Multi-shelled Hollow Spheres Research Articles

Intrinsically high light absorption and superhydrophobic inorganic multi-shelled hollow spheres derived composite phase change material

The fabrication of composite phase change materials (CPCMs) is significant for harvesting and converting solar energy. Hence, we first report novel CPCMs based on inorganic multi-shelled hollow spheres (MHS) via a facile hydrothermal method and calcination treatment. 1-Hexadecylamine (HDA) and Octadecylamine (ODA) were incorporated into MHS by a simple impregnation treatment to prepare CPCMs. Owing to its multi-shelled structure, the CPCMs have an outstanding ability of leakage resistance. In addition, the CPCMs themselves exhibit excellent solar absorption of up to 80 % without further surface modification. The thermal conductivity of the CPCMs containing HDA and ODA was increased by 1.03 times and 1.67 times by comparison with that of pure PCMs. The enthalpy of the as-resulted CPCMs is 207.6 J/g and 151.5 J/g, which is higher than most existing CPCMs, and the enthalpy of the CPCMs containing HDA and ODA after 100 times cycles can still attain 110.9 J/g and 104.7 J/g. Under 1sun irradiation, the light-to-thermal conversion efficiency of the CPCMs containing HDA and ODA was measured to be 90.0 % and 92.1 %, respectively. Taking advantage of its inherently physicochemical stability, superior light absorption and thermal conductivity and leakage resistance, scalable and cost-efficient fabrication process, such MHS-based CPCMs may have great potential for a wide variety of applications such as photothermal conversion, solar energy harvesting and storage, and so on.

Nanoarchitectonics of shape-stable composite phase change membrane based on multi-walled hollow microspheres for light-to thermal conversion

The development of shape-stable composite phase change materials (CPCMs) with outstanding light absorption and light-to thermal conversion performance is of great significant for harvesting and converting solar energy. Herein, we proposed a novel shape-stable composite phase change membrane based on multi-shelled hollow spheres (MHS) via a facile method. The MHS was fabricated by hydrothermal reaction and calcination treatment, and membrane was directly coated on glass plates after bonding the MHS. The as-resulted membranes possess excellent tensile strength, superior light absorption and light-to thermal conversion efficiency. The tensile strength of the membrane based MHS loaded 1-Hexadecylamine (HDA) can reach to 1.01 MPa. The light absorption of the membrane is about 93% under 1sun irradiation, and the photothermal conversion efficiency of the membrane is 81.4%. Moreover, the electro-to thermal conversion and heat dissipation of the membrane based CPCM were investigated. The results demonstrate that this membrane-based CPCM can not only be applied in solar energy capture, storage and conversion, but also has the prospect of being applied in the fields of electro-to thermal conversion and heat dissipation.

Combing Hollow Shell Structure and Z-Scheme Heterojunction Construction for Promoting CO2 Photoreduction

CO2 photoreduction is considered one of the potential ways to achieve carbon neutralization since it uses green solar energy without introducing additional carbon sources during the process of converting CO2 to fuels. However, limited light utilization and poor charge separation often give rise to undesirable CO2 photoreduction performance. Herein, a generic approach using carbon spheres as templates to construct transition metal oxides with multishelled hollow structures is reported. The multishelled hollow structure has been proven to be efficient for improving CO2 photoreduction. Furthermore, we constructed a Z-scheme heterojunction photocatalyst (CdS/Au/ZnCrO4) through introducing CdS into a multishelled hollow ZnCrO4 sphere with Au nanoparticles as a charge transfer medium. Benefiting from the multishelled hollow structure’s induced light utilization and large surface area and Z-scheme heterojuncion promoted charge separation, a high CO production of 2.95 μmol g–1 h–1 was achieved on CdS/Au/ZnCrO4 without using any sacrificial agents, which was 18.4 times and 24.6 times higher than that of CdS and ZnCrO4. This work provides a generic method for constructing controllable multishelled hollow spheres and is expected to offer guidance for promoting CO2 photoreduction through structure regulation and heterojunction construction.

