Hollow Nanospheres Research Articles

Enhancing cyclic voltammetry performance with N-graphene -supported coupled NiO/TiO2 hollow nanospheres as superior anode material

Enhancing cyclic voltammetry performance with N-graphene -supported coupled NiO/TiO2 hollow nanospheres as superior anode material

Ultrafine Ru nanoparticles anchored on N-doped mesoporous hollow carbon spheres as a highly efficient bifunctional catalyst for Li–CO2 batteries

Rechargeable Li–CO2 battery is a facilitative and promising device for the conversion of CO2 to electrochemical energy. However, it remains a challenge to enhance the sluggish decomposition kinetics of lithium carbonate as the discharge product. Herein, the Ru nanoparticles anchored on N-doped mesoporous hollow carbon nanospheres (Ru-AHCNs) are designed as cathode to enhance the electrochemical performance of Li–CO2 battery. The Ru-AHCNs cathode displays a high discharge specific capacity of 11194.4 mA h g−1 at the current density of 100 mA g−1. In addition, the Ru-AHCNs cathode can stably run over 50 cycles and maintain a small overpotential (<1.38 V) with a limited capacity of 1000 mA h g−1 at 100 mA g−1. The excellent stability and catalytic activity of the cathode are ascribed to the following factors: (i) Uniform deposition of Ru nanoparticles in hollow carbon nanospheres can enhance the decomposition of Li2CO3 and provide considerable exposure to active sites. (ii) N-doped mesoporous hollow carbon nanospheres can provide abundant electron transport channels and promote the nucleation of discharge products. These results evidently prove the reversible formation and decomposition of the discharge products, indicating that Ru-AHCNs cathode possesses excellent bifunctional catalytic activity.

Novel synthesis of FeF3·0.33H2O@hollow acetylene black nanosphere and its long-life electrochemical properties as a cathode for lithium-ion batteries

Iron (III) fluoride (FeF3), characterized by high voltage and high specific capacity and emerges as a promising candidate for the forthcoming generation of cathode materials in lithium-ion batteries. This study employs a novel methodology by introducing Fe3+ sources into hollow acetylene black particles through a vacuum impregnation method. This innovative approach results in the synthesis of a composite material comprising FeF3∙0.33H2O encapsulated within hollow acetylene black nanospheres, denoted as the FeF3∙0.33H2O @hollow acetylene black nanosphere composite material (FF@HCN). The composite exhibits a shell composed of highly graphitized carbon and a core containing FeF3∙0.33H2O particles in the range of 10–20 nm. The proportion of active materials is 75.56 %. The acetylene black has chain-like structure and high specific surface area, significantly enhances the material's conductivity, contributing 74.4 % to the pseudocapacitance at a scan rate of 1 mV s−1. The cavity graphite shell plays a crucial role in restricting the expansion and pulverization decay of FeF3∙0.33H2O nanoparticles, thereby markedly improving the cycle stability. The initial capacity of the FF@HCN composite is 224.4 mAh g−1, and after 1000 cycles at 0.1 C, it maintains a capacity of 162.3 mAh g−1, resulting in a capacity retention rate of 72.3 % and decay per cycle of 0.027 %.

MoS2/ReS2 Hollow Heterojunction for Enhanced Aqueous Zinc-Ion Storage Performance.

The research of cathode materials for water-based zinc ion batteries (ZIBs) is very hot because the current mainstream electrode makes it difficult to meet the requirements of high specific discharge capacity and maintain a stable structure in the electrochemical process. In this work, the cathode properties are adjusted by the modification idea of morphology regulation and heterojunction construction. The simple hydrothermal method is used to prepare the hollow bimetallic heterojunction nanospheres, and their electrochemical properties as cathode materials for ZIBs are studied for the first time. Herein, the optimized cathode delivers high-rate performance and long-term cycling stability (∼98.9% Coulombic efficiency at 0.1 A g-1 after 200 cycles). The results indicate that the hollow bimetallic heterojunction nanospheres can support the material structure and provide a wide Zn2+ migration channel. The excellent performance is because hollow heterojunction bimetallic sulfides can provide abundant catalytic active sites, improve the mobility of electrons, and enhance the battery performance fundamentally. Therefore, we firmly believe that the combination of the different modification ideas can coordinate to adjust the electrode performance of ZIBs, enriching the electrode types and expanding the energy system application range.

