Oxidation Process Research Articles

Unveiling the heterojunction of Fe3O4@MXene nanocatalyst for ultrafast degradation of antibiotics via non-radical pathway

The transfer of advanced oxidation processes (AOPs) to real-world applications faces several technology challenges involving oxidation performance, catalyst cost, poor reactive oxygen species (ROS) yield, and long-term stability. This work aims to develop a reactive, efficient, and stable MXene-based nanocatalyst, namely Fe3O4@Ti3C2Tx, for ultrafast removal of the selected sulfonamide antibiotics. As revealed by extensive nanocatalyst characterization, the MXene surface not only anchors Fe/Fe3O4 nanoparticles (NPs) but also prevents NP agglomeration. Notably, the conductive interface between MXene and Fe3O4 promotes the Fe(II)/Fe(III) redox cycle and accelerates peroxymonosulfate (PMS) activation. The Fe3O4@Ti3C2Tx demonstrates excellent catalytic activity by achieving complete sulfamethoxazole (SMX) degradation within 6 min and maintained its catalytic activity after 5 continuous cycles. In the Fe3O4@Ti3C2Tx/PMS system, multiple ROS (e.g., •OH, SO4•-, O2•-) are involved but 1O2 was found to be the primary ROS for SMX degradation. The presence of co-exiting inorganic impurities and pH changes may hinder SMX degradation. Finally, elucidating possible degradation pathways of SMX would greatly aid in treating antibiotic-containing wastewater.

Effect, Fate and Remediation of Pharmaceuticals and Personal Care Products (PPCPs) during Anaerobic Sludge Treatment: A Review.

Biomass energy recovery from sewage sludge through anaerobic treatment is vital for environmental sustainability and a circular economy. However, large amounts of pharmaceutical and personal care products (PPCPs) remain in sludge, and their interactions with microbes and enzymes would affect resource recovery. This article reviews the effects and mechanisms of PPCPs on anaerobic sludge treatment. Most PPCPs posed adverse impacts on methane production, while certain low-toxicity PPCPs could stimulate volatile fatty acids and biohydrogen accumulation. Changes in the microbial community structure and functional enzyme bioactivities were also summarized with PPCPs exposure. Notably, PPCPs such as carbamazepine could bind with the active sites of the enzyme and induce microbial stress responses. The fate of various PPCPs during anaerobic sludge treatment indicated that PPCPs featuring electron-donating groups (e.g., ·-NH2 and ·-OH), hydrophilicity, and low molecular weight were more susceptible to microbial utilization. Key biodegrading enzymes (e.g., cytochrome P450 and amidase) were crucial for PPCP degradation, although several PPCPs remain refractory to biotransformation. Therefore, remediation technologies including physical pretreatment, chemicals, bioaugmentation, and their combinations for enhancing PPCPs degradation were outlined. Among these strategies, advanced oxidation processes and combined strategies effectively removed complex and refractory PPCPs mainly by generating free radicals, providing recommendations for improving sludge detoxification.

Nature of Reactive Sites in TS-1 from 15N Solid-State NMR and Ti K-Edge X-Ray Absorption Spectroscopic Signatures Upon Pyridine Adsorption.

Ti-containing zeotypes, notably titanosilicalite-1 (TS-1), are prominent examples of heterogeneous catalysts that have found applications in selective oxidation processes with hydrogen peroxide. Despite extensive characterization studies including using various probe molecules to interrogate the nature and the local environment of Ti sites, their detailed structure (as well as reactivity) remains elusive. Here, we demonstrate that using low temperature 15N magic angle spinning (MAS) ssNMR spectroscopy of adsorbed pyridine on TS-1 combined with Ti K-edge XANES on a range of samples (dehydrated, hydrated, contacted with H2O2 and pyridine) provides unique information regarding the Ti sites, highlighting their reactivity and dynamic nature. While dehydrated TS-1 shows only Lewis acid sites, the presence of H2O generates Brønsted acid sites, whose amount correlates with water loading. Moreover, the methodology─based on 15N ssNMR and Ti K-edge XANES─applied to a library of samples with various Ti-loadings and absence of extraframework TiO2 also enables quantification of the amount of Lewis acid sites and to establish a structure-activity descriptor (ratio of pyridine adsorbed on silanols vs titanium). Complementary analysis including computational modeling reveals that the reaction of Ti sites with H2O generates an acidic bridging silanol Ti-(OH)-Si, upon hydrolysis of one Ti-O-Si linkage, where Ti expands its coordination from four to pentacoordinated according to XAS.

