Porous Nanocubes Research Articles

MOF-derived metal oxides with hollow porous nanocube structure realize ultra-wideband, lightweight, and anticorrosion microwave absorber

High density, skin effect, and environmental instability are significant limitations that restrict the application of metal-based microwave absorbers in achieving lightweight, high performance, and long service life. This study broke from traditional methods for preparing a microwave absorber Mn2O3-Fe3O4@PPy (polypyrrole) by employing an innovative annealing process to convert metal into metal oxide by the introduction of metal organic framework (MOF), which effectively achieving a more lightweight absorber material with hollow porous nanocube structure. Subsequently, PPy was coated onto the metal oxide surface to form a core-shell structure by a situ chemical oxidation synthesis method. The combination of metal oxide of the hollow porous nanocube structure and the core-shell structure formed by highly conductive PPy shell significantly enhanced heterogeneous interfaces and electromagnetic (EM) wave reflection. Excellent dielectric loss and impedance matching contributed evidently to the ultra-wideband EM wave absorption performance. It was demonstrated that, with a filling amount of only 20 wt%, the prepared Mn2O3-Fe3O4@PPy achieved an effective bandwidth (EAB) of 10.0 GHz at a thickness of 3.08 mm, with EABmax reaching 13 GHz. At a filling amount of only 10 wt%, the reflection loss (RL) was −62.13 dB, achieving an EAB of 7.4 GHz at 2.98 mm thickness, with EABmax reaching 11.4 GHz. Furthermore, the proposed strategy incorporating metal oxide and PPy enhanced corrosion resistance with higher charge transfer resistance.

Heterogeneous interface induced Co3O4-NiO catalyst for efficient electrocatalytic 5-Hydroxymethylfurfural oxidation

The electrooxidation of 5-hydroxymethylfurfural (HMF) provides an efficient and environmentally friendly approach to obtain high-value chemicals from biomass. In this study, porous nanocube framed Co3O4-NiO electrocatalysts with heterogeneous interface are constructed for efficient HMF oxidation reaction (HMFOR). The heterogeneous interface modulates the electronic properties of Co and Ni atoms, enhances the oxidation state of Ni species, which is favorable for the oxidation of HMF. Compared to pure Co3O4 and NiO, Co3O4-NiO exhibits a lower onset potential (1.22 V vs. RHE), higher FDCA yield (83.33 %) and Faraday efficiency (89.47 %). Furthermore, the results of open circuit potential (OCP), high-performance liquid chromatography (HPLC) product analysis and in-situ electrochemical impedance spectroscopy (EIS) demonstrate that the Co3O4-NiO heterogeneous interface effectively enhances the adsorption and transformation of organic molecules and OH– species, and facilitates the further oxidation of 5-formyl-2-furancarboxylic acid (FFCA) to 2,5-furandicarboxylic acid (FDCA), thus improving the performance of HMFOR. This work illustrates the effect of heterogeneous interface on Co3O4-NiO catalyst for HMFOR and provides a direction for the development of high-performance electrocatalysts for HMFOR.

Mo-doped CoFeP/nitrogen doped carbon porous nanocubes for alkaline hydrogen production

Mo-doped CoFeP/nitrogen doped carbon porous nanocubes for alkaline hydrogen production

An isopropanol sensor based on MOF-derived NiO/NiCoxFe2−xO4 porous nanocube with improved response and selectivity

Semiconductor oxides with porous structure have good gas permeability and large reaction surface, which is an important advantage as gas sensing materials. Here, an isopropanol sensor based on PBA-derived spinel NiO/NiCoxFe2−xO4 (x = 0, 0.02, 0.06, 0.10) porous nanocubes were successfully prepared. A series of techniques were used to characterize the crystal structure, morphology and element properties of the products. Gas-sensing measurements show that the doping of Co element can significantly improve the isopropanol-detecting ability of NiO/NiFe2O4. The reason for the improved sensitivity is that cobalt as a dopant can provide more active adsorption sites and the catalytic effect to enhance the gas response. The test results show that NiO/NiCo0.06Fe1.94O4 composite exhibits high response (Rg/Ra=11.2 at 183.5 °C) and selectivity to 100 ppm isopropanol, which is promising for the detection of isopropanol gas. Also, the isopropanol-sensing mechanism of the Co-doped NiO/NiFe2O4 porous nanocubes was discussed.