Super-Assembled Multilayered Mesoporous TiO2 Nanorockets for Light-Powered Space-Confined Microfluidic Catalysis.

In the field of sustainable chemistry, it is still a significant challenge to realize efficient light-powered space-confined catalysis and propulsion due to the limited solar absorption efficiency and the low mass and heat transfer efficiency. Here, novel semiconductor TiO2 nanorockets with asymmetric, hollow, mesoporous, and double-layer structures are successfully constructed through a facile interfacial superassembly strategy. The high concentration of defects and unique topological features improve light scattering and reduce the distance for charge migration and directed charge separation, resulting in enhanced light harvesting in the confined nanospace and resulting in enhanced catalysis and self-propulsion. The movement velocity of double-layered nanorockets can reach up to 10.5 μm s-1 under visible light, which is approximately 57 and 119% higher than that of asymmetric single-layered TiO2 and isotropic hollow TiO2 nanospheres, respectively. In addition, the double-layered nanorockets improve the degradation rate of the common pollutant methylene blue under sustainable visible light with a 247% rise of first-order rate constant compared to isotropic hollow TiO2 nanospheres. Furthermore, FEA simulations reveal and confirm the double-layered confined-space enhanced catalysis and self-propulsion mechanism.

Design and assembly of ZIF@PPy-derived hierarchical structure CeCo-NxCC electrocatalyst towards oxygen reduction reaction

The research of high-performance catalysts for ORR is always a great challenge in the field of zinc-air batteries (ZABs) applications. Herein, a near-regular dodecahedral ZIF-67-derived nitrogen-doped carbon material (CeCo-NxCC-700) with abundant hollow nanospheres on the surface is successfully constructed by introducing Ce ions to replace part of the Co ions and polymerizing pyrrole on the surface of the polyhedrons. PPy-coating is beneficial to improving the electrochemical stability and increasing the number of Co-Nx active sites, especially the pyrrole N and pyridine N sites. Ce-doping adjusts the charge density around the active sites. Meanwhile, the pyrolysis at 700 °C during the preparation process does not cause the structural collapse of CeCo-NxCC. Based on their decent ORR/OER performance, ZABs have been further assembled with CeCo-NxCC-700, which exhibit a high specific capacity of 815.4 mAh·g (Zn)−1 and cycling stability of more than 80 h, indicating a great application potentiality in ZABs manufacturing.

Polydopamine supporting method fabricating vanadium nitride nanoparticle enclosed into hierarchical hollow carbon nanospheres for supercapacitors

Nanostructure is crucial for achieving electrode materials with high capacity and high-power ascribing to pleasing specific surface area, intrinsic safety, and satisfactory ion transport pathways; nevertheless, the structural collapse that occurs during high-temperature treatment may lead to a decrease in the specific surface area of the electrode material, causing technical obstacles, and hence affecting its practical applicability. Vanadium nitride has become a promising electrode material since its superior conductivity and desirable theoretical capacity; unfortunately, its practical application is hindered by its limited rate capability, cycle stability, and tendency to dissolve in alkaline solutions. In this study, a template-free method is employed to prepare hollow nanosphere structures through the self-supporting effect of dopamine. When subjected to high-temperatures, it can successfully hinder the collapse of the hollow nanostructures. Graded vanadium nitride nanoparticles are generated in this process and encapsulated in hollow nanostructures. The issues of vanadium nitride dissolution and low transport rate in alkaline electrolytes can be efficiently resolved by leveraging the self-supporting action of dopamine and the subsequent formation of hierarchical vanadium nitride nanoparticles. The anode material endows a capacity of 387.14 F g−1 at a current density of 0.5 A g−1, as well as a coulombic efficiency of 98.28 % even after 10, 000 cycles at a current density of 3 A g−1. Additionally，the assembled device can achieve a maximum power density of 4, 000 W kg−1 and an energy density of 22.89 Wh Kg−1. This anode material displays potential applications in energy storage devices and offers a novel approach to material preparation.

"Cave Effect" Induces Self-Assembled Bimetallic Hollow Structure for Three-in-One Lateral Flow Immunoassay.