Trimetallic MOF–derived Fe–Mn–Sn oxide heterostructure enabling exceptional catalytic degradation of organic pollutants

Developing efficient and environmentally benign heterogeneous catalysts that activate peroxymonosulfate (PMS) for the degradation of persistent organic contaminants remains a challenge. Metal–organic frameworks (MOFs)–derived metal oxide catalysts in advanced oxidation processes (AOPs) have received considerable attention research fraternity. Herein, we report an innovative magnetic trimetallic MOF-derived Fe-Mn-Sn oxide heterostructure (FeMnO@Sn) with adjustable morphology, size and Sn content, prepared through an impregnation–calcination strategy. The formation of a novel magnetic Fe2O3/Fe3O4/Mn3O4 heterostructure induces the generation of abundant Fe2+ and Mn2+ sites on the FeMnO@Sn surface. Meanwhile, the introduction of SnO2 into the Fe2O3/Fe3O4/Mn3O4 heterostructure facilitates the cleavage of the OO bond in adsorbed PMS. The synergy among the different functionalities of each metal oxide plays a vital role in the swift and effective degradation of pollutants. In addition, the uniquely designed catalyst exhibits magnetic properties that facilitate easy recycling and repeated use, thereby meeting environmental protection requirements. Overall, this research highlights the design of heterogeneous catalysts for the effective activation of PMS and provides valuable insights for the advancement of future environmental catalysts.

Outstanding Activity and Durability of Supported NiCo2O4 Nanoparticles for Direct Ethanol Fuel Cells

ABSTRACTThe rational design of noble metal‐free electrocatalysts represents one of the basic stones for fuel cell development. With the exploration of eco‐friendly nanomaterials for the investigated alcohol oxidation process, nickel‐based electrodes have been recognized as the most auspicious anodes with promoted activity and stability. In this work, a series of NiCo2O4 nanoparticles were deposited onto graphite sheets (NiCo2O4/T) introducing varied proportions of cobalt oxide species. Co‐precipitation protocol of the respective metallic hydroxides onto the carbonaceous support was followed with consecutive annealing in an air atmosphere at 400°C. The fabricated mixed metallic oxide nanopowder was physically studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray analysis (EDX), X‐ray photoelectron spectroscopy (XPS), and selected area electron diffraction (SAED). Uniformly arranged nanoparticles were observed on graphite surface as evidenced by SEM and TEM. The cubic lattice structure of formed NiCo2O4 crystals was also confirmed by XRD through the defined peaks of binary metallic oxides clarifying their successful preparation scheme. The electrocatalytic properties of these NiCo2O4/T nanocatalysts were evaluated for oxidizing ethanol molecules in basic solution. Pronounced oxidation current densities were remarkably measured at NiCo2O4/T electrodes in relation to that at NiO/T. Differing the introduced cobalt oxide content into the synthesized nanocatalyst significantly controlled its catalytic performance. NiCo2O4/T‐20 exhibited the highest activity and stability among the prepared nanomaterials. Much decreased charge transfer resistances were also recorded at this electrode demonstrating its promoted electron transfer characteristics. This work could provide a reasonable route for the simple synthesis of comparable transition metallic oxides with promising attitudes for energy generation purposes.

Broad spectrum catalysis using Ca3Sn2S7 Ruddlesden-Popper perovskite under multi-stimulus

