Porous Hollow Microspheres Research Articles

In situ growth of 1T-MoS2 nanosheets on NiS porous-hollow microspheres for high-performance potassium-ion storage

In this study, a two-step route was adopted to in situ grow 1T-MoS2 nanosheets on NiS porous-hollow microspheres. It was found that the tiled MoS2 sheets tightly wrapped NiS spheres through coherent attachment via lattice-plane rotation, which would fully activate inert sulfur atoms on the basal plane of 1T-MoS2. This unique structure resembled a concentric spherical capacitor, which was able to store a large quantity of K+ ions with a capacity of 273.1 mAh/g at 5 A/g and deliver a stable capacity of 472.1 mAhg−1 after 1000 cycles at 0.2 A/g. In these multilevel hollow spheres, NiS phase mainly acted as a dielectric material to boost K-storage capability of MoS2 lamellae, and this electrical double-layer effect is more prominent either at high current densities or upon long-term cycling. It was anticipated that this work would shed new light on designing heterostructures of transition-metal dichalcogenides for high-performance potassium-ion storage.

Preparation of Double‐Layer Hollow Porous Carbon Microspheres by a Hydrothermal Method

AbstractDouble‐layer hollow porous carbon microspheres (DPCMs) with high specific surface area (up to 57.3 m2/g) were synthesized by a hydrothermal method using sucrose as the carbon source, SnCl4 ⋅ 5H2O as the porogen, and sodium dodecyl sulfate and sodium polyacrylate as the anionic surfactant and dispersant, respectively. The thickness and morphology of the inner and outer layers of the DPCMs (spherical, bowl‐like, mushroom‐like, or ellipsoidal) could be adjusted by changing the hydrothermal conditions. X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared analysis (FTIR) showed that the surface of the DPCMs was rich in −OH and −COOH functional groups, which was beneficial for subsequent chemical modification of the DPCMs. Because the prepared DPCM had a reactive surface layer and a stable carbonaceous double‐layer structure, the material could be used in supercapacitors and biochemistry, and as catalyst carriers, adsorption materials, and electrode materials, among other applications.

In-situ embedding of ultrasmall MnO nanoparticles into pollen biomass-derived hollow porous N heteroatoms enriched carbon microspheres as high-performance anode for lithium-ion batteries

The transition manganese monoxide (MnO) is investigated as the one of the most promising candidates of anode nanomaterials for lithium-ion batteries (LIBs) due to its irreplaceable advantages of higher theoretical capacity, restricted voltage hysteresis and favorable electrochemical kinetics. Nevertheless, it still remains a big challenge to simultaneously resolve the nonideal properties of the relatively low dispersion of MnO, the structural metastability as well as the undesirable permeability of electrolyte. Herein, the ultrasmall MnO nanoparticles/sulfuric-acid-pretreated camellia pollen carbon (MnO/SCPC) composites are successfully fabricated by a facile bio-templating method of carbonization hydrolysis of camellia pollen, wet-impregnation treatment of Mn/SCPC precursor and followed by thermal annealing, which delivers hollow porous microspheres structure where the shell components are formed by orderly stacking of multiple ultrasmall-size MnO-loaded nanocarbon spheres. This advantageous nano-structures not only allow for a large volume change during the lithiation/delithiation process, a large accessible contact area with electrolyte and a short transport path for Li+ ions, but also enhance the amounts of electrochemically active sites while simultaneously endow them with a superior structural stability through robust interfacial interaction. These clever designs enable the MnO/SCPC composites to perform exceptionally well electrochemically. More specifically, the MnO/SCPC-600 anode possesses a high initial discharge capacity (1490 mAh·g−1) at a current density of 0.1 A·g−1, and still retains 60% of the initial capacity (894 mAh·g−1) after 100 cycles. Besides, it also exhibits a high discharge capacity of 612 mAh·g−1 at a current density of 2.0 A·g−1 and an ultralong cycling life of 584 mAh·g−1 at 1.0 A·g−1 for long period of 1000 cycles. This work also paves up a facile direction for the application of MnO/biomass-derived carbonaceous nanomaterials in LIBs.

