Core-shell Nanostructures Research Articles

Strain-induced modulation of the band structure of GaAs/GaSb/GaAs core-dual-shell nanowires

The amalgamation of high-strained core/shell geometries in nanowire (NW) heterostructures with bandgap engineering enables the systems with novel transport and optical properties. Herein, the lattice-mismatch-high construction GaAs/GaSb/GaAs core-dual-shell (CDS) NWs were grown by molecular beam epitaxy (MBE), with a focus on exploring the impact of strain on their bandgap characteristics. Interestingly, the high stain between GaSb and GaAs leads to the surface roughening that favors Stranski-Krastanov (SK) mode growth, and coherent GaSb islands on GaAs NWs form plastically relaxed mounds at the edges of the NW sidewall facets. Strain properties of GaAs/GaSb/GaAs CDS NWs have been investigated systematically by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and Raman spectra. It is clearly revealed that the presence of different strains, with the strain diminished of GaSb shell layer in the large-scale NWs and amplified in the small-scale NWs. The optical properties of the GaAs/GaSb/GaAs CDS NWs were investigated by power- and temperature-dependent photoluminescence (PL) measurements, which reveal the emission properties with the exciton localization phenomenon. Our results on the unique optical properties of localized excitons in GaAs/GaSb/GaAs core-shell nanostructures open the way to the design of stable optoelectronic devices.

Enabling Multimodal Luminescence in a Single Nanoparticle for X-ray Imaging Encryption and Anticounterfeiting.

Multimodal luminescent materials hold great promise in a diversity of frontier applications. However, achieving the multimodal responsive luminescence at the single nanoparticle level, especially besides light stimuli, has remained a challenge. Here, we report a conceptual model to realize multimodal luminescence by constructing both mechanoluminescence and photoluminescence in a single nanoparticle. We show that the lanthanide-doped fluoride nanoparticles are able to produce excellent mechanoluminescence through X-ray irradiation, and color-tunable mechanoluminescence becomes available by selecting suitable lanthanide emitters in a core-shell-shell structure. Furthermore, the design of a multilayer core-shell nanostructure enables multimodal emissions including radioluminescence, persistent luminescence, mechanoluminescence, upconversion, downshifting, and thermal-stimulated luminescence simultaneously in a single nanoparticle under multichannel excitation and stimuli. These results provide new insights into the mechanism of X-ray induced mechanoluminescence in nanocrystals and contribute to the development of smart luminescent materials toward X-ray imaging encryption, stress sensing, and anticounterfeiting.

Photocatalytic Performance of ZnO@ZnS Core–Shell Heterostructures for Malachite Green and Rhodamine B Dye Degradation

The one‐step green synthesis of wide band gap zinc oxide@zinc sulfide (ZnO@ZnS) core–shell nanostructures offers promising prospects in wastewater treatment. These nanostructures exhibit a porous nature crucial for effective dye adsorption, as evidenced by Brunauer‐Emmett‐Teller (BET) and microscopic characterization. The synthesized material demonstrates high stability and minimal agglomeration, verified through BET analysis and zeta potential measurements. X‐ray powder diffraction confirms the presence of ZnO and ZnS phases. Transmission electron microscopy reveals the development of porous nanorods on the core surface, maximizing the surface area for dye adsorption. In wastewater treatment, the nanostructures exhibit notable performance, degrading 90% of malachite green and 50% of rhodamine B dyes within 120 min under normal conditions. Detailed discussions delve into the degradation mechanism, elucidating the major species responsible for the process. This study underscores the potential of ZnO@ZnS nanostructures in efficient organic pollutant removal, marking a significant advancement in environmental remediation.

Core–Shell Nanostructured Assemblies Enable Ultrarobust, Notch‐Resistant and Self‐Healing Materials

AbstractActuators based on stimulus‐responsive soft materials have attracted widespread attention due to their significant advantages in flexibility and structural adaptability over traditional rigid actuators. However, the development of fast‐actuating, mechanical robust and self‐healing actuators without compromising flexibility remains an ongoing challenge. Here, this study presents a photo‐responsive flexible actuator by incorporating core–shell liquid metal nano‐assemblies into a polyurethane matrix to construct a dynamic supramolecular interface. The nano‐assemblies are endowed with adaptive characteristics to external loading, being expected to dissipate energy via the reversible reconstruction of hydrogen bonding and deformation of nano‐assemblies. The obtained composites exhibit excellent mechanical strength (31 MPa), low modulus (2.02 MPa), high stretchability (1563.95%), autonomous self‐healing (92.5%), and NIR‐responsive actuation properties. Furthermore, the combination of high cohesive energy but fluxible nano‐liquid metal core, and strong dynamic interface not only achieves the balance of high tensile strength and high flexibility but also endows the actuators with outstanding notch‐resistant performance (fracture energy≈58.8 kJ m−2) through multiphase energy dissipation. This work provides a promising strategy for developing soft yet tough self‐healing materials in the fields of flexible robotics and artificial muscles.

