Explore the vast range of titles available.

The success of proton exchange membrane water electrolysis (PEMWE) depends on active and robust electrocatalysts to facilitate oxygen evolution reaction (OER). Heteroatom-doped-RuO x has emerged as a promising electrocatalysts because heteroatoms suppress lattice oxygen participation in the OER, thereby preventing the destabilization of surface Ru and catalyst degradation. However, identifying suitable heteroatoms and achieving their atomic-scale coupling with Ru atoms are nontrivial tasks. Herein, to steer the reaction pathway away from the involvement of lattice oxygen, we integrate OER-active Ir atoms into the RuO 2 matrix, which maximizes the synergy between stable Ru and active Ir centers, by leveraging the changeable growth behavior of Ru/Ir atoms on lattice parameter-modulated templates. In PEMWE, the resulting (RuIr)O 2 /C electrocatalysts demonstrate notable current density of 4.96 A cm −2 and mass activity of 19.84 A mg Ru+Ir −1 at 2.0 V. In situ spectroscopic analysis and computational calculations highlight the importance of the synergistic coexistence of Ru/Ir-dual-OER-active sites for mitigating Ru dissolution via the optimization of the binding energy with oxygen intermediates and stabilization of Ru sites. The development of durable catalysts for efficient hydrogen production from water faces challenges, particularly in the oxygen evolution reaction. Here, the authors report (RuIr)O 2 electrocatalysts with enhanced performance, achieved by tuning the growth of Ru/Ir on lattice-modulated templates.

The advancement of economical and readily available electrocatalysts for the oxygen reduction reaction (ORR) holds paramount importance in the advancement of fuel cells and metal‐air batteries. Recently, 2D non‐metallic materials have obtained substantial attention as viable alternatives for ORR catalysts due to their manifold advantages, encompassing low cost, ample availability, substantial surface‐to‐volume ratio, high conductivity, exceptional durability, and competitive activity. The augmented ORR performances observed in metal‐free 2D materials typically arise from heteroatom doping, defects, or the formation of heterostructures. Here, the authors delve into the realm of electrocatalysts for the ORR, pivoting around metal‐free 2D materials. Initially, the merits of metal‐free 2D materials are explored and the reaction mechanism of the ORR is dissected. Subsequently, a comprehensive survey of diverse metal‐free 2D materials is presented, tracing their evolutionary journey from fundamental concepts to pragmatic applications in the context of ORR. Substantial importance is given on the exploration of various strategies for enhancing metal‐free 2D materials and assessing their impact on inherent material performance, including electronic properties. Finally, the challenges and future prospects that lie ahead for metal‐free 2D materials are underscored, as they aspire to serve as efficient ORR electrocatalysts. This review presents recent advances in metal‐free 2D materials for the oxygen reduction reaction (ORR), covering mechanistic insights, catalyst development, and performance enhancement. It also addresses challenges and future prospects for the development of high‐performance metal‐free 2D electrocatalysts toward the ORR.

Ammonia, a key feedstock used in various industries, has been considered a sustainable fuel and energy storage option. However, NH3 production via the conventional Haber–Bosch process is costly, energy‐intensive, and significantly contributing to a massive carbon footprint. An electrochemical synthetic pathway for nitrogen fixation has recently gained considerable attention as NH3 can be produced through a green process without generating harmful pollutants. This review discusses the recent progress and challenges associated with the two relevant electrochemical pathways: direct and indirect nitrogen reduction reactions. The detailed mechanisms of these reactions and highlight the recent efforts to improve the catalytic performances are discussed. Finally, various promising research strategies and remaining tasks are presented to highlight future opportunities in the electrochemical nitrogen reduction reaction. This review discusses recent progress and challenges related to the electrochemical nitrogen reduction reaction. In addition, this review highlights promising research strategies and remaining tasks for future opportunities in electrochemical nitrogen reduction catalysis.

The structural analysis of nanocrystals via transmission electron microscopy (TEM) is a valuable technique for the material science field. Recently, two-dimensional images by scanning TEM (STEM) and energy-dispersive X-ray spectroscopy (EDS) have successfully extended to three-dimensional (3D) imaging by tomography. However, despite improving TEM instruments and measurement techniques, detector shadowing, the missing-wedge problem, X-ray absorption effects, etc., significant challenges still remain; therefore, the various required corrections should be considered and applied when performing quantitative tomography. Nonetheless, this 3D reconstruction technique can facilitate active site analysis and the development of nanocatalyst systems, such as water electrolysis and fuel cell. Herein, we present a 3D reconstruction technique to obtain tomograms of IrNi rhombic dodecahedral nanoframes (IrNi-RFs) from STEM and EDS images by applying simultaneous iterative reconstruction technique and total variation minimization algorithms. From characterizing the morphology and spatial chemical composition of the Ir and Ni atoms in the nanoframes, we were able to infer the origin of the physical and catalytic durability of IrNi-RFs. Also, by calculating the surface area and volume of the 3D reconstructed model, we were able to quantify the Ir-to-Ni composition ratio and compare it to the EDS measurement result.