Carbon‐Coated Porous Hollow Silicon Microspheres for High‐Capacity and Durable Lithium Storage

AbstractSilicon‐based materials are promising lithium‐ion battery (LIB) anodes owing to their natural abundance and high capacity. However, their practical application is restricted by the poor electrical conductivity and large volume expansion. Herein, we successfully construct carbon coated porous hollow silicon microspheres (Si‐40@C) as LIB anode materials, which are derived from the acid etching of commercial AlSi alloy with subsequent chemical vapor deposition carbon coating. The porous hollow structure of Si‐40@C buffers the volume variation and promotes the transportation of Li+; the carbon coating enhances the overall conductivity as well as structural stability. The as‐prepared Si‐40@C porous hollow microspheres deliver a high reversible capacity (2029 mAh g−1 at 0.2 A g−1), good cyclability (1668 mAh g−1 after 100 cycles at 0.2 A g−1), and an ideal rate capability (1200 mAh g−1 at 10 A g−1).

Synthesis of microporous hollow spherical polystyrene carbons for the highly efficient CO2 adsorption and selectivity

Carbon materials with economic and high adsorption capacity attract much attention to reducing fossil fuel and industrial CO2 emissions. For this purpose, porous hollow spheres with high surface area and micropore volume, morphologically resembling fullerene or soccer balls, were first produced from the synthesized polystyrene by hydrothermal and conventional activation. The highest micropore volume and BET surface area were found in PS-hydroHCl with 0.61 cm3/g and 1481 m2/g, respectively. The CO2 adsorption capacities of PS-hydroHCl at 0 and 25 °C were relatively high and were obtained as 6.25 and 3.62 mmol/g, respectively. It was determined that all microporous spheres were influential in the isosteric heat of adsorption range of 17–26 kJ/mol, that is, typical CO2 physical adsorption. It has been found that hydrothermally synthesized PS-hydro and PS-hydroHCl contain higher amounts of oxygen than PS and PSHCl produced according to the conventional method. In addition, CO2/N2 selectivity at 25 °C, PS-hydroHCl, was three times more effective than PSHCl. As a result, it can be said that the synthesis of porous hollow microspheres is simple, and the starting material (polystyrene) is cheap and abundant; high CO2 adsorption and effective CO2/N2 selectivity will be promising for industrial applications.

Novel Bilayer-Shelled N, O-Doped Hollow Porous Carbon Microspheres as High Performance Anode for Potassium-Ion Hybrid Capacitors

HighlightsProposing a one-step pyrolysis strategy to fabricate a novel bilayer-shelled N, O-doped hollow porous carbon microspheres (NOHPC) anode.The optimized NOHPC anode displays a high K-storage capacity of 325.9 mAh g−1 at 0.1 A g−1 and excellent rate performance (201.1 mAh g−1 at 5 A g−1 after 6000 cycles).The assembled NOHPC//hollow porous activated carbon microspheres (HPAC) potassium ion hybrid capacitors deliver a high energy density of 90.1 Wh kg−1 at a power density of 939.6 W kg−1 even over 6000 cycles.

Atomic-scale storage mechanism in ultra-small size (FeCuCrMnNi)3O4/rGO with super-stable sodium storage and accelerated kinetics

Transition-metal high-entropy oxides show superior electrochemical properties and excellent long-term cycling stability in secondary batteries due to their entropy stabilization effect. However, the effects on storage mechanisms of Na+ batteries remains an open question, especially considering its larger ionic radius, sluggish kinetics movement, and serious volumetric expansion. In this work, ultra-small size spinel-structured (FeCuCrMnNi)3O4 composition of hollow porous microspheres is dispersed on the reduced graphene oxide net work. The architecture can effectively suppress the continuous volume expansion and maintain valid interface contact between electrode and electrolyte, thus achieving highly reversible sodium storage. Moreover, oxygen vacancies promote the desorption of Na+ during the charge process due to weak chemical bonding and migration barrier, improving cycling stability. Furthermore, highly reversible structural transformation of spinel to monometallic oxides and then to rock salt structure is observed by in situ XRD. The results provide an in-depth understanding of Na+ storage mechanism in HEOs with self-supporting electrode materials.

