Hollow Spheres Research Articles

Spatial confinement of Co3O4 in hollow carbon sphere to boost peroxymonosulfate activation for effective degradation of organic pollutants

Herein, hollow carbon sphere (HCS) is constructed via hard template method for loading the Co3O4, and obtained catalyst (namely Co3O4/HCS) is then employed to activate peroxymonosulfate (PMS) for the removal of tetracycline (TC). Owing to high specific surface area and good conductivity of HCS, Co3O4 modified with HCS exhibits low interface resistance and fast charge transfer rate. Meanwhile, hollow structure of HCS can provide spatial confinement effect for Co3O4 and accelerate the mass transfer process between Co3O4 and PMS. As predicted, peroxy bond break of PMS over Co3O4/HCS is significantly boosted compared with pure Co3O4, so reaction system can produce more SO4•–, OH•, 1O2 and high-valent metal complexes to conduct TC degradation. Importantly, Co3O4/HCS-mediated electron transfer process between PMS and TC is also involved in TC degradation. As a result, Co3O4/HCS shows excellent performance in TC degradation, and the highest removal efficiency of TC is more than 95 % within 10 min. Benefiting from the protective effect of HCS, only a small amount of Co ion is released from Co3O4/HCS during the reaction process. Besides, Co3O4/HCS possesses good reusability and anti-interference ability. In short, current work provides a promising catalyst for PMS activation to treat wastewater containing antibiotic.

Oxidative Coupling and Self-Assembly of Polyphenols for the Development of Novel Biomaterials.

In recent years, the development of biomaterials from green organic sources with nontoxicity and hyposensitivity has been explored for a wide array of biotherapeutic applications. Polyphenolic compounds have unique structural features, and self-assembly by oxidative coupling allows molecular species to rearrange into complex biomaterial that can be used for multiple applications. Self-assembled polyphenolic structures, such as hollow spheres, can be designed to respond to various chemical and physical stimuli that can release therapeutic drugs smartly. The self-assembled metallic-phenol network (MPN) has been used for modulating interfacial properties and designing biomaterials, and there are several advantages and challenges associated with such biomaterials. This review comprehensively summarizes current challenges and prospects of self-assembled polyphenolic hollow spheres and MPN coatings and self-assembly for biomedical applications.

Double-layered SnO2@NC hollow spheres as anode materials for high-performance lithium-ion batteries

Double-layered SnO2@NC hollow spheres as anode materials for high-performance lithium-ion batteries

Experimental Investigation on Fabrication of Cermet Hollow Spheres for Use as Reinforcement in the Production of Lightweight and Strong Metal Foams for High Energy Absorption Applications

Experimental Investigation on Fabrication of Cermet Hollow Spheres for Use as Reinforcement in the Production of Lightweight and Strong Metal Foams for High Energy Absorption Applications

Immunogenic Material Vaccine for Cancer Immunotherapy by Structure-Dependent Immune Cell Trafficking and Modulation.

Inherently immunogenic materials offer enormous prospects in enhancing vaccine efficacy. However, the understanding and improving material adjuvanticity remain elusive. Herein how the structural presentation of immunopotentiators in a material governs the dynamic dialogue between innate and adaptive immunity for enhanced cancer vaccination is reported. The immunopotentiator manganese into six differing structures that resemble the architectures of two types of pathogens (spherical viruses or rod-like bacteria) is precisely manipulated. The results reveal that innate immune cells accurately sense and respond to the architectures, of which two outperformed material candidates (151nm hollow spheres and hollow microrods with an aspect ratio of 4.5) show higher competence in creating local proinflammatory environment with promoted innate immune cell influx and stimulation on dendritic cells (DCs). In combination with viral peptides, model proteins, or cell lysate antigens, the outperformed microrod material remarkably primes antigen-specific CD8 cytolytic T cells. In prophylactic and therapeutic regimens, the microrod adjuvanted vaccines display optimal aptitude in tumor suppression in four aggressive murine tumor models, by promoting the infiltration of heterogeneous cytolytic effector cells while decreasing suppressive immunoregulatory populations in tumors. This study demonstrates that a rationally selected architecture of immunogenic materials potentially advances the clinical reality of cancer vaccination.