The evolution of display technology toward ultrahigh resolution, high color purity, and cost‐effectiveness has generated interest in metal halide perovskites, particularly colloidal perovskite nanocrystals (PeNCs). PeNCs exhibit narrow emission spectra, high photoluminescence quantum yields, and wide color gamuts, rendering them promising candidates for next‐generation displays. Despite significant advancements in perovskite light‐emitting diode (PeLED) technology, challenges remain regarding the efficiencies of PeNC‐based blue LEDs. Addressing these challenges, including both inherent and external instabilities of PeNCs and operational instabilities of the devices, is important as they collectively impede the broader acceptance and utilization of PeNCs. Herein, a comprehensive overview of the syntheses of dimension‐ and composition‐controlled blue colloidal PeNCs and critical factors influencing the performances of colloidal PeNC‐based blue LEDs is provided. Moreover, the advancements of colloidal PeNC‐based blue LEDs and challenges associated with the application of these LEDs are explored, and the potentials of these LEDs for application in next‐generation displays are emphasized. This review highlights the path forward for the future development of PeNC‐based blue LEDs. This review provides a comprehensive overview of the synthesis of colloidal perovskite nanocrystals and explores the key factors that influence the performance of PeNC‐based blue LEDs. It also discusses the challenges and recent advancements in applying these nanocrystals in blue LEDs.

: Magnetic relaxation switching (MRSw) induced by target-triggered aggregation or dissociation of superparamagnetic iron oxide nanoparticles (SPIONs) have been utilized for detection of diverse biomarkers. However, an MRSw-based biosensor for reactive oxygen species (ROS) has never been documented. : To this end, we constructed a biosensor for ROS detection based on PEGylated bilirubin (PEG-BR)-coated SPIONs (PEG-BR@SPIONs) that were prepared by simple sonication via ligand exchange. In addition, near infra-red (NIR) fluorescent dye was loaded onto PEG-BR@SPIONs as a secondary option for fluorescence-based ROS detection. Resul : PEG-BR@SPIONs showed high colloidal stability under physiological conditions, but upon exposure to the model ROS, NaOCl, , they aggregated, causing a decrease in signal intensity in T2-weighted MR images. Furthermore, ROS-responsive PEG-BR@SPIONs were taken up by lipopolysaccharide (LPS)-activated macrophages to a much greater extent than ROS-unresponsive control nanoparticles (PEG-DSPE@SPIONs). In a sepsis-mimetic clinical setting, PEG-BR@SPIONs were able to directly detect the concentrations of ROS in whole blood samples through a clear change in T2 MR signals and a 'turn-on' signal of fluorescence. : These findings suggest that PEG-BR@SPIONs have the potential as a new type of dual mode (MRSw-based and fluorescence-based) biosensors for ROS detection and could be used to diagnose many diseases associated with ROS overproduction.

Core/shell (C/S)-structured upconversion nanophosphor (UCNP)-incorporated polymer waveguide-based flexible transparent displays are demonstrated. Bright green- and blue-emitting Li(Gd,Y)F 4 :Yb,Er and Li(Gd,Y)F 4 :Yb,Tm UCNPs are synthesized via solution chemical route. Their upconversion luminescence (UCL) intensities are enhanced by the formation of C/S structure with LiYF 4 shell. The Li(Gd,Y)F 4 :Yb,Er/LiYF 4 and Li(Gd,Y)F 4 :Yb,Tm/LiYF 4 C/S UCNPs exhibit 3.3 and 2.0 times higher UCL intensities than core counterparts, respectively. In addition, NaGdF 4 :Yb,Tm/NaGdF 4 :Eu C/S UCNPs are synthesized and they show red emission via energy transfer and migration of Yb 3+  → Tm 3+  → Gd 3+  → Eu 3+ . The C/S UCNPs are incorporated into bisphenol A ethoxylate diacrylate which is used as a core material of polymer waveguides. The fabricated stripe-type polymer waveguides are highly flexible and transparent (transmittance > 90% in spectral range of 443–900 nm). The polymer waveguides exhibit bright blue, green, and red luminescence, depending on the incorporated UCNPs into the polymer core, under coupling with a near infrared (NIR) laser. Moreover, patterned polymer waveguide-based display devices are fabricated by reactive ion etching process and they realize bright blue-, green-, and red-colored characters under coupling with an NIR laser.

