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Polycaprolactone (PCL) is one of the promising linear aliphatic polyesters which can be used as mulching film. Although it has suitable glass transition temperature and good biodegradability, further practical applications are restricted by the limited temperature-increasing and moisturizing properties. The rational design of the PCL structure is a good strategy to enhance the related properties. In this study, thermally-induced phase separation (TIPS) was introduced to fabricate a PCL nanoporous thin film. The introduction of a nanoporous structure on the PCL surface (np-PCL) exhibited enhanced temperature-increasing and moisturizing properties when used as mulch film. In detail, the average soil temperature of np-PCL was increased to 17.81 °C, when compared with common PCL of 17.42 °C and PBAT of 17.50 °C, and approaches to PE of 18.02 °C. In terms of water vapor transmission rate, the value for np-PCL is 637 gm−2day−1, which was much less than the common PCL of 786 and PBAT of 890 gm−2day−1. As a result, the weed biomass under the np-PCL was suppressed to be 0.35 kg m−2, almost half of the common PCL and PBAT. In addition, the np-PCL shows good thermal stability with an onset decomposition temperature of 295 °C. The degradation mechanism and rate of the np-PCL in different pH environments were also studied to explore the influence of nanoporous structure. This work highlights the importance of the nanoporous structure in PCL to enhance the temperature-increasing and moisturizing properties of PCL-based biodegradable mulching film.

In this work, a polypropylene (PP) porous film was made-up by melt electrospinning. The fibrous film was coated by a superthin layer of silicon dioxide (SiO2) gel. The surface morphology of the SiO2 gel was decoded by scanning electron microscopy and atomic force microscopy. The SiO2 gel interface with film, as well as its crystallinity, were characterized by Fourier transform infrared spectroscopy, energy dispersive spectroscopy, and X-ray diffraction. The PP composite film's thermomechanical properties were studied through thermal shrinkage, thermal gravimetric analysis, dynamic mechanical analysis, and an Instron tensile machine with a heating chamber. The results showed that the coated SiO2 gel network could effectively reduce the PP film's thermal shrinkage by 48.5% without change of crystallinity. The coated SiO2 gel is capable of enlarging the decomposition temperature range and the storage modulus of the PP film. Meanwhile, it was discovered that, along with the increase of measured temperature, the loads on both pure PP film and PP/SiO2 gel film decreased under a constant strain, or the tensile strain of both of them was enhanced under the same load. The solid gel network endows the PP electrospun film with relatively higher thermal safety.

Fraction-controlled Pt–Cu-based porous films were prepared using an electrochemical deposition–stripping synthetic approach, and their structure, composition, and electronic structure were characte...

Background and Aims: Hexanoyl (Hx:C6) group-modified alkaline-treated gelatin porous film (HAG) is a newly developed degradable hydrogel characterized by strong adhesiveness and high affinity for vascular endothelial growth factor (VEGF). The aim of this study was to clarify the effect of HAG sheets on the healing process of post-endoscopic submucosal dissection (ESD) porcine gastric artificial ulcers. Methods: (1) To evaluate the adhesiveness of HAG sheets over time, we performed ESD to create 1 artificial ulcer and covered the lesion with 1 HAG sheet using 1 miniature swine. We observed 2 ulcers by endoscopic and microscopic examinations. (2) To examine the effect of HAG sheets on post-ESD ulcer healing, we performed ESD using 5 miniature swine. The artificial ulcers were covered with HAG sheets, or left uncovered after ESD (day 0), followed by macroscopic and microscopic examinations. On days 7 and 14, we observed 2 ulcers by endoscopic examinations. On day 14, the animals were sacrificed, and histological examination was performed on the 3 stomachs that could be extirpated. Results: (1) On day 7, adhesion of HAG sheets was observed. (2) Gastric ulcer area on day 7 was significantly larger in the covered ulcers than in the non-covered ulcers (p = 0.046). On day 14, although there was no significant difference in ulcer area irrespective of covering (p = 0.357), the covered ulcers tended to repair less fold convergence than non-covered ulcers. The covered ulcer sheets significantly decreased inflammatory cell infiltration (p = 0.011), but significantly increased the abundance of macrophages (p = 0.033), in submucosal layers. Also, the abundance of alpha-smooth muscle actin-positive cells in submucosal layers of the covered ulcers was significantly reduced (p = 0.044), leading to a decrease in collagen accumulation. In addition, fibrosis and atrophy of the muscularis propria were significantly lower for covered ulcers than for non-covered ulcers. Furthermore, microvessels and VEGF-positive cells were significantly more abundant in the submucosal layers of the covered ulcers (p < 0.001 and p = 0.024, respectively). Conclusions: HAG sheets induced post-ESD ulcer healing with less submucosal inflammation and muscularis propria injury and have the potential to decrease excess scarring.

