3D Hollow Research Articles

Establishment of 3D hollow tubular/spherical Fe3O4/MWCNTs/solid waste composites for enhanced electromagnetic absorbing property

Establishment of 3D hollow tubular/spherical Fe3O4/MWCNTs/solid waste composites for enhanced electromagnetic absorbing property

Confined pyrolysis to transfer MXene-like MOF into 2D carbon nanosheet boosting the ozone oxidation of antibiotic: Degradation behavior and intrinsic mechanism

Ozone oxidation as a means of water treatment has received great attention in recent years, but ozone has low solubility and utilization, which hinders their efficient treatment of refractory pollutants. Herein, a dopamine-encapsulated 2D MOF strategy is proposed, where different metal salts including (acetylacetone iron, manganese, copper, etc.) are doped in it as active site precursors. After pyrolysis, 2D hollow porous carbon nanosheet catalysts such as Mn-HCNSs, Fe-HCNSs, Cu-HCNSs and Co-HCNSs are formed due to the rigid interface-induction of dopamine. Mn-doped Mn-HCNSs exhibits the best catalytic degradation performance when the antibiotic tetracycline is used as the target pollutant, and the degradation efficiency reached 90 % within 25 min (k = 0.213 min−1). This excellent catalytic performance can be attributed to several advantages: (i) the hollow porous 2D structure facilitates mass transfer and enhances the reaction kinetic constants; (ii) the confinement effect of dopamine wrapping facilitates the generation of more dispersed active sites and accelerates its ozone decomposition efficiency. This study expands the application of 2D MOF-derived porous carbon materials in ozone oxidation.

A 2D/3D hierarchical hybrid enables energy-saving hydrogen production coupled with glycerol and urea electro-oxidation

The design and development of high-performance electrocatalysts is crucial to improve the utility of anodic reaction for energy-saving hydrogen production. Herein, we present a novel catalyst with 2D/3D multistage structure for the electro-oxidation of renewable biomass and harmful waste to assist hydrogen generation. The hierarchical configuration of NiO/CoO nanosheets interconnected by hollow carbon spheres, leveraging both 2D and 3D advantages. This structure provides rich surface and edge active sites as well as affluent electron and mass transfer pathways, resulting in the accelerated dynamics of electro-oxidation. The hollow carbon spheres serve as a buffering agent to alleviate the strain caused by repetitive redox reactions during electrolysis, thereby bestowing exceptional structural and chemical stability for prolonged operational durability. Additionally, the multiple continuous hetero-interfaces between NiO and CoO, NiO and carbon as well as CoO and carbon can ensure the fast electron transport, leading to the expedited reaction kinetics with the synergistic effect of phase engineering between NiO, CoO and carbon shell. As a result, the 3D carbon shells jointed 2D NiO/CoO hybrids demonstrate promising catalytic activities on electro-oxidation for energy-efficient hydrogen production (∼100 %FE) coupled with urea oxidation and formic acid synthesis with excellent selectivity (95.40 %) and satisfied faradic efficiency (91.6 %).

Gas-phase Kirkendall effect inducing built-in bifunctional ultrafine Cu nanocrystalline integrated 3D hollow nanoporous CuxO anode towards excellent lithium storage performance

Traditional CuxO (x = 1, 2) electrodes exhibit excellent specific capacity, but the poor stress-buffering performance and inferior conductivity hinder its further application. To solve these issues, herein, we develop a built-in bifunctional ultrafine Cu nanocrystalline networks hybridized 3D hollow nanoporous CuxO (BUCN@3D-HN CuxO) integrated anode by a facile gas-phase Kirkendall effect. The 3D hollow nanoporous (3D-HN) structure can bidirectionally retard the change of stress, while the built-in ultrafine Cu nanocrystalline networks (BUCN) own the effect of providing rapid internal electron transport across the active/inert Cu/CuxO system. Benefiting from the synergistic effect of the excellent stress-buffering ability and improved electronic conductivity, the designed BUCN@3D-HN CuxO electrode delivers a high initial reversible capacity of 1.67 mAh cm−2 under the current density of 1 mA cm−2. Besides, a high capacity retention of 0.96 mAh cm−2 with a high capacity retention ratio of 85.7 % is achieved even after 800 cycles at a high rate of 4 mA cm−2. This work provides a facile yet effective method to prepare hollow nanoporous electrodes and emphasizes the significance of active/inert system, which may shed light on the design of other high-performance electrodes beyond Lithium-ion batteries.

