Lower Degradation Rate Research Articles

Improved photocatalytic performance of SrTiO3 through a Z-scheme polymeric-perovskite heterojunction with g-C3N4 and plasmonic resonance of Ag mediator

A polymeric-perovskite heterostructure of SrTiO3/g-C3N4 modified by Ag nanoparticles was synthesized through a co-precipitation process in order to prepare a novel photocatalyst. In-depth analysis of the structural, optical, and morphological properties confirmed that the incorporation of g-C3N4 nanosheets and Ag nanoparticles into the host structure narrowed the band gap from 3.18 to 2.87 eV, reduced the mean particle size from 70 to 48 nm, increased the mean pore size and the specific surface area, in addition to modifying the electronic band structure. Using response surface methodology (RSM), the optimum experimental parameters for photocatalytic activity were determined to be a dye concentration of 11.2 mg/L, an irradiation time of 47 min, and a photocatalyst dosage of 1.23 g/L. The SrTiO3/g-C3N4/Ag photocatalyst shows a high photocatalytic activity by complete degradation of methylene blue (MB) dye under visible light irradiation. Following the scavenger test, the h+, •O2–, and •OH radicals are all essential to dye degradation. Rhodamine-B (RhB) and methyl orange (MO) dyes showed a lower degradation rate as compared with MB and dye. The experimental evidence supported the proposal of a Z-scheme charge transfer pathway for the photodegradation of organic dyes.

Electrochemical impedance analysis and degradation behavior of a Ni-GDC fuel electrode containing single cell in direct CO2 electrolysis

The challenges of high degradation rate and significant carbon deposition, which are common with Ni-YSZ electrodes, have shifted attention to other electrode materials with enhanced performance in SOECs using carbon-containing fuels. In this study, the performance and electrochemical behavior of the Ni-GDC fuel electrode under CO2 electrolysis were investigated. The study was performed over a range of operating conditions, varying the operating temperature, the CO2 content of the fuel gas as well as the oxygen partial pressures in the oxygen electrode gas. Long-term stability test was performed up to 1070 h at 900 °C and a current density of − 0.5 A‧cm−2. The electrochemical impedance spectra obtained from the various measurement were evaluated with DRT as well as an equivalent circuit model consisting of 4 time-constant; (LR-RQ1-RQ2-RQ3-Ws). The low frequency Warburg (short) element (Ws) was attributed to gas diffusion and surface processes at the fuel electrode, the mid frequency processes of RQ2 and RQ3 are assigned to the combined contribution of fuel and oxygen electrode. The high frequency RQ1 was assigned to the charge transfer process at the oxygen electrode. A low degradation rate of 31 mV‧Kh−1 was observed during the long-term stability test. Furthermore, analysis of the degradation rate illustrates that significant contributions to the degradation were from the mid and high frequency processes, in addition to ohmic resistance. SEM analysis of the measured cell shows agglomeration of Ni particles, increase in electrode porosity as well as Ni migration away from the electrode/electrolyte interface.

Co-Sintering of Spinel-Based Coating/Contact Dual-Layer Structure for Solid Oxide Fuel Cell Cathode-Side Application

A coating/contact dual-layer structure is fabricated via co-sintering in simulated interconnect/coating/contact/cathode test cells. Two different precursors are utilized to form Mn1.25Co1.75O4 and Ce-doped Mn1.25Co1.75O4 spinel coatings, while a mixture of Mn oxide and Co metal powders is employed as the contact material. After thermal conversion into a dense coating and a porous contact layer at 900 °C in air simultaneously, both test cells exhibit excellent electrical performance during the 1500-h area-specific resistance (ASR) measurement at 800 °C, due to the unique dual-layer structure via co-sintering. The cell with Ce-containing coating precursor shows better cell ASR behavior and lower degradation rate. Cross-sectional observation of the tested cells is conducted to assess the compatibility of the dual-layer structure with adjacent components as well as its effectiveness in inhibiting chromia scale growth and blocking Cr migration from the interconnect to the cathode.

Low protease activity in B cell follicles promotes retention of intact antigens after immunization.