The application of thermoelectric films is limited to retain the temperature gradient. In this study, the Bi-Te films are deposited on the AAO template with a pore size of 100 nm using thermal evaporation. The results show that the conductive types of the Bi-Te film are tuned by source temperature. The power factor of the p-type porous film decreases 36% by comparing to that of the p-type nonporous film (1020 μW/mK2 at 250 °C). Meanwhile, the temperature difference in the porous device is maintained and is approximately 5.0 °C. Thus, the maximum output power is achieved in the porous device (about 25 pW), which is 5 times higher than that of the nonporous device. This provides a method to improve the conversion efficiency of thermoelectric film device by maintaining the temperature difference by using porous structure.

Nanostructuring of metals is nowadays considered as a promising strategy towards the development of materials with enhanced electrochemical performance. Porous and fully dense CuNi films were electrodeposited on a Cu plate by electrodeposition in view of their application as electrocatalytic materials for the hydrogen evolution reaction (HER). Porous CuNi film were synthesized using the hydrogen bubble template electrodeposition method in an acidic electrolyte, while fully dense CuNi were electrodeposited from a citrate-sulphate bath with the addition of saccharine as a grain refiner. The prepared films were characterized chemically and morphologically by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The Rietveld analysis of the XRD data illustrates that both CuNi films have a nanosized crystallite size. Contact angle measurements reveal that the porous CuNi film exhibits remarkable superhydrophobic behavior, and fully dense CuNi film shows hydrophilicity. This is predominately ascribed to the surface roughness of the two films. The HER activity of the two prepared CuNi films were investigated in 1 M KOH solution at room temperature by polarization measurements and electrochemical impedance spectroscopy (EIS) technique. Porous CuNi exhibits an enhanced catalysis for HER with respect to fully dense CuNi. The HER kinetics for porous film is processed by the Volmer–Heyrovsky reaction, whereas the fully dense counterpart is Volmer-limited. This study presents a clear comparison of HER behavior between porous and fully dense CuNi films.

The breath-figure method using the condensation of water droplets can easily fabricate regular porous films. Although the method is simple, the phenomenon itself requires the control of man...

It is well known that molecular structure has great influence on the porous structure prepared by breath figures. However, the effect of graft architecture on porous structure from graft copolymer is unclear. Here, the cellulose-based graft copolymers with different graft architectures were synthesized and the highly ordered porous films were facilely prepared by breath figure method. The effects of graft architecture with four different structural parameters on porous structure were systematically investigated. It was found that the pore size increased with the increasing graft chain length, main chain length or molecular weight, while the pore size decreased with the increasing graft density under other similar structural parameters. The shorter main chain and the higher graft density resulted in the smaller pore size. Moreover, the shorter main chain was more beneficial for the formation of highly ordered porous structure than the longer main chain. These results will help to understand the effect of graft architecture on porous structure and regulate pore size by adjusting the graft architecture.

This work shows the effectiveness of using biocomposites based on nonwoven fibrous materials for the treatment of cancer. Polyhydroxybutyrate nonwoven materials were obtained by electrospinning. Hydroxyapatite was introduced into the interior of the fibers, and a porous film was created on the surface of the nonwoven material. Both the types of matrices included the anticancer drug endoxan. It was shown that the fiber-based matrices have a low endoxan release rate, while the film-coated matrices are characterized by a high rate of endoxan release.

Asymmetric multi-layered porous films were prepared by casting inverse emulsion following the breath figure method. The porous morphologies both on the surface and in the bulk of the fabricated film could be dynamically manipulated by tuning the emulsion composition as well as the environmental conditions. The model drug was efficiently loaded into the porous film by direct encapsulation during film fabrication, and remarkable sustained drug release from the porous film for more than 28 days was achieved.

