Degradation Mechanism Research Articles

Electrochemical performance of three-dimensional porous Sn/Cu3Sn/CuO/SnO composite as anode material for lithium-ion batteries

Sn is used as an anode material in lithium-ion batteries due to its high theoretical capacity, conductivity, and safety. However, due to the huge volume change during charging and discharging, it suffers serious mechanical degradation, and the capacity rapidly decays. In this study, a simple and feasible strategy was used to electroplate Sn on Cu foam, followed by heat treatment to obtain Sn composite anodes (Sn/Cu3Sn/CuO/SnO). The composite anode served to mitigate the volumetric expansion that was a consequence of the lithiation–delithiation process. It also prevented electrode pulverization and ensured that the overall integrity of the electrode was maintained, thereby enhancing its electrochemical performance. The capacity of the electrode reached 653.56 mAh/g at a current density of 0.2 C after 300 charge-discharge cycles. Thus, the prepared composite materials had a high capacity and long-term cyclic stability.

The use of chain extenders as processing aids in the valorization of single-use polylactide (PLA) products by rotomolding

Biodegradable plastics in single-use products have increased in popularity as a way to reduce the negative environmental impact of conventional plastics and meet the tightening law regulations. However, their recyclability needs to be assessed, as the environmental behavior of single-use plastics, even if compostable, is not negligible. Polylactide (PLA) is susceptible to thermal, oxidative, hydrolytic, and mechanical degradation during reprocessing, so the conditions of such cycles must be accurately controlled. The necessity of using additives to reduce such degradations during rotational molding, a process with long cycle times and oxidizing atmosphere, has been demonstrated. Chain extenders based on a carbodiimide (Bioadimide® 100 - KI), a methylene diphenyl diisocyanate (MDI), and a polystyrene-acrylic copolymer (Joncryl® ADR-4368c - J) have been added to post-consumer PLA wastes. It has been demonstrated that these three chain extenders enabled obtaining a higher molecular weight of the reprocessed polymer, compared to the ∼50% reduction for the neat PLA. The use of carbodiimide yielded the most similar performance to that of unprocessed raw material. All samples provided adequate thermal stability and processing parameters for the rotational molding. Carbodiimide is considered the most efficient additive, as it increases the molecular mass of the polymer as it remains unchanged after processing. Similarly, KI-modified PLA rheological behavior remains unchanged after processing, which means this compound can reduce thermooxidative and hydrolytic degradation reactions. Thus contributing to the achievement of improved processability and better performance; in particular, impact strength increased from 1.06 ± 0.56 for PLA to 8.12 ± 2.28 kJ/m2 for KI-modified PLA, and toughness of 5.36 ± 1.61 to 61.49 ± 8.01 J/mm3, respectively, leading to rotomolded items without structural defects. On the opposite, the use of Joncryl® and MDI led to structural defects in the rotomolded parts despite a higher molecular weight of the polymer, which resulted in poor mechanical properties, although better than PLA without any additive. All three chain extenders resulted in an amorphous PLA structure with increased glass transition temperature and improved thermal stability, which correlated with the reduced emissions of volatile compounds compared to neat recycled PLA. The presented findings significantly contribute to a better understanding of PLA and its modifications at a molecular scale required for its efficient and possibly environmentally burden-free reprocessing. Gathered knowledge will be crucial for optimizing its environmental performance and widening its applications, particularly in a process with long cycle times and oxidative character, such as rotational molding.

Enhanced mechanism of AO7 degradation by electrochemical activation of persulfate at carbon felt and electrogenerated H2O2 carbon black-modified cathodes in divided cell

Enhanced mechanism of AO7 degradation by electrochemical activation of persulfate at carbon felt and electrogenerated H2O2 carbon black-modified cathodes in divided cell

Photocatalyst for Antibiotics Degradation by In Situ Growth of Direct Z-Type Bi2S3/Bi4Ti3O12 Heterojunction.