Oxygen-vacancy-rich Ru-clusters decorated Co/Ce oxides modifying ZIF-67 nanocubes as a high-efficient catalyst for NaBH4 hydrolysis

Designing a cost-effective and high-performance catalyst for NaBH4 hydrolysis is a significant step in developing a sustainable hydrogen source. Herein, we prepared a cost-effective Ru-clusters decorated cobalt-cerium oxides coating ZIF-67 (Ru/Co6Ce1@ZIF-67) catalyst via a facile reduction method, displaying high performance and exceptional reusability in alkaline NaBH4 solution. The optimized catalyst exhibits a high hydrogen generation rate (HGR, 5726.1 mL min−1 g−1), turnover frequency (TOF, 413.9 molH2 min−1molRu−1), and low activation energy (Ea, 53.0 kJ mol−1), surpassing most of the recently reported catalysts. Furthermore, the catalytic performance does not change considerably after five cycles, indicating the catalyst's multi-cycle reusability. Studies imply the uniquely synergistic effect of Ru, Co/Ce oxides, abundant oxygen vacancies, as well as the porous nanocube structure, enabling the catalysts to possess high metal dispersion, outstanding catalytic performance and exceptional reusability. This work will open light on using an oxygen vacancies-rich strategy to design a high-activity catalyst for promoting NaBH4 hydrolysis.

Prussian-blue-analog derived hollow Co3O4/NiO decorated CeO2 nanoparticles for boosting oxygen evolution reaction

Exploration of efficient, inexpensive, and stable electrocatalysts for oxygen evolution reaction (OER) is of great significance for energy conversion and storage. Currently, transition metal oxides (TMOs) show huge potential as electrode materials for OER due to their low-cost, rich redox chemistry and high chemical stability. In this work, we report a facile route for uniformly coating CeO 2 nanoparticles (NPs) on the surface of nickel cobalt Prussian blue analogue (NiCo-PBA) derived Co 3 O 4 /NiO hollow porous nanocubes (Co 3 O 4 /NiO HPN). The accurate control of CeO 2 content on the Co 3 O 4 / NiO HPN (Co 3 O 4 /NiO@CeO 2 HPN) surface can effectively alter the surface electronic states, which tunes the ratio of Co 2+ /Co 3+ and Ni 2+ /Ni 3+ for creating abundant oxygen vacancies. The large surface area of hollow nanocubes derived from NiCo-PBA with porous structure offers more active sites, resulting in the great promotion of OER activity. The prepared Co 3 O 4 /NiO@CeO 2 -2 HPN heterostructure exhibits remarkable OER performance with a low overpotential (290 mV at 10 mA·cm −2 ), small Tafel slope (66 mV dec −1 ) and excellent durability. The present method opens a new avenue to the preparation of low-cost and efficient electrocatalysts in OER. A novel hollow and porous heterostructure of CeO 2 nanoparticles (NPs)-decorated NiO/Co 3 O 4 hollow porous nanocubes (Co 3 O 4 /NiO@CeO 2 HPN) was designed for boosting the oxygen evolution reaction activity. • Co 3 O 4 /NiO@CeO 2 HPN electrocatalyst is designed by an easy to realize strategy. • The microstructure and surface state of the catalyst can be regulated accurately. • Active sites and oxygen vacancies are obtained for boosting the OER performance. • Integration of high catalytic activity and excellent durability together.

High-entropy amorphous oxycyanide as an efficient pre-catalyst for the oxygen evolution reaction.

Herein, a high-entropy amorphous oxycyanide porous nanocube pre-catalyst was developed for the oxygen evolution reaction (OER). Benefitting from the facile pre-oxidation and enhanced intrinsic activity of the high-entropy catalyst, a highly efficient and ultrastable OER performance was achieved.

Ultrafast and Ultrastable Heteroarchitectured Porous Nanocube Anode Composed of CuS/FeS2 Embedded in Nitrogen-Doped Carbon for Use in Sodium-Ion Batteries.