Advanced oxidation processes emerged as effective alternatives to traditional approaches. The efficacy of these methods significantly depends on the intrinsic properties of a catalyst material. Semiconductor materials with robust photo absorption alongside inherent polarization emerged as subjects of great interest. In this study, we synthesized two-dimensional Ca3Sn2S7 nanosheets oriented as Ruddlesden-Popper type perovskite structure. The optimal compositions of these nanosheets exhibit excellent physical and optical characteristics while varying Sn ratios significantly impact the properties. Impressively, these compositions boast a wide optical window that spans from the visible to the far infrared region, featuring a narrow bandgap of approximately 0.6 eV. Band potentials in a positive regime make it highly favorable for the oxidation process. The electrochemical analysis further validates high mobility with low resistance in both compositions. The catalytic efficiency of the synthesized nanosheets is evaluated using rhodamine-B. Three energy sources, i.e., visible light, laser, and ultrasound vibrations, decomposed 96 %, 90 %, and 78 %, respectively, in 30 min. Remarkably accelerated degradation rates are achieved under each stimulus, owing to the presence of oxidative optical bands, large surface area, and potential internal polarization within the nanosheets. Preliminary findings strongly indicate the immense potential of this compound in catalytic and photovoltaic applications.

Enhancing the degradation of microplastics through combined KMnO4 oxidation and UV radiation

The pervasive issue of microplastics in aquatic environments presents a formidable challenge to traditional water treatment methodologies, including those utilizing KMnO4. This study pioneers advanced oxidation processes (AOPs) method aimed at improving the degradation of PE microplastics by employing a dual treatment strategy that combines KMnO4 oxidation with UV irradiation. Detailed analysis of the surface modifications and chemical functional groups of the treated PE microplastics revealed the establishment of Mn-O-Mn linkages on their surfaces. Weight reductions of 3.9%, 4.9%, and 7.5% were observed for the KMnO4/UVA, KMnO4/UVB, and KMnO4/UVC treatments over seven days, respectively. The emergence of carboxyl and hydroxyl groups played a crucial role in accelerating the degradation process. Notably, the combined application of UVC rays and KMnO4 resulted in the most effective degradation of PE microplastics observed in our study. The process significantly enhanced the formation of MnO2 particles from KMnO4 oxidation, with concentrations ranging from 0.036 to 0.070 mM for KMnO4/UVA, 0.066–0.097 mM for KMnO4/UVB, and 0.086–0.180 mM for KMnO4/UVC. Furthermore, the influence of varying pH levels, KMnO4 concentrations, and different water sources on the degradation efficacy was investigated. The pivotal role of free radicals and reactive manganese species in promoting the degradation of PE microplastics was identified. A comparative evaluation with treatments solely utilizing KMnO4 or UV light highlighted the enhanced effectiveness of the combined approach, demonstrating its potential as an efficient solution for reducing microplastic contamination in aquatic systems.

In-depth analysis of the roles and mechanisms of sulfate radical and hydroxyl radical in the degradation of metal-cyanide complexes

Persulfate-based advanced oxidation processes (PS-based AOPs), characterized by the coexistence of SO₄•⁻ and HO•, have been proven effective in treating a series of cyanide-bearing pollutants. However, the mechanisms of these reactive species in the degradation of cyanides, especially metal-cyanide complexes, remain unclear or contradictory. The degradation behavior of representative cyanides (including potassium cyanide and potassium ferricyanide) at different pH conditions (2, 7 and 12) in thermally activated persulfate system (T = 60 °C) was explored, and the roles of SO₄•⁻ and HO• in cyanide degradation were explored by leveraging the distinct characteristics of reactive species under different pH conditions. The study found that both HO• and SO₄•⁻ can react with free cyanide (CN⁻ and HCN). However, the reaction barrier between CN⁻ and HO• is lower than that between HCN and SO₄•⁻, resulting in a higher removal rate of free cyanide under alkaline conditions compared to acidic and neutral conditions. For complexed cyanide, the complex bonds in ferricyanide were completely broken within 24 h by thermally activated persulfate at pH 2, releasing free cyanide, indicating the effectiveness of SO₄•⁻ in breaking the Fe-C bonds in ferricyanide. In contrast, ferricyanide was barely decomposed at pH 12, implying the inefficacy of HO• in breaking the Fe-C bonds. This study also innovatively found that SO₄•⁻ breaks the Fe-C bonds by oxidizing Fe(Ⅲ) in ferricyanide to Fe(Ⅳ) or Fe(Ⅴ), releasing CN⁻, which is then converted to CNO⁻ by SO₄•⁻ and HO•. CNO⁻ is further mineralized to NO₃⁻, NH₄⁺, and N₂ through hydrolysis or oxidation reactions. This research clarifies, for the first time, the activity of SO₄•⁻ and HO• toward cyanide degradation in PS-based AOPs.