The structural integrity of vaccine antigens is critical to the generation of protective antibody responses, but the impact of protease activity on vaccination in vivo is poorly understood. We characterized protease activity in lymph nodes and found that antigens were rapidly degraded in the subcapsular sinus, paracortex, and interfollicular regions, whereas low protease activity and antigen degradation rates were detected in the vicinity of follicular dendritic cells (FDCs). Correlated with these findings, immunization regimens designed to target antigen to FDCs led to germinal centers dominantly targeting intact antigen, whereas traditional immunizations led to much weaker responses that equally targeted the intact immunogen and antigen breakdown products. Thus, spatially compartmentalized antigen proteolysis affects humoral immunity and can be exploited.

Evaluation of Selected Cellulose Macromolecular Properties after Its Chemical Treatment Using Size Exclusion Chromatography.

This work evaluates the effect of using selected inorganic chemicals as the main components of waterborne wood preservative systems on the degradation of the cellulose constituent in wood from model samples. The polymeric properties of cellulose and the homogeneity of the degradation process primarily reflect very well the degree of cellulose deterioration. Whatman papers, as pure cellulose model samples, were impregnated with 10 different 5 wt% solutions of inorganic salts and distilled water and consequently subjected to wet-thermal accelerated aging (T = 85 °C, RH = 65%, for 30 days). The samples were then derivatized to cellulose tricarbanilates (CTCs) through two different procedures (by precipitation in a methanol-water mixture/by evaporation of pyridine from the reaction mixture) and finally analyzed using size exclusion chromatography (SEC). Chemically treated and aged cellulose samples showed different changes in the degree of polymerization (DP) and polydispersity (PD) in terms of untreated non-aged standard caused by different ongoing degradation reactions, such as dehydration, hydrolysis, oxidation, and crosslinking. In general, the lowest degradation rate after treatment by chemicals and after accelerated aging was observed in samples treated by borates, NaCl, and ZnSO4·7H2O. The greatest depolymerization after treatment and after accelerated aging was caused by sulphates containing NH4+, Cu2+, and Fe3+ cations, with aging by NH4Cl and (NH4)2HPO4-treated samples also leading to significant depolymerization. The higher DP values are linked to the precipitated method of CTC preparation, though not for chlorides and phosphates. PD is also generally higher in precipitated and aged samples and is heavily influenced by the presence of low molecular weight products. This paper brings new insights regarding the complex evaluation of the polymeric properties of degraded cellulose by considering all important factors affecting the sample and the analysis itself through the use of statistics. From the statistical point of view, the influences of all factors (solution, aging, method) and their interactions (except aging*method) on DP are statistically significant. The influence of the sample processing method used for analysis of the desired results becomes important mainly in practice. This work recommends the evaporation method for more accurate description of more degraded cellulose.

The influence of sulfur impurities in industrial COx gases on solid oxide electrolysis cell (SOEC) degradation

High-temperature solid oxide cells (SOC) offer unrivaled Faradaic and energetic efficiencies during carbon dioxide electrolysis. However, it is still unclear which gas quality and impurity level is required for low degradation rates in their commercial application. Here, it is shown that the polarization resistance of electrolyte-supported cells (ESC) with Ni/Gadolinia-doped ceria (Ni/CGO) degrades strongly over time periods of up to 72 h when operated in CO/CO2 gas mixtures. X-ray photoemission spectroscopy (XPS) and high-resolution secondary ion mass spectrometry (SIMS) imaging techniques were used to show that this degradation effect is related to sulfur impurities in the feed gas and their poisoning of the Ni surface. Variation of the inlet gas composition showed that impurities are present in both CO and CO2. The degradation was significantly less pronounced for Ni/CGO fuel electrodes compared to Ni/Yttria-stabilized zirconia (YSZ) and also when hydrogen was introduced into the feed gas. Generic natural gas cleaning desulfurization units were not able to remove the impurities from the feed gases. After initial electrode deactivation, stable cell performance was obtained for >900 h. The results clearly underline the importance of feed gas purity and the necessity for advanced cleaning units for the commercialization of high-temperature CO2 electrolysis.

Development of 3D-Printed, Biodegradable, Conductive PGSA Composites for Nerve Tissue Regeneration.