High Stability Hypha-Like Core-Shell Nanostructure by In Situ Induced Phase Inversion for Zinc Metal Batteries.

Nanomaterials are widely used in many fields for their unique physical and chemical properties and especially demonstrate irreplaceability in energy storage systems. In this paper, a novel composite of copper sulfide with hypha-like core-shell nano-structure is synthesized by in situ phase inversion method, which serves as high stability negative electrode materials of zinc-ion batteries (ZIBs). The unique structure facilitates efficient electron and ion transport, enhances the kinetics of electrochemical reactions, and effectively suppresses the undesired expansion and decomposition of transition metal compounds. As a result, the half battery exhibits high specific capacity (250.2 mAh g-1 at 0.1 A g-1), reliable rate performance, and cycle stability (98.3 mAh g-1 at 1 A g-1 after 500 cycles). Additionally, when assembled with ZnxMnO2 positive to form a full battery, it demonstrates good cycling capacity at an intermediate current density of 2 A g-1, while maintaining excellent structural stability over 5,000 cycles (61% retention).

Engineering hyaluronic acid-based nanoassemblies for monoclonal antibody delivery – design, characterization, and biological insights

AbstractThe current spotlight of cancer therapeutics is shifting towards personalized medicine with the widespread use of monoclonal antibodies (mAbs). Despite their increasing potential, mAbs have an intrinsic limitation related to their inability to cross cell membranes and reach intracellular targets. Nanotechnology offers promising solutions to overcome this limitation, however, formulation challenges remain. These challenges are the limited loading capacity (often insufficient to achieve clinical dosing), the complex formulation methods, and the insufficient characterization of mAb-loaded nanocarriers. Here, we present a new nanocarrier consisting of hyaluronic acid-based nanoassemblies (HANAs) specifically designed to entrap mAbs with a high efficiency and an outstanding loading capacity (50%, w/w). HANAs composed by an mAb, modified HA and phosphatidylcholine (PC) resulted in sizes of ~ 100 nm and neutral surface charge. Computational modeling identified the principal factors governing the high affinity of mAbs with the amphiphilic HA and PC. HANAs composition and structural configuration were analyzed using the orthogonal techniques cryogenic transmission electron microscopy (cryo-TEM), asymmetrical flow field-flow fractionation (AF4), and small-angle X-ray scattering (SAXS). These techniques provided evidence of the formation of core-shell nanostructures comprising an aqueous core surrounded by a bilayer consisting of phospholipids and amphiphilic HA. In vitro experiments in cancer cell lines and macrophages confirmed HANAs’ low toxicity and ability to transport mAbs to the intracellular space. The reproducibility of this assembling process at industrial-scale batch sizes and the long-term stability was assessed. In conclusion, these results underscore the suitability of HANAs technology to load and deliver biologicals, which holds promise for future clinical translation.

Tamm plasmon-induced impressive optical nonlinearity of silver@graphite core–shell nanostructures

Abstract We demonstrate the enhancement in the optical nonlinearity of materials when incorporated within a Tamm plasmon cavity (TPC). This study quantitatively investigates the enhanced nonlinear optical effects exhibited by silver@graphite (Ag@C) core–shell nanostructures integrated within a Tamm plasmon cavity. The Ag@C core–shell nanostructures were synthesized by laser ablation. The transmittance characteristics of the TPC are well-matched with those of the simulated spectra. Nonlinear optical studies, conducted using the open aperture Z-scan technique, demonstrated reverse saturable absorption (RSA) behavior in the Tamm plasmon cavity structure, and a profound enhancement in nonlinear absorption compared to that of the bare material film was also observed. The optical limiting threshold value was found to be 2.5 J/cm2 which is indeed a better value when compared to the reported values. Computational simulations illustrated a significantly intensified electric field within the Tamm plasmon cavity, suggesting the creation of enhanced photonic states leading to increased light–matter interactions. These findings underscore the potential of Ag@C core–shell nanostructures within Tamm plasmon cavities for advancing nonlinear optical devices and applications.

