Fenton Reaction Research Articles

Application of Fenton’s Reaction for Removal of Organic Matter from Groundwater

In this study, the effectiveness of the Fenton process in removing natural organic matter (NOM) from groundwater was investigated. The subject of this study is groundwater characterised by increased content of NOM and iron (II) compounds. In laboratory-scale studies, the influence of the ratio of concentrations of Fe(II) ions, which are naturally occurring in groundwater, to hydrogen peroxide (H2O2) as well as oxidation time and pH on the removal efficiency of organic matter was determined. Indicators such as total organic carbon (TOC), dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), UV absorbance at 272 nm (UV272), and specific UV absorbance (SUVA254) were used to quantitatively and qualitatively assess the organic substances present in the raw water and after oxidation with Fenton’s reagent. Analysis of the results obtained showed that the highest removal efficiency of organic substances in the deep oxidation process using the Fenton reaction was obtained for a concentration ratio of Fe(II) to H2O2 = 1:5. Acidification of the water samples to a pH of about 4 and extending the oxidation time to 30 min significantly increased the removal efficiency of organic substances including mainly dissolved organic substances containing aromatic rings. The organic substances containing aromatic rings, determined at a wavelength of 254 nm, were degraded to other organic intermediates.

Usnic Acid Derivatives as Multi-Target Anti-Alzheimer's Disease Agents: Design, Synthesis, X-Ray Single Crystal Structure of Zn(II) Complex and Biological Activities.

Alzheimer's disease (AD) is multifactorial, which makes the design of multi-target-directed ligands an attractive strategy for the development of anti-AD drugs. In order to enhance the anti-AD effects and reduce the toxicity, two usnic acid (UA) derivatives (1-2) were designed, synthesized and fully characterized by introducing dimethylamine Schiff base moiety into the toxic "triketone" portion. Ellman's method and molecular docking were used to test the cholinesterase inhibitory activities. Antioxidant activities were studied with Fenton reaction, cyclic voltammetry and C. elegans. The results showed that compared with UA, 1-2 had stronger anti-cholinesterase activities and similar antioxidant activities. Notably, solvent evaporation of 2 and ZnCl2 formed a single crystal, which was revealed to be a Zn(II) complex with UA and tertiary amine as mixed ligands by X-ray diffraction. The hydrolysis of 2 was thus furtherly studied by HPLC. Furthermore, the crystal structure supported the replacement of toxic "triketone" moiety in the chelation process, playing a detoxifying role and at the same time regulating metal homeostasis. In silico prediction also showed low hepatotoxicity and acceptable drug-likeness of 1-2. Overall, this work provided useful insights into multi-target anti-AD candidates with the natural product UA as the lead compound.

Self-supply of hydrogen peroxide by a bimetal-based nanocatalytic platform to enhance chemodynamic therapy for tumor treatment.

The Tumor Microenvironment (TME) is characterized by low pH, hypoxia, and overexpression of glutathione (GSH). Owing to the complexity of tumor pathogenesis and the heterogeneity of the TME, achieving satisfactory efficacy with a single treatment method is difficult, which significantly impedes tumor treatment. In this study, composite nanoparticles of calcium-copper/alginate-hyaluronic acid (CaO2-CuO2@SA/HA NC) with pH and GSH responsiveness were prepared for the first time through a one-step synthesis using hyaluronic acid (HA) as a targeting ligand. Nanoparticles loaded with H2O2 can enhance the ChemoDynamic Therapy (CDT) effects. Simultaneously, Cu2+ can generate oxygen in the TME and alleviate hypoxia in tumor tissue. Cu2+ and H2O2 undergo the Fenton reaction to produce cytotoxic hydroxyl radicals and Ca2+ ions, which enhance the localization and clearance of nanoparticles in tumor cells. Additionally, HA and sodium alginate (SA) were utilized to improve the targeting and biocompatibility of the nanoparticles. FTIR, XRD, DLS, SEM, TEM, and other analytical methods were used to investigate their physical and chemical properties. The results indicate that the CaO2-CuO2@SA/HA NC prepared using a one-step method had a particle size of 220 nm, a narrow particle size distribution, and a uniform morphology. The hydrogen peroxide self-supplied nanodrug delivery system exhibited excellent pH-responsive release performance and glutathione-responsive •OH release ability while also reducing the level of reactive oxide species (ROS) quenching. In vitro cell experiments, no obvious side effects on normal tissues were observed; however, the inhibition rate of malignant tumors HepG2 and DU145 exceeded 50%. The preparation of CaO2-CuO2@SA/HA NC nanoparticles, which can achieve both chemokinetic therapy and ion interference therapy, has demonstrated significant potential for clinical applications in cancer therapy.

