Interconnected Nanopores Research Articles

Facile and Green Preparation of Three-Dimensionally Nanoporous Copper Films by Low-Current Electrical Field-Induced Assembly of Copper Nanoparticles for Lithium-Ion Battery Applications

Porous copper (Cu) films were facilely and greenly fabricated by low-current electrical field-induced assembly of ~ 3 nm Cu nanoparticles (NPs) in several minutes using generated hydrogen bubbles as dynamic negative templates. The porous films had open three-dimensionally (3D) interconnected nanopores and uniform pore size distribution and exhibited a hierarchical structure composed of supraparticles that were further composed of the Cu NPs. Lattice-to-lattice connectivity in the self-assembly of the NPs in the 3D structures enables fast charge transport. The structure/morphology of the porous Cu materials can be tuned by adjusting the concentration of the additives, applied potential/current densities and assembly time. A growth mechanism of the porous films was reasonably proposed for the field-induced assembly of the Cu NPs. The porous Cu film-supported Si electrode showed high capacity of 1173 mAh g−1 and retention rate of 87% after 10 cycles at 1 C. Our research sheds a light on preparing 3D nanoporous structures especially for suitable electrodes in electrochemical energy storage devices.

Synthesis of dandelion-like V2O3/C composite with bicontinuous 3D hierarchical structures as an anode for high performance lithium ion batteries

The dandelion-like V2O3/C composite was synthesized by a simple and facile template-free solvothermal method followed by a suitable thermal treatment. The dandelion-like V2O3/C composite is constructed by bicontinuous 3D hierarchical structures, which are formed by interconnected nanoparticles and interconnected pores, respectively. Moreover, the surface of interconnected nanoparticles is uniformly coated with an ultrathin carbon layer. Upon evaluation as an anode material for LIBs, the as-synthesized product shows superior electrochemical performance. Under the current density of 0.1 A g−1, the specific discharge capacity of V2O3/C composite is 737 mA h g−1 after 100 cycles. Moreover, after 1000 cycles at a high current density of 2 A g−1, the sample exhibits a discharge capacity of 315 mA h g−1 which is 94% of the first-cycle discharge capacity. This excellent electrochemical performance can be ascribed to its unique hierarchical structure with 3D interconnected nanopores and uniform carbon coating.

Porous Network Microstructures: Femtosecond Laser Direct Writing of Porous Network Microstructures for Fabricating Super‐Slippery Surfaces with Excellent Liquid Repellence and Anti‐Cell Proliferation (Adv. Mater. Interfaces 7/2018)

Porous network microstructures can be directly generated on various polymer surfaces by one-step femtosecond laser writing. Inspired by Nepenthes pitcher plant, a super-slippery surface was fabricated based on the porous PET substrate whose surface was fully covered by interconnected nanopores. The resultant slippery surface can repel various liquids. In addition, such a surface can completely inhibit the cells growth. This is reported by Feng Chen, Xiaoyun Lu and co-workers in article number 1701479.

A nanoporous MXene film enables flexible supercapacitors with high energy storage.

MXene films are attractive for use in advanced supercapacitor electrodes on account of their ultrahigh density and pseudocapacitive charge storage mechanism in sulfuric acid. However, the self-restacking of MXene nanosheets severely affects their rate capability and mass loading. Herein, a free-standing and flexible modified nanoporous MXene film is fabricated by incorporating Fe(OH)3 nanoparticles with diameters of 3-5 nm into MXene films and then dissolving the Fe(OH)3 nanoparticles, followed by low calcination at 200 °C, resulting in highly interconnected nanopore channels that promote efficient ion transport without compromising ultrahigh density. As a result, the modified nanoporous MXene film presents an attractive volumetric capacitance (1142 F cm-3 at 0.5 A g-1) and good rate capability (828 F cm-3 at 20 A g-1). Furthermore, it still displays a high volumetric capacitance of 749 F cm-3 and good flexibility even at a high mass loading of 11.2 mg cm-2. Therefore, this flexible and free-standing nanoporous MXene film is a promising electrode material for flexible, portable and compact storage devices. This study provides an efficient material design for flexible energy storage devices possessing high volumetric capacitance and good rate capability even at a high mass loading.

