Hollow Microboxes Research Articles

Self-templated growth of heterogeneous hollow Cu2-xS@1T-MoS2 microcubes with superior electromagnetic wave absorption

With the proliferation of the use of wireless communication technologies, lightweight, easily fabricated EMW absorbers are in great demand for commercial and stealth applications. In this paper, well-defined Cu2O microcubes were successfully transformed into Cu9S5@MoS2 hollow microboxes by a facile hydrothermal process through a template-directed in situ vulcanization/complexation synergistic reaction. The MoS2 nanosheets loaded on the microboxes exhibited a high 1T phase ratio. Compared to pure MoS2 nanosheets, Cu9S5@MoS2 is advantageous in building conducting networks and interfacial polarization due to its good structure. The composite of Cu9S5@MoS2 with paraffin showed good EMW absorption performance at 40 wt%. By adjusting the MoS2 loading, the attenuation and impedance coefficients can be further optimized, with an optimized RLmin of −52.2 dB at 2.1 mm and an EAB of 4.7 GHz.

N-doped carbon coated FeNiP nanoparticles based hollow microboxes for overall water splitting in alkaline medium

Stable, earth-abundant and efficient electrocatalysts for overall water splitting are urgently needed. In this work, we have reported the synthesis of FeNiP/NC hollow microboxes (FeNiP/NC) based bifunctional electrocatalyst via the phosphorization process using rationally designed cube-type metal-organic framework (FeNi-MOF) as both the template and carbon source. The FeNiP/NC, which were obtained by assembling the uniform FeNiP nanoparticals together through N-doped carbon, manifests outstanding catalytic performances for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in KOH solution. Notably, FeNiP/NC displays exceptional activity when it was utilized as both anode and cathode toward overall water splitting with potential of 1.54 V at a current density of 10 mA cm−2 in alkaline electrolyte, which is much better than FeP/NC and Ni2P/NC electrocatalyst. More importantly, the improvement of the catalytic activities of FeNiP/NC mainly benefits from the well dispersion of FeNiP nanoparticles on the surface of carbon support, the large active surface area and the doping of N and C derived from organic ligands. In addition, the enhanced electrocatalytic performance of FeNiP/NC for OER is closely related with the in-situ formed surficial MOOH (M = Fe, Ni) active sites, which has been confirmed by X-ray photoelectron spectroscopy (XPS) analysis.

Surface-disorder-engineered Zn2SnO4/SnO2 hollow microboxes with enhanced solar-driven photocatalytic activity

Engineering defects and/or amorphous shells is a promising strategy to improve the photocatalytic efficiency of the oxide materials. In this work, we developed a safe and easy magnesiothermic reduction method to prepare surface-disordered hybrid nanocomposites, taking Zn2SnO4/SnO2 hollow microboxes as an example. Our results demonstrate that the reduction treatment can successfully introduce oxygen vacancies and amorphous shells in the pristine Zn2SnO4/SnO2 sample, causing narrowing of the band gap and reinforced solar light harvesting. Moreover, the Mg-reduced Zn2SnO4/SnO2 heterojunction photocatalysts exhibit enhanced sunlight-driven hydrogen production activity and degradation performance of the organic pollutant. This strategy may disclose a new avenue for improving photocatalytic performance of defect-engineered heterojunction composites toward broader applications.

Designed synthesis CuO hollow microboxes coated with Pd nanosheets and SnO2 nanoparticles as a highly efficient Rochow reaction catalyst

We designed and synthesized CuO/SnO2/Pd hollow microboxes, which was developed based on prepared Cu2O cubes coated Pd nanosheets, controlled oxidation of Cu2O/Pd, and etching of Cu2O/CuO/Pd by SnCl4 solution. The catalytic property of the Cu2O, Cu2O/SnO2, Cu2O/Pd/SnO2, Cu2O/Pd, Cu2O/CuO/Pd, CuO/SnO2/Pd, CuO, and commercial catalyst for dimethyldichlorosilane synthesis via the Rochow reaction was investigated. As compared to control samples and commercial catalyst, the prepared CuO/Pd/SnO2 hollow microboxes exhibited much higher silicon conversion (76.6%), which is related to the synergistic effect between CuO, Pd and SnO2, and to the distinct catalyst hollow structure which allows the efficient transportation of the reactant molecules to the active component.

MgFe2O4 hollow microboxes derived from metal-organic-frameworks as anode material for sodium-ion batteries

Metal-organic-frameworks (MOFs) Prussian blue microcubes are used as the self-sacrificial templates to fabricate hollow MgFe2O4 microboxes via the process of hydrolysis, ion exchange and subsequent calcination. This hollow and porous architecture provides efficient sodium ion diffusion pathway and sufficient space to accommodate the volume expansion during the insertion/extraction of Na+. Obtained MgFe2O4 microboxes exhibit a good capacity of 406mAhg−1 at a current density of 50mAg−1 and maintain a reversible capacity of 135mAhg−1 after 150 cycles when evaluated as an anode material for sodium-ion batteries. With the increase of the amount of Super-P carbon black, the rate performance and conductivity of the MgFe2O4 microboxes electrode can be improved.

