Undoped ruthenium oxide as a stable catalyst for the acidic oxygen evolution reaction.

Reducing green hydrogen production cost is critical for its widespread application. Proton-exchange-membrane water electrolyzers are among the most promising technologies, and significant research has been focused on developing more active, durable, and cost-effective catalysts to replace expensive iridium in the anode. Ruthenium oxide is a leading alternative while its stability is inadequate.

Large enhancement of ferroelectric properties of perovskite oxides via nitrogen incorporation.

Perovskite oxides have a wide variety of physical properties that make them promising candidates for versatile technological applications including nonvolatile memory and logic devices. Chemical tuning of those properties has been achieved, to the greatest extent, by cation-site substitution, while anion substitution is much less explored due to the difficulty in synthesizing high-quality, mixed-anion compounds. Here, nitrogen-incorporated BaTiO thin films have been synthesized by reactive pulsed-laser deposition in a nitrogen growth atmosphere.

Photonic axion insulator.

Axions, hypothetical elementary particles that remain undetectable in nature, can arise as quasiparticles in three-dimensional crystals known as axion insulators. Previous implementations of axion insulators have largely been limited to two-dimensional systems, leaving their topological properties in three dimensions unexplored in experiment. Here, we realize an axion insulator in a three-dimensional photonic crystal and probe its topological properties.

The Missing Link in the Monogermanide Series: YbGe.

High-pressure, high-temperature synthesis at 12 GPa between 750 and 1000 °C for 30 to 300 min yields the last missing rare-earth metal monogermanide, YbGe. Powder and single-crystal X-ray diffraction measurements reveal that the compound crystallizes in a FeB-type structure (space group Pnma, a=7.901(2) Å, b=3.

Optimizing Acidic Oxygen Evolution Reaction via Modulation Doping in Van der Waals Layered Iridium Oxide.

Anodic oxygen evolution reaction (OER) exhibits a sluggish four-electron transfer process, necessitating catalysts with exceptional catalytic activity to enhance its kinetic rate. Van der Waals layered oxides are ideal materials for catalyst design, yet its stability for acidic OER remains large obstacle. Doping provides a crucial way to improve the activity and stability simultaneously.

A magneto-thermoelectric with a high figure of merit in topological insulator BiSb.

High thermoelectric performance is generally achieved by synergistically optimizing two or even three of the contradictorily coupled thermoelectric parameters. Here we demonstrate magneto-thermoelectric correlation as a strategy to achieve simultaneous gain in an enhanced Seebeck coefficient and reduced thermal conductivity in topological materials. We report a large magneto-Seebeck effect and high magneto-thermoelectric figure of merit of 1.

Multipocket synergy towards high thermoelectric performance in topological semimetal TaAs.

Charge-carrier compensation in topological semimetals amplifies the Nernst signal and simultaneously degrades the Seebeck coefficient. In this study, we report the simultaneous achievement of both a large Nernst signal and an unsaturating magneto-Seebeck coefficient in a topological nodal-line semimetal TaAs single crystal. The unique dual-high transverse and longitudinal thermopowers are attributed to multipocket synergy effects: the combination of a strong phonon-drag effect and the two overlapping highly dispersive conduction and valence bands with electron-hole compensation and high mobility, promising a large Nernst effect; the third Dirac band causes a large magneto-Seebeck effect.

Large Manipulation of Ferrimagnetic Curie Temperature by A-Site Chemical Substitution in ACuFeReO (A = Na, Ca, and La) Half Metals.

CaCuFeReO and LaCuFeReO quadruple perovskite oxides are well known for their high ferrimagnetic Curie temperatures and half-metallic electronic structures. By A-site chemical substitution with lower valence state Na, an isostructural compound NaCuFeReO with both A- and B-site ordered quadruple perovskite structures in -3 symmetry was prepared using high-pressure and high-temperature techniques. The X-ray absorption study demonstrates the valence states to be Cu, Fe, and Re.

Highly Efficient Photocatalytic HO Production under Ambient Conditions via Defective InS Nanosheets.