Self-templating construction of NiCo2S4/CoO multi-shelled hollow spheres as electrodes for hybrid supercapacitors

The strategy of combining well-designed hollow structure with compositional engineering has been aroused wide interest in the fields of energy storage. Herein, starting from Ni-Co coordination polymer spheres as self-templates, the NiCo2S4/CoO multi-shelled hollow spheres (NiCo2S4/CoO HMSs) are constructed through calcination and sulfurization, in which the shells consist of a large number of nanoparticles with heterostructures. By virtue of its structural and compositional advantages, the NiCo2S4/CoO HMSs present desirable energy storage properties including high specific capacity (860.1 C g−1 at 1 A g−1), outstanding rate performance and good cycling durability. It is also found that the NiCo2S4/CoO HMSs possess accelerated reaction kinetics. Furthermore, a hybrid supercapacitor device, assembled by NiCo2S4/CoO as the positive electrode and hierarchically porous carbon as the negative electrode, yields a high energy density of 55.35 Wh kg−1 at 790 W kg−1. This work would contribute to designing advanced heterostructures for high-performance electrode materials.

Multi-shelled bimetal V-doped Co3O4 hollow spheres derived from metal organic framework for high performance supercapacitors

Using hollow structures containing more than one transition metal oxide seems to be essential to respond to the new generation of energy storage electrodes with remarkable performance for advanced expansions of new electronic devices. In this work, facile and controllable synthesis of multi-shelled V-doped Co3O4 hollow spheres derived from metal-organic framework through a solvothermal process followed by annealing as heat treatment has been studied. A comprehensive investigation of the hollow spheres in case of morphological, structural, and electrochemical behavior has been carried out. The multi-shelled V-doped Co3O4 (MS-V-CO) electrode displays well results, including electrochemical behavior (little internal resistance, fast kinetics, great reversibility, an excellent specific capacitance of 1593 F g−1), and structural features (high surface area (61.4 m2 g−1), multi shell structure, and wrinkled surface). An asymmetric supercapacitor (ASC) device has been assembled using multi shell vanadium doped cobalt oxide as the positive electrode (anode) and activated carbon (AC) as the negative electrode (cathode) and investigated for electrochemical performance. MS-V-CO//AC shows good behavior with a maximum energy density of 66.88 Wh kg−1 and power density of 240 Wkg−1 at 0.3 A g−1, relying on the total mass of active materials on both electrodes.

Surface modification and reconstruction of ZnO hollow microspheres for selective electroreduction of CO2 to CO

Surface chemistry can be modified by introducing another component on the surface of catalyst due to the regulation of configuration and electronic properties. Herein, the nanostructured ZnO hollow microspheres were fabricated for selective CO2 reduction to CO. The addition of CuO weakens the strength of adjacent Zn-O bond and improves the formation of more zero-valence Zn. Small CuO entities can provide the active sites for CO2 adsorption, and the presence of surface defects due to Zn2+ reduction could enhance initial dissociation from CO2 to CO. More interestingly, the 3CuO/ZnO catalyst underwent reconstruction during electrocatalysis, and multi-shelled hollow spheres evolved into a thin flaky structure. The extended surface area of flaky morphology enhances the catalytic stability despite the occurrence of ZnO reduction. This study highlights the importance of surface modification for CO2 selective reduction to CO but also provides some insights on reconstruction during electrochemical reduction of CO2.

A high-energy-density supercapacitor with multi-shelled nickel-manganese selenide hollow spheres as cathode and double-shell nickel-iron selenide hollow spheres as anode electrodes.

Thanks to the attractive structural characteristics and unique physicochemical properties, mixed metal selenides (MMSes) can be considered as encouraging electrode materials for energy storage devices. Herein, a straightforward and efficient approach is used to construct multi-shelled nickel-manganese selenide hollow spheres (MSNMSeHSs) as cathode and double-shell nickel-iron selenide hollow spheres (DSNFSeHSs) as anode electrode materials by tuning shell numbers for supercapacitors. The as-designed MSNMSeHS electrode can deliver a splendid capacity of ∼339.2 mA h g-1/1221.1 C g-1, impressive rate performances of 78.8%, and considerable longevity of 95.7%. The considerable performance is also observed for the DSNFSeHS electrode with a capacity of 258.4 mA h g-1/930.25 C g-1, rate performance of 75.5%, and longevity of 90.9%. An efficient asymmetric apparatus (MSNMSeHS||DSNFSeHS) fabricated by these two electrodes depicts the excellent electrochemical features (energy density of ≈112.6 W h kg-1 at 900.8 W kg-1) with desirable longevity of ≈94.4%.

Mesoporous Silica Encapsulated Metal-Organic Frameworks for Heterogeneous Catalysis

Encapsulation of metal-organic frameworks (MOFs) with a shell of mesoporous silica can boost overall performance of MOFs, offering versatility for synthetic architecture of integrated nanocatalysts with reactor-like features. Recently, Yu et al. report a green approach to make yolk-shell nanoreactors.