Effective removal of antibiotics from aqueous solutions has emerged as a hot research topic in wastewater treatment. Photocatalytic degradation of antibiotics is one of the most effective methods to reduce ecological damage and environmental pollution. In this work, a novel photocatalyst consisting of Z-type heterojunction Bi2S3/Bi4Ti3O12 (BS/BTO) with visible light responses was prepared by an in situ growth method, and the obtained material was used for the degradation of tetracycline hydrochloride (TC). The best performing photocatalyst was BS/BTO-2, which exhibited high photocatalytic activity. The rates of TC degradation reached 97.9% within 40 min of illumination. The photocatalyst demonstrated a high stability and reproducibility even after 5 cycles. Electron spin resonance (EPR) tests and quenching experiments established that ·O2- and h+ were the main species responsible for the elimination of TC. On the basis of theoretical calculations and experimental data, a possible mechanism for the photocatalytic degradation of TC has been proposed. The heterojunction structure, which effectively increases the visible light absorption range and decreases the compounding efficiency of photogenerated electrons and holes, is principally responsible for the photocatalytic performance of BS/BTO. Additionally, liquid chromatography-mass spectrometry (LC-MS) was utilized to investigate the formation and degradation of reaction intermediates. The nontoxicity of the solution after tetracycline degradation was verified by cultivating wheat seeds. This work offers guidance for bismuth-based photocatalysts in the field of sustainable wastewater treatments.

Mechanism of unactivated peroxymonosulfate-induced degradation of amino-G acid: Kinetics and transformation pathway

Amino-G acid (7-amino-1,3-naphthalenedisulfonic acid), a pollutant produced during textile preparation and in dyeing industries, is discarded in wastewater and causes ecological problems. In this study, amino-G acid (50.0 μM) could be completely removed by unactivated peroxymonosulfate (PMS) (1.0 mM) within 240 min, and the reaction kinetics exhibited strong pH dependence. A species-specific parallel reaction describes this pH dependence well, and the species-specific reaction rate constants of [amino-G acid]2− and [amino-G acid]− with HSO5− were calculated to be 0.0826 ± 0.0019 and 000122 ± 0.0027 M−1 s−1. The reactivity of the six naphthalene sulfonic acids and unactivated PMS varied according to the structure, and the amino group in naphthalene sulfonic acid, a typical electron-donating group, was more vulnerable to attack by unactivated PMS, which was further confirmed by the density functional theory results. The high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) spectral analysis results indicated that naphthalene sulfonic acid was first oxidized to hydroxylamine products and then further oxidized to nitroso compounds, which exhibited more ecological toxicity. However, as the reaction processing, the toxicity of the product gradually decreased. Our results provide new insights into the in-situ oxidation of unactivated PMS.

Insight into the mechanism of abnormal degradation of duplex U-Nb alloy

Insight into the mechanism of abnormal degradation of duplex U-Nb alloy

Characteristics and biological mechanism of protein degradation by the black solider fly (Hermetia illucens L.) larvae gut strain Bacillus subtilis S4

Characteristics and biological mechanism of protein degradation by the black solider fly (Hermetia illucens L.) larvae gut strain Bacillus subtilis S4

Folic acid-coupled phosphorylated Fe2+ chelating peptide: The properties of Fe2+ chelating capacity and mechanisms of anti-gastrointestinal enzyme degradation

The aims of this study were to investigate the effect of precise phosphorylation of Ser in GL-Hyp-GPSGEEGKR on its Fe2+ chelating capacity, and the effects and mechanisms of folic acid coupling to GL-Hyp-GPS(PO4)GEEGKR on its resistance against degradation by gastrointestinal enzymes. The results demonstrated that GL-Hyp-GPS(PO4)GEEGKR exhibited significantly enhanced Fe2+ chelating capability compared to GL-Hyp-GPSGEEGKR. This was attributed to the phosphorylation of Ser introducing more Fe2+ chelating sites. Furthermore, the results of UV-Vis, FTIR, and 1H NMR showed that folic acid has successfully coupled with GL-Hyp-GPS(PO4)GEEGKR to generate folic acid-GL-Hyp-GPS(PO4)GEEGKR. Folic acid-GL-Hyp-GPS(PO4)GEEGKR demonstrated superior resistance against degradation by gastrointestinal enzymes. This may be attributed to the coupling of folic acid altering the original zeta potential of the peptide and the steric hindrance effect of folic acid hindering the interaction between enzymes and peptide. These findings can provide valuable insights for the production of high Fe2+ chelating peptides that resist gastrointestinal enzyme degradation.