Fabrication of enhanced aerogel template oleogels with enzyme-hydrolyzed soy protein isolate and covalent cross-linking

In recent years, the utilization of aerogel templates in oleogels to replace animal fats has garnered considerable attention due to health concerns. This study employed a “fiber-particle core-shell nanostructure model” to combine sodium carboxymethylcellulose (CMCNa) and soy protein isolate (SPI) or SPI hydrolysate (SPIH), and freeze-dried to form aerogel template, which was then dipped into oil to induce oleogels. The results showed that adding SPIH significantly improved the physicochemical properties of oleogels. The results of ζ-potential, FTIR, and rheology demonstrated a stronger binding of SPIH to CMC-Na compared to SPI. The CMC-Na-SPIH aerogels exhibited a coarser surface and denser network structure in contrast to CMC-Na-SPI aerogels, with an oil holding capacity (OHC) of up to 84.6 % and oil absorption capacity (OAC) of 47.4 g/g. The mechanical strength of oleogels was further enhanced through chemical crosslinking. Both CMC-Na-SPI and CMC-Na-SPIH oleogels displayed excellent elasticity and reversible compressibility, with CMC-Na-SPIH oleogels demonstrating superior mechanical strength. Additionally, CMC-Na-SPIH oleogels exhibited enhanced slow release of antimicrobial substances and antioxidant properties. Increasing the content of SPI/SPIH significantly improved the mechanical strength, antioxidant capacity, and OHC of the oleogels. This research presents a straightforward and promising approach to enhance the performance of aerogel template oleogels.

Polyimide impregnated silver nanowire-titanium oxide core–shell nanostructures as ultra-stable flexible transparent electrode for multiple applications

Silver nanowires (AgNWs)-based flexible-transparent conducting electrode (f-TCE) have various optoelectronic applications. Although, bare AgNW-based f-TCE faces challenges of poor adhesion with the substrate, rough surface and low thermal stability. In this work, we demonstrate preparation of f-TCE by coating a very thin layer of TiO2 over AgNWs to form AgNW-TiO2 core–shell structures. Due to very thin TiO2 film in core–shell structure, the amorphous TiO2 converted into crystalline and delivered excellent conductivity at low curing temperature of 100 °C. The adhesion and roughness issues are solved by impregnating the core–shell AgNW-TiO2 within polyimide (PI) matrix. The PI impregnated AgNW-TiO2 core–shell structure as f-TCE delivered excellent stability after 5000 times of bending and number of peeling off cycles. The as prepared f-TCE delivered sheet resistance (Rs) of 8.61 Ω/sq with transmittance of 85 % at 550 nm and Rs of 4.2 Ω/sq with transmittance of 81 % when cured at 250 °C. The surface temperature of f-TCE was found to increase up to 90 °C in 40 s after applying 4 V of supply indicating its potential as transparent heater. In addition to that the CIGS solar cell fabricated by utilization of our f-TCE exhibited efficiency of 9.6 %, demonstrating its applicability for photovoltaic applications.

Development of ATP-modified CoFe2O4@ZIF-8@ZIF-67 core–shell nanozyme for sensitive colorimetric detection of dopamine

Core-shell nanostructures (NSs) are a type of nanozyme broadly used in various fields due to their significant physicochemical advantages. In the present study, the CoFe2O4@ZIF-8@ZIF-67 core–shell were fabricated by a consecutive two-step synthesis method, including hydrothermal for CoFe2O4 metal spinel and epitaxial solvothermal growth of ZIFs bilayers on the metal spinel NSs. The core–shell surface was modified using ATP inspired by the active site of the natural peroxidase enzyme. The nanocomposites were characterized by XRD, FT-IR, SEM, EDX, and Dot-mapping techniques. The peroxidase-like activity of the ATP/CoFe2O4@ZIF-8@ZIF-67 was assessed by a colorimetric method. Modified nanocomposite displayed desirable peroxidase mimetic activity and could enzymatically generate hydroxyl radicals from H2O2 and oxidize TMB. The high catalytic activity of ATP-modified nanocomposite and its ability to oxidize TMB provides a rapid and sensitive platform for the colorimetric detection of dopamine. Dopamine consumes hydroxyl radicals, prevents TMB oxidation, and causes a color change in the detection solution, which the naked eye can recognize. The presented colorimetric test provided an excellent LOD for dopamine (0.4 µM) with a good linear range (0.2–18 µM) and selectivity, which was prosperously applied to dopamine assay in serum blood samples.

