Chiral flat-band optical cavity with atomically thin mirrors.

A fundamental requirement for photonic technologies is the ability to control the confinement and propagation of light. Widely used platforms include two-dimensional (2D) optical microcavities in which electromagnetic waves are confined in either metallic or distributed Bragg reflectors. Recently, transition metal dichalcogenides hosting tightly bound excitons with high optical quality have emerged as promising atomically thin mirrors.

Photoluminescence Switching in Quantum Dots Connected with Carboxylic Acid and Thiocarboxylic Acid End-Group Diarylethene Molecules.

We contrast the switching of photoluminescence (PL) of PbS quantum dots (QDs) cross-linked with photochromic diarylethene molecules with different end groups, 4,4'-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenecarboxylic acid] () and 4,4'-(1-cyclopentene-1,2-diyl)bis[5-methyl-2-thiophenethiocarboxylic acid] (). Our results show that the QDs cross-linked with the carboxylic acid end group molecules () exhibit a greater amount of switching in photoluminescence intensity compared to QDs cross-linked with the thiocarboxylic acid end group (). We also demonstrate that regardless of the molecule used, greater switching amounts are observed for smaller quantum dots.

Constructing Highly Porous Low Iridium Anode Catalysts Via Dealloying for Proton Exchange Membrane Water Electrolyzers.

Iridium (Ir) is the most active and durable anode catalyst for the oxygen evolution reaction (OER) for proton exchange membrane water electrolyzers (PEMWEs). However, their large-scale applications are hindered by high costs and scarcity of Ir. Lowering Ir loadings below 1.

Cooperative Atomically Dispersed Fe-N and Sn-N Moieties for Durable and More Active Oxygen Electroreduction in Fuel Cells.

One grand challenge for deploying porous carbons with embedded metal-nitrogen-carbon (M-N-C) moieties as platinum group metal (PGM)-free electrocatalysts in proton-exchange membrane fuel cells is their fast degradation and inferior activity. Here, we report the modulation of the local environment at Fe-N sites via the application of atomic Sn-N sites for simultaneously improved durability and activity. We discovered that Sn-N sites not only promote the formation of the more stable D2 FeNC sites but also invoke a unique D3 SnN-FeN site that is characterized by having atomically dispersed bridged Sn-N and Fe-N.

Tailored Ni(OH)/CuCo/Ni(OH) Composite Interfaces for Efficient and Durable Urea Oxidation Reaction.

Electrocatalytic urea oxidation reaction is a promising alternative to water oxidation for more efficient hydrogen production due to its significantly lower thermodynamic potential. However, achieving efficient electrochemical urea oxidation remains a formidable challenge, and development of an improved electrocatalyst with an optimal physicochemical and electronic structure toward urea oxidation is desired. This can be accomplished by designing a tailored two-dimensional composite with an abundance of active sites in a favorable electronic environment.

Broadband emission in alkali halides triggered by Sb doping.

Broadband emission in a series of alkali chlorides are achieved by doping NaCl, KCl, and RbCl with Sb. These compounds show photoluminescence peaks in the visible range of 536-574 nm with long lifetimes in the microsecond range. Our findings could offer valuable insights for the development of new lead-free phosphors.

Correction: Impacts of trace level chromium on formation of superoxide within uranyl triperoxide complexes.

Correction for 'Impacts of trace level chromium on formation of superoxide within uranyl triperoxide complexes' by Sarah K. Scherrer , , 2024, , 10584-10587, https://doi.org/10.

Elucidating the Discharge Behavior of Aqueous Zinc Sulfur Batteries in the Presence of Molybdenum(IV) Chalcogenide Catalyst: The Criticality of Interfacial Electrochemistry.

The aqueous zinc-sulfur battery holds promise for significant capacity and energy density with low cost and safe operation based on environmentally benign materials. However, it suffers from the sluggish kinetics of the conversion reaction. Here, we highlight the efficacy of molybdenum(IV) sulfide (MoS) to reduce the overpotential of S-ZnS conversion in aqueous electrolytes and study the discharge products formed at the solid-solid and solid-liquid interfaces using experimental and theoretical approaches.

Surface Self-Diffusion Induced Sintering of Nanoparticles.

Despite the critical role of sintering phenomena in constraining the long-term durability of nanosized particles, a clear understanding of nanoparticle sintering has remained elusive due to the challenges in atomically tracking the neck initiation and discerning different mechanisms. Through the integration of in situ transmission electron microscopy and atomistic modeling, this study uncovers the atomic dynamics governing the neck initiation of Pt-Fe nanoparticles via a surface self-diffusion process, allowing for coalescence without significant particle movement. Real-time imaging reveals that thermally activated surface morphology changes in individual nanoparticles induce significant surface self-diffusion.

Modification of ZIF-8 Membranes for Gas Separation Using X-ray Radiation.

We report an X-ray radiation-induced modification of the structure and gas permeation behavior of ZIF-8 membranes. With 300 min irradiation time, CO permeance decreases by only 9 %, while N and CH permeances reduce by 75 and 65 %, respectively, leading to 3.7- and 2.

Directing Nanoparticle Organization in Response to Diverse Chemical Inputs.

Signaling cascades are crucial for transducing stimuli in biological systems, enabling multiple stimuli to regulate a downstream target with precisely controlled timing and amplifying signals through a series of intermediary reactions. Developing a robust signaling system with such capabilities would be pivotal for programming complex behaviors in synthetic DNA-based molecular devices. However, although "software" such as nucleic acid circuits could potentially be harnessed to relay signals to DNA-based nanostructure hardware, such explorations have been limited.

Tuning collective behaviour in zebrafish with genetic modification.