NH4Cl-Assisted Electrosynthesis of P-Doped Co(OH)2 Nanosheet on Cu2S Hollow Nanotube Arrays for Glycerol Electrooxidation.

The glycerol oxidation reaction (GOR) for producing high-value-added organic compounds is of great research interest due to its potential in alleviating the energy crisis. Herein, a facile NH4Cl-assisted electrodeposition strategy is reported to fabricate 3D nano-forest array-like hollow nanostructures. The hierarchical heterojunction by combining phosphorus doping Co(OH)2 nanosheets with Cu2S nanotube arrays (P-Co(OH)2@Cu2S NTs/CF) is developed to realize the optimization on GOR. The optimized P-Co(OH)2@Cu2S NTs/CF catalyst exhibits an exceptional activity with a formate Faradaic efficiency (FE) of 97.40% at a potential of 1.30V (vs RHE). The experimental results indicate that this unique hollow nano-forest structure, grown on a conductive support, can expose more active sites and facilitate electron transfer, thereby demonstrating excellent GOR performance. This work provides new opportunities for the design of electrocatalysts of high-activity and low-cost hollow heterostructure electrocatalysts for glycerol electrooxidation.

2D hollow leaf shaped mesoporous carbon derived from ZIF-L for efficient capacitive deionization

Electrochemical treatment of saline or brackish water by capacitive deionization (CDI) is a novel resource-saving solution to ensure the availability of freshwater resources in the environment. MOF (metal–organic framework) derived carbon as a novel carbonaceous material in CDI has received considerable research attention. Among them, ZIF-L-derived carbon (ZC) suffers from problems such as self-aggregation, poor mesoporous structure, and low electrical conductivity, which lead to poor CDI performance. In this paper, a strategy of ZIF-L coated with polydopamine (PDA) is proposed to solve the above problems. When the amount of PDA was 0.5 g, ZIF-L@PDA0.5-derived carbon composite (ZPC0.5) is obtained for efficient capacitive deionization. The ZPC0.5 composite not only maintains the 2D leaf shaped structure consistent with ZIF-L, exposing more active sites, but also has an elevated mesopore occupancy ratio to promote solution diffusion. Meanwhile, the interaction between PDA and ZIF-L makes the ZPC0.5 have a cavity structure, which improves the mass transfer capacity. The resulting ZPC0.5 composite has a specific capacitance (165.8 F g−1) that is 3.86 times higher than that of ZC (42.9 F g−1). Consequently, in 1.2 V, 500 mg/L NaCl solution, the symmetric CDI cell ZPC0.5//ZPC0.5 exhibits an excellent desalination capacity (29.6 mg/g), which is 2.69 times that of the ZC//ZC.

Electrochemical Sacrificial Alchemy: Crafting Hollow Hydroxide Hierarchy for Practical Aqueous Energy Storage Solution

AbstractEffective utilization of internal active sites in high‐mass loading electrode materials is essential for advancing practical energy storage. Herein, a novel electrochemical sacrificial alchemy for the first time to directly transform the solid Co‐Ni‐Zn carbonate hydroxide (CH) into its hollow structure with a strategic hierarchical architecture is introduced. In contrast to the complex and often cumbersome procedures of traditional methods, the approach is built on the simple electrochemically induced in situ etching and remodeling process. The experimental and theoretical analyses highlight the significant role of electric field force‐induced Zn sacrificial etching and hydroxide redeposition in creating internal cavities and regenerating external active sites, leading to the final hollow hierarchical structure with primary 1D hollow nanorod arrays and secondary reconstructed 2D nanoflakes, effectively exposing abundant energy storage sites. Benefiting from the synergistic effect, the resulting Co‐Ni‐Zn CH exhibited exceptional electrochemical performance. As proof of concept, a modular pouch‐type hybrid supercapacitor (HSC) composed of Co‐Ni‐Zn CH cathode achieved an ultrahigh energy density of 46.9 Wh kg−1. This device can efficiently power consumer electronics with a faster charging speed compared to commercial shared power banks. This research unveils a facile electrochemical approach for structuring electrode materials in energy storage solutions.

