Nanoporous Structure Research Articles

Effect of Sodium Terephthalate on the Electrocatalytic Performance of Active Self‐Supporting Nanoporous PdAg Catalysts

Direct‐methanol fuel cells (DMFCs) have become a hot research topic in the energy field due to their excellent energy conversion efficiency and environmental sustainability. Optimization of catalyst preparation strategy is the key to enhance the performance of DMFC. In this study, melt quenching is employed to synthesize Al–Pd–Ag precursor alloy ribbons, and self‐supported nanoporous Pd–Ag catalysts with high activity are successfully prepared by a precisely controlled dealloying process. The catalysts are characterized microstructurally and tested electrochemically, and their performance is compared with samples without sodium terephthalate addition and with commercial Pt/C and Pd/C catalysts. In the results, it is shown that the maximum peak current density of methanol electrocatalytic oxidation is significantly enhanced to 1451.16 mA mg−1 with the addition of 15 mM sodium terephthalate, which is about 6.6 times higher than that of the unadded samples, and the catalytic performance is improved by a factor of 7.7 and 12.0, respectively, compared to those of commercial Pt/C and Pd/C. This remarkable performance enhancement is attributed to the innovative dealloying method, which not only refines the catalyst structure but also achieves a significant increase in catalytic performance through the assistance of active self‐supporting nanoporous structures and interfacial synergistic effects between palladium and silver.

Preprocessed Monomer Interfacial Polymerization for Scalable Fabrication of High-Valent Cluster-Based Metal-Organic Framework Membranes.

Current research on emergent membrane materials with ordered and stable nanoporous structures often overlooks the vital facet of manufacturing scalability. We propose the preprocessed monomer interfacial polymerization (PMIP) strategy for the scalable fabrication of high-valent cluster-based metal-organic framework (MOF) membranes with robust structures. Using a roll-to-roll device on commercial polymer supports, Zr-fum-MOF membranes are continuously processed at room temperature through the PMIP approach. These large-area membranes demonstrate the preeminent hydrogen separation capabilities, boasting an order of magnitude of permeance and a thrice-enhanced selectivity when juxtaposed with conventional polymeric membranes. The obtained PMIP-Zr-fum-MOF membranes possess superior stability in water compared with interfacial polymerization (IP)-processed low-valent metal-ion-based ZIF-8 membranes. Moreover, we have implemented the PMIP strategy's universality to process the other four diverse MOF membranes. The proposal of PMIP significantly advances the scalable fabrication of water-stable high-valent cluster MOF membranes.

Optical and photo-thermal investigations of MEH-PPV layer spin coated on nano-porous silicon structure

Optical and photo-thermal investigations of MEH-PPV layer spin coated on nano-porous silicon structure

ZIF-67 derived N doped carbon embedded CoxP for superior hydrogen evolution

Abstract Developing a sustainable non-noble hybrid electrocatalyst for effective electrocatalysis is the most crucial task; particularly in sustainable hydrogen energy production in the realm of energy conversion. In this work, effective thermal pyrolysis process followed by phosphorization strategy was employed to prepare and fabricate ZIF-67 (Zeolitic imidazole) assisted Co2P/N doped carbon electrocatalyst for hydrogen evolution reaction (HER). The optimized Co2P/N–C electrocatalyst exhibited hollow porous nanostructures as confirmed from the scanning electron microscopy. The achieved porous nanostructure improved the efficiency of the charge and mass transportation which is confirmed by the BET analysis, has high surface area value of 94.731 m2/g. In addition, a transition metal atom can regulate reactants adsorption and desorption capacity by modulating Co and P electronic configuration. The electrochemical studies of fabricated ZIF-67 derived Co2P/N–C electrode were analyzed using 1.0 M alkaline potassium hydroxide (KOH) medium in 3 electrode system process. Whilst, optimizing the pyrolysis temperature during the phosphorization will remarkably enhance the favourable characteristics of the hydrogen generation. Notably, the optimized ZIF-67 derived Co2P/NC at 350 °C electrode exhibited low overpotential (135 mV) at minimum 10 mA/cm2 and low 120.3 mV/dec Tafel slope. Besides, electrode stability at 10 mA/cm2 current density was verified by chronoamperometry test. Hence, this study furnishes the potential technique for the development of advanced hybrid MOF electrocatalyst as a successful alternative on large scale.