Zebrafish collective behaviour is widely used to assess their physical and mental state, serving as a valuable tool to assess the impact of ageing, disease genetics, and the effect of drugs. The essence of these macroscopic phenomena can be represented by active matter models, where the individuals are abstracted as interactive self-propelling agents. The behaviour of these agents depends on a set of parameters in a manner reminiscent of those between the constituents of physical systems.

Signature of Correlated Insulator in Electric Field Controlled Superlattice.

On a two-dimensional crystal, a "superlattice" with nanometer-scale periodicity can be imposed to tune the Bloch electron spectrum, enabling novel physical properties inaccessible in the original crystal. While creating 2D superlattices by means of nanopatterned electric gates has been studied for band structure engineering in recent years, evidence of electron correlations─which drive many problems at the forefront of physics research─remains to be uncovered. In this work, we demonstrate signatures of a correlated insulator phase in Bernal-stacked bilayer graphene modulated by a gate-defined superlattice potential, manifested as resistance peaks centered at integer multiples of single electron per superlattice unit cell carrier densities.

DNA Origami Incorporated into Solid-State Nanopores Enables Enhanced Sensitivity for Precise Analysis of Protein Translocations.

The rapidly advancing field of nanotechnology is driving the development of precise sensing methods at the nanoscale, with solid-state nanopores emerging as promising tools for biomolecular sensing. This study investigates the increased sensitivity of solid-state nanopores achieved by integrating DNA origami structures, leading to the improved analysis of protein translocations. Using holo human serum transferrin (holo-hSTf) as a model protein, we compared hybrid nanopores incorporating DNA origami with open solid-state nanopores.

Enhancing Stability of Surface Au under Oxidizing Conditions through Reduced Bulk Au Content.

Contrary to the common assumption that a higher bulk content of precious metals facilitates the preservation of more surface noble metal by serving as a reservoir for surface enrichment, we demonstrate that a lower bulk content of Au results in a more stable arrangement of Au atoms at the surface of Cu-Au nanoparticles when exposed to an O atmosphere. Using ambient pressure X-ray photoelectron spectroscopy, we investigate the surface segregation and oxidation behavior of Cu-Au nanoparticles across various compositions. Our results reveal that in Au-rich nanoparticles exposed to an H atmosphere, surface segregation prompts the formation of a continuous Au-enriched shell, which subsequently oxidizes into a complete CuO shell upon transitioning to an O atmosphere.

Self-Inhibition Phenomena in CuPt Oxidation by CO.

This study investigates the oxidation behavior of CuPt(100) in CO using a combination of ambient-pressure X-ray photoelectron spectroscopy, mass spectroscopy, and density functional theory modeling. Our in situ measurements reveal the simultaneous oxidation and reduction of CuO due to the opposing effects of atomic oxygen and CO generated from dissociative CO adsorption, leading to a dynamic equilibrium state of simultaneously occurring redox reactions. Complementary atomistic calculations elucidate the inhibitory effects of subsurface Pt enrichment and the counteracting roles of CO and CO in surface oxidation and reduction.

Characterizing Defects Inside Hexagonal Boron Nitride Using Random Telegraph Signals in van der Waals 2D Transistors.

Single-crystal hexagonal boron nitride (hBN) is used extensively in many two-dimensional electronic and quantum devices, where defects significantly impact performance. Therefore, characterizing and engineering hBN defects are crucial for advancing these technologies. Here, we examine the capture and emission dynamics of defects in hBN by utilizing low-frequency noise (LFN) spectroscopy in hBN-encapsulated and graphene-contacted MoS field-effect transistors (FETs).

Evolution of the Fermi Surface of 1T-VSe across a Structural Phase Transition.

Periodic lattice distortion, known as the charge density wave, is generally attributed to electron-phonon coupling. This correlation is expected to induce a pseudogap at the Fermi level in order to gain the required energy for stable lattice distortion. The transition metal dichalcogenide 1T-VSe also undergoes such a transition at 110 K.

Toward a Radically Simple Multi-Modal Nasal Spray for Preventing Respiratory Infections.

Nasal sprays for pre-exposure prophylaxis against respiratory infections show limited protection (20-70%), largely due to their single mechanism of action-either neutralizing pathogens or blocking their entry at the nasal lining, and a failure to maximize the capture of respiratory droplets, allowing them to potentially rebound and reach deeper airways. This report introduces the Pathogen Capture and Neutralizing Spray (PCANS), which utilizes a multi-modal approach to enhance efficacy. PCANS coats the nasal cavity, capturing large respiratory droplets from the air, and serving as a physical barrier against a broad spectrum of viruses and bacteria, while rapidly neutralizing them with over 99.

Probing the protonation and reduction of heptavalent neptunium with computational guidance.

Influence of pH on the speciation and stability of heptavalent neptunium is poorly understood although it is frequently invoked in the literature to explain experimental observations. The present study employs Density Functional Theory (DFT) methodology to assess the thermodynamic feasibility of protonation reactions for the Np(VII) anion complex and the impact on its reduction to Np(VI). This theoretical framework is then explored experimentally through the titration and systematic protonation of Np(VII) in solution and solid-state samples while monitoring them spectroscopically.

Atomic resolution scanning transmission electron microscopy at liquid helium temperatures for quantum materials.

Fundamental quantum phenomena in condensed matter, ranging from correlated electron systems to quantum information processors, manifest their emergent characteristics and behaviors predominantly at low temperatures. This necessitates the use of liquid helium (LHe) cooling for experimental observation. Atomic resolution scanning transmission electron microscopy combined with LHe cooling (cryo-STEM) provides a powerful characterization technique to probe local atomic structural modulations and their coupling with charge, spin and orbital degrees-of-freedom in quantum materials.