Enhanced Structural VS4 Grown onto Hollow Carbon Mesoporous Spheres via Surficial Bonding for High Cycling Stability in Sodium-Ion Batteries.

Transition metal sulfides are recognized as an excellent alternative to sodium ion anodes ascribed to the outstanding theoretical capacity. The unique crystal arrangement of VS4 gives it exceptional theoretical capacity, despite challenges like insufficient electrical conductivity and undesirable volume expansion. Herein, a novel stabilized anode featuring a distinctive 3D hollow spherical structure is proposed, providing a simple strategy to synthesize such anodes for VS4-HCMSs bonded via C-O-S and V-O-C interfaces. The kinetic investigations and density functional theory reveal that the unique structure connected by interfacial bonds enhances Na+ transport rate and charge transfer efficiency, while carbon greatly mitigates the volume expansion. Unsurprisingly, the VS4-HCMSs exhibit an impressive first-cycle Coulombic efficiency of 91.31% and an ultrahigh reversible capacity of 612 mAh g-1 after 300 cycles at 0.5 A g-1, even exhibit the reversible capacity of 498.8 mAh g-1 after 1000 cycles at 5 A g-1. Additionally, the NaFePO4//VS4-HCMSs full cell is cycled for 200 cycles at 0.2 C and powered the light-emitting diodes for up to 30 minutes afterward. Overall, this work enhances the conductivity and stability of the material by combining VS4 with hollow carbon mesoporous spheres through interfacial bonding, offering an efficient strategy to anode materials in sodium-ion batteries.

3D hollow mesoporous α-Fe2O3 sensor detecting liquified petroleum gas and humidity for diagnosing sleep hypopnea-apnea syndrome

Sensors utilizing mesoporous materials have garnered significant interest; however, they are primarily designed for detecting a single analyte. In this study, we successfully synthesized a three-dimensional (3D) hollow mesoporous α-Fe2O3 using a nanocasting process for the purpose of sensing LPG and humidity. The α-Fe2O3 obtained in this study maintained the cubic framework structure of MCM-48, demonstrating a mesoporous and hollow architecture. The Liquified Petroleum Gas (LPG) sensing characteristics of mesoporous α-Fe2O3 were examined at different operating temperatures (170–210 °C). The gas sensing response was optimized 99.3 % at 190 °C and the response/recovery time comes out to be 11.79 s & 0.84 s respectively. The humidity sensor's traits were evaluated at room temperature, with relative humidity (RH%) ranging from 11 % to 98 %, using mesoporous α- Fe2O3. The response/recovery time of mesoporous α-Fe2O3 as a humidity sensor comes out to be 6.3 s & 7.2 s respectively. The highly sensitive nature of the sensor along with negligible hysteresis, excellent repeatability and considerable stability for 30 days makes it a promisable candidate for real-time subtle respiration monitoring. Meanwhile, mesoporous α-Fe2O3 humidity sensor is also utilized for evaluation of sleep hypopnea-apnea syndrome.

Designing a hollow MoSe2/CuS nanospheres type-II heterojunction photocatalyst with superior UV-vis-NIR absorption for photocatalytic degradation of organic pollutants.

In this work, a hollow MoSe2/CuS type-II heterojunction was fabricated using hollow MoSe2 nanospheres as the basis for structural design. UV-Vis-NIR diffuse absorption tests show that MoSe2/CuS has a broad spectral absorption to extend the optical response range from UV-Vis to NIR. The light source utilization rate and interfacial area are increased by the hollow MoSe2/CuS core-shell structure. The broad absorption ability of MoSe2/CuS can facilitate the photocatalysis process. As the electrochemical impedance of MoSe2/CuS is lower than that of the MoSe2, MoSe2/CuS has a good photogenerated carrier separation efficiency. Benefiting from the synergistic facilitation effect of the multi-level 3D hollow nanosphere and the significant space charge region in type-II heterojunction, the RhB degradation efficiency of MoSe2/CuS reached 96.0% in 120.0minunder Xe (350W) broadband spectrum light irradiation. The photocatalysis mechanism of the hollow MoSe2/CuS core-shell structure was investigated. This work provides an insight into the application of broad spectrum semiconductor heterojunctions to solve environmental problems.