Self-assembled monolayers (SAMs) are emerging as materials that are candidates of barriers used in back-end-of–line interconnects of integrated circuits for future generations. In this study, SAMs were formed on the SiO2 and porous SiOCH (p-SiOCH) films by using decyltrimethoxysilane (DTMOS) precursor in vapor phase at a temperature of 100 °C. The effects of the formation of SAMs at the surfaces of SiO2 and p-SiOCH films on the electrical characteristics were characterized and compared. With O2 plasma irradiation, SAMs could successfully form on both SiO2 and p-SiOCH films, thereby enhancing the adhesion and dielectric breakdown field. In the p-SiOCH films, SAMs sealed the surface pores and had higher coverage, promoting the effectiveness of the Cu barrier. In the Cu/porous low-k integrated interconnects for advanced technological nodes, therefore, SAMs are promising emerging materials acting as a barrier and adhesive. On the other hand, for SiO2 films, SAMs weakened the barrier; however, they can act as an interfacial adhesion enhancer.

Journal of Metals, Materials and Minerals, 31, 1, 81-87

Eu3+ doped porous nanostructured SrTiO3 films and powder fabricated by sol-gel route without using any precursor template are characterized by different morphology and phase composition. The films and the power show red and yellow luminescence with the most intensive photoluminescence (PL) bands at 612 nm and 588 nm, respectively. Raman, secondary ion mass spectrometry (SIMS), and X-ray diffraction (XRD) analysis of undoped nanostructured porous SrTiO3 films showed the presence of TiO2, SrO, and SrTiO3 phases and their components. The undoped porous SrTiO3 films are photosensitive and demonstrate resistive switching. The capacitance-voltage hysteresis loops with the width of about 6 V in the frequency range of 2 kHz—2 MHz were observed.

For efficient electrolysis of water for hydrogen generation or other value-added chemicals, it is highly relevant to develop low-temperature synthesis of low-cost and high-efficiency metal sulfide electrocatalysts on a large scale. Herein, we construct a new core-branch array and binder-free electrode by growing Ni

We report here the preparation of porous single-crystal GaN films by direct top-down high temperature nitridation of β-Ga2O3. It is found that, although the crystallographic orientations of the original β-Ga2O3 samples are different, the GaN films converted from both bulk (200) β-Ga2O3 single crystal and (−201) β-Ga2O3 film have the same (0002) orientation and show no obvious stress. And we also found that the crystal quality of converted GaN strongly depends on the crystal quality of β-Ga2O3. In particular, we have successfully converted β-Ga2O3 film entirely to single-crystal GaN porous film on sapphire, and the self-separation happens naturally between the porous GaN film and sapphire.

Background The Tessari method, mixing air with the sclerosant through a 3-way tap and 2 syringes, is the most widely used method to prepare foam in foam sclerotherapy. Uniform foam with smaller bubbles has great clinical significance for venous insufficiency. We aim to modify the traditional 3-way tap to produce more uniform and stable foam with smaller bubbles. Methods The traditional 3-way tap was modified by inserting a porous film within its channel. Experiment design: the foam was prepared with 2 mL polidocanol plus 8 mL air plus 0.05 mL hyaluronic acid; group 1, foam prepared with 20 quick passes through a traditional 3-way tap; and groups 2–7, foam prepared using the modified 3-way tap, with 10, 12, 14, 16, 18, and 20 quick passes, respectively. The uniformity of the foam was observed under optical microscopy, and the size of bubbles quantified using the Nano measurement software. The stability of the foam was evaluated using the foam half-life time. Results The foam half-life times of groups 1–7 were 306.4, 257.4, 285.6, 304.4, 318.6, 330.2, 331.3 sec, respectively. The modified tap also produced a more uniform distribution of smaller bubbles (group 7) compared with traditional tap (group 1). Conclusions Modified 3-way tap enhanced the stability of the sclerosant foam, with a more uniform distribution of smaller bubbles.

