Core-shell Nanocubes Research Articles

Maximizing the Catalytic Performance of Pd@Aux Pd1-x Nanocubes in H2 O2 Production by Reducing Shell Thickness to Increase Compositional Stability.

We report a simple route based upon seed-mediated growth to the synthesis of Pd@Aux Pd1-x (0.8≤x≤1) core-shell nanocubes. Benefiting from the well-defined {100} facets and an optimal Au/Pd ratio for the surface, the nanocubes bearing a shell made of Au0.95 Pd0.05 work as an efficient electrocatalyst toward H2 O2 production, with high selectivity of 93-100 % in the low-overpotential region of 0.4-0.7 V. When the Au0.95 Pd0.05 alloy is confined to a shell of only three atomic layers in thickness, the electrocatalyst is able to maintain its surface structure and elemental composition, endowing continuous and stable production of H2 O2 during oxygen reduction at a high rate of 1.62 mol g(Pd+Au) -1 h-1 . This work demonstrates a versatile route to the rational development of active and durable electrocatalysts based upon alloy nanocrystals.

SnS2-CoS2@C nanocubes as high initial coulombic efficiency and long-life anodes for sodium-ion batteries

Bimetallic sulfides are considered as one of the most promising anode materials for sodium ion batteries (SIBs) due to their high conductivity and electrochemical activity. However, they still suffer from challenges such as large volume changes, low initial coulombic efficiency and poor cycling performance. Herein, we synthesize SnS2-CoS2@C (SCS@C) core-shell nanocubes with abundant mesopores through simple carbon coating and sulfidation strategies using polymeric resorcinol-formaldehyde as carbon source. The porous nanostructure of SCS@C is conducive to shortening the transport path of sodium ions and facilitating the infiltration of electrolyte, while the carbon shell can buffer volume expansion stress during charging and discharging processes. As a result, the SCS@C electrode exhibits an excellent sodium storage: an outstanding initial coulomb efficiency of 92.8%, remarkable cycling performance of 662 mAh g−1 at 100 mA g−1 after 70 cycles with extremely low capacity decay of 0.00013% per cycle, and long cycle durability of 402.5 mAh g−1 at 5 A g−1 over 500 cycles. Our study provides a viable strategy for the rational design of bimetallic sulfides anode materials with high efficiency and long term stability for sodium storage.

Shape Control of Cu/ZnO Core–Shell Nanocubes and Related Structures for Localized Surface Plasmon Resonance

Cu/ZnO nanomaterials exhibit useful optical properties and catalytic activity, but their shape-controlled colloidal synthesis remains underexplored. Here, a specific Cu/ZnO core–shell nanocube morp...

Fabrication of multi-layer CoSnO3@carbon-caged NiCo2O4 nanobox for enhanced lithium storage performance

Mixed transition metal oxides (MTMOs) are deemed as promising anode materials for lithium-ion batteries (LIBs) because of the high theoretical capacity and low cost. However, the low electrical conductivity, agglomeration effects, and huge volume variation during discharging/charging still seriously restrict the actual applications of MTMOs as anode materials. Herein, a novel core-shell structure of CoSnO3@carbon-caged NiCo2O4 nanobox (CNC) is rationally designed. It starts from the preparation of CoSnO3@ZIF-67 core-shell nanocubes, followed by chemical etching/anion exchange, dopamine coating and carbonization at high temperature in sequence. It is shown that the CNC achieves high activities from the applied MTMOs components, excellent relief of volume variation from the unique double hollow structure, improved conductivity and inhabited aggregations from the uniform-coated outmost carbon shell, and effective ion/electron transfer rates from the synergetic effects. As a result, the CNC exhibits a discharge capacity of 1548 mA h g−1 at the first cycle and a retention capacity of 992 mA h g−1 after 100 cycles at 0.1 A g−1. In addition, it exhibits a high reversible capacity of about 670 mA h g−1 after 500 cycles at a current density of 1 A g−1. The improved Li+ storage performances of CNC demonstrates that such rational design of double hollow structure could be a novel strategy to apply MTMOs as anode materials of LIBs.

