Generation Of Superoxide Radicals Research Articles

Mechanical milling assisted synthesis of FePc-gCN nanocomposite photocatalyst: Dye degradation, mechanism and DFT insights

We present here a mechanochemical method for facile synthesis of Iron phthalocyanine (FePc)- graphitic carbon nitride (gCN) composite with varying weight ratio (1:1, 1:2.5, 1:5) of FePc and gCN. The photocatalytic efficiency of FePc-gCN composite for the elimination of various synthetic dyes, viz, Methylene Blue (MB), Congo Red (CR) and Eosin B (EB) in aqueous media were investigated under visible radiation. The sample with FePc:gCN weight ratio of 1:5 resulted in a removal efficiency of 90 % for MB and 75 % for EB, much higher than their individual counterparts. The synergistic interaction, less charge recombination, and smaller charge transfer resistance in FePc-gCN composite contributed to the superior catalytic performances as confirmed from the impedance spectroscopy and the photoluminescence spectroscopy. Moreover, first principle based DFT calculations on the O2 adsorbed FePc-gCN heterostructure predicted a net transfer of |0.11e| charges from Fe to O atom, favoring the generation of super oxide (O2•−) radicals which contributes actively towards degradation of dye pollutants.

Sustainable photoelectrocatalytic oxidation of antibiotics using Ag–CoFe2O4@TiO2 heteronanostructures for eco-friendly wastewater remediation

Developing high-performance and durable catalysts presents a significant challenge for oxidizing toxic inorganic and pharmaceutical compounds in wastewater. Recently, there has been a surge in the development of new heterogeneous catalysts for degrading pharmaceutical compounds, driven by advancements in electrocatalysts and photoelectrocatalysts. In this study, a plasmonic Ag nanoparticles decorated CoFe2O4@TiO2 heteronanostructures have been successfully designed to fabricate a high-performing photoelectrode for the oxidation of pharmaceutical compounds. The developed Ag–CoFe2O4@TiO2 possessed a higher electrochemical stability and effectively harvested the UV to visible and NIR radiation in sunlight which generates the enormous photochemical reactive species that involved in the oxidation of ibuprofen in wastewater. Under direct sunlight irradiation, Ag–CoFe2O4@TiO2 achieved complete oxidation of ibuprofen in wastewater at 0.8 V vs RHE. This indicates that metallic Ag nanoparticles are involved in the charge separation and transport of charge carriers from the photoactive sites of CoFe2O4@TiO2, promoting the generation of abundant hydroxy, oxy, and superoxide radicals that actively break the bonds of ibuprofen. Additionally, oxidation agents such as urea and H2O2 were utilized to enhance the formation of superoxide ions and hydroxyl radicals, which rapidly participate in the oxidation of ibuprofen. Significantly, testing for recyclability confirmed the stability of the Ag–CoFe2O4@TiO2 photoanode, ensuring its suitability for prolonged use in photoelectrochemical advanced oxidation processes. Integrating Ag–CoFe2O4@TiO2 photoanodes into water purification systems could enhance economic feasibility, reduce energy consumption, and improve efficiency.

A Renal Clearable Nano-Assembly with Förster Resonance Energy Transfer Amplified Superoxide Radical and Heat Generation to Overcome Hypoxia Resistance in Phototherapeutics.

Given that type I photosensitizers (PSs) possess a good hypoxic tolerance, developing an innovative tactic to construct type I PSs is crucially important, but remains a challenge. Herein, we present a smart molecular design strategy based on the Förster resonance energy transfer (FRET) mechanism to develop a type I photodynamic therapy (PDT) agent with an encouraging amplification effect for accurate hypoxic tumor therapy. Of note, benefiting from the FRET effect, the obtained nanostructured type I PDT agent (NanoPcSZ) with boosted light-harvesting ability not only amplifies superoxide radical (O2 •-) production but also promotes heat generation upon near-infrared light irradiation. These features facilitate NanoPcSZ to realize excellent phototherapeutic response under both normal and hypoxic environments. As a result, both in vitro and in vivo experiments achieved a remarkable improvement in therapeutic efficacy via the combined effect of photothermal action and type I photoreaction. Notably, NanoPcSZ can be eliminated from organs (including the liver, lung, spleen, and kidney) apart from the tumor site and excreted through urine within 24 h of its systemic administration. In this way, the potential biotoxicity of drug accumulation can be avoided and the biosafety can be further enhanced.