This work focused on a fabrication of smart membranes using a novel grafting method comprising of plasma peroxide technique together with microwave-assisted polymerization. PNIPAm, thermo-responsive polymer, both with and without crosslinker, were grafted onto porous Nylon-6 membranes. Key parameters for grafting including the microwave irradiation time, output power, and monomer concentration have been investigated. Characterizations using scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) revealed that the PNIPAm have been successfully grafted onto the surface both on the top surface of the membrane and the surface inside the pores. Irradiation time of 10 min under 800 w were found to be an optimum condition which gave the highest yield of 10 wt%. For both the linear and crosslinked PNIPAm-grafted membranes, the highest grafting yield was obtained from using 3 wt% of NIPAm monomer solution. Because of this fast fabrication time and environmentally friendly method, new smart gating membranes can be produced which will help providing an ever-better performances transport control of gas and liquid for various fields including medical and packaging applications.

Polyvinylidene f luoride porous films containing through channels have been prepared for the first time. The films have been obtained via melt extrusion followed by annealing, uniaxial extension, and thermal fixation. Uniaxial extension has been carried out in two stages (“cold” and “hot” drawing) at room and elevated temperature, respectively. The effect of orientation efforts during formation of the porous structure of films on the overall porosity, permeability for liquids, the content of piezoactive β- phase in the crystalline part of sample, and piezo modulus d31 has been studied. The formation of through channels occurs via a percolation mechanism at the overall porosity of 23%. Under uniaxial extension of films, the pore formation competes with the polymorphic α → β transition. The conditions of porous film preparation allowing one to attain the maximum through permeability and piezo modulus values have been determined.

The volatilization, migration and contamination of lubricating fluids has seriously affected the durability of slippery liquid-infused porous surfaces (SLIPSs) and greatly limited their applications. To solve these problems, a stable solid slippery surface composed of paraffin wax and a porous film is reported in this work. Several liquid droplets with different surface tensions can slide on the surface without stain. Compared with SLIPSs, this solid slippery surface exhibits outstanding stability, even when immersed in different pH solutions and contacted with other materials. Significantly, the solid slippery surface can rapidly self-heal from physical damage during the heating–cooling process. The lowest self-healing temperature can be adjusted by tuning the percentage of paraffin wax and liquid paraffin. This work gives a new insight for dealing with the challenges of SLIPSs.

Porous films of metals and metal oxides exhibit larger surface areas and higher reactivities than those of dense films. Therefore, they have gained growing attention as potential materials for use in various applications. This study reports the use of a modified direct current magnetron sputtering method to form porous Zn-ZnO composite films, wherein a subsequent wet post-oxidation process is employed to fabricate pure porous ZnO films. The porous Zn-ZnO composite films were initially formed in clusters, and evaluation of their resulting properties allowed the optimal conditions to be determined. An oxygen ratio of 0.3% in the argon gas flow resulted in the best porosity, while a process pressure of 14 mTorr was optimal. Following deposition, porous ZnO films were obtained through rapid thermal annealing in the presence of water vapor, and the properties and porosities of the obtained films were analyzed. An oxidation temperature of 500 °C was optimal, with an oxidation time of 5 min giving a pure ZnO film with 26% porosity. Due to the fact that the films produced using this method are highly reliable, they could be employed in applications that require large specific surface areas, such as sensors, supercapacitors, and batteries.

In-situ monitoring of CO2 corrosion of carbon steel and FeCO3 precipitation, under continuous replenishing of condensed water conditions, was investigated using a newly developed electrochemical probe. Comparable results were obtained using electrochemical and non-electrochemical methods that validated the design and efficacy of the probe for monitoring corrosion processes such as those that occur in top-of-the-line corrosion. Electrochemical impedance spectroscopy (EIS) combined with cross-sectional analysis identified three stages of corrosion and film formation, namely; active dissolution, formation of a porous film and formation of a more protective film. The protective film consisted of two layers, an inner layer containing a mixture of FeCO3 and Fe3C and an outer layer of FeCO3. During the three stages of corrosion, the corrosion rate increased with time to a maximum value which then declined to minimum values that remained steady with time.

Recent literature has evinced a keen interest in porous electrodes. Numerous applications have been discussed and some aspects of the voltammetry investigated, a theoretical description of adsorption- and desorption processes though remains largely absent. The present study fills this important gap and provides a detailed analysis of the impact of adsorption on voltammetric electrode responses in porous materials. It is shown that in some cases, adsorption- and desorption processes may aid the detection of analytes while in other cases a planar unmodified electrode is superior in performance. Finally practical conclusions are drawn for the design of future experimental systems.