Multi-shelled CoS2–MoS2 hollow spheres as efficient bifunctional electrocatalysts for overall water splitting

The exploration of highly efficient non-precious electrocatalysts is essential for water splitting devices. Herein, we synthesized CoS2–MoS2 multi-shelled hollow spheres (MSHSs) as efficient electrocatalysts both for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using a Schiff base coordination polymer (CP). Co-CP solid spheres were converted to Co3O4 MSHSs by sintering in air. CoS2–MoS2 MSHSs were obtained by a solvothermal reaction of Co3O4 MSHSs and MoS42− anions. CoS2–MoS2 MSHSs have a high specific surface area of 73.5 m2g-1. Due to the synergistic effect between the CoS2 and MoS2, the electrode of CoS2–MoS2 MSHSs shows low overpotential of 109 mV with Tafel slope of 52.0 mV dec−1 for HER, as well as a low overpotential of 288 mV with Tafel slope of 62.1 mV dec−1 for OER at a current density of 10 mA cm−2 in alkaline solution. The corresponding two-electrode system needs a potential of 1.61 V (vs. RHE) to obtain anodic current density of 10 mA cm−2 for OER and maintains excellent stability for 10 h.

Versatile by design: Hollow Co3O4 architectures for superior lithium storage prepared by alternative green Pechini method

Co3O4 open hollow structures were synthesized by a new green alternative of Pechini method that implies three simple steps: (i) an initial formation of Co2+- citric soluble coordination compounds, (ii) hydrothermal processing (180 °C) in the presence of fructose followed by (iii) air thermal processing of the as-obtained precursor. Benefiting from its exclusive structural features, this appealing hollow Co3O4 material demonstrated superior specific capacity, rate performance and cycling stability (specific capacity of 848 mA h g−1 at an applied C-rate of 0.5 C with a coulombic efficiency of 98% after 250 cycles) in comparison with multi-shelled hollow spheres obtained in the absence of citric acid (525 mA h g−1 with a coulombic efficiency of 97% recorded under the same conditions).

Formation of graphene-wrapped multi-shelled NiGa2O4 hollow spheres and graphene-wrapped yolk-shell NiFe2O4 hollow spheres derived from metal-organic frameworks for high-performance hybrid supercapacitors.

To construct a supercapacitor (SC) with considerable performance, synthesis of an electrode material with a highly porous structure is necessary. Herein, an efficient metal-organic framework (MOF)-derived procedure is offered to construct a graphene wrapped multi-shelled NiGa2O4 hollow sphere (GW-MSNGOHS) positive electrode material and a graphene-wrapped yolk-shell NiFe2O4 hollow sphere (GW-YS-NFOHS) negative electrode material with a highly porous nature in SCs. The GW-MSNGOHS and GW-YS-NFOHS electrodes exhibit excellent capacities (∼411.25 mA h g-1 and 254.25 mA h g-1, respectively, at 1 A g-1), reasonable rate performances (75.85%, and 62.7%, respectively), and outstanding cyclability (98.9% and 90.9%, respectively). Benefiting from the reasonably engineered negative and positive electrodes, the fabricated asymmetric device (GW-MSNGOHS//GW-YS-NFOHS) can show an excellent energy density (ED) of 118.97 W h kg-1 at a power density (PD) of 1702 W kg-1, an exceptional robustness of 92.1%, and an excellent capacity (Cs) of 140.2 mA g-1.

Synthesis of ternary metal oxides as positive electrodes for Mg-Li hybrid ion batteries.