S-type Bi2S3/BiOBr heterojunction with robust piezo-photocatalytic dye removal activity: degradation performance and mechanism investigation

In this work, an efficient S-type Bi2S3/BiOBr piezo-photocatalysts was prepared by the decoration of Bi2S3 nanorods on the surface of BiOBr nanosheets. The piezo/photo/piezo-photocatalytic performance of samples were evaluated under the irradiation of ultrasonic and/or simulated-sunlight employing methyl orange (MO) as a target reactant, indicating that above catalytic activity of BiOBr is able to be elevated after Bi2S3 attachment. Particularly, the 10%Bi2S3/BiOBr sample exhibits the optimal catalytic performance. It is worth noting that the 10%Bi2S3/BiOBr sample achieves much higher piezo-photocatalytic MO removal efficiency than its photocatalysis and piezocatalysis, demonstrating a remarkable synergistic improvement between piezocatalysis and photocatalysis with a synergistic enhancement factor (SF) of ∼1.29. The formation of S-type heterojunction in the Bi2S3/BiOBr composite was directly confirmed by the combination of density functional theory (DFT) calculation and in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) measurement, elevating the surface separation of generated charges. Meanwhile, the ultrasonic-excited piezoelectric polarization field in BiOBr nanosheets excited by ultrasonic irradiation promotes the bulk segregate of generated charges. Benefiting from above two aspect effects, the overall separation of generated charges can be effectively achieved, leading to outstanding piezo-photocatalytic degradation activity of Bi2S3/BiOBr composite.

Hygrothermal aging on the mechanical property and degradation mechanism of carbon fiber reinforced epoxy composites modified by nylon 6

Hygrothermal aging on the mechanical property and degradation mechanism of carbon fiber reinforced epoxy composites modified by nylon 6

Impact of Porosity and Stiffness of 3D Printed Polycaprolactone Scaffolds on Osteogenic Differentiation of Human Mesenchymal Stromal Cells and Activation of Dendritic Cells.

Despite the potential of extrusion-based printing of thermoplastic polymers in bone tissue engineering, the inherent nonporous stiff nature of the printed filaments may elicit immune responses that influence bone regeneration. In this study, bone scaffolds made of polycaprolactone (PCL) filaments with different internal microporosity and stiffness was 3D-printed. It was achieved by combining three fabrication techniques, salt leaching and 3D printing at either low or high temperatures (LT/HT) with or without nonsolvent induced phase separation (NIPS). Printing PCL at HT resulted in stiff scaffolds (modulus of elasticity (E): 403 ± 19 MPa and strain: 6.6 ± 0.1%), while NIPS-based printing at LT produced less stiff and highly flexible scaffolds (E: 53 ± 10 MPa and strain: 435 ± 105%). Moreover, the introduction of porosity by salt leaching in the printed filaments significantly changed the mechanical properties and degradation rate of the scaffolds. Furthermore, this study aimed to show how these variations influence proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (hBMSC) and the maturation and activation of human monocyte-derived dendritic cells (Mo-DC). The cytocompatibility of the printed scaffolds was confirmed by live-dead imaging, metabolic activity measurement, and the continuous proliferation of hBMSC over 14 days. While all scaffolds facilitated the expression of osteogenic markers (RUNX2 and Collagen I) from hBMSC as detected through immunofluorescence staining, the variation in porosity and stiffness notably influenced the early and late mineralization. Furthermore, the flexible LT scaffolds, with porosity induced by NIPS and salt leaching, stimulated Mo-DC to adopt a pro-inflammatory phenotype marked by a significant increase in the expression of IL1B and TNF genes, alongside decreased expression of anti-inflammatory markers, IL10 and TGF1B. Altogether, the results of the current study demonstrate the importance of tailoring porosity and stiffness of PCL scaffolds to direct their biological performance toward a more immune-mediated bone healing process.

Photocatalytic degradation of cetirizine hydrochloride using polypyrrole decorated zinc ferrite nanohybrids under visible light irradiation.

The present work reports photocatalytic degradation of cetirizine hydrochloride (CTZ-HCl) utilizing polypyrrole (PPy) nanohybrids with ZnFe2O4 (ZnFe) nanoparticles. The synthesized materials were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectroscopy, BET, and scanning electron microscopy (SEM) techniques. UV diffuse reflectance studies (UV-DRS) revealed that the band gap was found to decrease with increase in the loading of PPy and Kubelka-Munk plots confirmed the bandgap values to be 2.14eV for ZnFe, 1.94eV for 1% PPy/ZnFe, 1.66eV for 3% PPy/ZnFe, and 1.38eV for 5% PPy/ZnFe. The photocatalytic performance against CTZ-HCl degradation was performed under visible light irradiation for 60min. The effect of catalyst dosage and the effect of drug concentration were investigated to confirm degradation behavior of the PPy/ZnFe photocatalysts. The degradation followed the pseudo-first-order kinetics model. Maximum photocatalytic degradation was observed to be 98% within 60min using 5% PPy/ZnFe as the photocatalyst. The recyclability tests revealed that the 5% PPy/ZnFe photocatalyst was reusable up to 4 cycles. Radical scavenging studies confirmed the generation of ●OH radicals that were responsible for the drug degradation. The degraded fragments were analyzed using LCMS technique and the tentative mechanism of degradation was proposed.