Shape memory polymers with interconnected nanopores and high mechanical strength

ABSTRACTThe fabrication of shape memory polymers with both interconnected nanopores and high mechanical strength is challenging. In this work, porous shape memory polymers (PSMPs) were prepared based on the combination of crystallization and phase separation in a ternary blend of poly(l‐lactic acid)/polyvinyl acetate/poly(ethylene oxide) (i.e., PLLA/PVAc/PEO). The phase separation between the PLLA and PVAc/PEO resulted in bicontinuous structures in microscale including a PLLA‐rich phase and a mixed PVAc/PEO phase. On one hand, the continuous PLLA‐rich phase contributed to the high mechanical strength and shape memory performance, in which tiny crystals and amorphous matrix of PLLA act as the shape fixed phase and reversible phase, respectively. On the other hand, the crystallization of PEO in the miscible PVAc/PEO blend produced submicrometer bicontinuous structures. The interconnected nanopores have been obtained by selective etching of the PEO. Our strategy opens a new avenue for fabricating PSMPs with both interpenetrated channels and high strength. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 125–130

700 F hybrid capacitors cells composed of activated carbon and Li4Ti5O12 microspheres with ultra-long cycle life

To address the large-scale application demands of high energy density, high power density, and long cycle lifetime, 700-F hybrid capacitor pouch cells have been prepared, comprising ∼240-μm-thick activated carbon cathodes, and ∼60-μm-thick Li4Ti5O12 anodes. Microspherical Li4Ti5O12 (M-LTO) synthesized by spray-drying features 200–400 nm primary particles and interconnected nanopore structures. M-LTO half-cells exhibits high specific capacities (175 mAhh g−1), good rate capabilities (148 mAhh g−1 at 20 C), and ultra-long cycling stabilities (90% specific capacity retention after 10,000 cycles). In addition, the obtained hybrid capacitors comprising activated carbon (AC) and M-LTO shows excellent cell performances, achieving a maximum energy density of 51.65 Wh kg−1, a maximum power density of 2466 W kg−1, and ∼92% capacitance retention after 10,000 cycles, thus meeting the demands for large-scale applications such as trolleybuses.

Fabrication of porous Mn2O3 microsheet arrays on nickel foam as high–rate electrodes for supercapacitors

Porous Mn2O3 microsheet arrays on nickel foam have been prepared by a mild chemical reaction combined with a calcination process. The porous Mn2O3 microsheet arrays are directly grown on the surface of the conductive nickel foam. The porous Mn2O3 microsheet arrays are composed of numerous interconnected nanopores with an average size of about 16 nm. The specific surface area of the porous Mn2O3 materials is 36.34 m2 g−1. The fabricated electrode materials exhibit a high specific capacitance of 566.6 F g−1 at a current density of 0.5 A g−1 and 294.4 F g−1 at a current density of 20 A g−1. The energy density of the porous Mn2O3 microsheet was 19.65 Wh kg−1 at a power density of 124.85 W kg−1 and it was reduced to 10.22 Wh kg−1 at a power of density of 5.00 kW kg−1. The good electrochemical capacitance is ascribed to the interconnected porous structure of the Mn2O3 microsheet, which facilitates electrolyte diffusion and enhances electron transport. The porous Mn2O3 microsheet arrays on nickel foam are a promising electrode material for supercapacitors.