RGO decorated N-doped NiCo2O4 hollow microspheres onto activated carbon cloth for high-performance non-enzymatic electrochemical glucose detection

This paper reports the first effective fabrication of a high-performance non-enzymatic glucose sensor based on activated carbon cloth (ACC) coated with reduced graphene oxide (RGO) decorated N-doped urchin-like nickel cobaltite (NiCo2O4) hollow microspheres. Hierarchically mesoporous N-doped NiCo2O4 hollow microspheres were synthesized using a facile solvothermal method, followed by thermal treatment in a nitrogen (N2) atmosphere. Subsequently, they were hydrothermally decorated with RGO nanoflakes. The resulting composite was dip-coated onto ACC, and its electrochemical and glucose sensing performances were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and chronoamperometric measurements in a three-electrode system. The composite electrode sensor demonstrates admirable sensitivity (6122 μM mM−1 cm−2) with an ultralow detection limit (5 nM, S/N = 3), and it performs well within a substantial linear range (0.5–1.450 mM). Additionally, it exhibits good long-term response stability and outstanding anti-interference performance. These outstanding results can be attributed to the synergistic effects of the highly electrically conductive ACC with multiple channels, the enhanced catalytic activity of highly porous N-doped NiCo2O4 hollow microspheres, and the large electroactive sites provided by its well-developed hierarchical nanostructure and RGO nanoflakes. The findings highlight the enormous potential of the ACC/N-doped NiCo2O4@RGO electrode for non-enzymatic glucose sensing.

Effect of surface amorphization on potassium storage behavior of NiS porous-hollow spheres

Surface modification of electrode materials played an important role in tailoring their electrochemical performance. Here, surface amorphization or distortion, which was fairly common in material synthesis, was studied for its impact on potassium storage behavior. To this aim, contrast experiments were conducted on a series of NiS porous-hollow microspheres, whose shells were composed of interwoven NiS nanosheets. HRTEM characterization showed that each nanosheet comprised crystalline inner core and amorphous outer layer. By adjusting the thickness of this amorphous layer, potassium storage mechanism could be transformed from a diffusion-controlled type to a hybrid of capacitive and diffusive type, accompanied by an improvement in potassium storage performance. At the optimal layer thickness, NiS electrode could deliver a capacity of 182.4 mAh g−1 at 5 A g−1 as well as maintain 427.0 mAh g−1 after 300 cycles at 0.2 A g−1.

Facile Preparation of V2O5 Hollow Microspheres with Mesoporous on the Shell and Their Electrochemical Properties for Lithium-Ion Batteries

In this work, vanadium pentoxide (V2O5) hollow microspheres with mesoporous on the shell were prepared by a solvothermal process followed by a high-temperature calcination step in air. The as-prepared hollow microspheres exhibit the mesoporous structure on the shells, which provide channels for electrolyte transfer and show excellent lithium storage properties for lithium-ion batteries. The electrochemical performances of formed V2O5 porous-hollow microsphere anodes were investigated and analyzed. Among the formed samples, integral V2O5 hollow microspheres with mesoporous on the shell achieved a reversible capacity of 710.2 mA h g−1 after 400 cycles at a current density of 0.5 A g−1. The results demonstrate an ascendant electrochemical characteristic of as-prepared V2O5 hollow microspheres with mesoporous on the shell for the energy storage devices.