Enhanced electrocatalytic activity by nanoconfinement effects at nanoporous indium tin oxide electrodes

AbstractAmong various strategies to enhance electrocatalytic activity, nanoporous structured electrodes have been widely utilized owing to their improved performance. Along with enlarged electrode surface, modified crystalline facets, and surface defects of nanoporous electrodes, recent studies have reported their unique electrocatalytic characteristics originating from the nanoconfined space, denoted as the nanoconfinement effect. Introducing nanoporous electrodes with controllable thickness made of indium tin oxide, an electrochemically inert material, has provided an optimal platform for analyzing the contribution of nanoporous structures to the catalytic effects. Nevertheless, the scope of reactants that has been studied based on this system so far is mostly limited to ferric/ferrous redox species in sulfate anion environment. Here, using the nanoporous indium tin oxide electrodes, we demonstrate the nanoconfinement effect toward the ferric/ferrous reaction in a different chemical environment that alters its electrokinetic characteristics compared to the previous studies. Furthermore, a complex multi‐electron transfer reaction of oxygen reduction is employed to explore the effects of nanoporous structure toward inner‐sphere reactions. Our work suggests that the nanoconfinement effects can be applied to a wider range of electrochemical reactions taking place in nanoporous electrodes.

Synthesis of Needle-like CoO Nanowires Decorated with Electrospun Carbon Nanofibers for High-Performance Flexible Supercapacitors.

Needle-like CoO nanowires have been successfully synthesized by a facile hydrothermal process on an electrospun carbon nanofibers substrate. The as-prepared sample mesoporous CoO nanowires aligned vertically on the surface of carbon nanofibers and cross-linked with each other, producing loosely porous nanostructures. These hybrid composite electrodes exhibit a high specific capacitance of 1068.3 F g-1 at a scan rate of 5 mV s-1 and a good rate capability of 613.7 F g-1 at a scan rate of 60 mV s-1 in a three-electrode cell. The CoO NWs@CNF//CNT@CNF asymmetric device exhibits remarkable cycling stability and delivers a capacitance of 79.3 F/g with a capacitance retention of 92.1 % after 10,000 cycles. The asymmetric device delivers a high energy density of 37 Wh kg-1 with a power density of 0.8 kW kg-1 and a high power density of 16 kW kg-1 with an energy density of 23 Wh kg-1. This study demonstrated a promising strategy to enhance the electrochemical performance of flexible supercapacitors.

Hydrogel loop-mediated isothermal amplification for ultra-fast diagnosis of Helicobacter pylori in stool samples without nucleic acid extraction

BackgroundThe gastrointestinal diseases caused by Helicobacter pylori (H. pylori) infection made the accurate detection of H. pylori infection more important. Non-invasive methods, such as molecular diagnostic methods, had become a promising method for detection of H. pylori. Stool samples combined with loop-mediated isothermal amplification (LAMP), showed potential practicability for real-time detection. However, complex nucleic acid extraction steps were required to remove the large numbers of amplification inhibitors in stool samples before LAMP reaction. And the limited number of H. pylori made the detection with long reaction time and low sensitivity. The problems mentioned above were urgently to be solved. ResultsIn this study, we proposed a strategy for ultra-rapid sensitive detection of H. pylori in stool samples by hydrogel LAMP (hLAMP) without extraction. The hydrogel was combined with stool samples after simple thermal cracking, and amplification spaces were formed in its nanopore structures by nano-localization. The LAMP reaction was accelerated by nano space-localization. Besides, this method based on hLAMP could specifically and sensitively detect as low as 100 CFU/mL H. pylori within 40 min from sampling to result due to good anti-inhibition effect on complex samples of hydrogel. The whole process involved sample simple disposal for 10 min and LAMP reaction for 30 min. Furthermore, the excellent anti-inhibition mechanism of hydrogel was discussed, and the mechanism of hydrogel accelerating LAMP was explored. SignificanceThis is the first application of that hydrogel and LAMP systematically combined to detect H. pylori in stool samples. The developed method had been verified in actual clinical applications that the accuracy rate reached 88.9% compared with routine histopathology. And it also provided a potential idea for the diagnosis and prevention of H. pylori.