Nano ZIF-67/PBA derived core-shell sulfides or phosphides for enhanced electrochemical performance of supercapacitors

Metal-organic frameworks (MOFs) possess large specific surface area, high porosity, and adjustable pore size, exhibiting a broad prospect in the field of supercapacitors. However, the poor stability and conductivity of MOFs limited their application in energy storage. The structure of MOF composites and their derivatives are beneficial for storing electric charge and boosting the diffusion of electrolyte ions. In this study, we prepared heterostructured ZIF-67/Prussian blue analogues (PBA) derived sulfides and phosphides using the hydrothermal and solid-phase phosphating method, respectively. The ZIF-67/PBA composites with an average particle size of approximately 1100 nm, retained the rhombic dodecahedral shape of ZIF-67. Compared with MOF-derived phosphides, MOF-derived sulfides more completely retained the rhombic dodecahedron morphology of ZIF-67/PBA and demonstrated good electrochemical performance, especially ZPS-3. The unique core-shell nanostructure provides more active sites and suitable ion transport paths for reversible oxidation-reduction reactions. In three-electrode system, the ZPS-3 electrode exhibited a specific capacity of 603.9 F g−1 at a current density of 0.5 A g−1, superior rate performance, and excellent cycle stability. This study established a new synthesis paradigm for the development of MOF derivatives as a potential class of electrode materials for supercapacitors.

Understanding of Lanthanide-Doped Core-Shell Structure at the Nanoscale Level.

The groundbreaking development of lanthanide-doped core-shell nanostructures have successfully achieved precise optical tuning of rare-earth nanocrystals, leading to significant improvements in energy transfer efficiency and facilitating multifunctional integration. Exploring the atomic-level structural, physical, and optical properties of rare-earth core-shell nanocrystals is essential for advancing our understanding of their fundamental principles and driving the development of emerging applications. However, our knowledge of the atomic-level structural details of rare-earth nanocrystal core-shell structures remains limited. This review provides a comprehensive discussion of synthesis strategies, characterization techniques, interfacial ion-mixing phenomena, strain effects, and spectral modulation in core-shell structures of rare-earth-doped nanocrystals. Additionally, we prospectively discuss the challenges encountered in studying the fine structures of rare-earth-doped core-shell nanocrystals, particularly the increasing demand for researchers to integrate interdisciplinary knowledge and utilize high-end precision instruments.

Universal Click-Chemistry Approach for the DNA Functionalization of Nanoparticles.

Nanotechnology has revolutionized the fabrication of hybrid species with tailored functionalities. A milestone in this field is the deoxyribonucleic acid (DNA) conjugation of nanoparticles, introduced almost 30 years ago, which typically exploits the affinity between thiol groups and metallic surfaces. Over the last decades, developments in colloidal research have enabled the synthesis of an assortment of nonmetallic structures, such as high-index dielectric nanoparticles, with unique properties not previously accessible with traditional metallic nanoparticles. However, to stabilize, integrate, and provide further functionality to nonmetallic nanoparticles, reliable techniques for their functionalization with DNA will be crucial. Here, we combine well-established dibenzylcyclooctyne-azide click-chemistry with a simple freeze-thaw method to achieve the functionalization of silica and silicon nanoparticles, which form exceptionally stable colloids with a high DNA surface density of ∼0.2 molecules/nm2. Furthermore, we demonstrate that these functionalized colloids can be self-assembled into high-index dielectric dimers with a yield of over 50% via the use of DNA origami. Finally, we extend this method to functionalize other important nanomaterials, including oxides, polymers, core-shell, and metal nanostructures. Our results indicate that the method presented herein serves as a crucial complement to conventional thiol functionalization chemistry and thus greatly expands the toolbox of DNA-functionalized nanoparticles currently available.

Smartphone-assisted portable amperometric immunosensor based on CoMn-LDH for the visualized detection of tylosin