One-step synthesis of BaTiO3/CaTiO3 core-shell nanocubes by hydrothermal reaction

ABSTRACT Novel cube-shaped nanocrystals of BaTiO3 (BT) surrounded by CaTiO3 (CT) that can be used for piezo-driven energy harvesters were synthesized using a one-step hydrothermal reaction with surfactant and additives at 250°C for 24 h. The size distribution of the nanocubes (NCs) was narrow, with an approximate average size of 50 ~ 60 nm. The nanocubes had a core-shell configuration, such that the Pbnm structured CT shell was grown on a P4mm structured BT core by sharing corresponding [001] directions. STEM-EDX and EELS indicated that Ba ions did not diffuse into the CT shell region. Piezoelectric hysteresis loops of BT/CT NCs were obtained by piezoresponse force microscopy.

Highly Sensitive Immunosensing of Carcinoembryonic Antigen Based on Gold Nanoparticles Functionalized PB@PANI Core-Shell Nanocubes as a Novel Signal Amplification Strategy

Herein, a novel strategy to amplify electrochemical signal by gold nanoparticles functionalized prussian blue@polyanline core-shell nanocures (Au NPs/PB@PANI) was proposed for the sensitive monitoring of carcinoembryonic antigen (CEA). Firstly, a facile low-temperature method was used to prepare the uniform PB@PANI core-shell nanocubes with the assistance of PVP, where PB acted as the electron transfer mediator to provide electrochemical signals, and the PANI with excellent conductive and desirable chemical stability not only played the role of a protective layer to prevent etching of PB in basic media but also effectively improved electron transfer. Importantly, the incorporation of highly conductive Au NPs could further enhance the electrochemical signal and capture a large amount of Ab 2 . Subsequently, by virtue of the novel redox-active nanoprobe advantages and the involvement of gold-platinum bimetallic nanoflower (AuPt NFs, behaved as electrode material), a novel sandwich-type electrochemical immunosensor was constructed for ultrasensitive determination of CEA. The as-developed immunosensor could obtain a dynamic working range of 0.01 pg mL −1 -100.0 ng mL −1 at a detection limit of 3.3 fg mL −1 via DPV (at 3σ). Furthermore, the new redox-active nanoprobe-based electrochemical immunosensor exhibited remarkable analytical performance, which brought about feasible ideas in disease diagnosis in future.

A unique ligand effect in Pt-based core–shell nanocubes to boost oxygen reduction electrocatalysis

A unique ligand effect mainly arising from the strong p–d orbital hybridization between Pt and Pb was demonstrated to play a key role in boosting the ORR properties of Pd3Pb@PtmPb/C catalysts.

Construction of hollow TiO2/CuS nanoboxes for boosting full-spectrum driven photocatalytic hydrogen evolution and environmental remediation

The plasma semiconductor Cu2-xS has disclosed enormous potential in the field of broad-spectrum driven photocatalyst design due to its unique LSPR effect in the NIR region. Nevertheless, ineffective carrier separation and severe photocorrosion hinder the further functional applications of this promising material. Here, the TiO2@CuS double-shell nanoboxes were successfully constructed via a multistep control strategy involving template participation, and were firstly employed to broad-spectrum photocatalytic hydrogen evolution and pollutant elimination. The hollow core-shell nanocubes with LSPR effect have prominent advantages in broad-spectrum light response, improved photocharge separation and effective photocorrosion inhibition. Besides, the heterogeneous cavity structure also provides a larger specific surface area and ameliorates the light efficiency. Consequently, the optimized TiO2@CuS double-shell nanoboxes exhibit superior activity for H2 production under full-spectrum/NIR light irradiation (2467 and 173 μmol g−1 h−1, respectively), and maintain high activity in the photodegradation of stubborn pollutants. This work will motivate hollow photocatalysts designed to effectively utilize the spectrum and protect the sulfide core.