DLC based substrate enabling single molecule detection by Surface Enhanced Raman Spectroscopy (SERS)

This work shows a new and surprising application of Diamond-Like Carbon as Surface Enhanced Raman Spectroscopy (SERS) substrate. It was investigated with the well-known Rhodamine 6G (R6G) as SERS test molecule and extended the detection limit to the astonishing attomolar level, which means single molecule detection. The SERS substrate started by depositing excellent quality Diamond-Like Carbon (DLC) on aluminum, followed by laser modification of the DLC in a delimited area that defines the SERS substrate. The laser action gives electrical conductivity between the scratched surface and the aluminum. Silver was electrodeposited on this delimited area. The high Enhancement Factor was around 5 × 1012 at an R6G concentration of 7 × 10−18 M, observed only at few (and difficult to hit upon) points since the surface density was smaller than 2 R6G molecules/mm2. At each of the larger concentrations tested (7 × 10−15, 7 × 10−12, 7 × 10−9 and 7 × 10−6 M), the Raman intensities were in the same order of magnitude along the whole substrate, indicating a pretty homogeneous sensitivity. The repeatability among 5 samples tested at 7 × 10−12 M showed a standard deviation of only 18 %. The nano porous structure of the silver deposits, shown by Field Emission Gun Scanning Electron Microscopy (FEG-SEM) appears to be like many other studies with electroplated silver. However, the Raman spectra backgrounds show that amorphous carbon is interacting with the silver nanoparticles. A probable explanation for the superior EF is the synergistic contributions of plasmon enhancement from silver and chemical enhancement from amorphous carbon nanostructure.

Multienzyme-mimic Fe single-atom nanozymes regulate infection microenvironment for photothermal-enhanced catalytic antibacterial therapy

The rational design of nanozymes with highly efficient reactive oxygen species (ROS) generation to overcome the resistant infection microenvironment still faces a significant challenge. Herein, the highly active Fe single-atom nanozymes (Fe SAzymes) with a hierarchically porous nanostructure were prepared through a colloidal silica-induced template method. The proposed Fe SAzymes with satisfactory oxidase (OD)-like and peroxidase (POD)-like activity can transform O2 and H2O2 to superoxide anion free radical (•O2-) and hydroxyl radical (•OH), which possess an excellent bactericidal effect. Also, the glutathione peroxidase (GPX)-like activity of Fe SAzymes can consume glutathione in the infection microenvironment, thus facilitating ROS generation to enhance the sterilization effect. Besides, the intrinsic photothermal effect of Fe SAzymes further significantly boosts the enzyme-like activity to generate much more reactive oxygen species for efficient antibacterial therapy. Accordingly, both in vitro and in vivo results indicate that the Fe SAzymes with synergistically photothermal-catalytic performances exhibit satisfactory antibacterial effects and biocompatibility. This work provides new insights into designing highly efficient SAzymes for effective sterilization applications by an amount of ROS generation.

Solvothermally grown Ni4W6O21(OH)2·4H2O films with rice-like and 3D porous nanostructures and their electrochromic properties

Solvothermally grown Ni4W6O21(OH)2·4H2O films with rice-like and 3D porous nanostructures and their electrochromic properties

Simulations of tungsten fuzz growth and erosion under He/Ar mixed plasma irradiation on LP-MIES

Extrinsic noble impurities seeding has been commonly used to reduce the heat flux on divertor target. However, the physical sputtering yield on the target could be obviously enhanced due to larger mass of noble impurities. On the other hand, it has been reported that tungsten fuzz can suppress the physical sputtering due to the trapping effect on sputtered particles. Hence, it is interesting to check the erosion behaviors of tungsten fuzz under the irradiation of noble impurities. Recently, experiments of He/Ar mixed plasma irradiation on W target were conducted on LP-MIES device. Dedicated simulations have been performed by SURO-FUZZ code to study the impact of Ar flux on fuzz growth and erosion, which can well reproduce the experimental measurements on LP-MIES. For the case of pure He incidence, the growth of porous nanostructure leads to an obvious reduction in the fraction of the implanted He particles, which stabilizes to 15 % when the fuzz layer thickness exceeds 1500 nm. For He/Ar mixed plasma irradiation, the dependence of the position of the net sputtering on the local porosity has been investigated in detail. It is found that the net physical sputtering mainly occurs in the regions with the local porosity larger than 0.6.