A novel hydroxyapatite-based hollow microsphere nanocomposite for copper ion adsorption

Hydroxyapatite (HAp) is an inorganic material that can be used as an adsorption material. Here we report a novel HAp-based hollow porous microsphere, in which Fe3O4 nanoparticles are uniformly embedded in the HAp microsphere shell. The specific surface area is 98.6 m2/g with an average pore size of 11.4 nm. The microsphere has been demonstrated to be a high-efficient absorbent for copper ion. Owing to the superparamagnetic property of Fe3O4 nanoparticles, the microspheres can be well dispersed in water and effectively segregated by magnet. Therefore, HAp-Fe3O4 hollow microsphere is a promising candidate for copper ion treatment.

Graphene Oxide-Wrapped Porous Hollow Co3O4 Microspheres with Enhanced Lithium Storage Performance

Porous hollow Co3O4 microspheres wrapped with graphene oxide were synthesized by a step solvothermal method and subsequent heat treatment. Benefiting from the design of special porous hollow microspheres, the effective specific surface area was greatly increased, the sufficient contact between the porous hollow Co3O4 microspheres and electrolyte was achieved, and then a charge specific capacity of 888.59 mA h g-1 was gained. Meanwhile, partial stress from the charging/discharging process was greatly relieved due to the abundant pores and hollow structure, excellent cycling stability was realized, and the charge specific capacity of the 1000th cycle was 465.75 mA h g-1 at 5 C (1 C = 890 mA g-1). In addition, the conductivity of Co3O4 microspheres was effectively improved due to the tight package of graphene oxide to Co3O4 microspheres, and superior rate performance was attained (280.99 mA h g-1 at 10 C).

Pd/Pt-Bimetallic-Nanoparticle-Doped In2O3 Hollow Microspheres for Rapid and Sensitive H2S Sensing at Low Temperature

H2S is a poisonous gas that is widespread in nature and human activities. Its rapid and sensitive detection is essential to prevent it from damaging health. Herein, we report Pd- and Pt-bimetallic-nanoparticle-doped In2O3 hollow microspheres that are synthesized using solvothermal and in situ reduction methods for H2S detection. The structure of as-synthesized 1 at% Pd/Pt-In2O3 comprises porous hollow microspheres assembled from In2O3 nanosheets with Pd and Pt bimetallic nanoparticles loaded on its surface. The response of 1 at% Pd/Pt-In2O3 to 5 ppm H2S is 140 (70 times that of pure In2O3), and the response time is 3 s at a low temperature of 50 °C. In addition, it can detect trace H2S (as low as 50 ppb) and has superior selectivity and an excellent anti-interference ability. These outstanding gas-sensing performances of 1 at% Pd/Pt-In2O3 are attributed to the chemical sensitization of Pt, the electronic sensitization of Pd, and the synergistic effect between them. This work supplements the research of In2O3-based H2S sensors and proves that Pd- and Pt-bimetallic-doped In2O3 can be applied in the detection of H2S.

Electrochemical properties and facile preparation of hollow porous V2O5 microspheres for lithium-ion batteries

Vanadium pentoxide (V2O5) has shown great potential to be used in lithium-ion batteries (LIBs), but it has limited applications because it has cycle instability and poor rate capability, and its lithiation mechanism is not well understood. In this work, hollow porous V2O5 microspheres (HPVOM) were obtained by a facile poly(vinylpyrrolidone) and ethylene glycol-assisted soft-template solvothermal method. Half cells with HPVOM exhibited good capacity, rate capability, and stability, delivering 407.9 mAh g−1 at 1.0 A g−1 after 700 cycles. Furthermore, a LiFePO4/HPVOM full cell had a discharge capacity of 109.9 mAh g−1 after 150 cycles at 0.1 A g−1. Using an equivalent circuit model (ECM) and distribution of relaxation times (DRT), we found that the charge-transfer (including the solid-state interface resistance) and bulk resistances varied regularly with the charge/discharge state, while the electrolyte resistance was largely maintained. The bulk resistance finally vanished, indicative of dynamic activation. The method used to prepare the hollow microspheres, as well as the display of electrode kinetics via ECM and DRT, could be broadly applied in developing efficient electrodes for LIBs.