UiO-66(Zr)-2OH-Supported Pd0 NP Catalysts Accelerated a Fenton-Like Reaction: Iron Cycling and Hydrogen Peroxide Generation Achieved Simultaneously.

Both the sluggish kinetics of Fe(II) regeneration and usage restriction of H2O2 have severely hindered the scientific progress of the Fenton reaction toward practical applications. Herein, a reduction strategy of activated hydrogen, which was used to simultaneously generate H2O2 and accelerate the regeneration of ferrous in a Fenton-like reaction based on the reduction of activated hydrogen derived from H2, was proposed. Two types of composite catalysts, namely, Pd/UiO-66(Zr)-2OH and Pd@UiO-66(Zr)-2OH, were successfully prepared by loading nano-Pd particles onto the outer and inner pores of UiO-66(Zr)-2OH in different loading modes, respectively. They were used to enhance the reduction of activated hydrogen. The characterization results based on the analysis of scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that the materials were successfully prepared. By using a trace amount of ferrous iron and without adding H2O2, trimethoprim (C0 = 20 mg·L-1), as a target pollutant, could be nearly 100% degraded within 180 min in the reaction system composed of these two materials. The cycle of iron and the self-generation of H2O2 were verified by the detection of ferrous H2O2 in the system. Density functional theory calculation results further confirmed that the pore-filled Pd0 NPs, as the main catalytic site for Pd@UiO-66(Zr)-2OH, could produce H2O2 under the combined action of hydrogen and oxygen. The Pd@UiO-66(Zr)-2OH system had excellent stability after multiple applications (at least 6 cycles), all of which resulted in 100% removal of trimethoprim. The degradation efficiency of the Pd/UiO-66(Zr)-2OH system for TMP gradually decreased from 97 to 80% after six cycles. The results of electron paramagnetic resonance combined with classical radical burst experiments revealed the degradation pathways in the reaction system with hydroxyl radicals and singlet oxygen as the main reactive oxygen particles.

Construction and demolition waste as a low-cost adsorbent for water treatment: kinetics, isotherm, thermodynamics, and Fenton regeneration.

The present study proposes to investigate the feasibility of using construction and demolition waste (CDW) as an aqueous remediation agent through adsorption. The CDW, with and without chemical and thermal pre-activation, was evaluated to remove the methylene blue (MB) dye from the water solution. Variables interfering with adsorption processes, such as adsorbent dosage, solution pH, and particle size, were evaluated. The material was characterized by pHZPC, FTIR, XRD, SEM, EDS, and TG. The kinetic and equilibrium data better fitted the Elovich and Sips models, respectively. A maximum adsorption capacity of 18.62mgg-1 at 60°C was observed. Thermodynamic data indicated that adsorption occurred through a spontaneous and favorable process governed mainly by physical processes. The regeneration studies were carried out using processes based on the Fenton reaction, where the catalytic action of the iron naturally present in the CDW was evaluated. The results showed that the desorption balance was the main limiting factor for the effective regeneration of the saturated material. Adding Fe2+ to the system made this process suitable for the regeneration of the CDW and degradation of the pollutant in the aqueous phase. A regeneration efficiency of 65%, maintained practically constant during five adsorption-regeneration cycles, was observed. These results highlight the high potential of using CDWs as an adsorbent material.

A triple-mode strategy combining low-temperature photothermal, photodynamic, and chemodynamic therapies for treating infectious skin wounds.

