Nanoporous Structure Research Articles

Confinement Effect and 3D Design Endow Unsaturated Single Ni Atoms with Ultrahigh Stability and Selectivity toward CO2 Electroreduction.

Developing single-atomic catalysts with superior selectivity and outstanding stability for CO2 electroreduction is desperately required but still challenging. Herein, confinement strategy and three-dimensional (3D) nanoporous structure design strategy are combined to construct unsaturated single Ni sites (Ni-N3) stabilized by pyridinic N-rich interconnected carbon nanosheets. The confinement agent chitosan and its strong interaction with g-C3N4 nanosheet are effective for dispersing Ni and restraining their agglomeration during pyrolysis, resulting in ultrastable Ni single-atom catalyst. Due to the confinement effect and structure advantage, such designed catalyst exhibits a nearly 100% selectivity and remarkable stability for CO2 electroreduction to CO, exceeding most reported state-of-the-art catalysts. Specifically, the CO Faradaic efficiency (FECO) maintains above 90% over a broad potential range (-0.55 to -0.95V vs. RHE) and reaches a maximum value of 99.6% at a relatively low potential of -0.67V. More importantly, the FECO is kept above 95% within a long-term 100h electrolyzing. Density functional theory (DFT) calculations explain the high selectivity for CO generation is due to the high energy barrier required for hydrogen evolution on the unsaturated Ni-N3. This work provides a new designing strategy for the construction of ultrastable and highly selective single-atom catalysts for efficient CO2 conversion.

Targeted Sequencing of Circular RNAs for Illumina-Based Counting and Nanopore Structure Determination.

In the past years, circular RNAs (circRNAs) became a major focus of many studies in animals and plants. circRNAs are generated by backsplicing from the same linear transcripts that are canonically spliced to produce, for example, mature mRNAs. They exhibit tissue-specific expression pattern and are potentially involved in many diseases, among them cardiovascular diseases. However, despite the tremendous efforts to establish circRNA catalogues, much less is known about the biological function of the vast majority of circRNAs. We have previously introduced Lexo-circSeq, a targeted RNA sequencing approach that can profile up to 110 circRNAs and their corresponding linear transcripts in one experiment from low amounts of input material on the Illumina platform. Here, we present an improved protocol for Lexo-circSeq and now extend our approach to Nanopore sequencing, which allows the structural assessment of small- and medium-sized circRNAs. Employing human-induced pluripotent stem-cell-derived cardiomyocytes originating from healthy controls or patients suffering from hypertrophic cardiomyopathy, we identify deregulated circRNAs and alternative exon usage.

Efficient hydrogen evolution enabled by in-situ synthesis of biphasic Mo2C/Mo16N7 nitrogen-doped carbon nanorods as catalysts

Molybdenum carbide (Mo2C) has gained significant recognition as a cutting-edge, non-precious transition metal catalysts for efficiently driving the hydrogen evolution reaction (HER). However, the desorption of Mo-H bonds on the pristine Mo2C surface are difficult, resulting in a slow Heyrovsky/Tafel step. Herein, biphasic Mo2C/Mo16N7 nitrogen doped carbon nanorods (Mo2C/Mo16N7@NRs) is synthesized as the high-performance HER electrocatalyst by using a one-step in-situ pyrolysis growth method. It is found that a suitable pyrolysis temperature can simultaneously tune the morphology of the catalyst and form abundant heterointerface. Benefit from abundant porous nanostructure and more electron-rich Mo active sites at the Mo2C-Mo16N7 interfaces, the optimized Mo2C/Mo16N7@NRs demonstrates exceptional catalytic activity. It achieves low overpotentials (η10) of 63.62 and 117.43 mV at 10 mA cm−2, accompanied by Tafel scopes of 49.73 and 64.44 mV dec−1 in both alkaline and acidic electrolytes. Also, Mo2C/Mo16N7@NRs shows long-lasting stability for 24 h in the different electrolytes. The experimental and theoretical findings explain the synergistic effects of unique morphology control and interface engineering on electrocatalyst activity. The one-step in-situ pyrolysis growth method is expected to produce non-precious metal catalysts with distinct morphology and heterointerfaces.