Construction and degradation mechanism of the magnetic CoFe1.95Y0.05O4/Ag/g-C3N4 Z-scheme heterojunction for enhanced photocatalytic activity

Construction and degradation mechanism of the magnetic CoFe1.95Y0.05O4/Ag/g-C3N4 Z-scheme heterojunction for enhanced photocatalytic activity

XPS analysis of damp heat aged and fractured polymer/glass laminates

Essential for the durability of photovoltaic (PV) modules is the polymeric encapsulant. In addition to the well-established ethylene vinyl acetate copolymers (EVA), polyolefin elastomers (POE) are gaining market relevance. The main objective of this paper was to elucidate the ageing and degradation mechanisms of PV relevant glass laminates based on UV-transparent EVA and POE encapsulants by X-ray photoelectron spectroscopy (XPS).Special focus was given to the polymer/glass interfaces. Therefore, glass laminates were damp heat aged and debonded by monotonic compressive shear testing. Subsequently, the polymer side of the fractured surfaces was characterized by XPS and Fourier-transform infrared spectroscopy (FTIR). The polar EVA encapsulant revealed more pronounced deterioration than the less polar POE material.Significant differences were already discernible after 1kh of damp heat exposure. The diffusion of Na ions from the glass substrate into the polymer matrix and the formation of Na salts at the interface were ascertained for EVA and to a less extent also for POE. While EVA laminates failed primarily close to the interface, but still within the EVA material, glass residues were detected on the fractured POE surfaces indicating interface-near glass corrosion and a fracture path propagating back and forth within POE and glass.

Enhanced photocatalytic performance of (Mg, Cu) Dual-Doped ZnS nanosheets for Solar-Driven water treatment and embedded with PVA polymer membrane for reusability

Photocatalysis uses semiconductor materials to solar energy effectively purify to water by eliminating pollutants. Organic Dye degradation serves as a standard to assess the photocatalytic effects of the materials. In this study Mg, Cu dual-doped ZnS nanosheets were synthesized using the coprecipitation method. The impact of the concentration on the structural, morphology, optical, and degradation efficiency was investigated with XRD, XPS, TEM with EDAX, and UV spectroscopy. The pure ZnS and Zn0.98-xCu0.02MgxS (x = 0, 0.01, 0.02) (ZCM1, ZCM2, ZCM3, and ZCM4) nanosheets, exhibited cubic structure with high phase purity. The average crystalline size was calculated as 1.66, 1.60, 1.45, and 1.47 nm for the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets, respectively. TEM analysis revealed the presence of crumpled nanosheets. The bandgap of the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets were 3.99, 3.78, 4.03, and 4.09 eV respectively. This study investigated the photocatalytic activity of crystal violet dye when exposed to natural sunlight irradiation. Notably, ZCM3 nanosheets exhibited a high degradation rate of 99 % over 120 min under sunlight. Furthermore, the proposed dye degradation mechanism, effect of dosage, effect of dye variation, reusability, scavenging activity, and hemolytic activity were comprehensively discussed. The nanosheets embedded with the Polyvinyl alcohol (PVA) polymer membrane for reusability.

Unveiling degradation mechanisms of anode-free Li-metal batteries

Anode-free Li-metal batteries (AFLMBs), in which Li+ ions from the cathode are deposited on a Cu substrate and the deposited Li-metal serves as the anode, exhibit higher energy density compared to Li-metal batteries (LMBs). However, achieving stable cycle performance, even at moderate operating conditions, is difficult and has so far hindered their practical uses. In AFLMBs, the homogeneity of solid electrolyte interphase (SEI), initially created by electrolyte reduction on Cu substrate, is not maintained during Li-metal deposition, leading to uncontrolled electrolyte decomposition. The SEI is therefore not conserved, and uneven Li deposition morphology is induced on the Cu substrate and the eventual instability of SEI leads to the overall degradation of AFLMBs. Here, we report on the failure mechanisms of AFLMBs through a comparative study with LMBs using 3 M lithium bis(fluorosulfonyl)imide (LiFSI) dissolved in N,N-dimethylsulfamoyl fluoride. Our investigation reveals that the SEI inhomogeneity in AFLMBs makes Li+ transport through SEI sluggish and non-uniform, triggering local compositional changes of the initially formed SEI on the Cu substrate and unwanted consumption of FSI– anion from the electrolyte. This work provides clear understanding to the interfacial engineering and important roles of Li-metal on the Cu substrate in AFLMBs, promising the creation of stable SEI, reversible electrochemical reaction of Li-metal, and interfacial stability of the cathode in LMBs.