The skin is the first natural barrier of the human body. Bacterial infections severely hinder the healing process of skin wounds and pose a great threat to human health. Therefore, it is particularly urgent to develop new antimicrobial strategies for bacterial pathogen clearance and wound healing. In this study, a metal-organic framework (MOF), Fe-MIL88B-NH2, was incorporated with the photosensitizer indocyanine green (ICG) to construct composite nanoparticles (MOF@ICG NPs) with multiple antibacterial activities. Under mild near-infrared (NIR) irradiation, the photosensitizer ICG in the MOF@ICG NPs undergoes photothermal conversion (∼45 °C) and photodynamic reactions to generate heat and singlet oxygen (1O2). In addition, the Fenton reaction of the NPs with hydrogen peroxide (H2O2) in the bacterial infection microenvironment resulted in the generation of hydroxyl radicals (˙OH), thus achieving the three-mode combination of low-temperature photothermal therapy (PTT)/photodynamic therapy (PDT)/chemodynamic therapy (CDT). The in vitro experimental results showed that MOF@ICG MPs had excellent antibacterial properties and good cytocompatibility, with some ability to promote the migration of L-929 fibroblasts. Furthermore, under NIR irradiation, MOF@ICG NPs could significantly kill bacteria and promote skin wound healing according to the results of animal experiments. The wound healing rate reached 87.1% after 7 days of treatment. The research results break through the limitations of single-mode antibacterial technology and provide certain theoretical guidance and technical support for the research and development of new antibacterial materials.

Intracellular Magnetic Hyperthermia Sensitizes Sorafenib to Orthotopic Hepatocellular Carcinoma Via Amplified Ferroptosis.

Sorafenib (SRF) is recognized as the primary treatment for hepatocellular carcinoma (HCC), yet the emergence of SRF resistance in many HCC patients results in unfavorable outcomes. Enhancing the efficacy of SRF in HCC remains a significant challenge. SRF works in inducing ferroptosis, a form of cell death, in cancer cells through the inhibition of glutathione peroxidase 4 (GPX4). The effectiveness of this process is limited by the low levels of cellular iron and reactive oxygen species (ROS). A promising approach to circumvent this limitation is the use of intracellular magnetic hyperthermia (MH) mediated by magnetic iron oxide nanomaterials (MIONs). When MIONs are subjected to an alternating magnetic field (AMF), they heat up, enhancing the Fenton reaction, which in turn significantly increases the production of ROS within cells. In this study, we explore the capability of MH facilitated by high-performance ferrimagnetic vortex-domain iron oxide nanoring (FVIO) to enhance the effectiveness of SRF treatment in HCC. The increased iron uptake facilitated by FVIO significantly enhances the sensitivity of HCC cells to SRF-induced ferroptosis. Moreover, the nanoheat generated by FVIO in response to an AMF further elevates ROS levels and stimulates lipid hydroperoxide (LPO) production and GPX4 inactivation, thereby intensifying ferroptosis. Both in vitro and in vivo animal studies demonstrate that combining FVIO-mediated MH with SRF significantly reduces cell viability and inhibits tumor growth, primarily through enhanced ferroptosis, with minimal side effects. The effectiveness of this combination therapy is affected by the ferroptosis inhibitor ferrostatin-1 (Fer-1) and the iron chelator deferoxamine (DFO). The combination treatment of FVIO-mediated MH and SRF offers a strategy for HCC treatment by promoting accelerated ferroptosis, presenting a different perspective for the development of ferroptosis-based anticancer therapies.

Structural characteristics and antioxidant activity of a low-molecular-weight jujube polysaccharide by ultrasound assisted metal-free Fenton reaction

This study used an ultrasonically accelerated metal-free Fenton (H2O2-Vc system) reaction to promote water-extracted degrading polysaccharides from Ziziphus Jujuba cv. Muzao (DZMP). A novel jujube polysaccharide (DPZMP3) was obtained by degradation using DEAE-Sepharose Fast Flow and Sephacryl S-100 column chromatography. Methylation analysis, HPGPC, ion chromatography, FT-IR, and NMR spectroscopies were used to clarify the chemical structures of DPZMP3. Monosaccharide compositional analysis of DPZMP3 revealed the presence of Rha, Ara, Gal, and GalA at a molar ratio of 1.00:1.49:1.60:7.68, and the HPGPC data demonstrated the average Mw of 34.3 kDa. Based on the structural and linkage research using NMR spectroscopy and GC–MS, it was determined that DPZMP3 was a homogalacturonan pectic polysaccharide with a (1 → 4)-Galp branch at C-6 and a small amount of Araf and Rhap residues. The ultrasonic-aided Fenton treatment did not significantly alter the structure of DPZMP3. It may also be useful for DZMP and enhancing their antioxidant activity in vitro. The current study's findings could pave the way for the food sector to use jujube polysaccharides obtained by degradation as a functional food component.