Mixed surfactant assisted synthesis of single-crystal Ni2P hollow spheres with excellent adsorption performance

The single-crystal Ni2P hollow spheres have been synthesized via a solvothermal route in presence of mixed surfactant. It is showed that solvent played a significant role for the synthesis of Ni2P. Furthermore, the structure of hollow spheres would be obtained only using the mixtures of cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS) which act as soft template rather than single CTAB or pure SDBS. Finally, it turned out that the single-crystal Ni2P hollow spheres exhibit excellent adsorption activity for malachite green (MG) organic dyes.

Mastering the art: Proficient finite element implementation and robust evaluation of a strain-hardening porous ductile material crack growth prediction model at finite strain

Accurate prediction of crack extension is crucial for ensuring the structural integrity of metal components exposed to diverse loads. While the Gurson model and its extensions are widely accepted for delineating ductile fracture stages, especially in porous materials with a rigid-perfectly plastic matrix, their efficacy diminishes in the presence of strain-hardening matrices. To address this limitation, our study introduces a robust numerical implementation and assessment of Perrin's model. In contrast to Gurson's approach, Perrin's model incorporates two distinct strain-hardening parameters derived from an intricate analysis of a strain-hardening hollow sphere subjected to axisymmetric loading.Moving beyond theoretical discussions, this paper actively engages in the rigorous evaluation of Perrin's model under various scenarios, encompassing isotropic, kinematic, and mixed isotropic-kinematic hardening conditions. The model's effectiveness is convincingly demonstrated through meticulous comparisons between numerical simulations and real-world experimental observations conducted on pre-cracked specimens.Facing challenges related to achieving global elastic-plastic convergence in large-scale simulations, our research introduces a sophisticated approach. Leveraging stiffness tangent moduli ensure the maintenance of quadratic convergence in global Newton method iterations. This not only enhances the reliability of our simulations but also underscores the practical applicability of our findings.The study also focuses on the necking and crack propagation of a cylindrical specimen through meticulous computational modeling. Our mesh captures intricate details and addresses stress gradients, revealing coplanar crack propagation contrary to prior beliefs. The confirmation of the cup-cone fracture effect challenges previous interpretations, emphasizing the critical role of void nucleation. This reinforces the credibility and applicability of our approach in advancing the understanding of material fracture behavior.In summary, this study significantly contributes to existing knowledge in fracture prediction models, offering a robust framework for predicting ductile fracture under substantial deformations. The presented findings pave the way for advancements in structural engineering, providing invaluable insights for optimizing the performance and resilience of metal structures in real-world applications.

SO2-resistant hollow carbon spheres encapsulated Pt nanoparticles for benzene oxidation

In the catalytic combustion of volatile organic compounds (VOCs) using noble metal catalysts, resistance to SO2 poisoning poses a significant challenge. To tackle this problem, Pt nanoparticle catalysts encapsulated in hollow carbon spheres (Pt@HCS catalysts) are synthesized. The Pt@HCS catalyst exhibits excellent benzene conversion, achieving 100 % conversion at 165 °C under an air velocity of 20,000 mL/(g h). Compared to the conventional supported Pt/HCS catalyst, the Pt@HCS catalyst demonstrates a significantly improved resistance to SO2 poisoning. In the presence of 25 ppm SO2, the Pt@HCS catalyst is capable of maintaining a 100 % benzene conversion rate within 24 h, whereas the conversion rate of Pt/HCS drops substantially to approximately 52 %. It is confirmed that the hollow porous structure provided a larger specific surface area and more adsorption sites, thereby facilitating benzene oxidation. More importantly, in situ DRIFTS reveals that the adsorption and desorption processes of SO2, along with the generation of substances like SO32−, are strictly limited to the surface of the carbon shell, thereby preserving the integrity of the internal reaction environment. Multiple characterizations combined with density functional theory (DFT) have demonstrated a unique separation effect over Pt@HCS, whereby the hydroxyl groups on the carbon shell preferentially capture SO2 while allowing benzene molecules to enter the cavities of the catalyst. In this way, any internal ingress of SO2 and competition with benzene for Pt adsorption is effectively avoided. This study offers a potential solution to enhance the performance of noble metal catalysts in the presence of sulfur compounds.