Study on Fenton-based discoloration of reactive-dyed waste cotton prior to textile recycling

The aim of this study is to investigate the feasibility of an alternative Fenton-based advanced oxidation process for the discoloration of reactive-dyed waste cotton as a pre-treatment for textile recycling. For that, pre-wetted dark-colored (black and blue) knitted samples of 300 cm2 are treated in 1200mL Fenton-solution containing 14 mM Fe2+ and 280mM H2O2 at 40 °C. Characterization of the textiles before and after the treatments are performed by UV VIS-spectrophotometry measuring color strength, microscopy, FTIR spectroscopy, thermal analysis and tensile testing measuring tenacity and elongation. Afterwards, the cotton is mechanically shredded for qualitative analysis of the recyclability. The color-strength measurements of the black and blue cotton led to discoloration-efficiencies of respectively 61.5 and 72.9%. Microscopic analysis of discolored textile fabric also showed significant fading of the colored textiles. Mechanical analysis resulted in reduced tensile strength after treatment, indicating oxidation of the cellulosic structure besides the degradation of the dye-molecules, also confirmed by reductions in thermal stability found after thermal analysis. Shredding of the fabric resulted in enhanced opening, but shorter remaining fibers after treatment. The findings of this study provide a proof-of-concept for an alternative color-stripping treatment concerning a Fenton-based advanced oxidation process as a pre-treatment for textile recycling.

Crystallographic Evidence for Bi(I) as the Heaviest Halogen Bond Acceptor.

Complexation of the green bismuthinidene (RBi) with two equivalents of a highly fluorinated aryl iodide at low temperature allows the crystallographic identification of an unstable red species that can be regarded as an intermediate in an overall Bi(I) → Bi(III) oxidation process. Both C-I bonds are orientated toward the filled 6p orbital of bismuth (Bi-I distances 3.44-3.52 Å), leading to an elongation of the C-I bonds by 0.05 and 0.07 Å. Density functional theory (DFT) calculations confirm that the Bi(I) center is indeed acting as an electron donor, establishing two strong and directional halogen bonds. The color change from green to red upon halogen bond formation is a consequence of the energetic stabilization of a Bi(I) lone pair by interactions with the sigma-holes of the halogen bond donors. Overall, this study presents the first structural proof of bismuth, and more generally of heavy organopnictogen(I) compounds, acting as halogen bond acceptors.

Effect of Oxidation of the Hydroalcoholic Extract of Myracrodruon urundeuva All. (Anarcadiaceae) on its Antimicrobial Activity

This study investigates the relaction between oxidation and antimicrobial activity of the hydroalcoholic extract of Myracrodruon urundeuva, a plant known for its traditional medicinal uses. The primary objective was to evaluate how the oxidation of bioactive compounds within the extract affects its antimicrobial efficacy against common pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The extract was prepared following a standardized methodology, and its antimicrobial properties were assessed using disk diffusion assays over a 60-day period, with samples tested every 15 days to monitor changes in activity. The results revealed that the extract exhibited significant antimicrobial activity, particularly at higher concentrations (100%~50%), with inhibition zones reaching up to 16.7 mm against Staphylococcus aureus by day 30. However, a notable decline in activity was observed between days 30 and 45, indicating a potential degradation of the extract's efficacy over time. Interestingly, lower concentrations (12.5% and 0.4%) showed a resurgence in inhibitory activity towards the end of the study, suggesting that certain oxidative processes may enhance the antimicrobial properties of specific compounds. The study highlights the complex relationship between oxidation and antimicrobial activity demonstrating that certain compounds lose effectiveness, while others become more potent after oxidative modification. This finding is particularly relevant in the context of increasing bacterial resistance to conventional antibiotics, as it suggests that the oxidation of plant-derived compounds could be a viable strategy to enhance their antimicrobial properties. Overall, this research underscores the potential of Myracrodruon urundeuva as a natural alternative in combating resistant pathogens and emphasizes the need for further investigation into the mechanisms by which oxidation influences the activity of bioactive compounds in medicinal plants.