The precise and rapid analysis of antibiotics containing in food stuffs is essential for guaranteeing the safety of food products and drinking water. Thus, the sensitive determination of antibiotics is highly urgent. Herein, CoMn-LDH derived from bimetallic CoMn-ZIF was utilized as the sensitive material and ink for modifying the screen-printed electrode (SPE) to manufacture the visualized amperometric immunosensor to detect tylosin (TYL) with the smartphone assistance. Benefiting to the features of CoMn-ZIF, the achieved CoMn-LDH exhibited large specific surface area and pore size, abundant oxygen vacancies, rich and exposed metal sites, high functionality, and core–shell nanostructure with thin shell thickness. Thus, CoMn-LDH illustrated the high adhesive force with the SPE, the improved affinity toward the TYL-targeted antibody and fast electronic response. Thereby, the manufactured CoMn-LDH-based amperometric immunosensor displayed the wide linear range from 1.0 fg mL−1 to 1.0 ng mL−1 with an ultralow detection limit of 0.89 fg mL−1 toward TYL. Also, the developed amperometric immunosensor has demonstrated the good sensing ability of high selectivity, good reproducibility and stability, and accepted regenerated performance, as well as the great potential for the electronic visualized analysis of TYL containing in diverse real samples. This work has provided a new amperometric immunosensing strategy for the efficient analysis of antibiotics in food samples through the visual way.

A Method for Determining Incorporation Depth in Core-Shell UiO-66 Nanoparticles Synthesized Via Postsynthetic Exchange.

Postsynthetic exchange (PSE) is a key technique for integrating sensitive linkers into metal-organic frameworks (MOFs). Despite its importance, investigations into linker distributions have primarily focused on micrometer-sized crystals due to the analytical limitations, leaving nanoparticles less explored, although they are commonly synthesized and used in applications. In particular, the emergence of core-shell nanostructures via PSE has shown potential for applications in CO2 adsorption and selective catalysis. This study addresses this gap by investigating the formation of core-shell structures on nanoparticles under diffusion-controlled PSE conditions. By analyzing volume-to-surface ratios and conducting time-dependent experiments, we confirmed that these conditions facilitate the development of core-shell architectures. We also developed a straightforward method to calculate the minimum incorporation depth using basic parameters such as particle size and the total amount of incorporated linker. The accuracy of our approach was validated against data obtained from transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. These findings enhance the understanding of PSE in MOF nanoparticles and open up promising avenues for developing advanced MOF core-shell structures for various applications.

Stepwise Construction of MoS2@CoAl-LDH/NF 3D Core-Shell Nanoarrays with High Hole Mobility for High-Performance Asymmetric Supercapacitors.

Supercapacitors (SCs) have received widespread attention as excellent energy storage devices, and the design of multicomponent electrode materials and the construction of ingenious structures are the keys to enhancing the performance of SCs. In this paper, MoS2 nanorods were used as the carrier structure to induce the anchoring of CoAl-LDH nanosheets and grow on the surface of nickel foam (NF) in situ, thus obtaining a uniformly distributed MoS2 nanorod@CoAl-LDH nanosheet core-shell nanoarray material (MoS2@CoAl-LDH/NF). On the one hand, the nanorod-structured MoS2 as the core provides high conductivity and support, accelerates electron transfer, and avoids agglomeration of CoAl-LDH nanosheets. On the other hand, CoAl-LDH nanosheet arrays have abundant interfacially active sites, which accelerate the electrolyte penetration and enhance the electrochemical activity. The synergistic effect of the two components and the unique core-shell nanostructure give MoS2@CoAl-LDH/NF a high capacity (14,888.8 mF cm-2 at 2 mA cm-2) and long-term cycling performance (104.4% retention after 5000 charge/discharge cycles). The integrated MoS2@CoAl-LDH/NF//AC device boasts a voltage range spanning from 0 to 1.5 V, achieving a peak energy density of 0.19 mW h cm-2 at 1.5 mW cm-2. Impressively, it maintains a capacitance retention rate of 84.6% after enduring 10,000 cycles, demonstrating exceptional durability and stability.

Towards core–shell engineering for efficient luminescence and temperature sensing

Research on the core–shell design of rare earth-doped nanoparticles has recently gained significant attention, particularly in exploring the synergistic effects of combining active and inert shell layers. In this study, we successfully synthesized 8 types of spherical core–shell Na-based nanoparticles to enhance the efficiency of core–shell design in upconversion luminescence and temperature sensing through the strategic arrangement of inert and active layers. The most effective upconversion luminescence was observed under 980 nm and 808 nm laser excitation using NaYF4 inert shell NaYF4:Yb3+, Er3+@ NaYF4 and NaYF4@ NaYF4:Yb3+, Nd3+ core–shell nanostructures. Moreover, the incorporation of the NaYbF4 active shell structure led to a significant increase in relative sensitivity in ratio luminescence thermometry. Notably, the NaYF4:Yb3+, Nd3+, Er3+@ NaYbF4 core–shell structure demonstrated the highest relative sensitivity of 1.12 %K−1. This research underscores the crucial role of inert shell layers in enhancing upconversion luminescence in core–shell structure design, while active layers play a key role in achieving high-sensitivity temperature detection capabilities.