High-performance insulating materials with high breakdown strength and low permittivity for eco-friendly electrical equipment

High-performance insulating materials are essential for developing lightweight, compact, and green offshore wind power equipment. It has been shown that nanoporous structures can limit the development of electron avalanche, leading to a significant increase in the breakdown electric strength of dielectrics. Hence, we fabricated a polysiloxane nanoporous biopolymer insulating material (PNBIM) with the nanoporous structure that presents exceptionally high electrically insulating properties. Under a CO2 atmosphere, the breakdown electric strength of the PNBIM was remarkably improved, exhibiting 761.01 % enhancement relative to that of the pure gas gap. Moreover, the PNBIM demonstrates excellent dielectric performance, with a low dielectric constant (1.63) and dielectric loss (0.014), as well as high hydrophobicity and excellent thermal stability. The investigations revealed that the nanopores inside the material can effectively suppress gas discharge and improve the breakdown electric strength. This study widens our understanding of conventional insulating materials and provides a promising approach for exploring high-performance insulating materials provide valuable insights.

Tailored Design of a Nanoporous Structure Suitable for Thick Si Electrodes on a Stiff Oxide-Based Solid Electrolyte.

Oxide-based all-solid-state batteries are ideal next-generation batteries that combine high energy density and high safety, but their realization requires the development of interface bonding technology between the stiff solid electrolyte and electrode. Even if the interface could be bonded, it is difficult to hold the interface, because only the electrode expands/contracts unilaterally during charge/discharge reactions. In particular, silicon (Si), which has eagerly awaited as a next-generation negative-electrode material for many years, changes in volume by several hundred percent. To solve these problems, in this work, highly porous silicon oxide (SiOx) electrodes with different porous structures were fabricated on a stiff garnet-type Li7La3Zr2O12 solid electrolyte, the three-dimensional nanoporous structure was analyzed quantitatively, and the charge/discharge characteristics were investigated. The microscopic observation and electrochemical analysis revealed how we should control the porous structure, such as sizes of pores and SiOx, size distribution, and porosity, for repeated and stable charge/discharge cycles. In addition, the resultant porous SiOx electrodes demonstrated superior charge/discharge cycle performance even when it thickened to 5 μm, whereas non-porous SiOx easily peeled off from the solid electrolyte when its thickness exceeded 0.1 μm. The thick SiOx films greatly improved the energy density per unit area (mAh cm-2). Nanosized fine pores with an interconnected open-pore architecture effectively mitigated the internal and interfacial stress upon expansion (charge)/contraction (discharge) of Si, and as a result, the thick and porous SiOx electrode maintained the interfacial joint with the stiff solid electrolyte after repeated charge/discharge cycles. These results will provide useful insights for effectively designing more practical porous SiOx powder effectively.

Melamine-based nanoscale porous organic frameworks as multifunctional separator modifiers to mitigate the polysulfide shuttle effect in lithium–Sulfur batteries

The shuttling of polysulfides between electrodes in lithium-sulfur (Li-S) batteries significantly impairs cycle stability. This study explores the use of melamine-based nanoscale porous organic frameworks (POFs) as polysulfide reservoirs to modify glass fiber (GF) separators. Melamine was reacted with dibromoalkanes of varying carbon chain lengths (n = 4, 8, and 12) to produce a series of POF materials, POF-Cn, with different nanoscale pore sizes and solubilities. The POF composites, POF-Cn/SP/PVP, which include conductive carbon Super P (SP) and a polyvinylpyrrolidone (PVP) binder, were coated onto GF membranes to create modified separators for Li-S batteries. Batteries with these modified GF separators exhibited higher initial capacities, improved rate performance, and better long-term cycle stability compared to those with non-modified separators. Among the POF composites, POF-C8/SP/PVP exhibited the best performance, with an initial specific capacity of 1392 mAh g-1 at 0.1C and a high capacity retention of 90% after 300 cycles at 0.5C. The enhanced capacity, stability, and rate performance are attributed to the nanoporous structure of POF-C8 and its high nitrogen content, which effectively traps soluble LiPSs and reduces their diffusion toward the Li anode. The good solubility of POF-C8 facilitates uniform dispersion in the modifying layer, promoting efficient polysulfide trapping and maximizing their utilization in electrochemical reactions, aided by the conductive SP in the composite.