Preparation of Zn2SnO4/SnO2@Mn2O3 Microbox Composite Materials with Enhanced Lithium‐Storage Properties

AbstractIn this work, the composite materials of Zn2SnO4/SnO2@Mn2O3 microboxes have been synthesized after the calcination of precursor Zn2SnO4/SnO2@MnCO3, which is prepared by using a simple hydrothermal process. Preliminary results of the electrochemical performances of Zn2SnO4/SnO2@Mn2O3 microboxes, Zn2SnO4/SnO2 microboxes, and Mn2O3 nanoparticles have been also reported. On the one hand, the robust ZTO/SnO2 hollow microboxes can not only buffer the volume variation, but also efficiently prevent the aggregation of Mn2O3 nanoparticles. On the other hand, Mn2O3 nanoparticles provide more active sites, owing to the nanostructures of Mn2O3, as well as consolidate the hollow cubic structure during the lithium insertion/extraction process. In virtue of the synergistic effects of Zn2SnO4/SnO2 and Mn2O3, the Zn2SnO4/SnO2@Mn2O3 microboxes exhibit a higher initial discharge capacity (1505.3 mAhg−1) as well as a better cycling performance (597.2 mAhg−1 after 100 cycles) and rate capacity compared to Zn2SnO4/SnO2 and Mn2O3.

Carbon-Coated Fe3O4/VOx Hollow Microboxes Derived from Metal-Organic Frameworks as a High-Performance Anode Material for Lithium-Ion Batteries.

As the ever-growing demand for high-performance power sources, lithium-ion batteries with high storage capacities and outstanding rate performance have been widely considered as a promising storage device. In this work, starting with metal-organic frameworks, we have developed a facile approach to the synthesis of hybrid Fe3O4/VOx hollow microboxes via the process of hydrolysis and ion exchange and subsequent calcination. In the constructed architecture, the hollow structure provides an efficient lithium ion diffusion pathway and extra space to accommodate the volume expansion during the insertion and extraction of Li+. With the assistance of carbon coating, the obtained Fe3O4/VOx@C microboxes exhibit excellent cyclability and enhanced rate performance when employed as an anode material for lithium-ion batteries. As a result, the obtained Fe3O4/VOx@C delivers a high Coulombic efficiency (near 100%) and outstanding reversible specific capacity of 742 mAh g-1 after 400 cycles at a current density of 0.5 A g-1. Moreover, a remarkable reversible capacity of 556 mAh g-1 could be retained even at a current density of 2 A g-1. This study provides a fundamental understanding for the rational design of other composite oxides as high-performance electrode materials for lithium-ion batteries.

Fabrication of FeOOH hollow microboxes for purification of heavy metal-contaminated water.

FeOOH, a frequently used adsorbent, has been widely applied in purifying aqueous heavy metals, and its performance can be greatly improved by enlarging the number of surface active sites. To this end, we fabricated FeOOH hollow microboxes constructed from numerous 2D nanosheets via a template-engaged reaction between Prussian blue (PB) and NaOH solution. With combined observations from X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), we confirmed that the hollow microboxes corroded from PB were composed of ample frizzy FeOOH nanosheets, which ensured extensive exposure of the surface active sites. Moreover, the FeOOH microboxes were utilized as an adsorbent in the removal of heavy metals (As(III), As(V) and Se(IV)) from water and the maximum adsorption capacities were reached up to 192.19 mg g(-1), 250.0 mg g(-1) and 169.9 mg g(-1) at pH = 7.0, 4.0 and 5.0, respectively. The superior adsorptive performance of the FeOOH microboxes was derived from their large content of reactive exposed hydroxyl groups, which was unambiguously confirmed by X-ray adsorption fine structure spectroscopy (XAFS), as well as by surface site density analysis.

Adsorption properties of ZrO2 hollow microboxes prepared using CaCO3 cubes as templates

ZrO2 hollow microboxes prepared using CaCO3 cube as template exhibit excellent dye adsorption performance from wastewater.

ZnO/C microboxes derived from coordination polymer particles for superior lithium ion battery anodes

A CPPs-derived ZnO/C hollow microboxes Li-ion anode with superior capability and rate performance was achieved by a simple solvothermal method.

Metal–Organic-Frameworks-Derived General Formation of Hollow Structures with High Complexity

Increasing the complexity of hollow structures, in terms of chemical composition and shell architecture, is highly desirable for both fundamental studies and realization of various functionalities. Starting with metal-organic frameworks (MOFs), we demonstrate a general approach toward the large-scale and facile synthesis of complex hollow microboxes via manipulation of the template-engaged reactions between the Prussian blue (PB) template and different alkaline substances. The reaction between PB microcubes with NaOH solution leads to the formation of Fe(OH)3 microboxes with controllable multishelled structure. In addition, PB microcubes will react with the conjugate bases of metal oxide based weak acids, generating multicompositional microboxes (Fe2O3/SnO2, Fe2O3/SiO2, Fe2O3/GeO2, Fe2O3/Al2O3, and Fe2O3/B2O3), which consist of uniformly dispersed oxides/hydroxides of iron and another designed element. Such complex hollow structures and atomically integrated multiple compositions might bring the usual physiochemical properties. As an example, we demonstrate that these complex hollow microboxes, especially the Fe2O3/SnO2 composite microboxes, exhibit remarkable electrochemical performance as anode materials for lithium ion batteries.

A magnesium carbonate recyclable template to synthesize micro hollow structures at a large scale

A facile strategy by using magnesium carbonate as the recyclable template has been developed to synthesize a variety of uniform inorganic hollow structures whose composition, size and shape can be readily modulated to generate interesting structures such as TiO(2), Al(2)O(3), SiO(2), Gd(2)O(3) and NiO microtubes and TiO(2), SiO(2) hollow microboxes.