Surface‐amorphized nickel sulfide with boosted electrochemical performance for aqueous energy storage

AbstractThe ingenious structural design of electrode materials has a great influence on boosting the integrated conductivity and improving the electrochemical behavior of energy storage equipment. In this work, a surface‐amorphized sandwich‐type Ni3S2 nanosheet is synthesized by an easy hydrothermal and solution treatment technique. Because of the in‐built defect‐rich feature of the amorphous Ni3S2 layer, the constructed crystalline/amorphous heterointerface as well as dual nanopore structure of Ni3S2 nanosheet, the electron/ion transport and interfacial charge transfer is boosted, which contribute to high ionic conductivity and low resistance of the SA‐Ni3S2 electrode. The SA‐Ni3S2 electrode shows high specific capacitance (1767.6 F g−1 at 0.5 A g−1); the SA‐Ni3S2//AC device delivers high specific capacitance (131.2 F g−1 at 0.2 A g−1) and outstanding cycle stability (75% capacitance retention after 10000 cycles). In Ni‐Zn battery measurement, the SA‐Ni3S2//Zn exhibits satisfying specific capacity (211.2 mAh g−1 at 0.5 A g−1) and cycle durability (68% capacity decay after 2000 cycles). The results imply that the rational design of surface‐amorphized heterostructure is helpful for fabrication of electrode materials with high electrochemical performance in energy storage applications.

Top-Down Thickness Reduction Synthesis of Biomass-Derived Carbon Nanosheets with Hierarchical Pore Structure for High-Performance Supercapacitors.

Carbon electrode materials with superior rate performance are highly demanded in application scenarios of high power output/input, especially when paired with organic electrolyte for extended voltage window and high energy storage. By extracting thin sheets of entangled cellulose fibers from cell wall structures, porous carbon nanosheets as templated from the cellulose sheets are synthesized. Evident thickness reduction effect has been demonstrated with thickness reduced from several micrometers to several nanometers of the obtained thickness-reduced activated carbon nanosheets (TRAC), which endow the material with a large surface area and high pore volume. The obtained TRAC exhibits significantly enhanced ion diffusion kinetics and superior rate capability thanks to the shortened diffusion pathway and suitable pore size distribution. Effects of sonication time have also been investigated, showing a trade-off between ion diffusion kinetics and pseudocapacitive contribution. This thickness-reduction method is extendable to many other biomass sources as cellulose sheets are widely existed in nature, offering a practical and easy-to-implement strategy of fabricating porous carbon nanostructures for efficient energy storage and utilization.

Highly dispersed palladium nano-catalyst anchored on N-doped nanoporous carbon microspheres derived from chitosan for efficient and stable hydrogenation of quinoline

Under the background of green chemistry, the synthesis of N-heterocycles using efficient, stable and long-life catalysts has still faced great challenges. Herein, we used biomass resource chitosan to fabricate a nanoporous chitosan carbon microsphere (CCM), and successfully designed a stable and efficient Pd nano-catalyst (CCM/Pd). Various physicochemical characterizations provided convincible evidences that the palladium nanoparticles (NPs) were tightly and evenly dispersed on the CCM with a mean diameter of 2.28 nm based on the nanoporous structure and abundant functional N/O groups in CCM. Importantly, the graphitized constructure, the formed defects and larger surface area in CCM were able to promote the immobilization of Pd NPs and the electron transfer between Pd and CCM, thereby significantly improving the catalytic activity. The CCM/Pd catalyst was applied for hydrogenation of quinoline compounds, which showed excellent catalytic activity and durability, as well as good substrate applicability. The application of renewable biomass-based catalysts contributes to the progression of a green/sustainable society.