Synergistic role of dual-metal sites (Ag–Ni) in hexagonal porous g-C3N4 nanostructures for enhanced photocatalytic CO2 reduction

Harnessing solar energy to convert CO2 into hydrocarbon fuels presents a viable strategy for mitigating CO2 emissions. For effective photocatalytic CO2 reduction (PCR), it is crucial to optimize both photoinduced and chemical reactions synergistically. In this research, hexagonal porous g-C₃N₄ (CN) nanostructures with Ag–Ni dual metal site loadings were synthesized using a hydrothermal method followed by calcination, significantly enhancing PCR efficiency. The optimal results demonstrated significant production rates of 77.65 μmol/g for CO and 17.89 μmol/g for CH4, showcasing exceptional photocatalytic performance. This enhanced performance is attributed to several factors: the high porosity of the g-C₃N₄, the synergistic effects at the Ag–Ni dual metal sites, and the increased surface area. Detailed experimental measurements, coupled with comprehensive density functional theory (DFT) calculations, have elucidated the mechanisms underlying the significant improvements in the photocatalytic activity of the developed catalyst. This study not only demonstrates an effective approach for converting CO₂ into valuable hydrocarbon fuels but also significantly advances our understanding of complex photocatalytic systems, providing insights that could guide future developments in this field.

Hierarchical Bifunctional NiO Electrocatalyst: Highly Porous Structure Boosting the Water Splitting Activity.

The development of an efficient, low-cost and earth-abundant electrocatalyst for water splitting is crucial for the production of sustainable hydrogen energy. However their practical applications are largely restricted by their limited synthesis methods, large overpotential and low surface area. Hierarchical materials with a highly porous three-dimensional nanostructure have garnered significant attention due to their exceptional electrocatalytic properties. These hierarchical porous frameworks enable the fast electron transfer, rapid mass transport, and high density of unsaturated metal sites and maximize product selectivity. Here the process involved obtaining monodispersed microrod-shaped Ni(OH)2 through a hydrothermal reaction, followed by a heat treatment to convert it into hierarchical microrod-shaped NiO materials. N2 sorption analysis revealed that the BET surface area increased from 9 to 89 m2/g as a result of the heat treatment. The hierarchical microrod-shaped NiO materials demonstrated outstanding bifunctional electrocatalytic water splitting capabilities, excelling in both HER and OER in basic solution. Overpotential of 347 mV is achieved at 10 mA/cm2 for OER activity, with a Tafel slope of 77 mV/dec. Similarly, overpotential of 488 mV is achieved at 10 mA/cm2 for HER activity, with a Tafel slope of 62 mV/dec.

Magnesium oxide nanoparticle reinforced pumpkin-derived nanostructured cellulose scaffold for enhanced bone regeneration

Considering global surge in bone fracture prevalence, limitation in use of traditional healing approaches like bone grafts highlights the need for innovative regenerative strategies. Here, a novel green fabrication approach has reported for reinforcement of physicochemical performances of sustainable bioinspired extracellular matrix (ECM) based on decellularized pumpkin tissue coated with Magnesium oxide nanoparticles (hereafter called DM-Pumpkin) for enhanced bone regeneration. Compared to uncoated scaffold, DM-Pumpkin exhibited significantly improved surface roughness, mechanical stiffness, porosity, hydrophilicity, swelling, and biodegradation rate. Obtained nanoporous structure provides an ideal three-dimensional microenvironment for the attachment, migration and osteo-induction in human adipose-derived mesenchymal stem cells (h- AdMSCs). Calcium deposition and mineralization, alkaline phosphatase activity, and SEM imaging of the cells as well as increased expression of bone-related genes after 21 days incubation confirmed capability of DM-Pumpkin in mimicking the biological properties of bone tissue. The presence of MgONPs had a silencing effect on inflammatory factors and improved wound closure, verified by in vivo studies. Increased expression of collagen type I and osteocalcin in the h- AdMSCs cultured on DM-Pumpkin compared to control further corroborated gained results. Altogether, boosting physicochemical and biological properties of DM-Pumpkin due to surface modification is a promising approach for guided bone regeneration.