Bimetallic hollow structures have attracted much attention due to their unique properties, but they still face the problems of nonuniform alloys and excessive etching leading to structural collapse. Here, uniform bimetallic hollow nanospheres are constructed by pore engineering and then highly loaded with hemin (Hemin@MOF). Interestingly, in the presence of polydopamine (PDA), the competitive coordination between anionic polymer (γ-PGA) and dimethylimidazole does not lead to the collapse of the external framework but self-assembly into a hollow structure. By constructing the Hemin@MOF immune platform and using E. coli O157:H7 as the detection object, we find that the visual detection limits can reach 10, 3, and 3 CFU/mL in colorimetric, photothermal, and catalytic modes, which is 4 orders of magnitude lower than the traditional gold standard. This study provides a new idea for the morphological modification of the metal-organic skeleton and multifunctional immunochromatography detection.

Facile synthesis, characterization, biocompatibility and protein loading/release property of zinc-doped hollow mesoporous bioactive glass nanospheres

Facile synthesis, characterization, biocompatibility and protein loading/release property of zinc-doped hollow mesoporous bioactive glass nanospheres

Sulfur vacancies and heterogeneous interfaces promote high performance sodium storage of bimetallic chalcogenide hollow nanospheres

Transition metal sulfides have high theoretical capacities and are considered as potential anode materials for sodium-ion batteries. However, due to low inherent conductivity and significant volume expansion, the electrochemical performance is greatly limited. In this study, a nickel/manganese sulfide material (Ni0.96Sx/MnSy-NC) with adjustable sulfur vacancies and heterogeneous hollow spheres was prepared using a simple method. The introduction of a concentration-adjustable sulfur vacancy enables the generation of a heterogeneous interface between bimetallic sulfide and sulfur vacancies. This interface collectively creates an internal electric field, improving the mobility of electrons and ions, increasing the number of electrochemically active sites, and further optimizing the performance of Na+ storage. The direction of electron flow is confirmed by Density functional theory (DFT) calculations. The hollow nano-spherical material provides a buffer for expansion, facilitating rapid transfer kinetics. Our innovative discovery involves the interaction between the ether-based electrolyte and copper foil, leading to the formation of Cu9S5, which grafts the active material and copper current collector, reinforcing mechanical supporting. This results in a new heterostructure of Cu9S5 with Ni0.96Sx/MnSy, contributing to the stabilization of structural integrity for long-cycle performance. Therefore, Ni0.96Sx/MnSy-NC exhibits excellent electrochemical properties following our modification route. Regarding stability performance, Ni0.96Sx/MnSy-NC demonstrates an average decay rate of 0.00944% after 10,000 cycles at an extremely high current density of 10000 mA g−1. A full cell with a high capacity of 304.2 mA h g−1 was also successfully assembled by using Na3V2(PO4)3/C as the cathode. This study explores a novel strategy for interface/vacancy co-modification in the fabrication of high-performance sodium-ion batteries electrode.

ZnO-CeO2 Hollow Nanospheres for Selective Determination of Dopamine and Uric Acid.

ZnO-CeO2 hollow nanospheres have been successfully synthesized via the hard templating method, in which CeO2 is used as the support skeleton to avoid ZnO agglomeration. The synthesized ZnO-CeO2 hollow nanospheres possess a large electrochemically active area and high electron transfer owing to the high specific surface area and synergistic effect of ZnO and CeO2. Due to the above advantages, the resulting ZnO-CeO2 hollow spheres display high sensitivities of 1122.86 μA mM-1 cm-2 and 908.53 μA mM-1 cm-2 under a neutral environment for the selective detection of dopamine and uric acid. The constructed electrochemical sensor shows excellent selectivity, stability and recovery for the selective analysis of dopamine and uric acid in actual samples. This study provides a valuable strategy for the synthesis of ZnO-CeO2 hollow nanospheres via the hard templating method as electrocatalysts for the selective detection of dopamine and uric acid.

Decorating highly efficient VN quantum dots onto N-doped hollow carbon nanospheres enables effective inhibition of the shuttle effect and acceleration of LiPSs conversion in lithium–sulfur batteries

Decorating highly efficient VN quantum dots onto N-doped hollow carbon nanospheres enables effective inhibition of the shuttle effect and acceleration of LiPSs conversion in lithium–sulfur batteries

Room-temperature NH3-sensor: SnO2@PANI core-shell hollow spheres

A novel room-temperature NH3-sensing material (SnO2@PANI core-shell hollow nanospheres) was synthesized by coating various amounts of PANI on SnO2 hollow nanospheres using a simple in-situ chemical oxidation polymerization method. The morphology and nanostructures of the synthesized sensing materials were characterized using SEM, TEM, FTIR, and XRD. Gas-sensing tests demonstrate that SP-5 exhibits the highest response to NH3 at room temperature, with a response value (26.48 at 500 ppm) more than 6 times higher than that of pure PANI (4.35). This sensor displays excellent selectivity, with good anti-interference capability to CO and NO2. The improved sensing performance of the core-shell hollow structure is attributed to the unique structure and p-n heterojunction between PANI and SnO2, which is confirmed by EIS spectra.