Electron-Withdrawing Substituents Enhance the Type I PDT and NIR-II Fluorescence of BODIPY J Aggregates for Bioimaging and Cancer Therapy.

Organic dyes with simultaneously boosted near-infrared-II (NIR-II) fluorescence, type I photodynamic therapy (PDT), and photothermal therapy (PTT) in the aggregate state are still elusive due to the unclear structure-function relationship. Herein, electron-withdrawing substituents are introduced at the 5-indolyl positions of BODIPY dyes to form tight J-aggregates for enhanced NIR-II fluorescence and type I PDT/PTT. The introduction of an electron-rich julolidine group at the meso position and an electron-withdrawing substituent (-F) at the indolyl moiety can enhance intermolecular charge transfer and the hydrogen bonding effect, contributing to the efficient generation of superoxide radicals in the aggregate state. The nanoparticles of BDP-F exhibit NIR-II fluorescence at 1000 nm, good superoxide radical generation ability, and a high photothermal conversion efficiency (50.9%), which enabled NIR-II fluorescence-guided vasculature/tumor imaging and additive PDT/PTT. This work provides a strategy for constructing phototheranostic agents with enhanced NIR-II fluorescence and type I PDT/PTT for broad biomedical applications.

Advanced Nix/MoSx/MOF-2@g-C3N4 carbon nanostructures for the effective eradication of the Methylene blue dye

In this research, we investigated different hybrid photocatalysts: Ni/Mo.S2/MOF-2@g-C3N4, Mo.S2/MOF-2@g-C3N4, Ni.S2/MOF-2@g-C3N4 and Ni/Mo.S2/MOF-2. These photocatalysts were synthesized using a solvothermal method by incorporating Ni.x/Mo.Sx, the heterojunction showed improved separation of photoinduced charges due to disparity in charge transfer. This resulted in a narrower energy band gap and excellent catalytic activity in photodegradation. The Ni/Mo.S2/MOF-2@g-C3N4 heterostructure demonstrated outstanding photocatalytic efficiency, with up to 91% degradation of methylene blue (MB). This significant degradation was driven by the generation of superoxide (O2 •) and hydroxyl (•OH) radicals. The process adhered to pseudo-first-order kinetics and was effectively completed within 90 min of light exposure. Remarkably, the Ni/Mo.S2/MOF-2@g-C3N4 heterostructure displayed excellent stability, with only minimal performance degradation observed after five consecutive cycles. These results underscore the superior stability of the heterostructure. In summary, our research confirms that the Ni/Mo.S2/MOF-2@g-C3N4 heterojunction photocatalyst is a highly efficient material for the effective removal of methylene blue dye.

Manganese (III) phthalocyanine complex nanoassembly: Oxygen-Independent generation of superoxide radicals and singlet oxygen for ultrasound-augmented chemodynamic therapy

Singlet oxygen (1O2), an excellent reactive oxygen species (ROS) for tumor therapy, has garnered significant attention recently. However, its production is hindered by the low oxygen content in solid tumors characterized by hypoxia. Consequently, it is urgent to develop an O2-independent generator. In this study, we present a novel nano-assembly composed of manganese (Ⅲ) phthalocyanine complex (MnClPc) encapsulated by human serum albumin (MnClPc@HSA). MnClPc@HSA serves as a conventional sonosensitizer, facilitating the conversion of O2 to 1O2 under ultrasonic stimulation (US). Moreover, MnClPc@HSA enables the conversion of endogenous hydrogen peroxide (H2O2) within tumor to superoxide radical (·O2–) and 1O2 and further enhanced by US. This O2-independent generation of multiple ROS by MnClPc@HSA overcomes the limitations imposed by tumor hypoxia, while inducing immunogenic cell death (ICD) and enhancing the infiltration of T cells as well. When combined with conventional PD-L1 immunotherapy, this approach effectively inhibits the proliferation of distal and lung-metastatic tumors, while concurrently eliminating primary tumors in the bilateral-tumor model of 4 T1 tumor-bearing mice.