The enhancement of the structural stability of conversion-based metal sulfides at high current densities remains a major challenge in realizing the practical application of sodium-ion batteries (SIBs). The instability of metal sulfides is caused by the large volume variation and sluggish reaction kinetics upon sodiation/desodiation. To overcome this, herein, a heterostructured nanocube anode composed of CuS/FeS2 embedded in nitrogen-doped carbon (CuS/FeS2 @NC) is synthesized. Size- and shape-controlled porous carbon nanocubes containing metallic nanoparticles are synthesized by the two-step pyrolysis of a bimetallic Prussian blue analog (PBA) precursor. The simple sulfurization-induced formation of highly conductive CuS along with FeS2 facilitates sodium-ion diffusion and enhances the redox reversibility upon cycling. The mesoporous carbon structure provides excellent electrolyte impregnation, efficient charge transport pathways, and good volume expansion buffering. The CuS/FeS2 @NC nanocube anode exhibits excellent sodium storage characteristics including high desodiation capacity (608 mAh g-1 at 0.2 A g-1 ), remarkable long-term cycle life (99.1% capacity retention after 300 cycles at 5 A g-1 ), and good rate capability up to 5 A g-1 . The simple, facile synthetic route combined with the rational design of bimetallic PBA nanostructures can be widely utilized in the development of conversion-based metal sulfides and other high-capacity anode materials for high-performance SIBs.

Framework-derived Fe2O3/Mn3O4 nanocubes as electrochemical catalyst for simultaneous analysis of Cu(II) and Hg(II)

Exploiting advanced bimetallic oxide as sensing materials for electroanalysis offers new opportunity to improve the electrochemical performance, but still presents a tough challenge. Herein, we synthesized the uniform Fe2O3/Mn3O4 nanocubes from a framework structure in a facile approach, which were developed as the electrochemical catalyst for individual and simultaneous analysis of Cu(II) and Hg(II) in 0.1 M HAc-NaAc buffer solution (pH5.0). It showed the excellent electrochemical behavior for the simultaneous analysis Cu(II) and Hg(II) with high sensitivities of 69.29 and 190.55 μA μM cm−2. The corresponding limit of detection values (LODs) were calculated to be 3.94 nM and 1.39 nM, respectively. The excellent electrochemical behavior of Fe2O3/Mn3O4 could be attributed to the large specific surface area, which could provide a large number of adsorption sites for Cu(II) and Hg(II). Meanwhile, the bimetallic Fe and Mn atoms arranged in the porous nanocubes could offer a synergistic effect and improve the electrochemical activity. Moreover, it could be successfully applied for the simultaneous analysis of Cu(II) and Hg(II) in real water samples with the favorable recovery rate. The results confirmed that the Fe2O3/Mn3O4 nanocubes could serve as a reliable platform for the simultaneous analysis of Cu(II) and Hg(II).

Graphene encapsulated Mn2SnO4/G nanocubes as high-capacity and cycle-stable anode material for sodium ion batteries

The study exploits the functional advantages of combining alloy and conversion based material to reap the maximum energy from tin based ternary Mn2SnO4 (MSO) composite containing graphene. Herein, we specifically designed porous Mn2SnO4 nanocubes with graphene via a simple and scalable hydrothermal approach and explored as an anode material for sodium battery applications, for the first time. Our exclusively designed architecture provides the structural and cycling stability of Mn2SnO4/Graphene (MSO/G) nanocubes anode by effectively accommodating the volume changes during cycling through porous nature of Mn2SnO4 nanocubes and with the effective wrapping of graphene sheets. As a result, Mn2SnO4/G nanocubes anode delivers an appreciable stable capacity of 257 mA h g−1 at 100 mA g−1 after 100 cycles with 94% capacity retention. Interestingly, a capacity of 106 mA h g−1 at 1 A g−1 is obtained up to 1000 cycles with a negligible capacity fade. Porous nanocubes driven volume expansion free charge/discharge characteristics, conducting graphene aided capacity advantages upon extended cycles and manganese offered viability on cost economics, synergistically qualify the chosen Mn2SnO4/G anode for its deployment as a potential candidate in sodium ion batteries.

Fabrication of polypyrrole coated cobalt manganate porous nanocubes by a facile template precipitation and annealing method for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries suffer from the poor conductivity originated from sulfur and shuttle effect arisen from the polysulfides dissolution. Herein, cobalt manganate (CoMn2O4) porous nanocubes coated with polypyrrole (PPy) as sulfur carrier are prepared using MnCO3 nanocube template through a precipitation method and a subsequent annealing process. The unique approach can obtain porous CoMn2O4 nanocubes with uniform morphology and abundant exposed active sites. The plentiful mesopores among the porous nanocubes are beneficial to accommodation of sulfur. In addition, the porous CoMn2O4 nanocubes can trap polysulfides in the cycling process owing to the chemical bonds between CoMn2O4 and polysulfides. Moreover, PPy coating severed as conductive layer not only enhances electrical conductivity of the cathode, but also confines polysulfides via the formation of N–Li–S bonds during cycling process. Therefore, the porous CoMn2O4/S@PPy nanocubes with 66.9% sulfur mass content delivered a capacity of 533 mAh g−1 over 500 cycles at 1 A g−1 with a capacity decay rate of 0.064% each cycle, and a Coulombic efficiency of 98%, suggesting the enhanced cycling performance of cathode. The facile template precipitation method combined with an annealing process contribute a new approach to synthesize unique porous CoMn2O4 structure as sulfur carrier for Li–S batteries