Nerve conduits are used to reconnect broken nerve bundles and provide protection to facilitate nerve regeneration. However, the low degradation rate and regeneration rate, as well as the requirement for secondary surgery are some of the most criticized drawbacks of existing nerve conduits. With high processing flexibility from the photo-curability, poly (glycerol sebacate) acrylate (PGSA) is a promising material with tunable mechanical properties and biocompatibility for the development of medical devices. Here, polyvinylpyrrolidone (PVP), silver nanoparticles (AgNPs), and graphene are embedded in biodegradable PGSA matrix. The polymer composites are then assessed for their electrical conductivity, biodegradability, three-dimensional-printability (3D-printability), and promotion of cell proliferation. Through the four-probe technique, it is shown that the PGSA composites are identified as highly conductive in swollen state. Furthermore, biodegradability is evaluated through enzymatic degradation and facilitated hydrolysis. Cell proliferation and guidance are significantly promoted by three-dimensional-printed microstructures and electrical stimulation on PGSA composites, especially on PGSA-PVP. Hence, microstructured nerve conduits are 3D-printed with PGSA-PVP. Guided cell growth and promoted proliferation are subsequently demonstrated by Schwann cell culture combined with electrical stimulation. Consequently, 3D-printed nerve conduits fabricated with PGSA composites hold great potential in nerve tissue regeneration through electrical stimulation.

The combined effect of zinc and calcium on the biodegradation of ultrahigh-purity magnesium implants

Magnesium (Mg)-based implants are promising candidates for orthopedic interventions, because of their biocompatibility, good mechanical features, and ability to degrade completely in the body, eliminating the need for an additional removal surgery. In the present study, we synthesized and investigated two Mg-based materials, ultrahigh-purity ZX00 (Mg–Zn–Ca; <0.5 wt% Zn and <0.5 wt% Ca, in wt%; Fe-content <1 ppm) and ultrahigh-purity Mg (XHP-Mg, >99.999 wt% Mg; Fe-content <1 ppm), in vitro and in vivo in juvenile healthy rats to clarify the effect of the alloying elements Zn and Ca on mechanical properties, microstructure, cytocompatibility and degradation rate. Potential differences in bone formation and bone in-growth were also assessed and compared with state-of-the-art non-degradable titanium (Ti)-implanted, sham-operated, and control (non-intervention) groups, using micro-computed tomography, histology and scanning electron microscopy. At 6 and 24 weeks after implantation, serum alkaline phosphatase (ALP), calcium (Ca), and Mg level were measured and bone marrow stromal cells (BMSCs) were isolated for real-time PCR analysis. Results show that ZX00 implants have smaller grain size and superior mechanical properties than XHP-Mg, and that both reveal good biocompatibility in cytocompatibilty tests. ZX00 homogenously degraded with an increased gas accumulation 12 and 24 weeks after implantation, whereas XHP-Mg exhibited higher gas accumulation already at 2 weeks. Serum ALP, Ca, and Mg levels were comparable among all groups and both Mg-based implants led to similar relative expression levels of Alp, Runx2, and Bmp-2 genes at weeks 6 and 24. Histologically, Mg-based implants are superior for new bone tissue formation and bone in-growth compared to Ti implants. Furthermore, by tracking the sequence of multicolor fluorochrome labels, we observed higher mineral apposition rate at week 2 in both Mg-based implants compared to the control groups.Our findings suggest that (i) ZX00 and XHP-Mg support bone formation and remodeling, (ii) both Mg-based implants are superior to Ti implants in terms of new bone tissue formation and osseointegration, and (iii) ZX00 is more favorable due to its lower degradation rate and moderate gas accumulation.

Effectiveness of Opuntia ficus-indica mucilage as a carrier agent in microencapsulation of bioactive compounds of Amaranthus hypochondriacus var. Nutrisol

The effectiveness of maltodextrin (10%) and cactus mucilage (CM) (0%, 0.25%, 0.50%, 0.75%, and 1%) as carrier agents was evaluated in the encapsulation of bioactive amaranth compounds. Spray drying, an efficient encapsulation method, achieved high yields (62.9%–68%). The increase in CM concentration significantly augmented the water absorption index (WAI), bulk density, and hygroscopicity of the encapsulated amaranth powders. Conversely, it significantly decreased the moisture content, water activity, and water solubility index (WSI). The glass transition temperatures (>40 °C), Hausner ratio (HR), and Carr's index (CI) values indicated the suitability of powders for handling and processing. Moreover, no cracks were observed in the microcapsules surface, which favoured the bioactive amaranth compounds retention and stability. Thus, low degradation rate constants and long half-life time values were determined for the encapsulated amaranth powders, indicative of its storage appropriateness. Incorporation of 0.75% CM was an efficient concentration to achieve high percentage retention of betacyanins (55.5%), betaxanthins (58%), total polyphenols (73.3%), amaranthine (56.8%), isoamaranthine (62.7%), individual polyphenols (44.6%–81%), and antioxidant activity (79.6%). These results demonstrated the efficiency of CM as an encapsulating agent in the food industry.