Fabrication of a bimodal micro/nanoporous copper cladding layer by the high-speed laser cladding and dealloying

The Cu30Mn70 cladding layer was prepared by high-speed laser cladding technology and successfully combined with chemical dealloying method to prepare a bimodal micro/nanoporous copper coating. The 0.1 M HCl solution was experimentally determined as the dealloying solution. During the dealloying, the Mn-rich regions were preferentially corroded and formed micron pores in situ; the remaining regions served as a framework to form nanoporous structures on both sides. With increasing time, the transformation of the nanoporous structure led to micron ligaments thinning or fracture, resulting in the structural collapse of the bimodal microporous/nanoporous copper coating surface. Repeated oxidation-dissolution processes on the surface accelerate the structural collapse of the surface and inhibit the demanganization layer thickness growth. The same structure was formed in the cross-sectional direction, with no structural collapse due to continuous H+ consumption and low corrosivity in the micropores. The bimodal microporous/nanoporous copper coatings remained highly porosity and rapidly increased in thickness to 340 μm from 24 to 72 h. After 72 h, the surface structure started to collapse and the growth of the demanganization layer thickness slowed down.

Biogenic synthesis of porous CuO nanoparticles: Synergistic effects in photocatalytic dye degradation and electrochemical energy storage applications

This study explores the biogenic synthesis of CuO nanoparticles functionalized with Solanum nigrum, using Acalypha indica leaf extract as a reducing agent. The biogenically synthesized CuO nanoparticles were comprehensively characterized by various analytical techniques, involves X-ray diffraction analysis (XRD), BET surface area analysis (BET), energy-dispersive X-ray spectroscopy (EDAX), X-ray photoelectron spectroscopy (XPS), UV–Visible spectral analysis (UV), Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, photocatalytic degradation, antimicrobial assay, cytotoxicity assay, electrochemical analysis, and linear sweep voltammetry studies. The XRD analysis revealed end centered monoclinic phase with a 10 nm average crystalline size. BET analysis showed a mesoporous structure with a surface area of 11.54 m2/g. XPS and EDAX confirmed the presence of Cu2+ and O2− ions. SEM and TEM images indicated spherical, and porous nanostructures. UV–Visible spectroscopy identified an active optical range of 508–518 nm (2.40–2.45 eV), suggesting potential photocatalytic activity. The photocatalytic degradation efficiencies of Methylene blue (98.8 %) and Rhodamine B (95 %) were achieved after 100 min of irradiation. Antimicrobial tests demonstrated effectiveness against Staph. aureus, E. coli, Shigella flexneri, and Candida tropicalis. The nanoparticles exhibited notable cytotoxicity against colorectal cancer cells with IC50 values of 58.66 μg/ml and 66.78 μg/ml. Additionally, a symmetric supercapacitor electrode using these nanoparticles achieved a specific capacitance of 375 Fg−1 at the current density of 1 Ag−1. This research underscores the versatile applications of biogenic CuO nanoparticles in photocatalysis, antimicrobial treatments, cancer therapy, and energy storage.

MnO2-decorated flexible carbon nanofibers with controllable hierarchical porous nanostructures for high energy density supercapacitors

Constructing hierarchical porous structures and reducing material size enhance the electrochemical efficiency of porous carbon-based electrodes. In this study, ultrafine hierarchical porous carbon-based nanofibers were synthesized via electrospinning a blend of polyacrylonitrile, polymethyl methacrylate (PMMA), and zinc acetate dihydrate (ZAH), followed by pre-oxidation, carbonization, and acid washing. Adjusting the ZAH content allowed precise control of fiber diameters (300-600nm) and promoted significant hierarchical porous structures, achieving an optimal mesopore to micropore ratio (1.65) and a high specific surface area (SSA) of 599 m²/g. MnO2 nanosheets were in-situ modified on the carbon nanofibers, forming a hybrid electrode (MnO2@HPCNFs) with excellent flexibility, high SSA value, and rich pore structure. This electrode demonstrated a specific capacitance value equal to 1035 F/g at 0.5 A/g and maintained 80.7% capacitance at 10 A/g. The assembled asymmetric supercapacitor achieved an energy density of 54.81 Wh/kg. This study presents new possibilities for binder-free, self-supporting electrodes in electrochemical energy storage devices.