Ionic liquid-functionalized antibiofouling nanofiltration membranes

Nanofiltration membranes hold great potential for water treatment applications, but are susceptible to fouling issues. In this study, we demonstrate the fabrication of NF membranes with high permeability, high rejection, antibiofouling and scaling resistance. The membrane was prepared through interfacial polymerization by doping the aqueous phase with 1-aminoethyl-3-methylimidazolium tetrafluoroborate ionic liquid. The TFC-0.2 membrane exhibited a more open nanoporous structure, resulting in an increased permeability from 5 ± 0.5 L·m−2·h−1·bar−1 (LMH/Bar) to 11.1 ± 0.4 LMH/Bar, while maintaining a comparable salt rejection performance to the original TFC membrane. Additionally, the TFC-0.2 membrane demonstrated excellent retention performance, with a removal efficiency exceeding 90 % for emerging contaminants such as antibiotics and PFOA. Notably, the TFC-0.2 membrane exhibited significant differences in the rejection of Na2SO4 and CaCl2, indicating its strong resistance to gypsum fouling. Furthermore, it is worth highlighting that the TFC-0.2 membrane displayed remarkable antibiofouling performance due to the bactericidal properties of AMIT. This capability allowed for the sterilization of bacteria at the early stage of attachment to the membrane surface, effectively mitigating biofouling. The findings of this study offer a simple yet effective strategy for fabricating high-performance nanofiltration membranes with exceptional antifouling properties.

Solvent-Free Synthesis of Covalent Organic Framework/Graphene Nanohybrids: High-Performance Faradaic Cathodes for Supercapacitors and Hybrid Capacitive Deionization.

Covalent organic frameworks (COFs) with flexible periodic skeletons and ordered nanoporous structures have attracted much attention as potential candidate electrode materials for green energy storage and efficient seawater desalination. Further improving the intrinsic electronic conductivity and releasing porosity of COF-based materials is a necessary strategy to improve their electrochemical performance. Herein, the employed graphene as the conductive substrate to in situ grow 2D redox-active COF (TFPDQ-COF) with redox activity under solvent-free conditions to prepare TFPDQ-COF/graphene (TFPDQGO) nanohybrids and explores their application in both supercapacitor and hybrid capacitive deionization (HCDI). By optimizing the hybridization ratio, TFPDQGO exhibits a large specific capacitance of 429.0Fg-1 due to the synergistic effect of the charge transport highway provided by the graphene layers and the abundant redox-active centers contained in the COF skeleton, and the assembled TFPDQGO//activated carbon (AC) asymmetric supercapacitor possesses a high energy output of 59.4Whkg-1 at a power density of 950Wkg-1 and good cycling life. Furthermore, the maximum salt adsorption capacity (SAC) of 58.4mgg-1 and stable regeneration performance is attained for TFPDQGO-based HCDI. This study highlights the new opportunities of COF-based hybrid materials acting as high-performance supercapacitor and HCDI electrode materials.

Exploring the impact of graphene oxide on mechanical and durability properties of mortars incorporating demolition waste: micro and nano-pore structure effects

In this study is explored the use of construction and demolition waste as fine aggregate in mortars. The addition of nano-graphene oxide (0.1%wt) has also been evaluated. Tests were conducted to determine their density, humidity content, water absorption capacity and open void porosity (using water absorption) and the micro and nano-porosity using Hg intrusion and N2 absorption techniques, as well as their flexural and compressive strength and resistance to acid attacks. The mechanical properties of mortars manufactured with standard sand were better (30%) than made with waste aggregate. Mortars with both aggregates can be classified as M20. Nano-Graphene oxide acts as a filler, reducing the volume of macro and micro pores, thereby increasing the mechanical performance, especially when recycled aggregates are used (30% the flexural strength for recycled aggregates and 4% for standard sand). The addition of nano-graphene oxide reduces the transmission channels of acid within mortar.

Effect of physical and chemical activation methods on the structure, optical absorbance, band gap and urbach energy of porous activated carbon

In this study, activated carbon was synthesized using the almond shell and palm kernel by physical activation with water vapor and chemical activation with phosphoric acid (H3PO4) methods. Then, the structural and optical properties of the activated carbons were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy. The SEM images showed that in the raw sample of hard almond shell and palm kernel, there is no porosity and pores, but in the activated carbon samples, porosity and structural defects were clearly observed. The XRD patterns showed that porous and amorphous structure was formed in all samples synthesized with physical and chemical activation. The results of FTIR spectra of activated carbons showed that there are carbon functional groups in all samples. The optical absorption coefficient (α) of the activated carbon with physical and chemical activation methods was obtained in order of 105–106. The band gap measurement of porous nanostructures showed that the activated carbon synthesized with chemical and physical activation methods have energy gap (Eg) in region = 2.80 to 3.15 eV and urbach energy (EU) in region = 120 to 210 meV.