Preparation and performance of random- and oriented-fiber membranes with core-shell structures via coaxial electrospinning.

The cells and tissue in the human body are orderly and directionally arranged, and constructing an ideal biomimetic extracellular matrix is still a major problem to be solved in tissue engineering. In the field of the bioresorbable vascular grafts, the long-term functional prognosis requires that cells first migrate and grow along the physiological arrangement direction of the vessel itself. Moreover, the graft is required to promote the formation of neointima and the development of the vessel walls while ensuring that the whole repair process does not form a thrombus. In this study, poly (l-lactide-co-ε-caprolactone) (PLCL) shell layers and polyethylene oxide (PEO) core layers with different microstructures and loaded with sodium tanshinone IIA sulfonate (STS) were prepared by coaxial electrospinning. The mechanical properties proved that the fiber membranes had good mechanical support, higher than that of the human aorta, as well as great suture retention strengths. The hydrophilicity of the oriented-fiber membranes was greatly improved compared with that of the random-fiber membranes. Furthermore, we investigated the biocompatibility and hemocompatibility of different functional fiber membranes, and the results showed that the oriented-fiber membranes containing sodium tanshinone IIA sulfonate had an excellent antiplatelet adhesion effect compared to other fiber membranes. Cytological analysis confirmed that the functional fiber membranes were non-cytotoxic and had significant cell proliferation capacities. The oriented-fiber membranes induced cell growth along the orientation direction. Degradation tests showed that the pH variation range had little change, the material mass was gradually reduced, and the fiber morphology was slowly destroyed. Thus, results indicated the degradation rate of the oriented-fiber graft likely is suitable for the process of new tissue regeneration, while the random-fiber graft with a low degradation rate may cause the material to reside in the tissue for too long, which would impede new tissue reconstitution. In summary, the oriented-functional-fiber membranes possessing core-shell structures with sodium tanshinone IIA sulfonate/polyethylene oxide loading could be used as tissue engineering materials for applications such as vascular grafts with good prospects, and their clinical application potential will be further explored in future research.

3D-printed PLA-Gr-Mg composite scaffolds for bone tissue engineering applications

3D porous PLA-graphite composite scaffolds are recently introduced as promising candidates in tissue engineering practices owing to their significantly enhanced mechanical strength in comparison with pure PLA. However, they mainly suffer from low degradation rate as well as undesirable hydrophobic surface. In this regard and to address such challenges, Mg particles, as one of the lightest metallic fillers, were added to PLA-graphite scaffolds via the fused deposition modeling (FDM) technique. The obtained results indicated that introduction of 1 wt% Mg inhibited polymeric chain mobility of PLA, and hence, increased the glass transition temperature. Also, Mg particles behaved as nucleating agents, thus crystallization temperature was decreased. Compression and tensile tests demonstrated an enhanced trend in strength with the incorporation of Mg. Notably, the hydrophobic surface of PLA-graphite scaffold changed to a hydrophilic surface with the addition of Mg, which also led to a higher degradation rate of Mg-incorporated PLA-graphite composite scaffolds. The obtained results indicated the beneficial effects of Mg in tackling the challenges of PLA-graphite scaffolds for bone tissue applications.

Two-Phase Extraction Processes, Physicochemical Characteristics, and Autoxidation Inhibition of the Essential Oil Nanoemulsion of Citrus reticulata Blanco (Tangerine) Leaves