Ultrasensitive electrochemical detection of neuron-specific enolase based on spiny core-shell Au/CuxO@CeO2 nanocubes

As a specific biomarker, neuron-specific enolase (NSE) is an essential clinical indicator for diagnosing small cell lung cancer. In this paper, a sandwich-type electrochemical immunosensor was designed for the quantitative detection of NSE. AuPt nanoblock spherical nanoarchitectonics (AuPt NSNs), a bimetallic nanoparticle with a rugged morphology, were utilized as the substrate, which could enhance the electronic conduction and increase the immobilization capacity of the primary antibody (Ab1). Moreover, through a simple hydrothermal method, Au/CuxO@CeO2 was prepared as a spiny core-shell nanocube with cerium dioxide (CeO2) and gold nanoparticles (Au NPs) loading. The combination of Cu2O, CuO, and CeO2 showed favorable catalytic activity toward hydrogen peroxide (H2O2). Furthermore, the deposition of Au NPs on the spiny surface structure enhanced the specific surface area and biocompatibility, thereby rendering it more effective for loading the second antibody (Ab2). As the label material, the Au/CuxO@CeO2 achieved signal amplification and sensitive detection with the immunosensor. Under optimal conditions, the designed immunosensor possessed a broad linear range of 50 fg mL−1 to 100 ng mL−1 and a limit of detection of 31.3 fg mL−1, along with satisfactory performance in sensitivity, selectivity, and stability.

Hierarchical porous Co3O4 nanocages with elaborate microstructures derived from ZIF-67 toward lithium storage

Increasing the complexity of external or internal structure of hierarchical nanomaterials is essential to improve the specific capacity and stability of anode for lithium ion batteries (LIBs). Three types of porous Co3O4 nanocubes (concave-cube, yolk-shell cube and porous cube) with novel hollow structures were synthesized straightforwardly by annealing zeolitic imidazolate framework (ZIF-67) under varied temperatures of 350 °C, 450 °C and 550 °C, respectively. Consequently, the resulting concave, core-shell and porous Co3O4 nanocubes exhibited superior specific capacities of 1009, 1148 and 696 mA h g−1, respectively, at a current density of 200 mA g−1 after 200 cycles. Even at a high current density of 10 A g−1, the core-shell Co3O4 nanocube still showed a large reversible capacity of 317 mA h g−1. The complex hierarchical texture, porous shell and core, and well-defined hollow structure of the Co3O4 nanocubes were contributed greatly to the good lithiation/delithiation reversibility, ultralong cycling stability and enhanced rate capability.

Controlling the Degree of Coverage of the Pt Shell in Pd@Pt Core–Shell Nanocubes for Methanol Oxidation Reaction

The synthesis of Pd@Pt core–shell nanocubes was achieved through a direct seed-mediated growth method. This process represents a simple and cost-effective way to produce core–shell nanocubes. The morphology of the Pd@Pt core–shell nanocubes varied from simple cubic to concave cubic, depending on the reducing agent and the Pt content. The selection of the reducing agent is important because the reduction rate is directly related to the shell growth. The catalytic activity and stability of the Pd@Pt core–shell nanocubes in the methanol oxidation reaction were different for the nanocubes with partial and full Pt shells.

Well-Designed Au Nanorod-Doped Cu2O Core-Shell Nanocube-Embedded Reduced Graphene Oxide Composite for Efficient Removal of a Water Pollutant Dye.

To ensure environmental safety, the removal of organic pollutants has gained increasing attention globally. We have synthesized uniform Au nanorod (NR)-doped Cu2O core–shell nanocubes (CSNCs) via a seed-mediated route embedded on the surface of rGO sheets. The Au NRs@Cu2O/rGO nanocomposite was characterized using various techniques such as transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FT-IR) and Raman spectroscopies. The scanning TEM-energy-dispersive spectroscopy (STEM-EDS) elemental mapping of the AuNRs@Cu2O/rGO nanocomposite indicates that the Au NR (40 nm) is fully covered with the Cu2O particles (∼145 nm) as a shell. N2 gas sorption analysis shows that the specific surface area of the composite is 205.5 m2/g with a mesoporous character. Moreover, incorporation of Au NRs@Cu2O CSNCs increases the nanogaps around the nanoparticles and suppresses the stacking/bundling of rGO, which significantly influences the pore size and increase the surface area. A batch adsorption experiment was carried out under various parameters, such as the effect of pH, contact time, temperature, initial dye concentration, and adsorbent dosage, for the removal of methylene blue (MB) in aqueous solution. The high surface area and mesoporosity can cause the adsorption capacity to reach equilibrium within 20 min with a 99.8% removal efficiency. Both kinetic and isotherm data were obtained and fitted very well with the pseudo-second-order kinetic and Langmuir isotherm model. The Langmuir isotherm revealed an excellent dye sorption capacity of 243.9 mg/g at 298 K. Moreover, after five adsorption cycles, the dye removal efficiency decreased from 99 to 86%. This novel route paves a new path for heterogeneous adsorbent synthesis, which is useful for catalysis and electrochemical applications.