Interfacial interactions of polyoxometalate and Au0Pdδ+ alloy boosting aerobic oxidation of alcohols

It is significant to gain insights into the electronic interfacial interactions on non-reducible oxides as they can effectively improve the catalytic performance. Herein, we reported the fabrication of Au0Pdδ+ alloy (average size: 1.9 nm) co-modified with Na12[α-P2W15O56] (P2W15) nanoclusters on aluminum oxide (denoted as AuPd/P2W15-Al2O3) by deposition–precipitation and covalent immobilization strategy. The as-prepared AuPd/P2W15-Al2O3 exhibited 92 % conversion, 96 % selectivity of benzaldehyde with the reaction rate of 4.9 × 104h−1 when applied for the selective oxidation of benzyl alcohol, which was superior to AuPd/Al2O3, Au/P2W15-Al2O3 and Pd/P2W15-Al2O3 catalysts. Such excellent catalytic performance can be ascribed to the fact that: the electrons transfer from P2W15 to Au0Pdδ+ alloy resulted in the electron-rich Au0Pdδ+ alloy species, and the enhanced interfacial interactions between Au0Pdδ+ alloy and P2W15 nanoclusters facilitated activation of O2 to generate superoxide radicals •O2–. Moreover, density-functional theory (DFT) calculation confirmed that the P2W15 clusters modulated the d-band center of Au0Pdδ+ alloy and accelerated the adsorption of benzyl alcohol, O2 activation and desorption of benzaldehyde.

Short‐Term Soil Waterlogging Improves Cotton Tolerance to High Temperature by Triggering Antioxidant Defence System in Cotton Seedlings

ABSTRACTSoil waterlogging and high temperature (HT) are serious abiotic stresses that negatively affect cotton growth and yield. Yet effects of prewaterlogging to HT subsequently in cotton seedlings have not been obtained. To address this, two temperature conditions (30/20°C and 35/25°C) and two soil waterlogging levels (0 and 3 days) were established during the cotton seedling stage. Results showed that indexes of plant performance were decreased markedly under HT. Unexpectedly, plant performance for the treatment of HT combined with 3 days of soil waterlogging (HW) was better than HT treatment (specifically, increase of 7.9%, 9.0%, 10.2%, 5.4% and 4.6% in leaf area, plant height, belowground biomass, aboveground biomass and root‐to‐shoot ratio was detected). Decreases in MDA (malondialdehyde), H2O2 (hydrogen peroxide) contents and (superoxide radicals) generation rate under HW treatment were observed by 14.1%, 7.7% and 14.1%, respectively, compared with HT. Moreover, ASA (ascorbic acid) content and DHAR (dehydroascorbate reductase) activity were improved by 19.7% and 13.8% for HW treatment relative to HT, however, the opposite situation for activities of APX (ascorbate peroxidase) and GR (glutathione reductase). Besides, activities of SOD (superoxide dismutase), CAT (catalase) and POD (peroxidase) in HW treatment were increased by 16.7%, 8.3% and 18.4%, separately. Thus, we concluded that short‐term soil waterlogging improved cotton cross‐tolerance to the continued high‐HT stress by enhanced SOD, CAT, POD and DHAR activities, increased ASA content in cotton seedlings. These results were expected to provide a theoretical basis for understanding cotton's cross‐tolerance to abiotic stress.

Co–N–C anchored g-C3N4 plate enhancing surface activity for efficient visible-light photocatalytic rhodamine-B elimination and CO2 conversion