Combined ultrasound-microwave techniques and pre-enzymatic treatment (hemicellulase and cellulase) enhance essential oil isolation from Citrus reticulata Blanco (tangerine) leaves (CrBL). Subsequently, synergistic effects of modified amorphous octenyl succinic anhydride starch (OSA-MS), almond oil, and high-energy microfluidics were studied in synergy with ultrasound techniques in the production of CrBL essential oil (CrBL-EO) nanoemulsion (CrBL-EONE). GC-MS was used to study the extraction technique. Dynamic light scattering (DLS) analysis was used with confocal laser scanning microscopy (CLSM) techniques to investigate the nanoemulsion matrices' physical and chemical properties. The D-limonene nanoemulsion (D-LNE) reached the optimal size of droplets (65.3 ± 1.1 r.nm), polydispersity index (PDI) (0.167 ± 0.015), and ζ-potential (-41.0 ± 0.4 mV). Besides, the CrBL-EONE obtained the optimal size of droplets (86.5 ± 0.5 r.nm), PDI (0.182 ± 0.012), and ζ-potential (-40.4 ± 0.8 mV). All the nanoparticle treatments showed significant values in terms of the creaming index (CI%) and inhibition activity (IA%) in the β-carotene/linoleate system with a low degradation rate (DR). The current study's findings showed that integrated ultrasound-microwave techniques and pre-enzymatic treatment could enhance the extraction efficiency of the CrBL-EO. In addition, OSA-MS and almond oil can also be employed to produce CrBL-EONE and D-LNE.

Heterologous expression of β-alanine betaine biosynthesis gene increases &lt;i&gt;Nicotiana tabacum&lt;/i&gt; resistance to abiotic stresses

Plant genetic modification in order to increase their tolerance to various abiotic stresses has been of exceptional importance in recent years. Heterologous expression of glycine betaine (GB) biosynthetic genes leads to increased salt and drought tolerance in various plant species by maintaining the osmotic balance with the environment and stabilizing the quaternary structure of complex proteins. However, GB biosynthesis in transgenic plants is limited by choline availability. Members of the Plumbaginaceae family accumulate -alanine betaine (AB) instead [1]. The synthesis of AB is not limited by the availability of choline, as it follows the methylation pathway of the aproteinogenic amino acid -alanine.&#x0D; For the first time, we have generated Nicotiana tabacum plants expressing the -alanine N-methyltransferase (LlBANMT) gene of Limonium latifolium. Transgenic plants were much less affected by such abiotic stresses as increased salinity, excessive illumination, and low temperature. The experimental Nicotiana tabacum lines had lower rates of chlorophyll degradation under stress conditions compared to the control plants. LlBANMT expression also resulted in less biomass loss under stress conditions, which was associated with higher activities of reactive oxygen species detoxification systems and healthier cell membranes. The presented data demonstrate for the first time the protective properties of LlBANMT heterologous expression and shed light on the mechanisms of its action.

Fabrication and characterization of electrospun GelMA/PCL/CS nanofiber composites for wound dressing applications

In the present study, the effect of different ratios of GelMA concentration has been exhibited for wound dressing implementation by the electrospinning method using a new polymer combination of Gelatin methacrylate (GelMA)/Polycaprolactone (PCL)/Chitosan (CS). The nanofiber composites were fabricated due to their biocompatible, biodegradable, improved mechanical strength, low degradation rate, and hydrophilic nature to develop cell-mimicking, cell adhesion, proliferation, and differentiation. Different concentrations of GelMA were added to the PCL/CS solution as 5, 10, and 20 wt%, respectively, in the formic acid/acetic acid (7:3) solution. A photoinitiator was added to the solution for photo-crosslinking of GelMA. The influence of different solution concentrations (5, 10, and 20 wt%) on the structure’s nanofiber production and fiber morphology was examined. SEM micrographs revealed that varied GelMA concentrations resulted in suitable and stable nanofiber composites. The average diameter of nanofiber composites grows as the GelMA concentration rises. FTIR, DSC, tensile test, degradation, and swelling test were evaluated. The results demonstrated that high mechanical strength, hydrophilic properties, and a slow degradation rate were observed with the presence and increment of GelMA concentration within the nanofiber composites. The antibacterial potential of GelMA/PCL/CS nanofiber composites was evaluated against P. aeruginosa and S. aureus using a disc diffusion assay. In vitro cell culture research was conducted by seeding NIH 3T3 fibroblast cells on nanofiber composites, proving these cells’ high cell proliferation rate, viability, and adhesion. 10 wt% GelMA-based nanofiber composites were found to have great potential for wound dressing applications.

Production of 3D Printed Bi-Layer and Tri-Layer Sandwich Scaffolds with Polycaprolactone and Poly (vinyl alcohol)-Metformin towards Diabetic Wound Healing.