A highly permeable nanoplatform based on functionalized carbon dots for synergistic reactive oxygen/nitrogen species tumor therapy

Reactive oxygen species (ROS)-based antitumor strategies, particularly chemodynamic therapy, have garnered considerable attention. However, challenges such as difficulties in achieving deep penetration, relatively low H2O2 levels in the tumor microenvironment, the requirement for low pH by the Fenton reaction, and their short lifespan have impeded satisfactory therapeutic outcomes. Hence, we have developed a nanoplatform with enhanced permeability that not only generates significant amounts of ROS but also converts them into longer-lasting reactive nitrogen species (RNS), thereby improving tumor therapy efficacy. In our study, carbon dots were functionalized by doping with gold atoms and grafting nitrosoglutathione (GSNO) to form ACN, which exhibits glucose oxidase-like properties and enables laser-responsive NO release. ACN and indocyanine green (ICG) were then loaded onto MnO2 nanoflowers to form MnO2@AI. Upon arrival at the tumor site, MnO2 reacts with H2O2 and GSH, leading to its degradation and the subsequent release of ACN, which is characterized by three permeation-promoting properties: ultra-small size, positive charge, and NO content. In addition, ACN promotes H2O2 production through glucose metabolism and reduces pH, both of which enhance the Fenton-like reaction of MnO2, thereby amplifying ROS generation. The ICG in MnO2@AI enhances its photothermal properties, leading to the responsive release of NO from GSNO grafted onto ACN, which then reacts with the increased ROS to generate more toxic RNS. Collectively, the approach described herein offers substantial potential for advancing the treatment of malignant tumors.

Removal of Methylene Blue from Aqueous Solution through Adsorption and Heterogeneous Fenton Reaction using Iron Oxides Produced by Different Methods

Direct discharge of industrial wastewater containing dyes into water bodies has contributed to the scarcity of drinking water. As environmental legislation becomes stricter, it is increasingly important to develop efficient methods for wastewater treatment. Traditional methods are commonly costly and have limited efficiency. This study aimed to prepare iron oxides via different synthetic routes and evaluate the effect of synthesis method on the efficiency of these materials as adsorbents and heterogeneous Fenton catalysts for the removal of methylene blue from aqueous solution. Iron oxides were synthesized by non-hydrolytic sol–gel (NHSG) and co-precipitation (CP) methods, followed by hydrothermal treatment for different times. CP oxides demonstrated high efficiency in dye adsorption, particularly the sample subjected to hydrothermal treatment for 6 h (CP-R6). This sample achieved 94.04% removal in 120 min. NHSG materials, by contrast, were less effective. The CP series of materials showed superior catalytic performance in heterogeneous Fenton experiments, with CP-R6 reaching 98.79% decolorization in 240 min. X-ray diffraction analysis indicated that iron oxides were composed of crystalline hematite and maghemite. Scanning electron microscopy revealed that CP materials were more porous and homogeneous than NHSG materials. The results demonstrated the efficiency of the developed iron oxides in removing methylene blue via adsorption and heterogeneous Fenton degradation and clarified how synthesis method influences adsorptive and catalytic properties.

Co-Delivery of Renal Clearable Cerium Complex and Synergistic Antioxidant Iron Complex for Treating Sepsis.

The mononuclear phagocytic system clears the circulating inorganic nanomaterials from the bloodstream, which raises concerns about the chronic toxicity of the accumulated metal species. A better understanding of the behavior of each metal after systemic injection is thus required for clinical translations. This study investigates the significance of the metal-ligand interaction on the accumulation of cerium and demonstrates that only the form in which cerium is coordinated to a multidentate chelator with a strong binding affinity does not accumulate in major organs. Specifically, cerium complexed with diethylenetriamine pentaacetic acid (DTPA) forms renally excretable nanoparticles in vivo to circumvent the leaching of cerium ions, whereas weakly coordinated cerium-based nanomaterials produce insoluble precipitates upon encountering physiological phosphate anions. Ceria-based renally clearable nanoparticles (CRNs) derived from cerium-DTPA are utilized as the antioxidant pair with iron-DTPA, in which their combination leverages the Fenton reaction to synergistically scavenge hydrogen peroxide. This reduces the gene expression of pro-inflammatory factors in the macrophages activated with lipopolysaccharide as well as improves the survival rate of septic mice by alleviating the systemic inflammatory response and its downstream tissue injury in the liver, spleen, and kidneys. This study demonstrates that CRNs combined with iron-DTPA can be utilized as nonaccumulative nanomedicines for treating systemic inflammation, thereby overcoming the limitations of conventional ceria nanoparticle-based treatments.