Humidity-resistant antireflective (AR) porous films with ultralow refractive indices were prepared via an one-step sol–gel process by assembly of methylated hollow silica nanospheres (HSNs). The hydrophobicity and refractive indices of silica-based AR porous films could be varied between 66.0° and 115.0°, and between 1.08 and 1.14, respectively, by tuning the MTES/TEOS molar ratios. A possible assembly mechanism was proposed according to the microstructure of methylated HSNs and porous films. The various properties of silica-based AR porous films were investigated and the AR porous film could demonstrate a good AR capability of 97.6% and excellent humidity resistance.

Over the past few years, researchers have made numerous breakthroughs in the field of aluminum anodizing and faced the problem of the lack of adequate theoretical models for the interpretation of some new experimental findings. For instance, spontaneously formed anodic alumina nanofibers and petal-like patterns, flower-like structures observed under AC anodizing conditions, and hierarchical pores whose diameters range from several nanometers to sub-millimeters could be explained neither by the classical field-assisted dissolution theory nor by the plastic flow model. In addition, difficulties arose in explaining the basic indicators of porous film growth, such as the nonlinear current–voltage characteristics of electrochemical cells or the evolution of hexagonal pore patterns at the early stages of anodizing experiments. Such a conceptual crisis resulted in new multidisciplinary investigations and the development of novel theoretical models, whose evolution is discussed at length in this review work. The particular focus of this paper is on the recently developed electroconvection-based theories that allowed making truly remarkable advances in understanding the porous anodic alumina formation process in the last 15 years. Some explanation of the synergy between electrode reactions and transport processes leading to self-organization is provided. Finally, future prospects for the synthesis of novel anodic architectures are discussed.

Colloidal quantum dots (CQDs) are emerging as ideal building blocks for the development of sensitive and low-cost gas sensors because of their large surface area and solution processability. So far, the construction of CQD gas sensor is limited to lab-scale, batch-processing methods such as spin coating. Here, we demonstrated highly sensitive and fast-response CQD gas sensors through a room-temperature spray-coating route in ambient air. Unlike the spin-coating process, a porous film morphology could be achieved by the spray-coating of ultrasmall PbS CQDs (4.0 nm in diameter) on the alumina ceramic substrates, possibly explaining their superior gas-sensing performance. Moreover, we investigated the effect of the dispersing solvent on the spray-coated PbS CQD films and found that organic solvents with lower boiling point were preferred in producing porous and sensitive CQD films. The response of the optimal gas sensors toward 50 ppm of NO2 at room temperature was high as 44, with response and recovery times short as 1 s and 28 s, respectively. The enhanced gas-sensing capabilities, coupled with the promise for mass production at room temperature, make the spray-coated CQD gas sensors very attractive in the future gas-sensing technology.

Results of optical investigations of the isotropic-nematic and nematic-smectic A phase transitions in porous polyethyleneterephthalate (PET) films filled with octyl-cyanobihenyl (8CB) liquid crystal (LC) are reported. Samples of porous films of thickness 23 µm with normally oriented cylindrical pores of a radius R ranging from 10 nm to 1000 nm were prepared using the track-etched membrane technology. The dynamic light scattering method was used to probe the nematic orientational fluctuations of confined LC samples. The corresponding relaxation time τ was measured as a function of R and temperature T at slow enough cooling rates (0.3–0.6 K/h) to locate the phase transition temperatures. Changes in τ(T) dependencies relatively sensitivity fingerprint the LC phase transformations. Experimental results are analysed using the Landau-de Gennes-Ginzburg phenomenological approach.

Tin (II) sulfide (SnS) films have been deposited on glass substrates by oblique angle deposition (OAD) technique. The structural properties of the prepared samples were investigated by using XRD, Raman, and FESEM characterization techniques. The optical properties of the specimens were studied by UV–Vis spectroscopy technique. The photosensitivity properties of the samples were measured by red and amber lights with different intensities. The OAD technique was found able to reduce the response time of the samples from 2.15s to 0.69s for the amber light, and from 3.59s to 1.49s for the red light. Besides, a significant reduction in the decay time of the specimens was found from 12.21s to 8.48s and from 11.18s to 8.77s for amber and red lights, respectively.