Constructing a mesoporous carbon nanobowls embedded with ultrafine CoSe2 Nanocrystals for High-Performance potassium ion battery electrode

In the quest for advanced electrode materials for potassium ion batteries (KIBs), an innovative anode featuring ultrafine CoSe2 nanocrystals embedded within mesoporous carbon nanobowls (CoSe2@MCNBs) is presented herein. Diverging from conventional hollow carbon nanospheres, the distinctive bowl structure is crafted to enhance the structural integrity and volumetric energy density of the electrodes. CoSe2@MCNBs synthesized using an iterative drop and dry method followed by selenization exhibit well-preserved morphology with a shell thickness of 20 nm. The successful integration of ultrafine CoSe2 nanocrystals into MCNBs imparts the nanobowls with the benefits of conventional hollow carbon-based composites, including abundant ion storage sites and high electrical conductivity. Simultaneously, the bowl structure boasts a higher packing density than the conventional hollow mesoporous carbon sphere (HMCS) structure, significantly augmenting the volumetric energy density of the fabricated electrode. Capitalizing on these advantages, the CoSe2@MCNB electrode displays exceptional cycling stability, achieving a reversible capacity of 523 mA h g−1 after 500 cycles at 0.5 A/g and an impressive rate capacity of 247 mA h g−1 at 2.0 A/g. This study demonstrates the strong potential of CoSe2@MCNB as an electrode material for the next generation of KIBs.

A sensitive electrochemical biosensor for detection of carbaryl based on hollow covalent-organic frameworks-gold nanoparticles nanospheres

Carbaryl as an important insecticide is always used in agricultures to achieve higher yields. So, rapid detection of carbaryl residues in agricultural products is very necessary due to its potential harm to human beings. Herein, a hollow covalent-organic frameworks (HCOFTFPB-DBD) gold nanoparticles (AuNPs) nanospheres was used to construct a sensitive electrochemical carbaryl biosensor. The surface of electrode modified by HCOFTFPB-DBD-AuNPs nanospheres was negatively charged and repelled the [Fe(CN)6]3-/4-. The acetylcholinesterase (AChE) immobilized on HCOFTFPB-DBD-AuNPs nanospheres catalyzed the hydrolysis of acetylcholine chloride to thiocholine (TCh). The obtained positively charged TCh was adsorbed on the electrode surface by Au-S, which made the electrode surface positively charged to adsorb the negatively charged [Fe(CN)6]3-/4-, showing enhanced oxidation current of [Fe(CN)6]3-/4-. After carbaryl was added, the oxidation current of [Fe(CN)6]3-/4- deceased because ChE activity were inhibited by carbaryl. So, the sensitive detection of carbaryl was achieved at a low potential, which resulted in a high selectivity. The biosensor had a detection limit of 0.38 μM, a linear range of 1.10 μM-40.0 μM, a sensitivity of 0.00863 mA μM−1 and better performance in actual sample.

N-doped hollow carbon nanospheres embedded in N-doped graphene loaded with palladium nanoparticles as an efficient electrocatalyst for formic acid oxidation

Efficient electrocatalysts with a low cost, high activity and good durability play a crucial role in the use of direct formic acid fuel cells. Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCNs) embedded in an assembly of N-doped graphene (NG) with a three-dimensional (3D) porous structure by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Because of the unique porous configuration of interconnected layers doped with nitrogen atoms, the Pd/NHCN@NG catalyst with Pd nanoparticles has a large catalytic active surface area, superior electrocatalytic activity, a high steady-state current density, and a strong resistance to CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. When the HCN/GO mass ratio was 1:1, the Pd/NHCN@NG catalyst had an outstanding performance in the catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work indicates a way to produce superior carbon-based support materials for electrocatalysts, which will be beneficial for the development of fuel cells.