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.

Construction of Functional Phenolic Resin and Carbon Hollow Spheres by Manipulating Structural Inhomogeneity.

Hollow carbonaceous spheres are extraordinarily attractive for their unique structural features and wide applications in various fields. Herein, a facile and effective synthesis methodology based on the extended Stöber process for construction of phenolic resin hollow spheres has been presented. Combined with a series of characterization techniques, the synthesis process was systematically investigated, and a possible synthesis mechanism was proposed. It is revealed that the structural inhomogeneity of the polymer product achieved by using dodecylamine and alkane is responsible for the formation of hollow architecture, which depends on spontaneous selective dissolution during the synthesis process. Different metal-doped carbonaceous hollow spheres can be obtained by introducing corresponding precursors into the synthetic system and meeting requirements of different application fields. This work presented a novel synthesis strategy of hollow carbonaceous spheres, which is significant for building a new platform of advanced functional carbon-based composites.

Development of a bifunctional material incorporating carbon microspheres for the intensified hydrogen production by sorption-enhanced glycerol steam reforming

Glycerol steam reforming is a green and sustainable alternative to hydrocarbon steam reforming for hydrogen production. Reaction intensification by in-situ CO2 removal using Ni/CaO-based bifunctional sorbent-catalyst materials was investigated in this paper to improve the hydrogen yield and purity significantly. Employing carbon microspheres as the foundation for sorbent synthesis resulted in the development of a hollow CaO sphere sorbent with higher and more stable sorption capacity over multiple adsorption/regeneration cycles compared to sorbents synthesized with conventional methods. The incorporation of different stabilizers improved further the capacity and stability of sorbents. The sorbent materials were tested under different sorption and regeneration temperatures in a dry and wet atmosphere. The intensified sorption-enhanced steam reforming process was evaluated under various reaction temperatures, weight hourly space velocities, and steam-to-carbon molar feed ratios. The bifunctional materials synthesized with carbon microspheres led to improved reaction performances, including a more extended pre-breakthrough period and a more stable behavior during reaction/regeneration cycles.

A novel Co9S8–MoS2 nanosheet arrays@HCSs with superior capacitive and cycling performance for hybrid supercapacitor

Due to high conductivity and electrochemical activity, transition metal sulfides and their complexes have emerged as attractive electrode materials for supercapacitors. Herein, heterostructures of Co9S8–MoS2 nanosheet arrays on the hollow carbon spheres (HCSs) with yolk-shell structure (Co9S8–MoS2 NSAs@HCSs) are synthesized by a hydrothermal method and in-situ sulfurization of silicates. This core-shell structure can effectively improve the conductivity and reaction kinetics, resulting in a notable improvement in the cycling and capacity properties. The Co9S8–MoS2 NSA@HCSs electrode has an outstanding cycle stability (96.9 %) after 10, 000 cycles at 10 A g−1 and a high specific capacity of 804C g−1 at 1 A g−1. The effects of solution concentration and sulfurization time on the microstructures and electrochemical properties of the electrode are also investigated. Furthermore, the hybrid supercapacitor (HSC) is assembled with Co9S8–MoS2 NSA@HCSs (positive electrode) and HCSs (negative electrode). Additionally, the HSC delivers 98.2 % of cycling stability after 10, 000 cycles at 10 A g−1. The energy density of 45.6 Wh kg−1 can be obtained at the power density of 770.4 W kg−1.

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.

Investigation of Drying Shrinkage Characteristics in Lightweight Engineered Cementitious Composites

