrophobic backbone in Nafion thin films changed significantly when the annealing treatment exceeded the cluster transition temperature, which decreased proton conductivity, due to the constrained hydrophilic/hydrophobic phase separation, and increased the crystalline-rich domain. This research contributed to the understanding of ionomer thermal stability in the catalyst layer, which is subjected to thermal annealing during the hot-pressing process.

Water Oxidation through Interfacial Electron Transfer by Visible Light Using Cobalt-Modified Rutile Titania Thin-Film Photoanode.

TiO is a good photoanode material for water oxidation to form O; however, UV light (λ < 400 nm) is necessary for this system to operate. In this work, cobalt species were introduced onto a rutile TiO thin film grown on a fluorine-doped tin oxide (FTO) substrate for visible-light activation of TiO and to construct water oxidation sites. TiO thin films were prepared on the FTO surface by the thermohydrolysis of TiCl, followed by annealing at 723 K in air; the loading of the cobalt species was achieved simply by immersing TiO/FTO into an aqueous Co(NO) solution at room temperature, followed by heating at 423 K in air.

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn-Ga Layered Double Hydroxide Using Urea as the Nitriding Agent.

A solid solution of GaN and ZnO (GaN:ZnO) is promising as a photocatalyst for visible-light-driven overall water splitting to produce H. However, several obstacles still exist in the conventional preparation procedure of GaN:ZnO. For example, the atomic distributions of Zn and Ga are nonuniform in GaN:ZnO when a mixture of the metal oxides, i.

Ground-State Copper(III) Stabilized by N-Confused/N-Linked Corroles: Synthesis, Characterization, and Redox Reactivity.

Stable square planar organocopper(III) complexes (CuNCC2, CuNCC4, and CuBN) supported by carbacorrole-based tetradentate macrocyclic ligands with NNNC coordination cores were synthesized, and their structures were elucidated by spectroscopic means including X-ray crystallographic analysis. On the basis of their distinct planar structures, X-ray absorption/photoelectron spectroscopic features, and temperature-independent diamagnetic nature, these organocopper complexes can be preferably considered as novel organocopper(III) species. The remarkable stability of the high-valent Cu(III) states of the complexes stems from the closed-shell electronic structure derived from the peculiar NNNC coordination of the corrole-modified frameworks, which contrasts with the redox-noninnocent radical nature of regular corrole copper(II) complexes with an NNNN core.

Undoped Layered Perovskite Oxynitride Li LaTa O N for Photocatalytic CO Reduction with Visible Light.

Oxynitrides are promising visible-light-responsive photocatalysts, but their structures are almost confined with three-dimensional (3D) structures such as perovskites. A phase-pure Li LaTa O N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium-rich oxide precursor. Li LaTa O N exhibited high crystallinity and visible-light absorption up to 500 nm.

Effects of the SrTiO support on visible-light water oxidation with CoO nanoparticles.

The photocatalytic activity of SrTiO modified with CoO nanoparticles for water oxidation under visible light (λ > 480 nm) was investigated with respect to the physicochemical properties of the SrTiO support. SrTiO was synthesized by a polymerized complex method or a hydrothermal method, followed by calcination in air at different temperatures in order to obtain SrTiO particles having different sizes. CoO nanoparticles, which provide both visible light absorption and water oxidation centers, were loaded on the as-prepared SrTiO by an impregnation method using Co(NO) as the precursor, followed by heating at 423 K in air.

Bis-Copper(II)/π-Radical Multi-Heterospin System with Non-innocent Doubly N-Confused Dioxohexaphyrin(1.1.1.1.1.0) Ligand.

A contracted doubly N-confused dioxohexaphyrin(1.1.1.

Copper-manganese mixed oxides: CO2-selectivity, stable, and cyclic performance for chemical looping combustion of methane.

Chemical looping combustion (CLC) is a key technology for oxy-fuel combustion with inherent separation of CO2 from a flue gas, in which oxygen is derived from a solid oxygen carrier. Multi-cycle CLC performance and the product selectivity towards CO2 formation were achieved using mixed oxide of Cu and Mn (CuMn2O4) (Fd3[combining macron]m, a = b = c = 0.83 nm) as an oxygen carrier.