Nanosheets-assembled hollow N-doped carbon nanospheres encapsulated with ultrasmall NiSe nanoparticles for electrocatalytic hydrogen evolution

Developing highly active and stably non-precious metal electrocatalysts for hydrogen production in alkaline conditions is of paramount importance to hydrogen economy. Herein, nanosheet-assembled hollow nitrogen-doped carbon nanospheres confined with ultrasmall NiSe nanoparticles (NiSe@NC) are synthesized by employing a SiO2 template-assisted approach. As expected, the as-prepared NiSe@NC electrocatalyst delivers an overpotential of 169 mV at the current density of 10 mA/cm2 without iR-correction, and sustains at least 80 h for continuous operation, far outperforming the NiSe-p catalyst in 1 M KOH medium toward hydrogen evolution reaction (HER). The appealing HER performance is mainly ascribed to the synergy effect between hollow nitrogen-doped carbon and highly active NiSe nanoparticles, which improves catalytically active sites, expedites electron transfer rate and optimizes the electronic structure of NiSe@NC nanomaterial. More strikingly, this study presents the feasible insights for constructing robust cost-effective electrocatalysts towards efficient HER in harsh alkaline media.

Highly selective QCM sensor based on functionalized hierarchical hollow TiO2 nanospheres for detecting ppb-level 3-hydroxy-2-butanone biomarker at room temperature

Highly selective QCM sensor based on functionalized hierarchical hollow TiO2 nanospheres for detecting ppb-level 3-hydroxy-2-butanone biomarker at room temperature

Yeast‐Controlled Double‐Shelled CaCO3/CaF2 Hollow Nanospheres with Hierarchically Porous for Sustained pH‐Sensitive Drug Release

Comprehensive SummaryHierarchically porous materials (HP materials) are believed one of the most hopeful matrix materials because of their distinctive multimodal pore structures and tremendous application potentials in the field of biomedicine. However, green and facile synthesis of hierarchically porous nanomaterials with beneficial water dispersibility and biocompatibility is still a great challenge. Herein, a novel biomimetic strategy is proposed to prepare the cell‐tailored double‐shelled HPCaCO3/CaF2 hollow nanospheres under the mediation of yeast cells. The biomolecules derived from the secretion of yeast cells are used as conditioning and stabilizing agents to control the biosynthesis of the HPCaCO3/CaF2 materials, which exhibit excellent water dispersibility and favorable biocompatibility. The double‐shelled CaCO3/CaF2 nanospheres hold hierarchically porous structure and have abundant pore channel and large specific surface area, showing high drug‐loading and a prolonged drug sustainable release profile by the pore‐by‐pore diffusion pattern of the hierarchical pores. Otherwise, the HPCaCO3 with pH‐sensitivity could controllably release drug doxorubicin hydrochloride (DOX) at the acidic tumor microenvironment. Both in vitro and in vivo results demonstrate that HPCaCO3/CaF2 has the sustainable pH‐sensitive drug release property, showing an enhanced therapeutic effect. Summarily, this study provides a biomimetic strategy to synthesize the hierarchically porous double‐shelled hollow nanomaterials for applying in sustainable drug delivery system.

Amino acid driven synthesis of gold nanoparticles: A comparative study on their biocompatibility

Gold nanoparticles (GNps) were successfully synthesized via 17 different l-Amino acids (AA-GNps) as reducing agents, in a one-pot reaction. Comparative characterization of AA-GNps revealed variations in their size, morphology, and structure, highly dependent on the nature of the employed amino acid. Aromatic amino acids proved to be fast-reducing agents directing the formation of GNps. Hydroxylic and basic amino acids were the slowest reducing agents for the synthesis of GNps. Aliphatic amino acids produced GNps of similar behavior, except Isoleucine which led to the formation of hollow nanospheres. GNps formulated by aspartic acid and asparagine have comparable properties to citrate-synthesized GNps, which is the golden standard in plasmonic nanoparticles. A new protocol was established for the determination of gold content in GNps’ colloidal solutions via a simple and cost-effective standard curve method employing UV–Vis spectroscopy. Most AA-GNps are colloidally stable, in both aqueous dispersion and simulated body fluid, posing as excellent candidates for in vitro experimentation. Comparative screening for their biocompatibility demonstrated the non-hemolytic and cytocompatible profile of most AA-GNps, via different in vitro assay protocols, performed on blood samples and the healthy cell line of Human Embryonic Kidney cells (HEK-293).