Poor light-harvesting, fast recombination of photo-induced charge carriers, and unfavorable surface adsorption remain the major issues restricting the photocatalytic activity of g-C3N4. In this study, the Co-N-C decorated g-C3N4 (Co-N-C/g-CN) plate was developed by constructing Co-N-C on the surface of g-CN plate to improve photocatalytic rhodamine-B (RhB) degradation and CO2 conversion. The as-prepared 0.5Co-N-C/g-CN plate exhibited an exceptionally high efficiency in photocatalytic RhB degradation, with a rate of 99.5 % achieved in mere 30 min. Besides, the 0.5Co-N-C/g-CN plate also demonstrated an outstanding photocatalytic CO2 conversion rate of 33.7 μmol g−1cat h−1 within 4 h, which was more than 3.4-fold that of g-CN (9.9 μmol g−1cat h−1). Experiments demonstrated that the surface-constructed Co-N-C enhanced the visible light-harvesting and the separation of photo-induced charge carriers, boosting the optical property. Moreover, the density functionalized theory (DFT) calculations verified that the Co-N-C cocatalyst optimized O2 adsorption for the generation of superoxide radicals (·O-2), accelerating the photocatalytic RhB removal. Meanwhile, the Co-N-C was advantageous for the adsorption and activation of CO2, facilitating the photocatalytic CO2 conversion. This study provides a perspective on the surface engineering of g-CN toward enhanced photocatalytic performance.

Thymoquinone as an electron transfer mediator to convert Type II photosensitizers to Type I photosensitizers

The development of Type I photosensitizers (PSs) is of great importance due to the inherent hypoxic intolerance of photodynamic therapy (PDT) in the hypoxic microenvironment. Compared to Type II PSs, Type I PSs are less reported due to the absence of a general molecular design strategy. Herein, we report that the combination of typical Type II PS and natural substrate carvacrol (CA) can significantly facilitate the Type I pathway to efficiently generate superoxide radical (O2–•). Detailed mechanism study suggests that CA is activated into thymoquinone (TQ) by local singlet oxygen generated from the PS upon light irradiation. With TQ as an efficient electron transfer mediator, it promotes the conversion of O2 to O2–• by PS via electron transfer-based Type I pathway. Notably, three classical Type II PSs are employed to demonstrate the universality of the proposed approach. The Type I PDT against S. aureus has been demonstrated under hypoxic conditions in vitro. Furthermore, this coupled photodynamic agent exhibits significant bactericidal activity with an antibacterial rate of 99.6% for the bacterial-infection female mice in the in vivo experiments. Here, we show a simple, effective, and universal method to endow traditional Type II PSs with hypoxic tolerance.

Fabrication of photo-induced molecular superoxide radical generator for highly efficient therapy against bacterial wound infection

The pressing need for highly efficient antibacterial strategies arises from the prevalence of microbial biofilm infections and the emergence of rapidly evolving antibiotic-resistant strains of pathogenic bacteria. Photodynamic therapy represents a highly efficient and compelling antibacterial approach, offering promising prospects for effective control of the development of bacterial resistance. However, the effectiveness of many photosensitizers is limited due to the reduced generation of reactive oxygen species (ROS) in hypoxic microenvironment, which commonly occur in pathological conditions such as inflammatory and bacteria-infected wounds. Herein, we designed and prepared two phenothiazine-derived photosensitizers (NB-1 and NB-2), which can effectively generate superoxide anion radicals (O2●–) through the type I process. Both photosensitizers demonstrate significant efficacy in vitro for the eradication of broad-spectrum bacteria. Moreover, NB-2 possesses distinct advantages including strong membrane binding and strong generation of O2●–, rendering it an exceptionally efficient antibacterial agent against mature biofilms. In addition, laser activated NB-2 could be applied to treat MRSA-infected wound in vivo, which offers new opportunities for potential practical applications.

Concerted Two-Proton-Coupled Electron Transfer from Piceatannol to Electrogenerated Superoxide in N,N-Dimethylformamide.

The reactivity of 4-[(E)-2-(3,5-dihydroxyphenyl)ethenyl]benzene-1,2-diol (piceatannol) toward electrochemically generated superoxide radical anion (O2 •-) was investigated using electrochemistry and in situ controlled-potential electrolytic electron spin resonance (ESR) measurements in N,N-dimethylformamide with density functional theory (DFT) calculations. The quasireversible cyclic voltammogram of dioxygen/O2 •-, modified in the presence of piceatannol, indicated that the electrogenerated O2 •- was scavenged by piceatannol via proton-coupled electron transfer. Differences in the reactivities of piceatannol and 5-[(E)-2-(4-hydroxyphenyl)ethen-1-yl]benzene-1,3-diol (trans-resveratrol) toward O2 •-, originating from the presence of the benzene-1,2-diol (catechol) moiety, were observed in the voltammograms and ESR measurements. The electrochemical and computational results show that the reaction mechanism is a concerted two-proton-coupled electron transfer (2PCET) via the catechol moiety of piceatannol. The stilbene moiety of piceatannol kinetically promotes 2PCET via its catechol moiety. These findings indicate that piceatannol is a better O2 •- scavenger than catechol and trans-resveratrol.