Oxygen and water generating hydrogen peroxide (HO) by optical drive is an extremely promising pathway, and the large amount of oxygen in air and natural sunlight illumination are excellent catalytic conditions. However, the separation efficiency of photogenerated electron-hole pairs greatly limits the photocatalytic efficiency, especially in the absence of sacrificial agents. Here, we report an InS nanosheet with an S vacancy (S-InS).

Optimizing Acidic Oxygen Evolution with Manganese-Doped Ruthenium Dioxide Assembly.

Ruthenium dioxide (RuO) is one of the promising catalysts for the acidic oxygen evolution reaction (OER). However, designing RuO catalysts with good activity and stability remains a significant challenge. In this work, we propose the manganese (Mn)-doped RuO assembly as a catalyst for the OER with improved activity and stability.

Pressure-Dependent Electronic Superlattice in the Kagome Superconductor CsV_{3}Sb_{5}.

We present a high-resolution single crystal x-ray diffraction study of kagome superconductor CsV_{3}Sb_{5}, exploring its response to variations in pressure and temperature. We discover that at low temperatures, the structural modulations of the electronic superlattice, commonly associated with charge-density-wave order, undergo a transformation around p∼0.7  GPa from the familiar 2×2 pattern to a long-range-ordered modulation at wave vector q=(0,3/8,1/2).

Optimized Adsorption of H and OH over Amorphous SrRuPtOH Nanobelts towards Efficient Alkaline Fuel Cell Catalysis.

PtRu-based catalysts toward hydrogen oxidation reaction (HOR) suffer from low efficiency, CO poisoning and over-oxidation at high potentials. In this work, an amorphization strategy is adopted for preparation of amorphous SrRuPtOH nanobelts (a-SrRuPtOH NBs). The a-SrRuPtOH NBs has optimized adsorption of intermediates (H and OH), increased number of active sites, highly weakened CO poisoning and enhanced anti-oxidation ability owing to the special amorphous structure.

Signatures of ambient pressure superconductivity in thin film LaNiO.

Recently, the bilayer nickelate LaNiO has been discovered as a new superconductor with transition temperature T near 80 K under high pressure. Despite extensive theoretical and experimental work to understand the nature of its superconductivity, the requirement of extreme pressure restricts the use of many experimental probes and limits its application potential. Here, we present signatures of superconductivity in LaNiO thin films at ambient pressure, facilitated by the application of epitaxial compressive strain.

Controllable orbital angular momentum monopoles in chiral topological semimetals.

The emerging field of orbitronics aims to generate and control orbital angular momentum for information processing. Chiral crystals are promising orbitronic materials because they have been predicted to host monopole-like orbital textures, where the orbital angular momentum aligns isotropically with the electron's crystal momentum. However, such monopoles have not yet been directly observed in chiral crystals.

Nanoscale imaging and control of altermagnetism in MnTe.

Nanoscale detection and control of the magnetic order underpins a spectrum of condensed-matter research and device functionalities involving magnetism. The key principle involved is the breaking of time-reversal symmetry, which in ferromagnets is generated by an internal magnetization. However, the presence of a net magnetization limits device scalability and compatibility with phases, such as superconductors and topological insulators.

X-ray linear dichroic tomography of crystallographic and topological defects.

The functionality of materials is determined by their composition and microstructure, that is, the distribution and orientation of crystalline grains, grain boundaries and the defects within them. Until now, characterization techniques that map the distribution of grains, their orientation and the presence of defects have been limited to surface investigations, to spatial resolutions of a few hundred nanometres or to systems of thickness around 100 nm, thus requiring destructive sample preparation for measurements and preventing the study of system-representative volumes or the investigation of materials under operational conditions. Here we present X-ray linear dichroic orientation tomography (XL-DOT), a quantitative, non-invasive technique that allows for an intragranular and intergranular characterization of extended polycrystalline and non-crystalline materials in three dimensions.