Novel C/MoS2 hollow nanocomposites enhance lithium storage in battery anodes

With society's rapid progress, there is an increasing need for electricity among individuals, but the prevailing source of electricity is still mainly obtained through the burning of nonrenewable fossil fuels, which are not renewable and pose serious environmental hazards. Lithium-ion batteries are used widely for excellent rechargeable capabilities and high energy density. Recently, researchers have become increasingly interested in transition metal sulfides owing to their cost-effectiveness and remarkable specific capacity. However, their commercialization has been hindered by the expansion of material volume and low electrical conductivity during charging and discharging. We have successfully designed and synthesized MoS2 nanosheets loaded on carbon spheres with a 3D hollow structure starting from SiO2 as a template. Due to the doping of carbon materials and particular 3D hollow structures, the optimal C/MoS2-0.3 hollow nanocomposites exhibit excellent electrochemical performance. Following exposure to over 900 cycles at a 0.5 A g-1 ampere density, the materials exhibited an exceptional 958.50 mAh g-1 reversible capacity, demonstrating their remarkable performance.

Nanoarchitectonics of few-layer Ni3Fe nanosheets embedded porous nitrogen-doped carbon derived from asphalt waste: An efficient electrocatalyst for oxygen evolution reaction

The design and fabrication of stable, high-performance, and affordable oxygen evolution reaction (OER) electrocatalysts is essential for performing practical water electrolysis and generating green hydrogen energy. Here, we report that 2D few layer Ni3Fe nanosheets embedded with 2D porous nitrogen doped carbon (N-NixFe@CF) from asphalt waste and then convolved and assembled into 1D hollow nanotube structures by Lewis acid molten salt etching method, which were used as electrocatalysts for OER. Benefiting from the integrate of 1D hollow nanotube structure and 2D porous nanosheets, the close contact between catalysts and support, and the increased conductivity, the resultant N-Ni3Fe@CF catalysts exhibited high catalytic activities in the OER with low overpotential at a current density of 10 mA cm−2 (114 mV), low Tafel slope (166.6 mV dec−1), and excellent electrochemical stability. This work provides a new concept for expanding the use of asphalt wastes and by-products, as well as a straightforward synthesis method for producing economical, efficient, and long-lasting alkaline OER electrocatalysts.

Tubular-like Nanocomposites with Embedded Cu9S5-MoSx Crystalline-Amorphous Heterostructure in N-Doped Carbon as Li-Ion Batteries Anode toward Ultralong Cycling Stability.

Transition metal sulfides (TMSs) show the potential to be competitive candidates as next-generation anode materials for Li-ion batteries (LIBs) due to their high theoretical specific capacity. However, sluggish ionic/electronic transportation and huge volume change upon lithiation/delithiation remain major challenges in developing practical TMS anodes. We rationally combine structural design and interface engineering to fabricate a tubular-like nanocomposite with embedded crystalline Cu9S5 nanoparticles and amorphous MoSx in a carbon matrix (C/Cu9S5-MoSx NTs). On the one hand, the hybrid integrated the advantages of 1D hollow nanostructures and carbonaceous materials, whose high surface-to-volume ratios, inner void, flexibility, and high electronic conductivity not only enhance ion/electron transfer kinetics but also effectively buffer the volume changes of metal sulfides during charge/discharge. On the other hand, the formation of crystalline-amorphous heterostructures between Cu9S5 and MoSx could further boost charge transfer due to an induced built-in electric field at the interface and the presence of a long-range disorder phase. In addition, amorphous MoSx offers an extra elastic buffer layer to release the fracture risk of Cu9S5 crystalline nanoparticles during repetitive electrochemical reactions. Benefiting from the above synergistic effect, the C/Cu9S5-MoSx electrode as an LIB anode in an ether-based electrolyte achieves a high-rate capability (445 mAh g-1 at 6 A g-1) and superior ultralong-term cycling stability, which delivers an initial discharge capacity of 561 mAh g-1 at 2 A g-1 and its retention capacity after 3600 cycles (376 mAh g-1) remains higher than that of commercial graphite (372 mAh g-1).