Three Dimensional Interconnected Nanopores Current Collector for Drastically Enhanced Pseudocapacitive Performance

Three dimensional (3-D) nanopores array has been widely regarded as the promising current collector for fabrication of pseudocapacitor electrodes, mainly due to its large surface area, efficient electron and ion transport, and strong structural stability. Typically, anodization of high purity aluminium (Al) is the facile method to achieve highly packed nanopores with straight channels, of which the structural parameters could be facilely tuned by anodization voltage and etching time. By deposition of conductive and active materials, each channel could serve as the unit cell to store the energy. Nevertheless, the drawbacks still exist in such structure from the following aspects: i) Each channel has the electronic connection only at the top of the nanopores, leading to long pathway for electron transport. ii) The ions diffusion pathway is cut off by the side walls of anodized aluminium oxide (AAO), resulting in the one dimensional diffusion way along the channel. iii) The volume/space occupied by AAO side walls has no contribution to the capacitance, resulting in the low efficient utilization of the nanostructure. To address above issues, we have engineered the 3-D interconnected nanopores array by anodization of unique Al alloy. In such an architecture, the side pores are uniformly distributed along the main channel of AAO, forming more porous and mechanically stable nanopores array. By controllable deposition of fluorine doped tin oxide (FTO) with the cost-effective method of ultrasonic spray pyrolysis, and electrochemical deposition of MnO2, the as-built pseudocapacitor electrode renders the highest areal capacitance of 322.6 mF cm-2 and volumetric capacitance of 80.65 F cm-3 at the discharging current density of 0.1 mA cm-2, and still maintains 236 mF cm-2 and 59 F cm-3 at the discharging current density of 1.5 mA cm-2. By contrast, the values for the pseudocapacitor electrode fabricated based on the traditional nanopores array current collector are 273.8 mF cm-2 and 68.45 F cm-3, respectively, and drastically degrade to 50 mF cm-2 and 12.5 F cm-3. The performance enhancement is much larger when the comparison falls on planar pseudocapacitor electrode. We ascribe the largely enhanced rate capability to two reasons: i) The interconnected nanopores structure offers more space, which benefits for loading of nanostructured MnO2. ii) The side pores allow ions to move freely into neighbouring channels, resulting in the faster ion diffusion. In this case, we regard such interconnected nanopores array as the superior current collector in pursuit of high performance pseudocapacitor electrode. Figure 1

Micro-nano structure hard carbon as a high performance anode material for sodium-ion batteries.

Superior first-cycle Coulomb efficiency (above 80%) is displayed by filter paper-derived micro-nano structure hard carbon, and it delivers a high reversible capacity of 286 mAh g−1 after 100 cycles as the anode for Na-ion battery at 20 mA g−1. These advantageous performance characteristics are attributed to the unique micro-nano structure, which reduced the first irreversible capacity loss by limiting the contact between the electrode and electrolyte, and enhanced the capacity by accelerating electron and Na-ion transfer through inter-connected nano-particles and nano-pores, respectively. The good electrochemical performance indicates that this low-cost hard carbon could be a promising anode for Na-ion batteries.

Highly Active and Selective Zr/MCF Catalyst for Production of 1,3-Butadiene from Ethanol in a Dual Fixed Bed Reactor System

Copper and zirconium oxide clusters were highly dispersed on mesocellular siliceous foam (MCF), a mesoporous silica support with ultra large, interconnected nanopores. These catalysts (denoted as Cu/MCF and Zr/MCF) were separately loaded into two fixed bed reactors as catalysts for the conversion of ethanol (EtOH) to 1,3-butadiene (BD). Under optimal conditions, high BD selectivity (up to 73%) and ethanol conversion (up to 96%) were achieved at weight hourly space velocities of 1.5 and 3.7 h–1. This translates to an unprecedented productivity of 1.4 gBD/gcatalyst h–1 (208 gBD/lcatalyst h–1). The high catalytic performance is attributed to the highly selective and active catalysts. The EtOH dehydrogenation activity of Cu/MCF could be accurately controlled in the first reactor, which delivers a fixed ratio of the acetaldehyde/EtOH mixture to Zr/MCF in the second reactor. The optimal ratio minimizes EtOH dehydration to ethylene by Zr/MCF, while maximizing the selectivity to BD. MCF was found to be superior o...