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by impaired insulin secretion, sensitivity, and hyperglycemia. Diabetic wounds are one of the significant complications of T2DM owing to its difficulty in normal healing, resulting in chronic wounds. In the present work, PCL/PVA, PCL/PVA/PCL, and metformin-loaded, PCL/PVA-Met and PCL/PVA-Met/PCL hybrid scaffolds with different designs were fabricated using 3D printing. The porosity and morphological analysis of 3D-printed scaffolds were performed using scanning electron microscopy (SEM). The scaffolds' average pore sizes were between 63.6 ± 4.0 and 112.9 ± 3.0 μm. Molecular and chemical interactions between polymers and the drug were investigated with Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Mechanical, thermal, and degradation analysis of the scaffolds were undertaken to investigate the physico-chemical characteristics of the scaffolds. Owing to the structure, PCL/PVA/PCL sandwich scaffolds had lower degradation rates than the bi-layer scaffolds. The drug release of the metformin-loaded scaffolds was evaluated with UV spectrometry, and the biocompatibility of the scaffolds on fibroblast cells was determined by cell culture analysis. The drug release in the PCL/PVA-Met scaffold was sustained till six days, whereas in the PCL/PVA-Met/PCL, it continued for 31 days. In the study of drug release kinetics, PCL/PVA-Met and PCL/PVA-Met/PCL scaffolds showed the highest correlation coefficients (R2) values for the first-order release model at 0.8735 and 0.889, respectively. Since the layered structures in the literature are mainly obtained with the electrospun fiber structures, these biocompatible sandwich scaffolds, produced for the first time with 3D-printing technology, may offer an alternative to existing drug delivery systems and may be a promising candidate for enhancing diabetic wound healing.

Electrochemical and degradation behaviour of single cells comprising Ni-GDC fuel electrode under high temperature steam- and co-electrolysis conditions

The present study investigates the electrochemical performance and degradation behaviour of a Nickel - Gd2O3 doped CeO2 (Ni-GDC) electrode containing single cell under steam electrolysis and co-electrolysis modes. The cell consists of the Ni-GDC fuel electrode, an 8 mol% Y2O3 stabilized ZrO2 (8YSZ) electrolyte layer, a GDC barrier layer and a (La,Sr)(Co,Fe)O3 (LSCF) oxygen electrode. Firstly, the electrolyte-supported single cells were fabricated and characterized using DC- and AC-techniques in the 750–900 °C temperature range. Distribution of relaxation times (DRT) analysis was employed to resolve frequency-dependent electrode processes. The observed processes were further modelled using an equivalent circuit model (ECM) with 3 R//CPE (resistor//constant phase element) in series with a finite length diffusion element (Warburg short - Ws). Long-term stability tests of the single cells were carried out under steam electrolysis (H2O:H2, 50:50) and co-electrolysis (H2O:CO2:CO, 40:40:20) conditions at 900 °C with −0.5 A‧cm−2 current density for 500 h. Steam electrolysis conditions exhibit the highest degradation rate of 499 mV‧kh−1, while a lower degradation rate of 308 mV‧kh−1 is observed under co-electrolysis conditions. The post-test analysis of the operated cell shows increased Ni particles size, suggesting Ni agglomeration in both electrolysis modes.

Multilayered hydrocarbon ionomer/PTFE composite electrolytes with enhanced performance for energy conversion devices

A new multilayered composite membrane was prepared by impregnating a sulfonated poly(arylene ether sulfone) (SPAES) ionomer into a porous polytetrafluoroethylene (PTFE) substrate for application in proton exchange membrane fuel cells (PEMFCs) and water electrolyzers (PEMWEs). The PTFE substrate was treated with n-propyl alcohol to mediate the interfacial interactions between the SPAES solution and PTFE. Using the 10- and 5-μm-thick PTFE substrates, three-layered and five-layered composite membranes were prepared, respectively, to investigate the effect of PTFE thickness on impregnation of the SPAES ionomer. When 5-μm-thick PTFE was applied, the SPAES ionomer was effectively impregnated without noticeable defects, indicating a strong interlocking structure between the two incompatible components. Therefore, the five-layered composite membrane showed enhanced dimensional stability and mechanical properties compared to the SPAES membrane, and the effect of the PTFE on proton conductivity was minimized. Consequently, the cell performances of the five-layered composite membrane were reflected by current densities of 1.71 A/cm2 at 0.5 V and 9.76 A/cm2 at 1.9 V for PEMFC and PEMWE, respectively, corresponding to 44% and 32% increases compared to those of Nafion 212, owing to its smaller membrane resistance. Moreover, the prepared composite membrane presented excellent durability, which resulted in stable wet-dry cyclability and low degradation rates.