The influence of CeO2 on the oxidation resistance of TaC/Ni composites

The in-situ TaC/Ni composites with different CeO2 content (0 wt%, 1 wt%, 2 wt%) were prepared by reactive sintering method, and their oxidation behavior in air at 1073 K was analyzed by static cyclic oxidation method to investigate the influence mechanism of CeO2 on the oxidation resistance of composites. The results show that the CeO2 particles are distributed around the TaC particles in the Ni matrix, and the oxidation behavior of composites with different CeO2 content conforms to the linear kinetic law. The oxide film is mainly composed of NiTa2O6 and a small amount of NiO. The generation reactions of Ta2O5 and NiTa2O6 induce a high expansion and compressive stress in oxide scale, leading to the formation of nonprotective oxide film with pores and cracks on the surface. As the addition of CeO2 increases from 0 wt% to 2 wt%, the thickness of oxide scale on composites obviously reduces from 505 μm to 122 μm, and the Ni and Ta oxides content decreases, leading to the reduction of pores and cracks in oxide scale. The Ce ion generated from the dissolution of CeO2 particles mainly distributes in the Ta oxides during the oxidation process, which hinders the outward diffusion of Ni and Ta ions, resulted in the improved oxidation resistance of TaC/Ni composites.

Oxidative Processes and Xenobiotic Metabolism in Plants: Mechanisms of Defense and Potential Therapeutic Implications.

Plants are continuously exposed to environmental challenges, including pollutants, pesticides, and heavy metals, collectively termed xenobiotics. These substances induce oxidative stress by generating reactive oxygen species (ROS), which can damage cellular components such as lipids, proteins, and nucleic acids. To counteract this, plants have evolved complex metabolic pathways to detoxify and process these harmful compounds. Oxidative stress in plants primarily arises from the overproduction of hydrogen peroxide (H2O2), superoxide anions (O2•-), singlet oxygen (1O2), and hydroxyl radicals (•OH), by-products of metabolic activities such as photosynthesis and respiration. The presence of xenobiotics leads to a notable increase in ROS, which can result in cellular damage and metabolic disruption. To combat this, plants have developed a strong antioxidant defense mechanism that includes enzymatic antioxidants that work together to eliminate ROS, thereby reducing their harmful effects. In addition to enzymatic defenses, plants also synthesize various non-enzymatic antioxidants, including flavonoids, phenolic acids, and vitamins. These compounds effectively neutralize ROS and help regenerate other antioxidants, offering extensive protection against oxidative stress. The metabolism of xenobiotic substances in plants occurs in three stages: the first involves modification, which refers to the chemical alteration of xenobiotics to make them less harmful. The second involves conjugation, where the modified xenobiotics are combined with other substances to increase their solubility, facilitating their elimination from the plant. The third stage involves compartmentalization, which is the storage or isolation of conjugated xenobiotics in specific parts of the plant, helping to prevent damage to vital cellular functions. Secondary metabolites found in plants, such as alkaloids, terpenoids, and flavonoids, play a vital role in detoxification and the defense against oxidative stress. Gaining a deeper understanding of the oxidative mechanisms and the pathways of xenobiotic metabolism in plants is essential, as this knowledge can lead to the formulation of plant-derived strategies aimed at alleviating the effects of environmental pollution and enhancing human health by improving detoxification and antioxidant capabilities, as discussed in this review.

Dynamics of Free Radical Oxidative Processes During the Latent Period of Experimental Metastasizing to the Liver

Purpose — to investigate the dynamics of the content of antioxidant enzymes superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPO1), glutathione reductase (GR) and lipid peroxidation products diene conjugates (DC), malondialdehyde (MDA) in the spleen and liver during the latent period of growth and metastasis of experimental tumor.Materials and methods. Using 28 white male rats, a model of hematogenous liver metastasis was created by transplanting sarcoma 45 cells (S45) into the spleen, previously lead out under the skin 3 weeks before. Previously, was determined that a tumor visualized in the spleen at 5 weeks, and liver metastases at 7 weeks after transplantation S45. Levels of SOD1, GPO1, GR and MDA were determined using ELISA and DC by biochemical method in spleen and liver homogenates during the latent period of tumor growth and metastasis (1–2 weeks post-transplantation).Results. Significant changes (1.5–5.2 times, р < 0.050–0.001) in studied factors levels were observed compared to intact rats and rats with the spleen lead out. Activation of lipid peroxidation and antioxidant system was noted in the spleen (tumor-carrying organ) during tumor growth and metastasis. At the same time, in the liver (the target organ of metastasis) observed also increased lipid peroxidation but simultaneously a pronounced decreased GR levels (5 times, p < 0.001) without affecting SOD1 levels.Conclusion. Liver tissue exhibited the inferiority of antioxidant protection and the formation of pro-oxidant condition during the latent period of tumor growth, which may prepare the soil for metastasis.