Carbothermic reduction synthesis of red phosphorus-filled 3D carbon material as a high-capacity anode for sodium ion batteries

Phosphorus is an attractive negative electrode material for sodium ion batteries due to its high theoretical specific capacity of 2596mAhg−1. However, it suffers poor conductivity (10−12Sm−1), slow reaction dynamics, and large volume expansion (~440%) during the sodiation process, leading to rapid capacity decay upon cycling. Great attention has been devoted to improving the electrical conductivity via mixing phosphorus particles with conductive carbon materials, yet little emphasis has been placed on addressing the volume expansion issue, which may leads to the loss of electrical contact between the active material and the current collector, and the sequent deterioration of the overall electrochemical performance. Here, we demonstrate a carbothermic reduction method to fabricate ultrafine red phosphorus particles (~10nm) embedded in a three-dimensional carbon framework, in which numerous interconnected nanopores are generated accompanied by the carbonization of polyethylene glycol. During discharge/charge processes, nanosized phosphorus particles accommodate the large stress without cracking, and decrease the diffusion length, as well as connect strongly with carbon framework, resulting in an improved conductivity, a reversible specific capacity of 1027mAhg−1 (at 0.2C) and high capacity retention of 88% over 160 cycles.

Perovskite Photovoltaics with Outstanding Performance Produced by Chemical Conversion of Bilayer Mesostructured Lead Halide/TiO2 Films.

A new method of producing high-quality perovskite films via sequential deposition is presented, introducing a PbX2 capping layer that is endowed with a network of interconnected nanopores. The mesoporous lead halide architecture provides a powerful tool to accomplish rapid and complete transformation of lead halide into the perovskite for high-efficiency solar cells.

Effect of varying the composition and nanostructure of organic carbonate-containing lyotropic liquid crystal polymer electrolytes on their ionic conductivity

Nanostructured composite electrolyte films consisting of a cross-linked lyotropic liquid crystal (LLC) monomer, an organic carbonate liquid electrolyte (propylene carbonate, dimethylcarbonate, diethylcarbonate) and a Li salt (LiClO_4, LiBF_4, LiPF_6) were systematically prepared and characterized at two electrolyte concentrations (0.245 and 1.0 m) and four liquid loading levels (5, 15, 30, 50 wt %). The LLC morphology of the films was investigated using polarized light microscopy and powder X-ray diffraction; their ionic conductivity was investigated using AC impedance measurements. Higher liquid electrolyte loadings and Li salt concentrations generally increased ionic conductivity, regardless of the liquid electrolyte or salt used. Some mixed-phase LLC morphologies displayed good ionic conductivity; however, as initially prepared, these formulations were at the limit of liquid uptake. In contrast, composites with a type II bicontinuous cubic (QII) LLC phase containing ordered, three-dimensional interconnected nanopores exhibited good conductivity using much less liquid electrolyte and a lower Li salt concentration, indicating that this structure is more amenable to ion transport than less ordered/uniform morphologies. When wetted with electrolyte solution and integrated into Li/fluorinated carbon coin cells, the QII films were sufficiently strong to act as an ion-conductive separator and displayed stable open-circuit potentials. Many of the mixed-phase films gave shorted cells.

Lotus pollen derived 3-dimensional hierarchically porous NiO microspheres for NO2 gas sensing

Hierarchically porous NiO microspheres with interconnected nano-pores were prepared with chemical bath deposition by using lotus pollens as bio-templates. The NiO microspheres thus derived have a specific surface area of 95.58m2/g and the average pore size is 20.98nm, such a nanostructure is ideal for gas sensing. To enhance the performances, the NiO microspheres were further decorated with Pd/PdO, and the sensor based on the Pd-decorated NiO microspheres demonstrated a high sensitivity (S=203), fast response/recovery (73s/169s) and excellent selectivity to 1.8ppm NO2 gas at 250°C. Compared with the other NO2 gas sensors based on NiO reported in previous works, the sensitivity of the NO2 sensor of this work is the highest and the response/recovery is among the fastest.