The Preparation of N-Doped Titanium Dioxide Films and Their Degradation of Organic Pollutants.

N-doped TiO2 films supported by glass slides showed superior photocatalytic efficiency compared with naked TiO2 powder due to them being easier to separate and especially being responsive to visible light. The films in this study were prepared via the sol-gel method using TBOT hydrolyzed in an ethanol solution and the nitrogen was provided by cabamide. The N-doped TiO2 coatings were prepared via a dip-coating method on glass substrates (30 × 30 × 2 mm) and then annealed in air at 490 °C for 3 h. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis. The doping rate of N ranged from 0.1 to 0.9 (molar ratio), which caused redshifts to a longer wavelength as seen in the UV-vis analysis. The photocatalytic activity was investigated in terms of the degradation of phenol under both UV light and visible light over 4 h. Under UV light, the degradation rate of phenol ranged from 86% to 94% for all the samples because of the sufficient photon energy from the UV light. Meanwhile, under visible light, a peak appeared at the N-doping rate of 0.5, which had a degrading efficiency that reached 79.2%, and the lowest degradation rate was 32.9%. The SEM, XRD and UV-vis experimental results were consistent with each other.

Tailoring the Durability of Carbon-Coated Pd Catalysts Towards Hydrogen Oxidation Reaction (HOR) in Alkaline Media

For the hydrogen oxidation reaction (HOR), platinum group metal (PGM) catalysts are still the norm, and their large initial catalytic activity is counterbalanced by their uncertain durability in alkaline environments: harsh degradations proceed, like detachment and agglomeration of metallic nanoparticles from the carbon support, as witnessed from dedicated accelerated stress tests (AST). Herein, a strategy to increase such catalysts’ durability is provided, using carbon layers surrounding the Pd-based carbon-supported nanoparticles. The robustness of such catalysts, baring 0.5- or 0.7-nm-thick carbon cap over the Pd nanoparticles, is evaluated from AST combined with several pre/post-test characterization techniques: identical location transmission electron microscopy (IL-TEM), ex situ X-ray photoelectron spectroscopy (XPS) and ex situ inductively coupled plasma mass spectrometry (ICP-MS). The carbon layer protection limits the Pd-based nanoparticles’ agglomeration, detachment, and metal leaching, improving long-term catalyst durability in HOR-like operation. Thicker carbon layers surrounding the Pd nanoparticles lead to higher materials durability and lower degradation rate (larger performance stability) upon AST, compared to thinner carbon layers. In addition, the carbon-capped catalysts enable to maintain better the required Pd/PdO state of the surface that is essential for fast HOR, resulting in superior intrinsic HOR activity versus unprotected Pd/C. Overall, this work demonstrates that the activity-durability relationship can be tuned for carbon-capped catalysts.Graphical Abstract

Eco-sustainable design of humic acids-doped ZnO nanoparticles for UVA/light photocatalytic degradation of LLDPE and PLA plastics

The mismanagement of plastics is associated with high levels of waste and release into the environment, where they can persist for long times due to the low degradation rate. Photocatalytic methods, based on the action of Reactive Oxygen Species (ROS) generated by semiconductor materials, are promising eco-friendly and low-cost process for the plastics degradation. Here, eco-designed Humic Acids-doped/ZnO nanoparticles were synthesized via solvothermal route and tested as photocatalysts for the degradation of linear low-density polyethylene (LLDPE) and polylactic acid (PLA) thin films, under UVA/light irradiation. LLDPE is one of the most common commercial polymers widely used in packaging field wherein PLA is also broadly used to replace conventional plastics. The combination of analytical techniques allowed to define the structure-property-function relationships of the hybrid nanomaterials and to monitor the chemical, structural and morphological changes occurring on the polymeric films as a consequence of the photodegradation. Experimental results demonstrated the validity of this eco-sustainable approach to realize hybrid photocatalysts with enhanced ROS-generating ability suitable for an improved photo-oxidation of plastics in aqueous environment.