Engineered Core-Shell SiC@SiO2 Nanofibers for Enhanced Electromagnetic Wave Absorption Performance.

To enable SiC material to achieve high electromagnetic wave (EMW) absorption performance, solving its impedance mismatch with EMW is necessary. Therefore, a novel approach is proposed for the precise control of impedance matching by adjusting the shell thickness of SiO2 nanolayers on the surface of SiC nanofibers (NFs). High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) reveals the atomic scale oxidation process of SiC, providing fresh insights into the oxidation mechanism. By oxidizing to construct a heterogeneous core-shell structure nanofiber (NF) can effectively lock the incident EMW inside the NF through the generated charges gathered at the interface, forming an electronic barrier that prevents the outward propagation of EMWs. The produced SiC@SiO2 NFs-3 exhibits exceptional EMW absorption properties, including an impressive minimum reflection loss (RLmin) of -53.09dB and a broad maximum effective absorption bandwidth (EABmax) of 8.85GHz. These findings not only deepen understanding of the oxidation mechanism of SiC but also offer valuable insights for further enhancing the EMW absorption capabilities of SiC materials, paving the way for their application in advanced EMW technologies.

A Cost‐Effective Electrochemical Sensor Using a Graphite Pencil Electrode for Sensitive Quantification of Phenolic Antioxidants in Human Plasma and Food Samples

AbstractThe pressing challenge in electroanalysis revolves around the creation of a user‐friendly analytical sensor that is accessible to individuals lacking specialized expertise. Such sensor should offer minimal cost, while simultaneously ensuring high sensitivity and reproducibility. Herein, graphite pencil electrode (GPE) has emerged as a promising electrochemical sensor for the determination of polyphenolic compounds, including gentisic acid (GEN), gallic acid (GA), caffeic acid (CAF), and sinapic acid (SA). To comprehensively explore the electrochemical oxidation processes of these antioxidants, a range of electrochemical techniques, namely cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA), were deployed. The results of these investigations unveiled a diffusional oxidation wave associated with phenolic hydroxyl groups, involving a two‐electron/two‐proton loss step, occurring within the potential range of 0.4–0.6 V vs. Ag/AgCl. Crucially, the GPE exhibited the capacity to establish linear calibration curves for GEN, GA, CAF, and SA, encompassing concentrations from nanomolar to sub‐micromolar which highlighted by the corresponding limits of detection (LoD), recorded at 0.086, 0.046, 0.112, and 0.115 μM, respectively. The heightened sensitivity and reproducibility demonstrated by the GPE underscore its potential as an efficient tool for the determination of polyphenolic compounds. Beyond its analytical capabilities, the GPE displayed remarkable applicability in facilitating on‐site, cost‐effective determinations of polyphenolic compounds in both plasma and food samples. This versatility positions the GPE as a valuable asset in addressing the challenges associated with electrochemical analysis, making it an attractive option for a wide range of applications where simplicity, affordability, and reliability are paramount.