Tamoxifen Delivery to Breast Cancer Cells (MCF-7) Via Hydroxyapatite Microspheres

Drug delivery systems have been used in cancer treatment to increase drug effectiveness. The hydroxyapatite (HAP) based materials used in this area can provide drug transport to the target site without its deterioration. In this study, porous hollow hydroxyapatite microspheres (PHHMs) were produced by using the hydrothermal method. Tamoxifen (TAM) used in the treatment of breast cancer has been covalently attached to the produced microspheres. The obtained microsphere structures (tamoxifen-loaded hydroxyapatite, TAM/H) were successfully characterized by ATR-FTIR, FE-SEM, XRD, and DLS methods. The breast cancer cell line MCF-7 was used to examine the effect of the hybrid structure. The cytotoxic and genotoxic effects of TAM/H was compared with the TAM groups on MCF-7. Our results have showed that, the decrease in cell viability at 24 and 36 hours were still continued at 48 hours only in TAM/H groups. In addition, TAM/H was found to show a genotoxic affect by the increment in genetic damage index (GDI) and damaged cell percentage (DCP%). As a result, use of hydroxyapatite was suitable for the transport of TAM and that covalent binding was suitable for drug particle interaction with hybrid structure and thus controlled drug release occurred.

Promising broadband and enhanced microwave absorption of polypyrrole decorated hollow porous ZnO microspheres

The design of hollow porous microstructure and the selection of reasonable dielectric composition are effective ways to obtain microwave absorbing (MWA) materials with outstanding performance. In this paper, polypyrrole decorated ZnO hollow porous composites (ZnO@PPy HPC) with improved MWA performance were successfully prepared by an in situ polymerization method. The results showed that PPy was uniformly loaded on the surface of ZnO hollow porous microspheres (ZnO HPM) to build a hierarchically core–shell hollow structure. The addition and proportion regulation of PPy can effectively improve the dielectric properties, generate interfacial polarization effect and achieve good impedance matching, leading to enhanced MWA characteristics of composite materials. ZnO@PPy HPC exhibited promising broadband microwave absorption properties. The minimum reflection loss (RL min) reached −48.5 dB at 14.5 GHz with broad effective bandwidth (less than −10 dB) of 6.2 GHz when the matching thickness was 2.2 mm. This study provides guidance for the development on a new type of microwave absorbing materials composed of hollow porous structure and conductive polymer.

Snowball flower-like g-C3N4/ZnFe2O4 mesoporous hollow microspheres with enhanced triethylamine sensing properties

Herein, the snowball flower-like g-C3N4/ZnFe2O4 mesoporous hollow microspheres, in which two-dimensional (2D) g-C3N4 nanolayers were loaded onto the surface of ZnFe2O4 hollow microspheres, were constructed by a simple solid phase reaction. The effect of the g-C3N4 concentration on the structure, morphology and gas-sensing performance of the g-C3N4/ZnFe2O4 composites had been explored. On the basis of gas sensitivity test results, the composites owned lower working temperature (160 ℃) and better selectivity toward TEA in comparison with pure ZnFe2O4. Notably, the sensor based on the g-C3N4/ZnFe2O4-15 hollow microspheres (adding 15 ml of g-C3N4 aqueous solution) exhibited outstanding sensing properties, including superior response (18.3) toward 100 ppm TEA at optimum work temperature of 160 ℃, speedy response-recovery time (33, 30 s) and outstanding stability. And the sensor maintained high response of 4.3 to low concentration TEA (5 ppm). The improved gas-sensing performance of the composites could be attributed to the porous ZnFe2O4 hollow microspheres loaded by 2D g-C3N4 nanolayers with large specific surface area and the heterostructure formed between them. Hence, a potential application of the g-C3N4/ZnFe2O4 microspheres might be achieved in detecting TEA at a low optimum work temperature.