Atomically Dispersed Mn-Doped Ru@RuO Core/Shell Nanostructure with High Acidic Water Oxidation Performance Arising from Multiple Synergies.

The high overpotential and unsatisfactory stability of RuO-based catalysts seriously hinder their application in acidic oxygen evolution reaction (OER). Herein, a Ru@RuO core/shell catalyst doped with atomically dispersed Mn species, denoted as Ru@Mn-RuO, is reported, which is prepared by a facile one-pot method. Detailed structural characterizations confirm that Mn is homogeneously and atomically distributed in RuO shell, which causes lattice contraction of RuO.

Heavy Atom Cluster Chains with Strong Spin-Orbit Coupling and Magnetic Cations in Mn[PtBiI].

In the search for new magnetic topological insulators with strong spin-orbit coupling, by following conceptual considerations that have already proven to be suitable, the bismuth-rich subiodide Mn[PtBiI] was discovered. Single crystals were grown from mixtures of the elements and BiI using a temperature program developed on the basis of thermal analyses. Single-crystal X-ray diffraction revealed a rhombohedral structure of the cuboctahedral cluster anions [PtBiI], which are linked into chains via octahedrally coordinated Mn cations.

Selective light-driven methane oxidation to ethanol.

Methane (CH) photocatalytic upgrading to value-added chemicals, especially C products, is significant yet challenging due to sluggish energy/mass transfer and insufficient chemical driven-force in single photochemical process. Herein, we realize solar-driven CH oxidation to ethanol (CHOH) on crystalline carbon nitride (CCN) modified with CuS and Cu single atoms (CuS/Cu-CCN). The integration of photothermal effect and photocatalysis overcomes CH-to-CHOH conversion bottlenecks, with CuS as a hotspot to convert solar-energy to heat.

In Situ Self-Assembled 200 nm-Depth Highly Active Layer Non-Precious Metals Catalyst for Industrial Water Electrolysis.

Nickel-based electrocatalysts are promising for industrial water electrolysis, but the dense hydroxyl oxide layer formed during the oxygen evolution reaction (OER) limits active sites accessibility and presents challenges in balancing structural stability with effective charge transfer. Based on this, an efficient in situ leaching strategy is proposed to construct grain boundary-rich catalyst structure with high charge transfer ability and a deep catalytic active layer reached >200-nm. Under OER conditions, stable sub-nano NiAl particles are embedded in Ni(Fe)OOH, originating from leaching out the unstable NiAl phase of the initial NiAl/NiAl alloy doped with Fe.

Giant Topological Hall Effect and Colossal Magnetoresistance in Heusler Ferromagnet near Room Temperature.

Colossal magnetoresistance (CMR) is an exotic phenomenon that allows for the efficient magnetic control of electrical resistivity and has attracted significant attention in condensed matter due to its potential for memory and spintronic applications. Heusler alloys are the subject of considerable interest in this context due to the electronic properties that result from the nontrivial band topology. Here, the observation of CMR near room temperature is reported in the shape memory Heusler alloy NiMnIn, which is attributed to the combined effects of magnetic field-induced martensite twin variant reorientation (MFIR) and magnetic field-induced structural phase transformation (MFIPT).

Hollow Pt-Encrusted RuCu Nanocages Optimizing OH Adsorption for Efficient Hydrogen Oxidation Electrocatalysis.

As one of the best candidates for hydrogen oxidation reaction (HOR), ruthenium (Ru) has attracted significant attention for anion exchange membrane fuel cells (AEMFCs), although it suffers from sluggish kinetics under alkaline conditions due to its strong hydroxide affinity. In this work, we develop ternary hollow nanocages with Pt epitaxy on RuCu (Pt-RuCu NCs) as efficient HOR catalysts for application in AEMFCs. Experimental characterizations and theoretical calculations confirm that the synergy in optimized Pt-RuCu NCs significantly modifies the electronic structure and coordination environment of Ru, thereby balancing the binding strengths of H* and OH* species, which leads to a markedly enhanced HOR performance.