Electron Structure of α‐, β‐Te2MoO7 and Photocatalytic Decomposition of Antibiotics

AbstractTwo modifications of Te2MoO7 oxide have been prepared by different synthetic methods. The crystal structure and composition have been studied by X‐ray diffraction analysis and X‐ray microanalysis. The phase of α‐Te2MoO7 has been synthesized by solid‐state reaction from ammonium salts and characterized by monoclinic structure with P21/c. The β‐Te2MoO7 compound has been formed in hydrothermal conditions and has amorphous nature. The thermal behavior of β‐Te2MoO7 modification is characterized by the phase transition into α‐form, however after melting the amorphous state has restored. The electron structure has been investigated experimentally by X‐ray photoelectron spectroscopy and UV‐vis diffusion reflectance spectra and theoretically by approximation using atomic electronegativity. Despite the same composition, the band gap of β‐Te2MoO7 corresponds to visible light, whereas α‐Te2MoO7 adsorbs light in UV region. The both modifications are able to generate superoxide radicals in vacuum or air and hydroxyl radicals in water under irradiation. The HPLC‐MS analysis has shown the quite deep decomposition of dye and antibiotics by α‐Te2MoO7, whereas amorphous phase almost does not lead to any oxidation.

Insights into the Formation Mechanism of Reactive Oxygen Species in the Interface Reaction of SO2 on Hematite.

The interplay between sulfur and iron holds significant importance in their atmospheric cycle, yet a complete understanding of their coupling mechanism remains elusive. This investigation delves comprehensively into the evolution of reactive oxygen species (ROS) during the interfacial reactions involving sulfur dioxide (SO2) and iron oxides under varying relative humidity conditions. Notably, the direct activation of water by iron oxide was observed to generate a surface hydroxyl radical (•OH). In comparison, the aging of SO2 was found to markedly augment the production of •OH radicals on the surface of α-Fe2O3 under humid conditions. This augmentation was ascribed to the generation of superoxide radicals (•O2-) stemming from the activation of O2 through the Fe(II)/Fe(III) cycle and its combination with the H+ ion to produce hydrogen peroxide (H2O2) on the acidic surface. Moreover, the identification of moderate relative humidity as a pivotal factor in sustaining the surface acidity of iron oxide during SO2 aging underscores its crucial role in the coupling of iron dissolution, ROS production, and SO2 oxidation. Consequently, the interfacial reactions between SO2 and iron oxides under humid conditions are elucidated as atmospheric processes that enhance oxidation capacity rather than deplete ROS. These revelations offer novel insights into the mechanisms underlying •OH radical generation and oxidative potential within atmospheric interfacial chemistry.

Ti-MOG derived TiO2 facet heterojunction rich in C/Ti3+/Ov for adsorption-photocatalytic removal of pharmaceutical pollutants from water

Developing efficient, stable, and broad-spectrum responsive photocatalysts is an effective way to degrade pharmaceutical pollutants in water. In this work, using concentrated hydrochloric acid (HCl) as a modulator, titanium metal–organic gel (Ti-MOG) was prepared and used as a template for calcination in air to obtain anatase TiO2 facet heterojunction rich in C/Ti3+/oxygen vacancy (Ov) (MOG-TiO2), which has a hierarchical porous structure, large specific surface area, and highly dispersed active site. Compared to P25, P25 + C and MIL-125(Ti) derived TiO2 (MOF-TiO2), MOG-TiO2 exhibited obviously enhanced adsorption-photocatalytic performance for tetracycline (TC) and low concentrations ethenzamide (ETH) under broad-spectrum light irradiation. The photocatalytic degradation efficiency of ETH by MOG-TiO2 reached 92.8, 100 and 98.7 % within 240, 60 and 6 min under Vis, UV and VUV light illumination, respectively, which were much higher than those of P25 (62.7, 33.2 and 73.0 %), P25 + C (61.7, 31.2 and 72.5 %) and MOF-TiO2 (79.2, 86.8 and 88.7 %). Furthermore, concentrated HCl promoted the formation of Ti3+/Ov in MOG-TiO2, which was conducive to the improvement of its photocatalytic performance. MOG-TiO2 also displayed great adsorption-photocatalytic stability and reusability. Moreover, the biotoxicity of TC toward E. coli DH5a obviously decreased after photocatalytic degradation. Based on the TiO2 facet heterojunction rich in C/Ti3+/Ov and the generation of hole, hydroxyl radicals, and superoxide radicals, the possible photocatalytic degradation mechanism of MOG-TiO2 was proposed. Overall, this work provides insights into constructing a novel hierarchical porous carbon-doped facet heterojunction photocatalyst for efficient pharmaceutical contaminants removal.