Novel porous calcium aluminate/phosphate nanocomposites: in situ synthesis, microstructure and permeability.

Permeable porous nanomaterials have extensive applications in engineering fields. Here, we report a novel system of porous calcium aluminate/phosphate (CaAl-CaP) nanocomposites fabricated by pore generator free processing. The CaAl rich samples have close micropores and are not permeable. Interestingly, the CaP rich composites have a unique three-dimensional nanosieve structure with interconnected nanopores and exhibit excellent liquid permeability and adsorbability. The pore size has a narrow distribution of 200-500 nm. The CaAl nanoplatelets in the CaP rich composite have a thickness of 202 nm, a diameter of 1600 nm and an aspect ratio of 8. The porosity is from 19% to 40%. The bending strength and compressive strength are 40.3 MPa and 195 MPa, respectively. The CaP rich nanocomposite is highly permeable so that a water droplet can completely penetrate in 10 seconds (1 mm thick disk). The blue dye can be desorbed in 45 min by ultrasonic vibration. Given the nanosieve porous structure, good permeability/adsorbability and high mechanical properties, the CaP rich nanocomposite has big potential in applications for chemical engineering, biomedical engineering and energy/environmental engineering.

COMPARATIVE ANALYSIS OF THREE-DIMENSIONAL NANOSTRUCTURE OF POROUS BIOCOMPATIBLE SCAFFOLDS MADE OF RECOMBINANT SPIDROIN AND SILK FIBROIN FOR REGENERATIVE MEDICINE

Aim.To perform a comparison of three-dimensional nanostructure of porous biocompatible scaffolds made of fibroinBombix moriand recombinant spidroin rS1/9.Materials and methods.Three-dimensional porous scaffolds were produced by salt leaching technique. The comparison of biological characteristics of the scaffolds shows that adhesion and proliferation of mouse fibroblastsin vitroon these two types of scaffolds do not differ significantly. Comparative experimentsin vivoshow that regeneration of bone tissue of rats is faster with implantation of recombinant spidroin scaffolds. Three-dimensional nanostructure of scaffolds and interconnectivity of nanopores were studied with scanning probe nanotomography (SPNT) to explain higher regenerative activity of spidroin-based scaffolds.Results.Significant differences were detected in the integral density and volume of pores: the integral density of nanopores detected on 2D AFM images is 46 μm–2 and calculated volume porosity is 24% in rS1/9-based scaffolds; in fibroin-based three-dimensional structures density of nanopores and calculated volume porosity were 2.4 μm–2 and 0.5%, respectively. Three-dimensional reconstruction system of nanopores and clusters of interconnected nanopores in rS1/9-based scaffolds showed that volume fraction of pores interconnected in percolation clusters is 35.3% of the total pore volume or 8.4% of the total scaffold volume.Conclusion.Scanning probe nanotomography method allows obtaining unique information about topology of micro – and nanopore systems of artificial biostructures. High regenerative activity of rS1/9-based scaffolds can be explained by higher nanoporosity of the scaffolds.

Osteogenic potential of human adipose-derived stromal cells on 3-dimensional mesoporous TiO2 coating with magnesium impregnation.