Efficient Hydrolysis of Ammonia Borane for Hydrogen Evolution Catalyzed by Plasmonic Ag@Pd Core–Shell Nanocubes

Developing an efficient catalyst for H2 generation from hydrolysis of ammonia borane (AB) in a controllable and sustainable way is a prerequisite to implementing H2 as an alternative energy vector....

Front Cover: Crystallinity Variation in Seeded Growth of Gold@Silver Core‐Shell Nanocrystals: Truncated Right Bipyramids and Their Hollow Derivatives (Eur. J. Inorg. Chem. 31/2020)

The Front Cover shows the crystallinity transition occurring in the seeded growth of gold@silver core-shell nanocrystals. In particular, when silver is deposited on single-crystal gold seeds under kinetic control, the resultant products exhibit planar defects, and thus the shape of a truncated right bipyramid, instead of forming gold@silver core-shell nanocubes with crystallinity consistency. The current strategy enables more precise control over the morphology of multi-metallic nanocrystals. More information can be found in the Full Paper by Y. Zheng et al.

Forward and Backward Unidirectional Scattering by the Core-Shell Nanocube Dimer with Balanced Gain and Loss.

An optical nanoantenna consisting of a Au-dielectric core-shell nanocube dimer with switchable directionality was designed and described. Our theoretical model and numerical simulation showed that switching between forward and backward directions can be achieved with balanced gain and loss, using a single element by changing the coefficient κ in the core, which can be defined by the relative phase of the polarizability. The optical response indicated a remarkable dependence on the coefficient κ in the core as well as frequency. The location of the electric field enhancement was specified by the different coefficient κ and, furthermore, the chained optical nanoantenna and coupled electric dipole emitted to the optical nanoantenna played significant roles in unidirectional scattering. This simple method to calculate the feasibility of unidirectional and switchable scattering provides an effective strategy to explore the functionalities of nanophotonic devices.

Facile preparation of a hollow core-shell nanocomposite for the ultrasensitive sensing of glucose

A core-shell Cu(OH)2@Au@Co(OH)2 nanocomposite with hollow nano-flower morphology fabricated by a facile and non-surfactant template-engaged reaction was applied for highly sensitive detection of glucose. The prussian blue analogues (PBA) of core-shell nanocubes (CuFe@Au@CoFe) were synthesized as the template through the accurate control of the reaction rate. In this nanocubes, Au nanoparticles for accelerating electron transfer rate were reduced at the interface of CoFe (core) and CuFe (shell) to improve their conductivity. These nanocubes were then etched controllably to form three-dimensional hollow nanoflowers stacked by nanosheets. It provided abundant electrode-electrolyte channels and high surface areas for OH− and glucoses adsorption and the following reactions. Due to the sandwich structure and synergic effect of the nanomaterials, the as-prepared sensors exhibited an ultrahigh sensitivity of 3427 μA mM-1 cm-2 for glucose detection, as well as a wide linear range of 0.001–5.2 mM with a low detection limit of 0.5 μM. In addition, the Cu(OH)2@Au@Co(OH)2 nanocomposite showed long-term stability and good reproducibility for glucose detection in serum with comparable results as measured with commercial glucometer. We believe the nanocomposite provided a good candidate for glucometer in future clinical applications.