MoSe2 nanosheets implanting on 3D hollow carbon sphere for high-efficiency electromagnetic wave absorption

Carbon-based electromagnetic wave absorption (EMA) materials are extensively studied due to their unique advantages. Nevertheless, impedance matching issues was still constraining their further research. Consequently, we successfully synthesized MoSe2 nanosheets implanting on 3D hollow carbon sphere (HCS@MoSe2) composites with core–shell structure. The complex core–shell structure high-entropy composites provided multiple dissipation mechanisms for efficient dissipation of incident electromagnetic wave energy. The implanting MoSe2 nanosheets optimized the dielectric constant of the composites, thus ensuring optimal impedance matching. The HCS@MoSe2-1 composites exhibit excellent EMA properties and a significant minimum reflection loss (RLmin) of −56.19 dB. And HCS@MoSe2-1 had an ultra-wide effective absorption bandwidth (EAB) of 7.43 GHz. The significant EMA capability attributed to the synergistic effects of conductive loss, polarization loss, and optimized impedance matching. This work paved a new path for synthesizing transition metal selenide-modified carbon-based composite materials, offering great potential as high-performance materials for EMA applications.

Carbon-Coated Mesoporous Silica Nano-Quills from Bioderived Cellulosic Templates for Low-Cost Anodes

The escalating global energy demands, driven by population growth and the electrification of transportation, have positioned rechargeable lithium-ion batteries (LIBs) as critical components in phasing out traditional fuel-based technologies. To date, several high-capacity active materials have been developed to replace current graphite-based anodes for boosting the energy density of LIBs. Silicon dioxide (SiO2, or silica) has emerged as a promising alternative, with a high theoretical capacity of 1965 mAh g-1, five times higher than conventional graphite, along with a comparatively smaller volume change than elemental Si during battery cycling. In this study, we report a patented synthesis process that harnesses wood-derived cellulose nanocrystals (CNCs) to craft a unique three-dimensional (3D) silica architecture for developing low-cost LIB anodes. Our cost-effective method yields a mesoporous silica material, termed silica nano-quill (SilicaNQ), with distinctive hollow 1D arms. In addition, we propose a direct annealing strategy for transforming CNC templates into a conformal carbon coating to fabricate SilicaNQ@C powder material. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provided a detailed exploration of the elemental composition and the bonding states at the atomic level. Anodes comprising SilicaNQ@C active material delivered a stable reversible capacity of 1030 mAh g-1 after cycling at 200 mA g-1 for 200 cycles. We performed X-ray diffraction (XRD) measurements on SilicaNQ@C half cells to identify phase changes at various state-of-charge levels and explore the evolution of interface components over cycling.

Enhanced electrocatalytic activity in MOFs-derived 3D hollow NiCo-LDH nanocages decorated porous biochar for simultaneously ultra-sensitive electrochemical sensing of Cu2+ and Hg2+

Layered double hydroxides (LDHs) have attracted significant attention due to their compositional and structural flexibility. However, it is challenging but meaningful to design and fabricate hierarchical mixed-dimensional LDHs with synergistic effects to increase the electrical conductivity of LDHs and promote the intrinsic activity. Herein, 3D hollow NiCo-LDH nanocages decorated porous biochar (3D NiCo-LDH/PBC) has been synthesized by using ZIF-67 as precursor, which was utilized for constructing electrochemical sensing platform to realize simultaneous determination of Cu2+ and Hg2+. The 3D NiCo-LDH/PBC possessed the characteristics of hollow material and three-dimensional porous material, revealing a larger surface area, more exposed active sites, and faster electron transfer, which is beneficial to enhancing its electrochemical performance. Consequently, the developed sensor displayed good performance for simultaneously detecting Cu2+ and Hg2+ with ultra-low limit of detection (LOD) of 0.03 μg L−1 and 0.03 μg L−1, respectively. The proposed sensor also demonstrated excellent stability, repeatability and reproducibility. Furthermore, the sensor can be successfully used for the electrochemical analysis of Cu2+ and Hg2+ in lake water sample with satisfactory recovery, which is of great feasibility for practical application.