In Situ Growth of Hollow Trimetallic Nanocubes on Nickel Foam for the Electrocatalytic Oxygen Evolution Reaction

The Cover Feature shows a trimetallic oxide composite with a porous nanocubes structure, which is grown in situ on nickel foam to form an electrode material, NiO/FeOX/Co3O4@NF. The pore structure is conducive to the contact between the electrolyte and the catalyst, thus improving the electrocatalytic performance of the material toward the oxygen evolution reaction. More information can be found in the Article by Z. Li et al.

Fe-doped NiCoP/Prussian blue analog hollow nanocubes as an efficient electrocatalyst for oxygen evolution reaction

Fabrication of highly efficient and earth-abundant electrocatalysts for oxygen evolution reaction (OER) is vital renewable energy production. In this work, the Fe-doped NiCoP/Prussian blue analog hollow porous nanocubes (Fe-NiCoP/PBA HNCs) were synthesized through a facile cation exchange of NiCo PBA HNCs followed by the phosphidation treatment. The optimal 2.5Fe-NiCoP/PBA HNCs exhibits a low OER overpotential of 290 mV at a current density of 10 mA cm‒2 and good stability, which is superior to the reported PBA-derived OER electrocatalyst. This high OER activity can be ascribed to the synergy effects of interfacial structure of Fe-NiCoP and PBA as well as the hollow porous structures, which could improve the electron transfer rate, reduce the reaction kinetics and expose more active sites. This work underscores that formation of multiple active components derived from the PBA is an effective strategy for designing high performance OER catalysts.

Preparation and electrochemical properties of Fe/Fe3O4@r-GO composite nanocage with 3D hollow structure

Fe/Fe3O4@r-GO composite nanocages with a hollow porous heterostructure, which look like “flower cluster,” are prepared by a mild, simple, and flexible method, followed by a thermal treatment. Metal-organic framework Prussian blue (PB), used as a precursor of Fe3O4, possesses a special hollow porous morphology, which is able to shorten transmission path and relives the mechanical stress during charge/discharge cycles. Verified by SEM and TEM characterizations, the Fe/Fe3O4 nanocage coated with uniform graphene sheets is achieved. Furthermore, XRD and XPS analysis combined with TEM results also prove that the composite is mainly composed of Fe, Fe3O4, and C. A series of electrochemical tests show that Fe/Fe3O4@r-GO composite electrodes exhibit a superior reversible capacity, rate capability, and cycling stability. The composite delivers a high reversible capability of 1200 mAh g−1 after 160 cycles at a current density of 100 mA g−1. Especially, when the current density is increased to 1000 mA g−1, the composite delivers a capacity of 455 mAh g−1. Even at a current density of 2000 mA g−1, a capacity of 355 mAh g−1 is retained. The outstanding electrochemical performances are mainly attributed to the integrity of hollow porous nanocube structure and doping of moderate graphene, which enables to promote the conductivity of electrode and build a continue network between Fe/Fe3O4 nanocubes to further accelerate ion/electron migration rate and relieve mechanical stress during cycles.

Hydrothermally derived three-dimensional porous hollow double-walled Mn2O3 nanocubes as superior electrode materials for supercapacitor applications

Although Mn2O3 has been widely used as an electrode material for lithium-ion batteries, it has not been explored as a supercapacitor electrode material due to its low specific area, irregular morphology, low porosity, and low ionic conductivity. Targeting this gap, in this study, we attempted to develop regular and porous hollow double-walled Mn2O3 cubes, which can simultaneously provide a large surface area and enhance charge diffusion to result in a high capacitance. We synthesized cube-like 3D hierarchically porous double-walled Mn2O3 (c-HDW-Mn2O3) using a simple hydrothermal method followed by calcination. The optimized electrode material c-HDW-Mn2O3@9 exhibited excellent capacitance and 90% retention over 3000 consecutive charge-discharge cycles at a fixed current density. Such high performance and good stability can be attributed to the porous and crystalline structure and high surface area of the optimized electrode. Finally, these hierarchically porous nanocubes can be considered as suitable materials for energy-storage applications.