Al–Cu core-shell nanoparticles as an alternative to noble metal plasmonics: A computational study

While aluminum has been considered as an alternative to gold and silver as a plasmonic material, its utility has been restricted by spontaneous surface oxidation. One of the ways to bypass this problem is to coat Al with another metal: however, this has been extremely challenging until recently. New reports on the stabilization of Al(0) in water by coating it with a thin Cu shell have opened up a fresh avenue to explore corrosion resistant aluminum plasmonics. However, the effect of a Cu shell on the plasmonic properties of Al is hitherto unknown and needs to be understood. Moreover, almost no studies have been carried out on the optical properties of Al-core metallic-shell nanoparticles. Hence, for the first time, we report here a study on the absorption and scattering cross-sections of Al–Cu core shell nanoparticles (spheres, cubes and cuboids with a characteristic dimension between 50 and 100 nm) under an illumination of 300–900 nm. Notably, the addition of a 10 nm Cu shell shifts the scattering peak of a 100 nm Al nanosphere from 390 nm to 590 nm. The peak absorption and scattering wavelengths of core-shell nanocubes increase almost linearly with shell thickness. The effect of oxidation of the Cu shell is shown to be negligible for small oxide thicknesses (~1 nm). Thus, a Cu shell seems to improve the plasmonic performance of Al. We hope that these results spur further investigations into the size-controlled synthesis of Al–Cu core-shell nanoparticles for low-cost plasmonic applications.

Imaging the kinetics of anisotropic dissolution of bimetallic core\u2013shell nanocubes using graphene liquid cells

Chemical design of multicomponent nanocrystals requires atomic-level understanding of reaction kinetics. Here, we apply single-particle imaging coupled with atomistic simulation to study reaction pathways and rates of Pd@Au and Cu@Au core-shell nanocubes undergoing oxidative dissolution. Quantitative analysis of etching kinetics using in situ transmission electron microscopy (TEM) imaging reveals that the dissolution mechanism changes from predominantly edge-selective to layer-by-layer removal of Au atoms as the reaction progresses. Dissolution of the Au shell slows down when both metals are exposed, which we attribute to galvanic corrosion protection. Morphological transformations are determined by intrinsic anisotropy due to coordination-number-dependent atom removal rates and extrinsic anisotropy induced by the graphene window. Our work demonstrates that bimetallic core-shell nanocrystals are excellent probes for the local physicochemical conditions inside TEM liquid cells. Furthermore, single-particle TEM imaging and atomistic simulation of reaction trajectories can inform future design strategies for compositionally and architecturally sophisticated nanocrystals.

Controlling synthesis of Au@AgPd core–shell nanocubes and in situ monitoring SERS of their enhanced catalysis

Surface-enhanced Raman spectroscopy (SERS) displays extraordinary application value in studying chemical reaction mechanism catalyzed by noble metal nanocomposites in recent years by identifing ‘‘fingerprint” information of molecules from their vibrational transitions. Herein, we successfully fabricated Au@AgPd core-shell nanocomposites with integration of catalytic and SERS activities, via a facile process by simultaneously reducing Ag and Pd precursors (AgNO3 and PdCl2) in the presence of Au nanocubes. By easily adjusting the amount of AgNO3 and PdCl2, we can optimize the SERS and catalytic activities of Au@AgPd core-shell nanocomposites. Various spectroscopic and microscopic techniques were employed to characterize the nanocomposites. The optimal Au@AgPd core-shell nanocomposites were used to follow the catalytic reduction process of 4-nitrothiophenol in the presence of NaBH4 by SERS. The prepared Au@AgPd core-shell nanocomposites are effective and suitable for sensitively investigating the catalytic reaction process by in situ SERS.

Strain‐Enhanced Metallic Intermixing in Shape‐Controlled Multilayered Core–Shell Nanostructures: Toward Shaped Intermetallics

AbstractControlling the surface composition of shaped bimetallic nanoparticles could offer precise tunability of geometric and electronic surface structure for new nanocatalysts. To achieve this goal, a platform for studying the intermixing process in a shaped nanoparticle was designed, using multilayered Pd‐Ni‐Pt core–shell nanocubes as precursors. Under mild conditions, the intermixing between Ni and Pt could be tuned by changing layer thickness and number, triggering intermixing while preserving nanoparticle shape. Intermixing of the two metals is monitored using transmission electron microscopy. The surface structure evolution is characterized using electrochemical methanol oxidation. DFT calculations suggest that the low‐temperature mixing is enhanced by shorter diffusion lengths and strain introduced by the layered structure. The platform and insights presented are an advance toward the realization of shape‐controlled multimetallic nanoparticles tailored to each potential application.