Oxidation anisotropy of 4H-SiC wafers during chemical-mechanical polishing

4H silicon carbide (4H-SiC) wafers are widely used in high-power, high-temperature, and high-frequency electronics owing to their excellent physical and electrical properties. In the processing of 4H-SiC wafers, chemical-mechanical polishing (CMP) is commonly employed to realize atomic-scale smoothness, damage-free surface, and global planarization. The CMP process is the synergy of wet oxidation and mechanical grinding, whose efficiency significantly relies on the oxidation process. Therefore, understanding the wet oxidation mechanism of Si face and C face of 4H-SiC wafers is critical to high-efficiency double-side CMP. In this work, the anisotropic CMP performance of Si face and C face of 4H-SiC wafers are investigated. It has been found that the material removal rate of the C face is 2–3 times that of the Si face. The thicknesses of the transient oxide layer on the C face and Si face are 8.71 nm and 3.50 nm, respectively. X-ray photoelectron spectroscopy analysis reveals that the oxygen content on the C face is higher than that on the Si face after wet KMnO4 oxidation. This indicates that the C face of 4H-SiC is easier to oxidize, which results in more oxides that that on the Si face of 4H-SiC. Our work shows that accelerating the oxidation of the Si face of 4H-SiC wafers during the simultaneous double-sided CMP process is crucial for the efficient polishing of 4H-SiC wafers.

Hydroxyl Radical Mediated Heterogeneous Photocatalytic Baeyer‐Villiger Oxidation over Covalent Triazine/Heptazine‐Based Frameworks

The Baeyer‐Villiger oxidation of ketones to the corresponding lactones/esters is a classic and essential reaction in the chemical industry. However, this oxidation process has not yet been achieved in ambient conditions with the aid of oxygen and heterogeneous photocatalysts. In this study, we developed an organic photocatalytic system using covalent triazine/heptazine‐based frameworks (CTF‐TB/CHF‐TB) to enable the B‐V oxidation reaction under mild conditions through a cascade reaction pathway. Experimental data and theoretical calculations showed that heptazine/triazine units can "chelate” and decompose the in situ generated H2O2 into hydroxyl radicals (•OH). Compared to conventional methods that primarily involve metal‐activated benzaldehyde at elevated temperatures (e.g., 60 oC), the •OH generated in our study can readily cleave the C‐H bond of benzaldehyde, forming an active intermediate that drives subsequent sequential processes: O2→H2O2→•OH→Ph‐CO•→Ph‐COOO•. By employing this photocatalytic process, a yield of 91% and a selectivity of over 99 % were obtained in the oxidation of cyclohexanone to caprolactone at room temperature. This performance is comparable to the state‐of‐the‐art catalysts, and our CHF‐TB catalyst demonstrates impressive reusability, maintaining a high yield after 5 consecutive runs. This work presents a straightforward approach for C‐H cleavage by organocatalysts to produce ε‐caprolactone in a mild manner by Baeyer‐Villiger oxidation.

Hydroxyl Radical Mediated Heterogeneous Photocatalytic Baeyer-Villiger Oxidation over Covalent Triazine/Heptazine-Based Frameworks.

The Baeyer-Villiger oxidation of ketones to the corresponding lactones/esters is a classic and essential reaction in the chemical industry. However, this oxidation process has not yet been achieved in ambient conditions with the aid of oxygen and heterogeneous photocatalysts. In this study, we developed an organic photocatalytic system using covalent triazine/heptazine-based frameworks (CTF-TB/CHF-TB) to enable the B-V oxidation reaction under mild conditions through a cascade reaction pathway. Experimental data and theoretical calculations showed that heptazine/triazine units can "chelate" and decompose the in situ generated H2O2 into hydroxyl radicals (•OH). Compared to conventional methods that primarily involve metal-activated benzaldehyde at elevated temperatures (e.g., 60 oC), the •OH generated in our study can readily cleave the C-H bond of benzaldehyde, forming an active intermediate that drives subsequent sequential processes: O2→H2O2→•OH→Ph-CO•→Ph-COOO•. By employing this photocatalytic process, a yield of 91% and a selectivity of over 99 % were obtained in the oxidation of cyclohexanone to caprolactone at room temperature. This performance is comparable to the state-of-the-art catalysts, and our CHF-TB catalyst demonstrates impressive reusability, maintaining a high yield after 5 consecutive runs. This work presents a straightforward approach for C-H cleavage by organocatalysts to produce ε-caprolactone in a mild manner by Baeyer-Villiger oxidation.

Enhancing Antibacterial Properties and Biocompatibility of Titanium Surfaces through Synergy of Plasma Electrolytic Oxidation and Hydrothermal Process

Enhancing Antibacterial Properties and Biocompatibility of Titanium Surfaces through Synergy of Plasma Electrolytic Oxidation and Hydrothermal Process