Morphology adjustable CoxN with 3D mesoporous structure and amorphous N-doped carbon for overall water splitting

In order to improve the efficiency of the water splitting system, many researchers have focused on controlling the nanostructure of the catalysts, which could reduce the overpotential value of the overall water splitting process. Herein, we report the characteristics of the overall water splitting of cobalt nitrides synthesized in the same way but differing only in the temperature of nitridation. Hierarchical phases (Co3N, Co3N/Co4N, and Co4N) and structures (mesoporous nanocubes, porous nanocubes, and aggregated particles) of CoxN with different thickness of amorphous N-doped carbon allowed CoxN to have different overpotential values (419 mV, 557 mV, and 606 mV at a current density of 10 mA∙cm−2), which is in contrast to known theoretical electrical properties. Our research about the comparison of hierarchical structure of CoxN offers the potential as advanced electrocatalysts for many materials that have not yet been morphologically controlled.

Facile preparation of porous palladium nanocubes via a one-pot process induced by 1-hexadecyl-3-methyl imidazolium bromide for methanol electro-oxidation

Pd porous nanocubes were synthesized by a one-pot method assisted by HMIB and exhibited higher activity than solid nanocubes and Pd/C.

MOF-derived CoS2 porous nanocubes assembled on graphene oxide nanosheets as electrode for supercapacitor applications

MOF (Co3[Fe(CN)6]2)-derived porous nanocube-like CoS2 is coupled with GO via solution-precipitation and chemical replacement method. Due to the proper loading and structure adjusting of CoS2, the prepared nanocomposites show a maximum specific capacitance of 842 F g−1 at 0.5 A g−1, high-rate stability (capacity retention of 77% from 0.5 up to 10 A g−1), and long-cycle life stability (capacity retention of 95% over 2000 cycles).

Porous nanocubes La0.9Co0.8Ni0.2O3−x as efficient catalyst for Li-O2 batteries

At present, Li-O2 batteries deliver the highest energy density among rechargeable batteries, but main obstacles including low discharge capacity, high charge overpotential and low cycle stability still exist. It is essential to exploit a desirable electrocatalyst with specific structure and activity to partially solve the problems of Li-O2 batteries. In this work, an efficient catalyst of porous nanocubes La0.9Co0.8Ni0.2O3−x perovskite (PN-LCN) has been synthesized by a facile hydrothermal method, with the special porous morphology and abundant oxygen vacancies. Hence, Li-O2 batteries with the PN-LCN can deliver a specific discharge capacity of 14,360 mAh g−1 with a coulombic efficiency of 88% and a cycle stability of over 100 cycles at 300 mA g−1, which is much better than that with dense particles La0.9Co0.8Ni0.2O3-x perovskite (DP-LCN) at the same current density. The PN-LCN with special morphology and abundant oxygen vacancies is demonstrated to be an efficient catalyst towards both oxygen reduction reaction and oxygen evolution reaction, with promising the application in Li-O2 batteries.

Modulating the Electronic Structure of Porous Nanocubes Derived from Trimetallic Metal-Organic Frameworks to Boost Oxygen Evolution Reaction Performance.

The preparation of noble metal-free catalysts for water splitting is the key to low-cost, sustainable hydrogen generation. Herein, through a pyrolysis-oxidation process, we prepared a series of Co-Fe-Ni trimetallic oxidized carbon nanocubes (Co1-X FeX Ni-OCNC) with a continuously changeable Co/Fe ratio (X=0, 0.1, 0.2, 0.5, 0.8, 0.9, 1). The Co1-X FeX Ni-OCNC shows a volcano-type oxygen evolution reaction (OER) activity. The optimized Co0.1 Fe0.9 Ni-OCNC achieves a low overpotential of 268 mV at 10 mA cm-2 with a very low Tafel slope of 48 mV dec-1 in 1 m KOH. At the same time, the stability of the Co0.1 Fe0.9 Ni-OCNC is also outstanding; after 1000 CV cycles, the LSV plot is almost coincident. Moreover, the potential remains almost of the same value at 10 mA cm-2 after 12 h in comparison to the initial value. The excellent electrocatalytic properties can be attributed to the synergistic cooperation between each component. Therefore, the Co0.1 Fe0.9 Ni-OCNC is a promising candidate instead of precious metal-based electrocatalysts for OER.