Characterization of Nanoporous Copper Using Scanning Probe Techniques

This study explores the mechanical and optical properties of nanoporous copper (NPC) films dealloyed in acid and base using qualitative and quantitative measurements. Two types of NPC films (NPC 1 and NPC 2) were prepared by dealloying precursor films in different corrosive solutions. The films were characterized using atomic force microscopy (AFM) and scattering scanning near-field optical microscopy (s-SNOM). The AFM analysis revealed distinct nanoporous structures in both films, with NPC 2 showing larger pore sizes and the presence of copper aggregations on the surface. Rugosity measures showed that NPC 2 had higher rugosity than NPC 1 and indicated fundamental differences in the height distributions of the surface nano-topography. The Minkowski connectivity analysis highlighted differences in connectedness and topological characteristics between the two samples. The analysis of the GLCM features showed clear distinctions in ASM, Contrast, Dissimilarity, Energy, and Homogeneity between NPC 1 and NPC 2. The s-SNOM results demonstrated altered optical properties, with NPC 1 showing higher contrast at 1550 nm, while NPC 2 exhibited reversed-phase contrast at 561 nm. The phase contrast at 638 nm indicated a red-shifted optical absorption peak in NPC 2 compared to NPC 1.

Conducting polymers/oxygen vacancies WO3 vertically nanowire arrays supported on carbon cloth as advanced electrodes for high-performance supercapacitors

The low energy density of supercapacitors (SCs) is one of the main factors restricting their development. WO3 with high theoretical capacitance is an ideal n-type material for anode electrode, but its narrow potential window and low conductivity are not conducive to the application of high-energy-density SCs. Herein, a high electrochemical activity poly(indole-5-carboxylic acid) (P5-ICA) as p-type material wrapping n-type oxygen vacancies WO3 vertically nanowire arrays supported on carbon cloth is prepared by hydrothermal method and subsequent electrodeposition method. This adhesive free flexible p/n-type hetero-structural P5-ICA@WO3 vertical nanowire array electrode has a three-dimensional porous nanostructure that not only provides a large surface area, but also promotes the penetration of electrolyte ions and the transmission of electrons. It is found that the P5-ICA@WO3 nanowire array with high areal specific capacitance (1430 mF cm−2 at 4 mA cm−2) and long cycle stability (94 % after 6000 cycles) exhibits a widened electrochemical activity window compared to individual material. The symmetrical SCs assembled using P5-ICA@WO3 can provide a high areal energy density of 137.6 μWh cm−2 at the power density of 1.4 mW cm−2, which is significantly higher than the SCs performance of previously used WO3-based electrode materials.

Hierarchical porous alumina ceramics as multi-functional support with excellent performance

Hierarchical porous nanostructure alumina ceramics (HP-Al2O3) were prepared through a novel approach involving polymer-assisted freeze-drying and subsequent calcination. The resulting material exhibits interconnected micro-meso-macro pores, distinguishing it from traditional Al2O3 nanoparticles (Al2O3-Nps) prepared without freeze-drying. By manipulating freeze-drying precursors and calcination temperatures, we tailor the morphology and structure of HP-Al2O3. Notably, the HP-Al2O3 demonstrates a remarkable 5.3-fold increase in adsorption efficiency for Congo red compared to Al2O3-Nps, attributed to its significantly larger specific surface area. The HP-Al2O3 is a versatile platform for building multi-functional composites, proved by immobilizing silver nanoparticles (AgNps) and graphitized carbonitride (g-C3N4) through chemical reduction and gas-solid reaction methods, respectively. When employed for the reduction of 4-nitrophenol and the degradation of Rhodamine B, Ag/HP-Al2O3 and g-C3N4/HP-Al2O3 display approximately 2.5 and 2.4 times higher reaction rate constants compared to Ag/Al2O3-Nps and g-C3N4/Al2O3-Nps. This enhanced catalytic performance is attributed to several key factors: the 3D porous framework of the HP-Al2O3 facilitates efficient catalyst immobilization, the microporous and mesoporous nature increases the active site and specific surface area, and the hierarchical porous structure enhances mass diffusion and light capture. Moreover, the self-supporting nature of the HP-Al2O3 simplifies separation and recovery from reaction solutions. With the integration of its hierarchical porous structure and commendable recovery properties, HP-Al2O3 emerges as a promising candidate for various functional applications, particularly in catalysis.