Rechargeable magnesium-ion batteries (MIBs) have emerged as promising energy storage systems owing to their highly stable magnesiation and de-magnesiation processes and high theoretical energy density. However, MIB technology is restricted by sluggish Mg2+ ion transportation inside the host cathode due to large impedance. Herein, a rechargeable Mg-Li hybrid ion battery (MLIB) is presented to achieve fast Mg2+ ion stripping/plating at a magnesium anode and Li+ ion intercalation/de-intercalation in a ternary transition metal oxide cathode. The (NiMnCo)3O4 multi-shelled hollow spheres prepared by a one-step hydrothermal method followed by thermal treatment were employed as a positive electrode in a Mg-Li hybrid ion battery, with a magnesium metal anode and all-phenyl-complex based dual ion electrolytes. The resulting prototype MLIB delivered a reversible capacity of 550 mA h g-1 at a current density of 50 mA g-1, which is significantly higher compared with reported MLIBs. Furthermore, the prototype MLIB exhibited an affordable specific energy (368 W h kg-1) and cycle life (a capacity of 277 mA h g-1 was retained even after 100 cycles at 100 mA g-1). The significant improvement in the electrochemical performance of the MLIB is achieved via rational design of the (NiMnCo)3O4 cathode with a reduced Li+ ion diffusion length and stable deposition/dissolution of Mg at the anode without the occurrence of side reactions. Furthermore, ex situ XRD, SEM, ICP and EIS techniques were used to understand the reaction kinetics of guest ions inside the (NiMnCo)3O4 hollow sphere cathode.

Rationalized Fabrication of Structure-Tailored Multishelled Hollow Silica Spheres

This work demonstrates a simple approach to rational fabrication of multishelled hollow silica spheres via periodic injections of a given amount of tetramethylammonium hydroxide (TMAH) to catalyze ...

Synthesis of Single-Component Metal Oxides with Controllable Multi-Shelled Structure and their Morphology-Related Applications.

Multi-shelled hollow spheres metal oxides, namely materials with more than three shells, have attracted increasing attention due to their unique structure. The preparation methods of typical metal oxides including NiO, Co3 O4 and ZnO etc. have been summarized in this review. Simultaneously, the parameters that influence the ultimate morphologies, shell number as well as the compositions have also been discussed. The potential application fields in energy conversion and storage, electromagnetic wave absorption, photocatalysis that related to the unique structure are also highlighted. Finally, the future researches of multi-shelled hollow spheres metal oxides are further discussed.

Advanced Reversible Long-Lasting Flexible Metal-Air Batteries Using Mn/Fe Hexaiminobenzene Metal-Organic Frameworks

Fast growing “Internet of Things” has an ever-increasing demand for advanced batteries with high energy density, robustness, flexibility, and environmental benignity for emerging high-tech electronic technologies, electric vehicles, and smart grids. Herein, we demonstrate robust aqueous and flexible ZABs employing three-dimensional dual-linked hexaiminobenzene metal-organic frameworks (Mn/Fe-HIB-MOF) as redox-active robust bifunctional electrocatalysts with ultrahigh intrinsic electrical conductivity and atomically tuned multi-shelled hollow spheres. Superionic functionalized bio-cellulose nanofibrous, solid-state membrane electrolyte (64 mS∙cm−1) is also presented with outstanding flexibility and water retention. The well-defined quintet-shelled hollow sphere MOFs possess a hierarchical porous structure, excellent packing density with a surface area of (2,298 m2.g-1), and chemical stability contrasted to conventional MOFs. The Mn/Fe-HIB-MOFs exhibited superior bifunctional oxygen electrocatalytic activity (0.627 V) with half-wave potential (0.883 V) for oxygen reduction and overpotential (280 mV @10 mA∙cm−2) for oxygen evolution reactions, outperforming commercial Pt/C and RuO2. The liquid and flexible ZABs with the present constituents revealed the world-record breaking cycling stability of 1,000 h (6,000 cycles) and 600 h (3,600 cycles) with fast fading and exceptionally high rate capacity (10 and 25 mA cm- 2), respectively, reported to date for rechargeable ZABs. These promising results illustrate great perspectives for sustainable rechargeable ZABs in the modern industries of electric vehicles and wearable electronics.

Coordination polymer derived general synthesis of multi-shelled hollow metal oxides for lithium-ion batteries.

Multi-shelled hollow metal oxide nanostructures have attracted tremendous attention in energy storage devices owing to their high specific capacity, rate capability and ameliorated cycling performance. Although great progress has been made in synthesizing multi-shelled hollow structures, most methods still depend on tedious template mediated strategies to generate complex interior structures. Herein, we developed a facile universal self-templated approach to synthesize a series of multi-shelled hollow metal oxide spheres with tailored compositions. This strategy involved the solvothermal preparation of uniform spherical coordination polymers (CPs) as precursors and a subsequent thermal treatment in air. Single-, binary- and ternary-metal multi-shelled hollow oxide spheres (Co, Mn-Co, Ni-Co, Ni-Co-Mn, etc.) were successfully obtained. To demonstrate their applications in energy storage, the electrochemical properties of ZnCo2O4 were investigated by testing the lithium-ion-storage performance. Owing to the unique structures, the multi-shelled hollow ZnCo2O4 spheres exhibited high specific capacity, excellent cycling durability (1200 mA h·g-1 after 200 cycles at 0.1 A g-1) and prominent rate capability (730 mA h·g-1 at 5.0 A g-1).