Photothermal Fe3O4 nanoparticles induced immunogenic ferroptosis for synergistic colorectal cancer therapy

Photothermal therapy (PTT) is a promising non-invasive treatment that has shown great potential in eliminating tumors. It not only induces apoptosis of cancer cells but also triggers immunogenic cell death (ICD) which could activate the immune system against cancer. However, the immunosuppressive tumor microenvironment (TIME) poses a challenge to triggering strong immune responses with a single treatment, thus limiting the therapeutic effect of cancer immunotherapy. In this study, dual-targeted nano delivery system (GOx@FeNPs) combined with αPD-L1 immune checkpoint blocker could inhibit colorectal cancer (CRC) progression by mediating PTT, ferroptosis and anti-tumor immune response. Briefly, specific tumor delivery was achieved by the cyclic arginine glycyl aspartate (cRGD) peptide and anisamide (AA) in GOx@FeNPs which not only had a good photothermal effect to realize PTT and induce ICD, but also could deplete glutathione (GSH) and catalyze the production of reactive oxygen species (ROS) from endogenous H2O2. All these accelerated the Fenton reaction and augmented the process of PTT-induced ICD. Thus, a large amount of tumor specific antigen was released to stimulate the maturation of dendritic cells (DCs) in lymph nodes and enhance the infiltration of CD8+ T cells in tumor. At the same time, the combination with αPD-L1 has favorable synergistic effectiveness against CRC with tumor inhibition rate over 90%. Furthermore, GOx@FeNPs had good magnetic resonance imaging (MRI) capability under T2-weighting owing to the presence of Fe3+, which is favorable for integrated diagnosis and treatment systems of CRC. By constructing a dual-targeted GOx@FeNPs nanoplatform, PTT synergistically combined with ferroptosis was realized to improve the immunotherapeutic effect, providing a new approach for CRC immunotherapy.

Self-Illuminating Copper-Luminol Coordination Polymers for Bioluminescence Imaging of Oxidative Damage.

Timely detection of reactive oxygen species (ROS) accumulated during inflammation is essential for an early disease diagnosis. Compared to fluorescence probes with limited sensitivity and accuracy, chemiluminescence (CL) imaging offers the potential for highly sensitive molecular visualization of ROS by minimizing background interferences. However, the development of bright and easily manufacturable CL probes for ROS imaging remains challenging. In this study, a novel chemiluminescent nanoprobe named Cu-Lum@NPs for ROS imaging in inflammation was synthesized by using a one-step solvothermal method. The Cu-Lum@NPs, which are composed of coordination polymers containing copper ions and luminol (Lum), demonstrate intrinsic peroxidase-like activity that relies on Cu(I) as the catalytic active center to initiate the Fenton reaction. This catalytic process facilitates the decomposition of hydrogen peroxide (H2O2) into hydroxyl radicals (•OH) and superoxide anion radicals (O2•-), leading to the oxidation of Lum and inducing strong luminescence. Cu-Lum@NPs, displaying nanozyme characteristics, were observed to accelerate and enhance the ROS-responsive luminescence (10-1600-fold in solution and over 100-fold in neutrophils) and notably extend persistent luminescence. The Cu-Lum@NPs allowed for CL imaging of endogenous ROS in living cells and animals with an outstanding signal-to-noise ratio exceeding 96 and facilitated oxidative damage luminescence imaging for tissue-specific detection. The study presents Cu-Lum@NPs, a highly sensitive and easily manufacturable chemiluminescent nanoprobe for ROS imaging both in vitro and in vivo, exhibiting enhanced luminescence and prolonged persistence for ROS-related disease detection.

Supramolecular PEG-DNA-Ferrocene Nanogels for Synergistically Amplified Chemodynamic Therapy via Cascade Reactions.