Lightweight engineered cementitious composites (LW-ECCs) not only offer comparable mechanical strengths compared with conventional concrete, but also increase the tensile strain of the composite and exhibit strain-hardening behavior, and can be utilized in weight-critical structures such as buildings in seismically active areas. Hollow glass microsphere is a type of ultra-lightweight inorganic non-metallic hollow sphere and it has been deemed as one of the potential sustainable fillers of cement composites. This study aims to investigate the drying shrinkage behavior of LW-ECCs mix designs incorporating different types of hollow glass microspheres (HGMs). Eight types of HGMs with different densities (0.2–0.6 g/cm3) and particle size distributions were incorporated to replace fly ash at 80 and 100 vol% with HGMs. Drying shrinkage was measured from the age of 2 days and up to 91 days. The results demonstrate that all LW-ECCs at 91 days showed greater shrinkage than the control mix, deformation ranged from 1140–1877 µε; 80% replacement ratio of HGMs was regarded as the optimum due to less shrinkage than 100% HGM mixes; the mix incorporating 80% H60 type of HGMs was the relatively most desired mix which had the least shrinkage at 91 days compared to other LW-ECCs, and the strains of the mix using H60 were 1140 and 1385 µε at 91 days for 80% and 100% replacement, respectively.

Efficient and robust CO2 hydrogenation to methanol achieved by copper nanoparticles anchored in copper phyllosilicate core-shell nanoreactor

Methanol synthesis by CO2 hydrogenation is a key process in a sustainable methanol-based economy. Copper silicate (CuSiO3) is considered as efficient for hydrogenation of C-O/CO bonds due to the synergistic effect from its unique dual-sites of Cu0-Cu+. However, it still confronts great obstacles of poor CO2 conversion and low methanol selectivity. Herein, we designed a core-shell CuSiO3 nanoreactor by hydrothermal method, the cavity of which between core and shell provided the reaction space for CO2 and H2 in CO2 hydrogenation. Interestingly, the cavity of the nanoreactor could be tuned by the hydrothermal time, and the product selectivity altered accordingly. Intrinsically, because of the spatial restriction effect of reactants, the reactant especially hydrogen can be enriched on the concave surface of nanotubes and hollow spheres, leading to a favorable activity. Furthermore, the longer diffusion path derived from the increased cavity volume would cause a deep hydrogenation to CH4. Based on this, we chose the nanoreactor with suitable cavity volume to impregnate copper nanoparticles to increased the active sites and regulate the ratio of Cu0/Cu+, achieving remarkable catalytic activity (the conversion of CO2 is 19.7% and yield of methanol reaches up to ∼18%). Moreover, the copper nanoparticles could be anchored by the core and shells, contributed to an excellent stability of the catalytic system (>120 h).

Lightweight, hydrostatic pressure‐resistance, thermal insulating epoxy syntactic foam with a multiscale ternary structure for marine engineering application

AbstractThe study of lightweight epoxy syntactic foams is of great significance for the exploitation of marine resources. In this work, glass fibers reinforced epoxy hollow spheres (GFs‐EHS) were first prepared using a template method, and a lightweight three‐phase epoxy syntactic foam (LWTP‐ESF) with a multiscale ternary structure was prepared using a molding pressing method with epoxy resin as matrix, hollow glass microspheres (HGMs), and GF‐EHS as the lightweight fillers. The effect of HGMs content on the density, uniaxial compression properties, water absorption, and thermal conductivity of obtained LWTP‐ESF was evaluated. The results indicated that the density, uniaxial compression strength, and thermal conductivity of LWTP‐ESF were consistently decreased, while the water absorption was increased with the increase in HGMs content. The highest specific compression strength and lowest thermal conductivity of LWTP‐ESF could reach 52.77 ± 0.82 MPa·cm3/g and 0.113 ± 0.005 W/(m·K), respectively. Moreover, the effect of hydrostatic pressure on the water absorption and thermal conductivity of LWTP‐ESF were also systematically analyzed. This study provides a novel system and method to prepare lightweight epoxy syntactic foams, and the prepared composites have potential applications in the field of lightweight thermal insulation materials for marine.Highlights The composites with a multiscale ternary structure were designed. The composites possessed significantly lower density and thermal conductivity. The water absorption of composites under hydrostatic pressure was evaluated. The thermal conductivity of composites under hydrostatic pressure was evaluated. The water absorption mechanism and thermal insulation mechanism were proposed.