Al and Al alloys are used for many purposes, e.g. automobiles, heat exchanger, electronics, because of their good properties such as lightness, high heat conductivity, good processability, hardness, and so on. However, corrosion protection of these materials are not so high, corrosion of Al, such as pitting corrosion and atmospheric corrosion, will occur during operation. From this, some kinds of surface treatments are needed for improvement of corrosion protection of Al used for long-term. A polymeric coating is one of popular technique to improve the corrosion protection of substrate metal. However, corrosion protection of substrate covered by polymeric coating will easily lose by mechanical damage of the coating, leading to exposure of substrate metal to surroundings and to the local corrosion of substrate under damaged area of coating. From above, new surface treatment techniques for Al substrate to keep high corrosion protection, even the surface was damaged, are developed in our research group. This is a coating, with self-healing property by dispersion of micro-capsules containing the healing agent of coating. When the coating is damaged, the healing agent flow out to the damaged area of coating and react with water vapor to form the self-healing structure and this can be covered to the damaged area of coating. However, the procedure of synthesis of micro-capsule containing healing agent is too complex and yield of this is too low to synthesize the capsules with low cost. From above, we start to develop the new type of self-healing coating. This coating can be formed on Al alloy anodized. As you know by anodic oxidation of Al alloy, electrochemically in some kind of acidic solution, porous type of anodic oxide film can be formed on Al alloy, which have many small pores arranged regularity. Pores of porous film are used as a container of healing agent of coating. Firstly, the pores in porous film formed on Al alloy were filled by healing agent. And then, this sample was covered by polyurethane coating. If this coating was damaged, mechanically, healing agent contained in pores of porous film, flow out to the damaged area and reaction with water to form polyurea as a self-healing structure and cover to the exposed Al substrate. In this study, healing property of this type of self-healing coating is investigated by observation of the surface of specimen with scratchin. #1050 Al alloy (size : 20 mm × 20 mm × 1.5 mmt) were electro-polished in CH3COOH / HClO4solution. And then anodic oxide films were formed on pretreated specimens by anodizing in (COOH)2 solution with a constant current density of 200 Am-2 for 1 hr. The anodized specimens immersed in IPDI for 100 min with ultrasonic bath, in order to promote that IPDI soln. to penetrate to pores of the porous film. After wiping the surface of the specimen by soft tissue, then a mixed solution of ethylene glycol and prepolymer of polyurethane coating was purged to specimen surface and leave for 24 h to form the polyurethane coating on anodized Al alloy surface. The prepolymer was synthesized by using the mixture of TDI, glycerol and cyclohexanone. Mixture was agitated under 600 rpm of stirring rate for 24 h. In order to remove the water dissolved in this mixture, the first 1 h of agitation, the mixture was bubbled by passing pure N2 gas. During the agitation, TDI reacts with glycerol to form the precursor of polyurethane. After specimen damaged by scratching with 7 N of load and ageing, corrosion protection of damaged Al alloy specimens with polyurethane coating were evaluated by immersion tests. The coated specimens were immersed to CuSO4 / KCl solution kept at room temperature for 1 day. After the immersion tests, to remove the coating, the specimens were immersed to the coating remover solution. And then, specimens were immersed to H3PO4 / K2CrO4 solution. Surfaces after immersion tests and removing of surface layer were observed by scanning electron microscopy (SEM). From the SEM observation for damaged specimen covered with porous film and normal coating, as shown in Fig. 1-a, sharp and deep scar can be seen at the canter of image of specimen surface. The scar can be seen on the image of damaged specimen with self-healing coating on anodized specimen, however, unique structure also can be observed at the bottom of scar, shown in Fig .1-b. This structure may be formed by the reaction between water in air and IPDI contained in the pore of porous film on Al alloy, thus, this coating has a self-healing property. Figure 1