Chemodynamic therapy (CDT) has been limited by the tumor microenvironment, such as the low concentration of hydrogen peroxide (H2O2). The combination of therapeutic strategies that increase H2O2 with CDT can synergistically enhance the therapeutic effect. Herein, a novel supramolecular PEG-DNA-ferrocene nanogel that can codeliver glucose oxidase (GOx) and the hypoxia-activable prodrug tirapazamine (TPZ) was developed to synergistically amplify CDT via cascade reactions. The DNA nanogel was size-controllable and DNase I-responsive and exhibited good biocompatibility. Induced by oxygen consumption and H2O2 generation in the catalytic reaction of GOx, the drugs TPZ and ferrocene in the nanogel underwent the hypoxia-based reaction and the Fenton reaction, respectively. The vitro model tests, intracellular ROS test, MTT experiments, and DNA damage assay demonstrated that the H2O2-based cascade Fenton reaction and the hypoxia-based cascade reaction obviously increased ·OH generation and promoted the apoptosis of cancer cells. This cascade supramolecular nanoplatform provided a promising therapeutic strategy to synergistically amplify CDT.

Turning Microenvironments of Porous Co─N─C Catalysts Enable Efficient Fenton-Like Reaction.

Metal nitrogen carbon (MNC)-based Fenton reactions leveraged with robust peroxymonosulfate (PMS) interaction effectively guarantee the elimination of refractory contaminants, yet the precise design of local microenvironment of MNC to couple with the multiple PMS activation pose major challenges. Herein, a porous Co single-atom catalyst (SAC) with nitrogen defects (Nv) (MCo/NC-6) is fabricated to initiate PMS oxidation reaction. The weaker but richer coordination between Co and N in the precursor facilitates the formation of Nv and porous structure during pyrolysis, achieving simultaneously electronic structure and spatial distribution tuning. Compared with the Co SAC (ZCo/NC-6), the optimized MCo/NC-6 significantly increase the bisphenol A (BPA) reactivity (k = 0.63 min-1), PMS utilization (78%), and singlet oxygen (1O2) yield (100%) by 15.3, 2.4, and 2.6 times, respectively. Experimental analyses and theoretical calculations reveal that the Co─N─C coordination regulated by both micro space and neighboring Nv is endowed high-mobility electrons, thus synergistically facilitating rapid generation and efficient utilization of 1O2. This work promises new opportunities for the design of local microenvironments-regulated SACs, and charts new trajectories in complex Fenton-like systems.

Designed magnetic nanoparticles for ferroptosis: Release of iron ions from metal-organic frameworks modified with iron oxides

The unique chemical properties of the catalytic and biocompatible metal organic framework MIL88b allow for considering it as prooxidant agent. The authors hypothesize whether additional modification of the MIL88b with an additional iron source as Fe3O4 nanoparticles can increase both pro-oxidant activity and provide magnetic properties contributing to target delivery. The prooxidant activity of the Fe3O4-MOF was studied using electron paramagnetic resonance spectroscopy and methylene blue degradation reactions in the presence of hydrogen peroxide. To understand the reaction mechanism, the authors studied the released iron ions, as well as the surface composition using the X-ray photoelectron spectroscopy method. The addition of iron oxide leads to a more prolonged release of iron ions and the production of hydroxyl radicals within 24 h. The native MIL88b demonstrates the highest Fenton reaction rate due to "sacrificial" behavior (despite lower concentration of iron ions in the composition and on the surface compared to the modified sample) and the blocking of the active centers of MIL88b by Fe3O4 on the surface.

Designing a series of RE based carbon composites (RE=Tb, Gd, Ho, Lu, Nd, Sm, Yb, Eu, and Ce)-especially Tb-N-Cs for oxygen reduction enhancement

Iron and nitrogen co-doped carbon materials (Fe–N–Cs) have enormous application prospects in cathodic oxygen reduction reaction (ORR) as efficient electrode materials. However, their stability is of great importance, but is still limited by severe Fenton reaction due to the preferential reaction between Fe2+ and H2O2. This paper intends to rationally design a series of rare earth (RE) metals based carbon matrix anchoring RE centers directly converted from RE oxides and small nitrogen-containing carbon molecules by employing the molten-salts-assisted pyrolysis. A class of prepared RE based carbon (RE-N-Cs) catalysts surprisingly exhibits ORR activities comparable to that of Pt/C. The Tb–N–Cs sample with the best catalytic activity among them was characterized by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) and X-Ray Diffraction (XRD). The characterization results show the presence of Tb single-sites in carbon substrate, with Eonset of 1.06 V and Jd of 6.37 mA cm−2, exceeding those of the commercial Pt/C (Eonset = 0.96 V vs. RHE; Jd = 5.64 mA cm−2).