The cation‐exchange reaction (CER), a promising nanocrystal (NC) engineering strategy, has undergone rapid progress in the past decade, sparking a big wave of interest in the post‐synthetic tuning of chemical compositions, crystal phases, interfaces, morphologies, and corresponding properties. However, a significant gap has existed between the theoretical and actual CERs, hindering the popularization of CERs for explosive expansion in NC designs. A notable roadblock in this area has been the inability to control the site of cation exchange within the nanostructure, although partial cation exchange at desired sites can open an avenue to the vast structural diversity of nanostructures and accompany new physicochemical properties. Several notable successes have been recorded recently in fabricating predesigned hetero‐nanostructures by thoroughly understanding the principles of cation exchange and by exploiting the peculiarity of each crystal system. Herein, recent advances achieved in the CER are introduced, unraveling the critical factors controlling regiospecificity by analyzing the developed theories and accumulated experimental results. It is further described how this knowledge can be harnessed to design advanced NCs, and the beneficial effect of regiospecificity on material properties is highlighted. Finally, the challenges and research directions are provided to encourage further research in this burgeoning field. Current challenges in cation‐engineered nanocrystals (NCs) have been addressed, emphasizing the importance of regiospecificity control during cation‐exchange reactions. In particular, a comprehensive list of studies on regiospecificity‐engineered hetero‐nanostructures is detailed, primarily focused on improving corresponding physicochemical properties, and the favorable effects of the geometrics are systematically organized based on the structures of NCs.

Metal–halide perovskite nanocrystals (NCs) have emerged as suitable light‐emitting materials for light‐emitting diodes (LEDs) and other practical applications. However, LEDs with perovskite NCs undergo environment‐induced and ion‐migration‐induced structural degradation during operation; therefore, novel NC design concepts, such as hermetic sealing of the perovskite NCs, are required. Thus far, viable synthetic conditions to form a robust and hermetic semiconducting shell on perovskite NCs have been rarely reported for LED applications because of the difficulties in the delicate engineering of encapsulation techniques. Herein, a highly bright and durable deep‐blue perovskite LED (PeLED) formed by hermetically sealing perovskite NCs with epitaxial ZnS shells is reported. This shell protects the perovskite NCs from the environment, facilitates charge injection/transport, and effectively suppresses interparticle ion migration during the LED operation, resulting in exceptional brightness (2916 cd m−2) at 451 nm and a high external quantum efficiency of 1.32%. Furthermore, even in the unencapsulated state, the LED shows a long operational lifetime (T50) of 1192 s (≈20 min) in the air. These results demonstrate that the epitaxial and hermetic encapsulation of perovskite NCs is a powerful strategy for fabricating high‐performance deep‐blue‐emitting PeLEDs. An effective perovskite encapsulation strategy is developed that enables the successful synthesis of deep‐blue‐emitting CsPb(Br1‐xClx)3/ZnS core/shell NCs. The epitaxial ZnS shell protects the perovskite NC from the environment, facilitates charge injection/transport, and effectively suppresses the interparticle ion migration during LED operation, achieving exceptional brightness (2916 cd m‐2) at 451 nm and high external quantum efficiency (EQE) of 1.32%.

Anion‐exchange membrane water electrolysis (AEMWE) holds immense promise for hydrogen (H2) production yet faces challenges due to the sluggish kinetics of the hydrogen evolution reaction (HER). Highly efficient and durable catalysts for HER are crucial for the successful implementation of AEMWE to produce hydrogen gas reliably. Ruthenium phosphides (RuxP) have emerged as promising non‐Pt catalysts for alkaline HER; however, they suffer from rapid degradation due to weak RuP bonding, which cannot protect the Ru center from further oxidation and subsequent dissolution. Herein, first‐principles calculations indicate the enhanced stability of RuSe against oxidation compared to RuP, highlighting the importance of introducing Se into the Ru2P phase. Electrochemical studies using the selenium (Se)‐doped Ru2P double‐walled nanotubes (Ru2(P0.9Se0.1) DWNTs) demonstrate significantly lower overpotentials (29 mV @ 10 mA cm−2) and robust stability (>50 h) in 1.0 m KOH, surpassing those of Pt/C. In AEMWE, Ru2(P0.9Se0.1) DWNTs exhibit an outstanding performance (10.31 A cm−2 @ 80 °C, stable @ 1.0 A cm−2 for ≈200 h), surpassing state‐of‐the‐art catalysts. The findings of this study highlight the pivotal role of anion modification in enhancing the catalytic stability and performance for efficient hydrogen production in AEMWE systems. Selenium‐doped ruthenium phosphide (Ru2(P0.9Se0.1)) is obtained via ion‐engineering techniques. Ru sites in Ru2(P0.9Se0.1) act as primary catalytic centers, optimizing intermediate adsorption energies. The precisely controlled Se doping enhances the Ru−OH moieties formation on the surface while preventing Ru dissolution. This catalyst demonstrates outstanding cell performances, indicating the promise of anion‐modified Ru2P for efficient hydrogen evolution in anion‐exchange membrane water electrolysis.