Construction of 3D hollow NiCo-layered double hydroxide nanostructures for high-performance industrial overall seawater electrolysis

Construction of 3D hollow NiCo-layered double hydroxide nanostructures for high-performance industrial overall seawater electrolysis

Exceptional Nitrate Reduction to Ammonia Catalyst Enabled by BO2− Anion Induction Effects Combining Heterogeneous Branching Architecture‐Driven Mass Transport Enhancement

AbstractIn this paper, an exceptional nitrate reduction to ammonia catalyst is reported, enabled by BO2− anion induction effects combining heterogeneous branching architecture‐driven mass transport enhancement strategies. The implantation of the BO2− anion can inductively enhance the electron cloud density and electron transmission paths of intrinsic catalysts, makes electron more active to improve the conductivity, regulates the adsorption and desorption rates of intermediates by space barrier effect, reduces the binding energy of the electron and 3d orbital of Ni in NiFe(BO2)O(OH), thereby lowing the transform free energy of the determining *NO3 to *HNO3 step. 3D hollow sea urchin lattice heterogeneous branching structure can self‐drive generate differentiated micro convection intervals, which will be beneficial for improving mass transfer dynamics especially localized disturbance mass transfer effect of catalyst for nitrate reduction reaction (NO3RR) catalysis process. Amazingly, the as‐prepared 3D NiFe metaborate oxyhydroxide hollow bionic sea urchins lattice catalyst has a high NH3 rate 6.27mmol·h−1·cm−2 with 98.7% Faradaic efficiency at low ‐0.25V(vs RHE) NO3RR potential. Moreover, the catalytic activity of this highly stable catalyst decreases only slightly over 100 h at ultra‐high 1500mA·cm−2 current. This work breaks through the bottleneck that plagues the performance improvement of non Cu‐based high‐current NO3RR catalysts.

Influence of an inclined thick partition on free convection heat transfer performance under surface radiation in a hollow block

In the present work, a computational analysis of the combined energy transfer by free convection, radiation, and heat conduction in 2D hollow block with an inclined partition was carried out. The inclined partition was made of a heat-conducting material and had a finite thickness. The closed space inside the brick was filled with air (Pr = 0.71) and the airflow is laminar. The external surfaces of the vertical borders are considered to be isothermal, and the remaining horizontal surfaces are supposed to be adiabatic. The finite difference technique is employed to work out numerically the differential equations. The in-house computational code was verified in detail using various problems. The major characteristics that determine the considered phenomena are surface emissivity of internal walls, Ra number, and material of solid walls and partition. As a result of the research, the distributions of streamlines and isotherms combined with the average Nusselt numbers were obtained. Depending on the material of the partition, the flow structure in the cavity changes significantly, which reflects the distribution of streamlines, namely, for the materials with low thermal conductivity the convective cell in the upper part of the cavity is elongated, while in the lower part it is shifted to the lower and left borders. The isotherms reflect the more intensive heating in the left part of the area. With an increase in the thermal conductivity coefficient, the streamlines reflecting the nature of the flow are restructured. It was shown that the presence of an inclined partition significantly reduces the intensity of convective heat transfer.

3D hollow superstructures endow PdAg electrocatalyst with selective ethanol electrooxidation

Direct ethanol fuel cells (DEFCs) have been considered as future power devices for many portable applications. The ethanol oxidation reaction (EOR), that is, a multielectron process, suffers from low efficiency owing to the high selectivity to the 4e− pathway (C2 pathway) and low selectivity to the 12e− pathway (C1 pathway). The preparation of efficient catalysts with high C1 pathway selectivity is regarded as a promising and fascinating field. Herein, we first advance a one-pot synthesis of 3D PdAg superstructures (SSs) with a hollow interior and ultrathin nanosheet shell. PdAg SSs achieve a mass activity of 5.27 A mg−1 for the alkaline EOR and a Faraday efficiency of 22.7 % for the C1 pathway, which is 5.7 and 7.5 times higher than that of commercial Pd/C, respectively. Mechanism studies confirm that the construction of the Pd-Ag system greatly facilitates the oxidation of the C1 intermediates (*CH3 and *CO) and enhances the CC bond cleavage ability of the catalyst. This work not only highlights an active Pd-based catalyst for the selective EOR, but also sheds light on the formation of 3D open nanostructure via self-assembly of 2D nanosheets.