Plasma-engineered GQD-inorganic membranes with tunable interactions for ultrahigh-efficiency molecular separations

Ultrahigh-efficiency molecular separation (MS) membranes with tunable size-selective molecular separation, chemical-mechanical robustness, and long-term stabilities are useful for fundamental studies and applications. However, conventional MS membranes are hampered by the problems of uncontrolled molecular interactions, low separation efficiency, and energy and time-consuming fabrications. Here, we show an effective plasma engineering of nitrogen doped graphene quantum dot (NGQD)-inorganic nanocomposites composed with NGQDs and alumina-based hollow fibers (AHFs) with controlled properties and tunable local physicochemical environments for size-selective molecular separations. Detailed spectroscopic study and membrane characterization suggest that the plasma-synthesized NGQDs with defined zero-dimensional (0D) carbon-based sp2 hybridization, tunable nitrogen dopants and surface functional groups can affect the properties of the GQD-inorganic nanocomposites, therefore controlling molecular separation between the nanocomposites and molecules with different dye molecular weights (MWs). Moreover, the NGQDs can further induce the formation of nanochannel and control the nanopore structures of the nanocomposites, leading a significant molecular separation performance with a high 92.68 separation factor (S) for the mixed molecules with a 200 Da MW difference and a high water permeability up to 36.64 L m−2 h−1 bar−1. Our work provides a step for the engineering of functional nanocomposites for fundamental studies of molecular transport and emerging applications including catalysis, green energy, optoelectronics, biomedical and environmental applications.

Super anti-corrosion surface of Al-Li alloy via femtosecond laser ablation treatment in water

Al-Li alloys are widely used in aerospace industry owing to their low density and high specific strength, but they are facing corrosion challenges in marine environment. In this work, femtosecond laser ablation (FLA) technique is employed to modify the surface of Al-Li alloy in order to enhance the corrosion resistance, and the effects of FLA in the air (FLA-Air) and FLA in the water (FLA-Water) are compared. It is found that the FLA-Air treated surfaces are hydrophilic, while the FLA-Water treated surfaces are near superhydrophobic with contact angle of 140–150°. The FLA-Water surface, treated by using the laser power of 240 mW, shows superior passivation ability, and its corrosion current density is three orders of magnitude lower than that of the alloy matrix. The synergistic effect of hair-like porous nanostructure and high oxidation degree of the surface contributes to the superior corrosion resistance of the FLA-Water treated alloy. Our work provides a novel strategy for the effective corrosion protection of light metal surfaces.

Nano structured diatom frustules incorporated into TiO2 photoelectrodes to enhance performance of quasi-solid-state dye-sensitized solar cells

Diatom frustules are incorporated into multilayer photoelectrodes intending to enhance efficiency in dye-sensitized solar cells utilizing their light interaction properties. A specific, but ubiquitous in all oceans, pennate-type diatom frustules were used to form the composite layers. Single, double, and triple-layer photoelectrodes were constructed with pure TiO2 (control measurements) as well as with a TiO2/diatom frustule composite. The electrodes were prepared using TiO2 nanoparticles of two sizes (13 and 21 nm) and were analyzed using UV visible absorption and XRD spectra. The morphology of frustules and electrodes were analyzed using scanning electron microscopy. The performance for each photoanode configuration was measured by assembling photoelectrochemical solar cells fabricated with a Pt counter electrode and a gel polymer electrolyte that excludes volatile solvents. The efficiency of the control cell is 3.37%. After replacing the topmost TiO2 layer with a TiO2/diatom frustule composite layer, efficiency increases to 6.78%. This is an impressive efficiency enhancement of 101%. The short circuit current density of frustule-incorporated three-layer cells is 18.1 mA cm−1 while for the control cell it is 8.98 mA cm−1. The enhanced efficiency of cells made with TiO2/diatom frustule composite electrodes and a polyethylene oxide-based gel polymer electrolyte can be attributed to the improved light absorption by the photoanode due to optical scattering and light-trapping effects caused by the presence of diatom frustules. Frustules also can assist in enhancing dye adsorption by increasing the effective specific surface area of the composite photoelectrode due to their nanoporous structure.