Atomistic simulation of temperature dependence of tensile properties and estimation of DBTT of Cu–Ag core–shell nanowires

An atomistic model of Cu-Ag core–shell nanowire using molecular dynamics is proposed. The simulation model was utilized for the evolution of temperature dependent (in the range of 10–500 K) tensile behavior and the identification of ductile-to-brittle transition temperature (DBTT) of single-crystal Cu-Ag core–shell nanowire. The evolution of defects such as point defects, dislocations, and stacking faults, arising from tensile deformation in the mentioned temperature rage were analyzed. The Wigner-Seitz Defect analysis, Dislocation analysis, and Common Neighbor analysis methods were implemented in this study to estimate the various defects concentration in the nanowire. The study identified that Cu-Ag core–shell (core diameter = 4 nm and shell thickness = 1 nm nanowire) exhibits DBTT somewhere in the temperature between 25 K to 30 K. The modulus of elasticity found to be increasing from 19.7 TPa at 10 K to 23.7 TPa at 30 K (within brittle regime), followed by a steep fall to 14.9 TPa at 500 K where fracture seems to be in ductile mode. The observed mechanical properties of the nanowire are discussed in the article in view of the dislocation and stacking faults generation in the core–shell nanostructures.

Active Sites of Mixed-Metal Core-Shell Oxygen Evolution Reaction Catalysts: FeO4 Sites on Ni Cores or NiN4 Sites in C Shells?

Water electrolysis for clean hydrogen production requires high-activity, high-stability, and low-cost catalysts for its particularly sluggish half-reaction, the oxygen evolution reaction (OER). Currently, the most promising of such catalysts working in alkaline conditions is a core-shell nanostructure, NiFe@NC, whose Fe-doped Ni (NiFe) nanoparticles are encapsulated and interconnected by N-doped graphitic carbon (NC) layers, but the exact OER mechanism of these catalysts is still unclear, and even the location of the OER active site, either on the core side or on the shell side, is still debated. Therefore, we herein derive a plausible active-site model for each side based on various experimental evidence and density functional theory calculations and then build OER free-energy diagrams on both sides to determine the active-site location. The core-side model is an FeO4-type (rather than NiO4-type) active site where an Fe atom sits on Ni oxide layers grown on top of the core surface during catalyst activation, whose facile dissolution provides an explanation for the activity loss of such catalysts directly exposed to the electrolyte. The shell-side model is a NiN4-type (rather than FeN4-type) active site where a Ni atom is intercalated into the porphyrin-like N4C site of the NC shell during catalyst synthesis. Their OER free-energy diagrams indicate that both sites require similar amounts of overpotentials, despite a complete shift in their potential-determining steps, i.e., the final O2 evolution from the oxophilic Fe on the core and the initial OH adsorption to the hydrophobic shell. We conclude that the major active sites are located on the core, but the NC shell not only protects the vulnerable FeO4 active sites on the core from the electrolyte but also provides independent active sites, owing to the N doping.

Single-atom Mn sites confined into hierarchically porous core–shell nanostructures for improved catalysis of oxygen reduction

Applications of zinc-air batteries are partially limited by the slow kinetics of oxygen reduction reaction (ORR); Thus, developing effective strategies to address the compatibility issue between performance and stability is crucial, yet it remains a significant challenge. Here, we propose an in situ gas etching-thermal assembly strategy with an in situ-grown graphene-like shell that will favor Mn anchoring. Gas etching allows for the simultaneous creation of mesopore-dominated carbon cores and ultrathin carbon layer shells adorned entirely with highly dispersed Mn-N4 single-atom sites. This approach effectively resolves the compatibility issue between activity and stability in a single step. The unique core–shell structure allows for the full exposure of active sites and effectively prevents the agglomerations and dissolution of Mn-N4 sites in cores. The corresponding half-wave potential for ORR is up to 0.875 V (vs. reversible hydrogen electrode (RHE)) in 0.1 M KOH. The gained catalyst (Mn-N@Gra-L)-assembled zinc-air battery has a high peak power density (242 mW cm−2) and a durability of ∼ 115 h. Furthermore, replacing the zinc anode achieved a stable cyclic discharge platform of ∼ 20 h at varying current densities. Forming more fully exposed and stable existing Mn-N4 sites is a governing factor for improving the electrocatalytic ORR activity, significantly cycling durability, and reversibility of zinc-air batteries.