Hydrodynamic parameters affecting flow-accelerated corrosion in elbows

Flow-accelerated corrosion (FAC) is a serious degradation mechanism affecting carbon-steel piping in the secondary coolant systems of nuclear power plants. Many researchers have investigated the correlation between wall thinning and hydrodynamic parameters; however, their relationship remains unclear. In this study, the hydrodynamic parameters influencing FAC in elbow sections were investigated for identifying the locations highly susceptible to FAC. Accelerated FAC tests and computational fluid dynamics (CFD) analyses were conducted on a specimen containing elbow sections. The results revealed that the side of the elbow pipe was the most susceptible to FAC because it experienced the most severe wall thinning. The velocity and vorticity vectors obtained from the CFD analysis were decomposed into axial, circumferential, and radial components within a cylindrical coordinate system to evaluate their effects. We found that all velocity and vorticity components contribute to the rate of wall thinning induced by FAC. Therefore, a combination of velocity and vorticity components should be used as hydrodynamic parameters to characterize FAC-induced wall thinning. Specifically, the circumferential velocity and axial vorticity were identified as dominant parameters influencing FAC in the elbows.

Vanishing Soft Electronics: Degradation Mechanisms of Transient Materials

Vanishing Soft Electronics: Degradation Mechanisms of Transient Materials

Investigation of efficient adsorption-electrochemical degradation performance of ZIF-8/MWCNTs nanocomposites toward 2,4-dichlorophenol

The highly toxic and recalcitrant organic pollutant, 2,4-dichlorophenol (2,4-DCP), is commonly found in wastewater. Therefore, it is critical to investigate novel techniques for the efficient removal of 2,4-DCP from wastewater. The present study employed a one-step synthesis method to fabricate ZIF-8/multi-walled carbon nanotubes (ZIF-8/MWCNTs) nanocomposites with well-defined mesoporous structures, which were subsequently coated onto carbon cloth (CC) to form the anode ZIF-8/MWCNTs/CC. Subsequently, the adsorption performance of ZIF-8/MWCNTs toward 2,4-DCP and the adsorption-electrochemical degradation performance of ZIF-8/MWCNTs/CC toward 2,4-DCP were investigated. ZIF-8/MWCNTs exhibit exceptional adsorption capacity and rate toward the 2,4-DCP. At 303 K, it achieved a saturated adsorption amount as high as 1056.78 mg·g−1 within only 30 min of reaching equilibrium. Moreover, when coated on CC substrates, the internal pore structure of ZIF-8/MWCNTs is effectively exploited during the adsorption. In addition, the incorporation of MWCNTs enhances the conductivity of the ZIF-8/MWCNTs/CC electrodes, leading to reduced resistance and improved electron transfer rate. Notably, ZIF-8/MWCNTs/CC enabled complete removal of a 25 mg·L-1 solution of 2,4-DCP within only 90 min and a 50 mg · L-1 solution within 120 min. Furthermore, the degradation mechanism of 2,4-DCP was analyzed by means of DFT modeling theoretical calculations and intermediate product determination analysis, while evaluating the toxicity of the generated material was evaluated. This study provides improved solutions and strategies for the treatment of chlorophenolic compound pollution in wastewater.

Ether-Free Alkaline Polyelectrolytes for Water Electrolyzers: Recent Advances and Perspectives.

Anion exchange membrane (AEM) water electrolyzers (AEMWEs) have attracted great interest for their potential as sustainable, environmentally friendly, low-cost sources of renewable energy. Alkaline polyelectrolytes play a crucial role in AEMWEs, determining their performance and longevity. Because heteroatom-containing polymers have been shown to have poor durability in alkaline conditions, this review focuses on ether-free alkaline polyelectrolytes, which are more chemically stable. The merits, weaknesses, and challenges in preparing ether-free AEMs are summarized and highlighted. The evaluation of synthesis methods for polymers, modification strategies, and cationic stability will provide insights valuable for the structural design of future alkaline polyelectrolytes. Moreover, the in-situ degradation mechanisms of AEMs and ionomers during AEMWE operation are revealed. This review provides insights into the design of alkaline polyelectrolytes for AEMWEs to accelerate their widespread commercialization.