Hydrogen bonding network in the electrical double layer mediates fast proton skipping to Get Rid of Fenton reaction pH dependence enables highly efficient alkaline water purification

A fundamental scientific quandary in environmental has always been the pH dependence in Fenton reaction, that is, the reaction kinetics decreases by approximately 1–3 orders of magnitude upon transitioning from an acidic to an alkaline state. Here, we discovered that protons significantly contribute to the Fenton reaction through an examination of the reaction's interfacial behavior characteristics. Proton transfer mediated by hydrogen bond network connectivity in the electric double layer is responsible for the pH dependence of Fenton reaction kinetics. On this basis, the surface potential of Fenton reaction catalyst was modified to optimize the distribution of H2O in the electrical double layer, enhancing the connectivity of the interfacial hydrogen bond network and providing a fast channel for rapid proton transfer. The consecutive hydrogen bond network mediates rapid proton hopping, increasing the proton concentration in the Helmholtz layer, and consequently promoting the proton conductivity from 5.38×10−7 S·cm−2 to 4.35×10−6 S·cm−2 in alkaline conditions for Fenton reaction. Meanwhile, the kinetics reaction rate was improved 20 times, and the pH dependence was reduced from 70.9 % to 12.6 %. This discovery clarifies the key role of the interfacial hydrogen bond network and proton transfer in Fenton reaction kinetics pH dependence. It provides new theories and methods for achieving alkaline high Fenton reaction kinetics.

One-Pot Synthesis of Fe-Norepinephrine Nanoparticles for Synergetic Thermal-Enhanced Chemodynamic Therapy.

Chemodynamic therapy (CDT) is an innovative and burgeoning strategy that utilizes Fenton-Fenton-like chemistry and specific microenvironments to produce highly toxic hydroxyl radicals (•OH), with numerous methods emerging to refine this approach. Herein, we report a coordination compound, Fe-norepinephrine nanoparticles (Fe-NE NPs), via a one-pot synthesis. The Fe-NE NPs are based on ferrous ions (Fe2+) and norepinephrine, which are capable of efficient Fe2+/Fe3+ delivery. Once internalized by tumor cells, the released Fe2+/Fe3+ exerts the Fenton reaction to specifically produce toxic •OH. Moreover, the internal photothermal conversion ability of Fe-NE NPs allows us to simultaneously introduce light to trigger local heat generation and then largely improve the Fenton reaction efficiency, which enables a synergetic photothermal and chemodynamic therapy to realize satisfactory in vivo antitumor efficiency. This proof-of-concept work offers a promising approach to developing nanomaterials and refining strategies for enhanced CDT against tumors.

Preparation of CIP@Fe3O4 particles and their impact on the fenton reaction processing performance of single-crystal SiC

This study proposes the preparation of CIP@Fe3O4 composite magnetic particles, which maintain excellent magnetic properties while exhibiting superior Fenton reaction performance for the magnetorheological chemical polishing of single-crystal SiC. The CIP@Fe3O4 particles were prepared by coating a nanoscale layer of Fe3O4 onto micron-sized carbonyl iron powder (CIP) using the co-precipitation method. Their Fenton reaction performance and magnetic properties were characterized, and CIP@Fe3O4 was used as a solid-phase catalyst in Fenton reaction-induced etching, frictional wear, and polishing experiments on single-crystal SiC. The prepared CIP@Fe3O4 particles have a saturation magnetization of 184.3 emu/g, representing only an 8.7 % reduction compared to CIP, yet achieved a decolorization rate of 76.2 % for the methyl orange indicator (compared to only 17.2 % with CIP alone). The Fenton reaction using CIP@Fe3O4 resulted in a prominent corrosion layer on the surface of single-crystal SiC, with the oxygen atomic fraction reaching 22.15 %. The study examined material removal from SiC under Fenton reactions with different solid-phase catalysts: CIP, CIP@Fe3O4, and CIP + Fe3O4. Frictional wear results indicated that the maximum scratch cross-sectional removal area on the SiC surface under the Fenton reaction with CIP@Fe3O4 was 474.38 μm2, representing a 207.3 % increase compared to without the Fenton reaction. Additionally, Si-O compounds were identified in the debris. Polishing experiments showed that the material removal rate (MRR) with the Fenton reaction was 3295 nm/h, an increase of 220.2 % compared to without the Fenton reaction, and the surface roughness was reduced to Ra 0.895 nm, a 73.4 % reduction compared to without the Fenton reaction. This study provides additional evidence for the application of magnetorheological technology and the Fenton reaction in the polishing field of single-crystal SiC.