Construction of Multishelled Binary Metal Oxides via Coabsorption of Positive and Negative Ions as a Superior Cathode for Sodium-Ion Batteries.

Multishelled binary metal oxide, which can exert a synergetic effect of different oxides, is a promising electrochemical electrode material. However, it is challenging to synthesize this kind of binary metal oxide due to the severe hydrolysis and/or precipitation reactions of the precursors between cations and anions of different metals. Herein, by using citric acid as a chelating agent to inhibit hydrolysis and precipitation, a series of multishelled binary metal oxide hollow spheres (Fe2(MoO4)3, NiMoO4, MnMoO4, CoWO4, MnWO4, etc.) were obtained via coabsorption of negative and positive metal ions. In addition, the chelation between a metal ion and citric acid is systematically validated by NMR, MS, Raman, and UV-vis. In particular, multishelled Fe2(MoO4)3 hollow spheres show excellent electrochemical performance as cathode material for sodium-ion batteries benefited from their structural superiorities. Especially, the quintuple-shelled Fe2(MoO4)3 hollow sphere shows the highest specific capacity (99.03 mAh g-1) among all Fe2(MoO4)3 hollow spheres, excellent stability (85.6 mAh g-1 was retained after 100 cycles at a current density of 2.2 C), and outstanding rate capability (67.4 mAh g-1 can be obtained at a current density of 10 C). This general approach can be extended to the synthesis of other multishelled multielement metal oxides and greatly enrich the diversity of hollow multishelled structures.

Mild Strategy to Fabricate Mnx Co3−xO4 Multi-Shelled Hollow Spheres with Superior Catalytic Property in CO Oxidation

Mild Strategy to Fabricate Mn<i>_x</i> Co_3−<i>x</i>O₄ Multi-Shelled Hollow Spheres with Superior Catalytic Property in CO Oxidation

Hollow Micro/Nanostructured Ceria-Based Materials: Synthetic Strategies and Versatile Applications.

Hollow micro/nanostructured CeO2 -based materials (HMNCMs) have triggered intensive attention as a result of their unique structural traits, which arise from their hollowness and the fascinating physicochemical properties of CeO2 . This attention has led to widespread applications with improved performance. Herein, a comprehensive overview of methodologies applied for the synthesis of various hollow structures, such as hollow spheres, nanotubes, nanoboxes, and multishelled hollow spheres, is provided. The synthetic strategies toward CeO2 hollow structures are classified into three major categories: 1) well-established template-assisted (hard-, soft-, and in situ template) methods; 2) newly emerging self-template approaches, including selective etching, Ostwald ripening, the Kirkendall effect, galvanic replacement, etc.; 3) bottom-up self-organized formation synthesis (namely, oriented attachment and self-deformation). Their underlying mechanisms are concisely described and discussed in detail, the differences and similarities of which are compared transversely and longitudinally. Niche applications of HMNCMs in a wide range of fields including catalysis, energy conversion and storage, sensors, absorbents, photoluminescence, and biomedicines are reviewed. Finally, an outlook of future opportunities and challenges in the synthesis and application of CeO2 -based hollow structures is also presented.

Easy synthesis of multi-shelled ZnO hollow spheres and their conversion into hedgehog-like ZnO hollow spheres with superior rate performance for lithium ion batteries

Herein, uniform multi-shelled ZnO hollow spheres were synthesized, especially hedgehog-like and triple-shelled ZnO hollow spheres were synthesized for the first time by a simple hydrothermal method capable of controlling the number of internal multishells, which are achieved by controlling the calcination process. Used as anodes for lithium ion batteries, the hedgehog-like ZnO hollow spheres show excellent rate capacity, good cycling performance, and high initial specific capacity. A superior capacity, up to 109 mAh g−1 with minimal irreversible capacity (i.e., coulomb efficiency of 99.1%) after 100 cycles is achieved at a current rate of 100 mA g−1, and a capacity of 98.8 mAh g−1 is obtained at a current rate of 1 A g−1. However, a high discharge of 253.6 mA h g−1 for the hedgehog-like ZnO hollow spheres can still be achieved when the current rate is reduced back to 100 mA g−1.