Oxygen-Centered Organic Radicals-Involved Unified Heterogeneous Self-Fenton Process for Stable Mineralization of Micropollutants in Water.

Removing organic micropollutants from water through photocatalysis is hindered by catalyst instability and substantial residuals from incomplete mineralization. Here, a novel water treatment paradigm, the unified heterogeneous self-Fenton process (UHSFP), which achieved an impressive 32% photon utilization efficiency at 470nm, and a significant 94% mineralization of organic micropollutants-all without the continual addition of oxidants and iron ions is presented. In UHSFP, the active species differs fundamentally from traditional photocatalytic processes. One electron acceptor unit of photocatalyst acquires only one photogenerated electron to convert into oxygen-centered organic radical (OCOR), then spontaneously completing subsequent processes, including pollutant degradation, hydrogen peroxide generation, activation, and mineralization of organic micropollutants. By bolstering electron-transfer capabilities and diminishing catalyst affinity for oxygen in the photocatalytic process, the generation of superoxide radicals is effectively suppressed, preventing detrimental attacks on the catalyst. This study introduces an innovative and cost-effective strategy for the efficient and stable mineralization of organic micropollutants, eliminating the necessity for continuous chemical inputs, providing a new perspective on water treatment technologies.

Novel angiogenesis inhibitors with superoxide anion radical amplification effect: Surmounting the Achilles’ heels of angiogenesis inhibitors and photosensitizers

Angiogenesis inhibitors and photosensitizers are pivotal in tumor clinical treatment, yet their utilization is constrained. Herein, eleven novel angiogenesis inhibitors were developed through hybridization strategy to overcome their clinical limitations. These title compounds boast excitation wavelengths within the “therapeutic window”, enabling deep tissue penetration. Notably, they could generate superoxide anion radicals via the Type I mechanism, with compound 36 showed the strongest superoxide anion radical generating capacity. Biological evaluation demonstrated remarkable cellular activity of all the title compounds, even under hypoxic conditions. Among them, compound 36 stood out for its superior anti-proliferative activity in both normoxic and hypoxic environments, surpassing individual angiogenesis inhibitors and photosensitizers. Compound 36 induced cell apoptosis via superoxide anion radical generation, devoid of dark toxicity. Molecular docking revealed that the target-recognizing portion of compound 36 was able to insert into the ATP binding pocket of the target protein similar to sorafenib. Collectively, our results suggested that hybridization of angiogenesis inhibitors and photosensitizers was a potential strategy to address the limitations of their clinical use.

Enhancing the Photocatalytic Activity of Halide Perovskite Cesium Bismuth Bromide/Hydrogen Titanate Heterostructures for Benzyl Alcohol Oxidation.