The aim of this study was to evaluate the osteogenic response of human adipose-derived stromal cells (ADScs) to mesoporous titania (TiO2) coatings produced with evaporation-induced self-assembly method (EISA) and loaded with magnesium. Our emphasis with the magnesium release functionality was to modulate progenitor cell osteogenic differentiation under standard culture conditions. Osteogenic properties of the coatings were assessed for stromal cells by means of scanning electron microscopy (SEM) imaging, colorimetric mitochondrial viability assay (MTT), colorimetric alkaline phosphates activity (ALP) assay and real time RT-polymerase chain reaction (PCR). Using atomic force microscopy (AFM) it was shown that the surface expansion area (Sdr) was strongly enhanced by the presence of magnesium. From MTT results it was shown that ADSc viability was significantly increased on mesoporous surfaces compared to the non-porous one at a longer cell culture time. However, no differences were observed between the magnesium impregnated and non-impregnated surfaces. The alkaline phosphatase activity confirmed that ADSc started to differentiate into the osteogenic phenotype after 2 weeks of culturing. The gene expression profile at 2 weeks of cell growth showed that such coatings were capable to incorporate specific osteogenic markers inside their interconnected nano-pores and, at 3 weeks, ADSc differentiated into osteoblasts. Interestingly, magnesium significantly promoted the osteopontin gene expression, which is an essential gene for the early biomaterial-cell osteogenic interaction.

Effect of rigidity of porous structure on electrochemical behavior of pristine Li4Ti5O12 microspheres

Highly controllable porous architecture is desirable to tailor the physical and chemical properties of functional materials in advanced lithium ion batteries. Here, porous microspheres of spinel lithium titanate (Li4Ti5O12), a promising alternative anode material for lithium ion batteries, are fabricated by mutual molten growth method in a controllable manner. The key role of the rigidity of the porous structure on the performance of the electrode materials in lithium ion batteries is demonstrated. Rigid framework of the materials is formed by second growth of the primary particles that fused together to generate an interconnected nanopore system inside the spheres, leading to better electrolyte diffusion and lower interparticle contact resistance, relative to the non-porous counterpart. The pristine Li4Ti5O12 microspheres with uniform pore distribution and continuous framework exhibit high tap density, remarkable reversible capacity and rate capability, as well as excellent cycling stability. The present method is scalable and may provide a new approach to fabricate other candidate electrode materials for applications that require both high power and high volumetric energy density.

Nanoporous gold on three-dimensional nickel foam: An efficient hybrid electrode for hydrogen peroxide electroreduction in acid media

A hybrid structure of nanoporous gold (NPG) on three-dimensional (3D) macroporous Ni foam has been synthesized by electrodeposition of Au–Sn alloy film followed by a facile chemical dealloying process under free corrosion conditions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used to characterize the morphology and structure of the NPG/Ni foam hybrids. It is shown that the Ni foam skeletons are uniformly wrapped by the NPG film which is composed of bicontinuous nanostructures consisting of interconnected ligaments and nanopores. Electroreduction of H2O2 on the NPG/Ni foam hybrid electrode in acid media is investigated by linear scan voltammetry, chronoamperometry and electrochemical impedance spectroscopy. It is found that such hierarchical porous electrode displays superior activity, durability and mass transport property for H2O2 electroreduction. These results demonstrate the potential of the NPG/Ni foam hybrid electrodes for the applications in fuel cell technology.

Mesoporous CNT@TiO2-C Nanocable with Extremely Durable High Rate Capability for Lithium-Ion Battery Anodes

A well-designed nanostructure CNT@TiO2-C with fine anatase TiO2 particle (< 8 nm), good electronic conducting network (inner CNT core and outer carbon layer), and mesoporous structure was prepared by a simple and green one-pot hydrothermal reaction. The utilization of glucose in the hydrothermal process not only solves the interfacial incompatibility between CNTs and titanate sol and controls the nucleation and growth of TiO2 particles, but also introduces a uniform, glucose-derived, carbon-layer on the TiO2 particles. The nanosized TiO2 particle, high conducting network, and interconnected nanopores of the CNT@TiO2-C nanocable greatly improve its electrochemical performances, especially rate capability. The CNT@TiO2-C nanocables show remarkable rate capability with reversible charge capacity of 297, 240, 210,178 and 127 mAh g−1 at 1C, 5C, 10C, 20C and 50C, respectively, as well as excellent high rate cycling stability with capacity retention of 87% after 2000 cycles at 50C.