Facile synthesis, in vitro biocompatibility, and antibacterial activity of porous hollow hydroxyapatite microspheres

AbstractIn this study, porous hollow hydroxyapatite (HAp) microspheres are prepared using chitosan microspheres as novel sacrificial templates and their microstructure, biocompatibility, and drug delivery properties are evaluated. Scanning electron microscope (SEM) observations show that HAp microspheres are spherical in morphology with a diameter of 100–300 μm and have a porous and core–shell structure. X‐ray diffractometer patterns show that HAp microspheres consist of apatite phase. MTT assay indicates that HAp microspheres are biocompatible and have no significant cytotoxicity. SEM observations show that HAp microspheres support attachment and proliferation of osteoblast MC3T3‐E1 cells. After being soaked in the solution of tetracycline hydrochloride (TH, model drug), HAp microspheres adsorb TH with an adsorption capacity of 47% to derive TH‐loaded HAp microspheres. When exposed to two types of representative bacteria: Escherichia coli and Staphylococcus aureus, TH‐loaded HAp microspheres maintain the biological activity of TH to inhibit the growth of bacteria.

Coupling surfactants with 3D hollow raspberry-like NiS/carbon microsphere with S vacancies for enhanced sensitivity monitoring of serotonin and L-tryptophan

Serotonin (ST) is a monoamine neurotransmitter synthesized from L-tryptophan (L-Try). Solving their simultaneous detection problem is necessary for assisting in diagnostics diseases. In this work, we designed NiS/carbon hybrids with NiS nanoparticles embedded on 3D hollow porous carbon microspheres (NiS/CS) via successive carbonization and sulfidation Ni-MOF for constructing electrocatalysts for the simultaneous electrooxidation of ST and L-Try. The formation of robust contact with surface S vacancies in NiS/CS nanointerfaces demonstrated a remarkably enhanced electrocatalytic activity towards ST and L-Try and the corresponding electrochemical signals appeared as two well resolved oxidation peaks with the significant peak-to-peak separation. Importantly, the dual amplification effect of the high electrocatalytic performance function of NiS/CS and the hydrophobic properties of surfactant CTAB coupling made CTAB/NiS/CS/GCE exhibit high sensitivity recognition to ST and L-Try, effectively shielding other coexisting interference. The developed sensor provided a 0.01–200.0 μmol/L linear response range and the low detection limit of 3.35 and 2.94 nmol/L for ST and L-Try, respectively. Finally, this sensing methodology enabled accurate determination of ST and L-Try amount in serum, urine and injection samples and with successful recovery outcomes.

Low-temperature selective catalytic reduction of NOx with NH3 over Ce-modified (Co, Mn)3O4 hollow porous microspheres

• Ce x -(Co, Mn) 3 O 4 de-NO x catalysts were synthesized by hydrothermal-calcination. • Modification with CeO x improved the low-temperature NO x removal activity. • Mn-Co-Ce mixed oxides exhibited the morphology of hollow and porous microsphere. • The interaction between metal cations produced higher atomic content of Mn 4+ and Co 3+ . CeO x -(Co, Mn) 3 O 4 catalysts with various Ce: Mn ratios were synthesized via the hydrothermal-calcination and then used for the selective catalytic reduction (SCR) of NO x by NH 3 . The modification of (Co, Mn) 3 O 4 by CeO x extended its operating temperature window and boosted its low-temperature catalytic activity. The optimum Ce-Co-Mn mixed-oxide catalyst converted over 98% NO x at 175–275 °C and displayed high N 2 selectivity, good thermal stability, and resistance against H 2 O and SO 2 . The characterization results showed that the hollow and porous microspheres supplied the catalyst with a high specific surface area and many exposed Lewis acid sites that adsorbed and activated the reactants. The uniform distribution of Mn, Co, and Ce species exerted a synergetic effect (Ce 4+ + Mn 3+ ↔ Mn 4+ + Ce 3+ , Ce 4+ + Co 2+ ↔ Co 3+ + Ce 3+ ) that improved the redox properties of the catalyst. A promising candidate for low-temperature SCR was obtained over Ce-modified (Co, Mn) 3 O 4 mixed-oxide catalyst.