Highly selective adsorption and biodegradation of emulsified oil by microorganisms embedded in SiO2 hollow sphere bioreactor

Highly efficient elimination and disposal of oils and organic contaminants from water is of great importance for the sustainable development of modern society. In this work, micron-sized “single pore” silica hollow spheres (SHMs) bioreactors were prepared using (W/O/W) ternary-phase microemulsion, and the size of pores was adjusted to the concept of “single-pore” composite microorganism bioreactor, preparation of single-pore silica hollow spheres with an average pore size of 8.572 μm, which enables the SHMs bioreactors to load microorganisms for oils biodegradation. The outer layer was sprayed with a layer of silica nanoparticles with a diameter of 500 nm produced by silane hydrolysis, which encapsulated the inner “single-pore” SHMs to form a core–shell structure (M/Microbe@SHMs). This micro-nano core–shell structure exhibits superhydrophobicity and superlipophilicity, which gives it excellent selective adsorption capacity. Interestingly, M/Microbe@SHMs have excellent emulsion-breaking effects in oil–water separation. In addition to the simultaneous oil/water separation ability, the adsorbed oil and grease can be subsequently degraded to CO2 and H2O by microorganisms' action in the inner layer of M/Microbe@SHMs. Based on this excellent selective adsorption and oil/water separation capacity, while one-step in-situ biodegradation, our microbial bioreactor may have a potential for a wide range of practical applications in wastewater treatment.

Formation of hollow spheres structures Co/CoO/ZnO@NC from metal-organic frameworks as a anode for lithium-ion batteries

Transition metal oxides have become a potential anode material for LIBs due to their large theoretical capacity, low cost, abundant resources. However, significant volume changes and severe particle aggregation occur during charge/discharge process. In this work, it is found that the composite of dual component active TMO and single metal, and coating by doped carbon are the effective methods to improve the electrochemical performance and adapt to volume changes in storing lithium. The specific process is based on the co-precipitation of Zn and Co ions in the presence of 2-methylimidazolium salts to produce imidazolium salt frameworks (ZIFs) of bimetallic zeolites, which are then thermally decomposed to form hollow spheres structures Co/CoO/ZnO@NC. The hollow sphere uses Co as the core and CoO/ZnO@NC particles coated with nitrogen doped carbon layer as the shell. These spherical structures exhibit excellent electrochemical performance, high reversible capacity, excellent cycling stability (702 mAh/g at 100 mAg−1 after 100 cycles), and good rate capability (735 mAh/g and 515 mAh/g at 100 mA g−1 and 2000 mA g−1 respectively).

Resolving the tradeoff between energy storage capacity and charge transfer kinetics of sulfur-doped carbon anodes for potassium ion batteries by pre-oxidation-anchored sulfurization

Sulfur-heteroatom doping is an effective approach to improve the capacity of carbon anodes for potassium-ion batteries due to the reversible K+-sulfur reaction. However, the random sulfur doping induces unresolved tradeoff between capacity and kinetics, which results from the fundamental difficulty in controllable sulfur incorporation using traditional approaches where breaking robust carbon-containing bonds is necessary. Herein, a pre-oxidation-anchored sulfurization approach is proposed to realize site-controlled and content-adjustable sulfur doping, demonstrating the optimum sulfur content of 9.8 at.% in sulfur-doped hollow carbon sphere (S-HCS). Intentional pre-oxidation introduces easy-to-break C-O/C-O-C bond-included oxygen-containing functional groups serving as anchoring sites for substitution with sulfur atoms. Consequently, S-HCS-9.8 % achieves superior performance for K+ storage (406.1 mA h g–1 at 0.1 A g–1, 112.6 mA h g–1 at 5 A g–1 and 170 mA h g–1 after 2,000 cycles at 2 A g–1). The enhanced electrochemical performances are attributed to the largest interlayer spacing and highest disorder degree resulting from the thiophene-sulfur-dominated configuration at high sulfur content, which realizes high structure reversibility and stable solid-electrolyte-interface layer. This work provides new insights and guiding principles for the development of heteroatom-doped carbon anodes for next-generation high-performance energy storage applications.

Facile synthesis and application of hyperbranched TiO2 hollow spheres for enhancement of power conversion efficiency of CdSeTe quantum dot-sensitized solar cells

Facile synthesis and application of hyperbranched TiO2 hollow spheres for enhancement of power conversion efficiency of CdSeTe quantum dot-sensitized solar cells