Oxygen reduction reaction (ORR) is a critical process in many emerging energy technologies, such as fuel cells and metal-air batteries, determining the energy conversion efficiency of devices.However, the complex electron transfer pathways involved in the oxygen-oxygen (O-O) bond cleavage makes ORR kinetically sluggish. Platinum (Pt)-based materials are the state-of-the-art ORR catalysts due to their proper surface electronic structures toward efficient cleavage of O-O bond. However, the high cost and limited natural availability of Pt severely hinder its large-scale commercial application for ORR. Even though many Pt-free catalysts have been claimed in recent years as alternatives to Pt, their ORR performances and production costs still can not really compete with Pt. Hence, it is of vital importance but very challenging to develop efficient ORR catalysts with low Pt loading. In this work, we used O2 bubbles as gaseous templates to fabricate PtNi nanoporous films with ultra-low Pt loading, which could be achieved through controlling oxygen evolution reaction (OER) during the programmable synthesis process. The rationally designed nanoporous PtNi catalysts have selectively exposed Pt (111) facets with ultra-low Pt loading (0.015 mg cm-2) for ORR. We discovered that the adsorbed O2 bubbles on the Pt surfaces act as protection agents, preventing Pt oxidation and dissolution. As a result, the enriched Pt (111) facets are preferentially exposed on the surface of PtNi PFs, showing superior ORR activity to other low-Pt catalysts.

We prepared microporous aramid films through a simple, inexpensive and green way, using ionic liquids (IL) as porosity promoters. Commercial poly(m-phenylene isophthalamide) (MPIA) films with different IL proportions were prepared, and then microporous films were obtained by removing the IL in distilled water. Microporous films presented density values between 0.34 and 0.71 g⋅cm (around five times lower to commercial MPIA), with a homogeneous and controlled cellular morphology dependent on the proportion of the IL, showing cell sizes in the microcellular range (radii between 1 and 8 µm). Thermal, mechanical and electrical properties (specifically ionic conductivity) of the aramid films were analyzed to evaluate the influence of the IL proportion. Finally, it was observed that the MPIA/IL system presented a reversible thermally induced phase-separation process around 60 °C, which was characterized through AFM-Raman images and spectra, together with the variation of the ionic conductivity., The financial support provided by FEDER (Fondo Europeo de Desarrollo Regional) and both the Spanish Agencia Estatal de Investigación (MAT2017-84501-R) and the Consejería de Educación- Junta de Castilla y León (BU306P18) is gratefully acknowledged.

Journal of Metals Materials and Minerals, 29, 4, 106-112

Highly-uniform In2O3/CuO bilayer and multilayer porous thin films were successfully fabricated using a self-assembled soft template and a simple sputtering deposition technique. The sensor based on the In2O3/CuO bilayer porous thin film shows obviously improved sensing performance to ethanol at a lower working temperature, compared to its single layer counterpart sensors. The response of the In2O3/CuO bilayer sensors exhibit nearly 3 and 5 times higher performance than those of the single layer In2O3 and CuO porous film sensors over the same ethanol concentration, respectively. The sensing mechanism based on the p-n hetero-junction, which contributed to the enhanced sensing performance, was also experimentally confirmed by a control experiment in which an SiO2 insulation layer was inserted between the In2O3 and CuO layers to break the p-n junction. In addition, the sensing performance can be further enhanced by increasing the number of In2O3/CuO junction layers. The facile process can be easily extended to the fabrication of other semiconductor oxide gas sensors for practical sensing applications.

Nanostructures like a piece of porous film with an array of nanoholes have many interesting properties with the existence of surface plasmon resonance. In this paper we use numerical simulation method to calculate the electric field and phase properties in near and far fields of a metal nanohole array. The effect of SPP on the near-field polarization state was found in the results. We also introduced a ring array structure which has a higher normalized transmission rate and two transmission peaks. In which we observed the existence of polarization singularities and the topology of the surrounding electric field is also determined.

Polyoxometalates (POMs) were used, together with chitosan (CS), to obtain hybrid nanoaggregates. Three representative POMs were efficiently assembled into nanoparticles of few hundred nm diameter, featuring entangled ribbons substructure. In order to establish suitable preparation and stability conditions, the assemblies were characterized in solution by UV-Vis spectroscopy, dynamic light scattering and ζ-potential. The nanoparticles were tested against E. coli (106 CFU/ml) in aqueous solution, showing a synergic activity of the heteropolyacid H5PMo10V2O40 and CS. For such components, a highly porous and antibacterial film was obtained upon lyophilisation of the colloidal mixture., European Union's Seventh Framework Programme (246039); MIUR (FIRB) (prot. RBAP11ETKA)