Halide perovskite Cs3Bi2Br9 (CBB) has excellent potential in photocatalysis due to its promising light-harvesting properties. However, its photocatalytic performance might be limited due to the unfavorable charge carrier migration and water-induced properties, which limit the stability and photocatalytic performance. Therefore, we address this constraint in this work by synthesizing a stable halide perovskite heterojunction by introducing hydrogen titanate nanosheets (H2Ti3O7-NS, HTiO-NS). Optimizing the weight % (wt%) of CBB enables synthesizing the optimal CBB/HTiO-NS, CBHTNS heterostructure. The detailed morphology and structure characterization proved that the cubic shape of CBB is anchored on the HTiO-NS surface. The 30 wt% CBB/HTiO-NS-30 (CBHTNS-30) heterojunction showed the highest BnOH photooxidation performance with 98% conversion and 75% benzoic acid (BzA) selectivity at 2 h under blue light irradiation. Detailed optical and photoelectrochemical characterization showed that the incorporating CBB and HTiO-NS widened the range of the visible-light response and improved the ability to separate the photo-induced charge carriers. The presence of HTiO-NS has increased the oxidative properties, possibly by charge separation in the heterojunction, which facilitated the generation of superoxide and hydroxyl radicals. A possible reaction pathway for the photocatalytic oxidation of BnOH to BzH and BzA was also suggested. Furthermore, through scavenger experiments, we found that the photogenerated h+, e- and •O2- play an essential role in the BnOH photooxidation, while the •OH have a minor effect on the reaction. This work may provide a strategy for using HTiO-NS-based photocatalyst to enhance the charge carrier migration and photocatalytic performance of CBB.

Synergistic oxidation of humic acid treated by H2O2/O3 activated by CuCo/C with high efficiency and wide pH range

Combination of oxidation processes are one of the most promising humic acid treatment technologies. Single oxidant or even two oxidants in advance oxidation process can hardly achieve satisfactory removal efficiency of refractory organic matter, mainly humic acid, in the treatment process of reverse osmosis concentrates from landfill leachate. To solve this problem, this study investigated the synergistic degradation of Humic acid (HA) using a Cu and Co supported on carbon catalyst (CuCo/C) in a Hydrogen peroxide (H2O2) with ozone (O3) system. The catalyst was characterized by performing SEM, XRD, BET, XPS and FTIR technologies. UV–vis spectra, 3D Excitation Emission Matrix Spectra (3D-EEM) and gas chromatography-mass spectrometry (GC–MS) were applied for exploring degradation mechanism of HA. To further understand the oxidation mechanism, electron paramagnetic resonance (EPR) was used to evaluate the generation of hydroxyl (·OH) and superoxide radicals (O2·-). As a result, CuCo/C catalyst possessed stable catalytic performance for HA degradation with a wide pH range from 5 to 8, while T = 40 °C，catalyst dosage of 2.4 g/L，O3 intake rate of 0.15 g/min and H2O2 dosage of 1.92 mL/L, the degradation rate of total organic carbon (TOC) achieved 40–46.5 mg·L−1min−1. As affirmed by the EPR, ·OH and O2·- were effectively generated with addition of the CuCo/C catalyst. Degradation performance of UV254 proved that the catalytic activity can still be maintained above 95% with removal rate of 82% after 5 cycles reuse. GC-MS shows that the oxidation products mainly consist of amide, benzoheterocyclic ring and carboxylic acid. This work promotes an effective method for degrading HA, which has the potential for satisfactory application in landfill leachate.

Regulating Reactive Oxygen Species over M-N-C Single-Atom Catalysts for Potential-Resolved Electrochemiluminescence.

The development of potential-resolved electrochemiluminescence (ECL) systems with dual emitting signals holds great promise for accurate and reliable determination in complex samples. However, the practical application of such systems is hindered by the inevitable mutual interaction and mismatch between different luminophores or coreactants. In this work, for the first time, by precisely tuning the oxygen reduction performance of M-N-C single-atom catalysts (SACs), we present a dual potential-resolved luminol ECL system employing endogenous dissolved O2 as a coreactant. Using advanced in situ monitoring and theoretical calculations, we elucidate the intricate mechanism involving the selective and efficient activation of dissolved O2 through central metal species modulation. This modulation leads to the controlled generation of hydroxyl radical (·OH) and superoxide radical (O2·-), which subsequently trigger cathodic and anodic luminol ECL emission, respectively. The well-designed Cu-N-C SACs, with their moderate oxophilicity, enable the simultaneous generation of ·OH and O2·-, thereby facilitating dual potential-resolved ECL. As a proof of concept, we employed the principal component analysis statistical method to differentiate antibiotics based on the output of the dual-potential ECL signals. This work establishes a new avenue for constructing a potential-resolved ECL platform based on a single luminophore and coreactant through precise regulation of active intermediates.