Synthesis of Porous and Oxide Nanostructures by the Method of Laser Irradiation Using Computer Optics Elements

Synthesis of Porous and Oxide Nanostructures by the Method of Laser Irradiation Using Computer Optics Elements

Adsorptive recovery of phosphate using iron functionalized biochar prepared via co-pyrolysis of wheat straw and sewage sludge

In recent years, the removal and recovery of phosphate (PO43−) from freshwater reservoirs using carbonaceous adsorbents has received much attention to address eutrophication issues and plant phosphate requirements. The viability of FeCl3 impregnated biochar (Fe@CBC) synthesized via co-pyrolysis of wheat straw (WS) and sewage sludge (SS) for phosphate removal from water under systematically designed sorption experiments and its subsequent potential as phosphatic fertilizer for improving plant growth, was thoroughly investigated in this study. The relatively higher PO43− sorption performance of Fe@CBC (5.23 mg/g) compared to FeCl3 impregnated biochars (Fe@WBC: 4.16 mg/g and Fe@SBC: 5.14 mg/g) synthesized via separate pyrolysis of WS and SS were primarily ascribed to the nano porous structure, higher point of zero charge (pHpzc) and enriched iron complexes on its surface (Fe-OH and FeC). Consequently, dominant sorption mechanism of PO43− ions towards Fe@WBC was associated to ligand exchange and chemisorption whereas that of Fe@SBC and Fe@CBC was identified as electrostatic surface complexation coupled with reduction. In comparison to Fe@WBC and Fe@SBC, the surface properties and identified phenomenon allowed Fe@CBC to efficiently recover PO43− ions under optimal water chemistry conditions and coexisting interfering species environment. Additionally, PO43- -sorbed Fe@CBC effectively improved the physical growth (root length: 2 cm, shoot length: 9 cm, fresh weight: 79 mg and dry weight: 8.3 mg) of mustard plants. Economic analysis suggested profit of PO43- removal and recovery by Fe@CBC was $1.5 per kg. Therefore, PO43- -sorbed Fe@CBC could be a promising phosphatic fertilizer for improving plant growth and may have agricultural applications.

Nanoporous structure development in PEI thin film foams

Nanoporous structure development in PEI thin film foams

Kinetics and isotherms of adsorption of arsenic (III) in aqueous solution using activated carbon with nanoporous structure obtained from organic sewage sludge

El objetivo de la investigación fue estudiar el proceso de adsorción de iones de As (III) con carbón activado de estructura nanoporosa obtenido de lodos orgánicos de aguas residuales. La obtención del carbón activado se realizó mediante una activación química usando ZnCl2 y una activación térmica a 650 °C. Los ensayos de adsorción se realizaron colocando en contacto 16 g/l de carbón activado con soluciones de 0.247, 0.406, 0.564, 0.683 y 0.801 mg/l de As (III) en vasos precipitados de 1 l a un tiempo de 24 horas. Todos los ensayos fueron sometidos a una velocidad de agitación de 720 RPM, a temperatura de 28 °C ± 0.5 y al pH natural de las muestras en laboratorio, el cual fue 3. Los resultados de la caracterización de carbón indicaron que este adsorbente presentó una estructura nanoporosa con presencia de grupos funcionales (hidroxilo y carboxilo). En cuanto a los ensayos de adsorción de As (III), se determinó que el carbón activado logró reducir la concentración del metal hasta 0.004 mg/l, valor que está por debajo de los establecidos por la Organización Mundial de la Salud (OMS) para el consumo de agua. Finalmente se concluye que el carbón activado presentó una eficiencia de 98.4 % de adsorción de iones de As (III) y los datos experimentales mostraron un mayor ajuste al modelo de pseudo-segundo orden y a la isoterma de Freundlich, lo cual indica que el proceso de adsorción de As (III) se realiza en centros enérgicamente heterogéneos mediante una interacción físico-química entre el metal y el adsorbente.