Generation Of Active Oxygen Species Research Articles

Incorporating Si into NiO support to facilitate oxygen activation for CH4 combustion

In this study, high-performance Pd/NiO-Si catalysts for lean methane oxidation were synthesized using the solution combustion and impregnation method. The incorporation of silicon in NiO promoted the generation of Ni2+ and strengthened the metal-support interaction. This enhanced interaction promoted the generation and movement of active oxygen species on surface, which are essential for maintaining Pd species in an active oxidized state, thereby ensuring the effective activation of CH4. The Pd/NiO-Si catalyst with an optimal amount of Si exhibited an excellent catalytic performance, achieving a T90 of 440 °C for methane oxidation under wet conditions. The elemental doping strategy in this study, which significantly enhances the production of highly active oxygen species with strong mobility, plays a crucial role in the effective utilization of precious metals such as Pd.

Enhanced antibiotic degradation using rGO composites under visible light photocatalysis

A robust reduced graphene oxide (rGO), polyaniline (PANI) with calcium (Ca) and magnesium (Mg) bimetallic nanocomposite was successfully prepared using an in-situ chemical facial reducing method and named rGO@PANI-Ca:Mg. Various spectroscopic techniques, including XRD, SEM, TEM, XPS, and supplementary methods, were utilized to characterize the catalyst phase, microstructure, and optical attributes. The composite's photocatalytic efficiency was assessed by degrading antibiotics such as ciprofloxacin (CP) and tetracycline (TC) using calcium peroxide (CaO2) under visible light irradiation. The rGO@PANI-Ca:Mg composite demonstrates superior degradation efficiency for CP, 45 %, and for TC, 70 %, achieving a correlation coefficient R² of 0.94 and 0.991 respectively. This performance surpasses that of pristine GO, rGO, and rGO@PANI. The heightened photocatalytic activity is ascribed to forming a heterojunction, effectively mitigating electron-hole pair recombination. The incorporation of CaO2 promotes the generation of additional active reactive oxygen species (ROS), particularly OH·, ·O2−, e-, h+, as verified by radical scavenging experiments, indicating an enhancement in the degradation and a potential mechanism is also suggested. The degradation rate of TC, CP, and real wastewater (RW) is about 71 %, 45 %, and 40.98 %, respectively. The composite demonstrates stability and reusability for up to three catalytic cycles. Our experiments also showed that when bacteria were treated with a 2 mg catalyst, the minimum inhibitory concentration (MIC) was determined to be at a 10−3 dilution. This MIC value represents the lowest concentration at which the catalyst effectively inhibited bacterial growth, as evidenced by clear inhibition zones.

Revealing Enhanced Active Oxygen Formation by Incorporating Chromium into Nickel Hydroxide Nanosheets for Improved Oxygen Evolution Reaction.

Nickel-based oxyhydroxides have emerged as promising catalysts for the oxygen evolution reaction (OER) among Earth-abundant metals. While the incorporation of foreign elements is recognized to enhance catalytic activity, the origin of this enhancement is still debated. We synthesize and examine Ni hydroxide nanosheets, both with and without Cr doping, to elucidate the underlying enhancements. Operando UV-vis and Raman spectroscopy are employed to unravel the behavior of the catalysts. The Cr doping facilitates the oxidation of Ni, resulting in the generation of active oxygen species. The enriched active oxygen species improves OER performance through a lattice oxygen-mediated pathway in Fe-free KOH, and further contribute to the creation and increased activity of FeOxHy sites in the presence of Fe impurities. This work provides a mechanistic understanding of the performance enhancement in Ni-based catalysts through Cr doping and suggests a strategy for the design of more efficient catalysts in the future.

Cu‐Doped 0D Bi2WO6 Nanoparticles for Efficient Visible‐Light‐Driven Photocatalytic Tetracycline Degradation

AbstractBismuth‐based photocatalysts have been widely employed in the photocatalytic degradation of organic pollutants in wastewater. However, the lack of rational structural design and the slow generation of active free radicals have hindered its efficiency. Here, we stabilized Bi2WO6 nanoparticles by wrapping them with hydroxyl groups, introduced metal Cu doping, and underwent an annealing process to construct Cu‐BiNP nanocatalysts with exposed active sites. Under visible light irradiation, 0.03Cu‐BiNP achieved a 94.5% TC degradation efficiency, which is 15.8 times higher than the rate of bulk BiWO. The 0D structure endows Cu‐BiNP with ample opportunities for O2 adsorption and activation, and Cu atomic doping reduces the bandgap and increases the oxygen vacancy, promoting the generation of active oxygen species. This work demonstrates the rapid charge separation and activation of O2 to generate active oxygen species by 0D bismuth‐based nanocatalysts in photocatalytic oxidation reactions, providing a scalable nanocatalyst platform for TC photocatalytic degradation.

In-situ realtime study of zinc selenide nanoparticles sustained by polypyrrole in alkaline water oxidation

Interest in metal electrodeposition for synthesizing customized nanomaterials has resurged, particularly for applications such as sensors and fuel cells. The present study involved the synthesis of ZnSe nanoparticles (via hydrothermal method) while polypyrrole and novel composite Ppy@ZnSePpy@Ppy (via sequential electrodeposition technique) on a glassy carbon (GC) electrode and their physiochemical, electrochemical, and operando spectro-electrochemical characterizations towards oxygen evolution reaction (OER). Results indicated that ZnSe nanoparticles are well embedded within the Ppy layers and during OER the composite electrocatalyst approached 398 mV at 10 mA cm−2 and exhibited Tafel value (b ∼ 75 mV dec−1) with ECSA (0.03) which shows better results than other two. In addition, the operando spectro-electrochemical spectra of the composite revealed the significant generation of active intermediate oxygen species of selenium and Zn2+. The important feature of the current work is the disclosure of Se's questionable role and species involved in OER found to be Se4+.

Role of morphology in improving the catalytic performance of ZnCo2O4 for soot oxidation

The extent of interaction between carbon and catalyst profoundly shapes soot oxidation results. The catalyst configuration notably influences the frequency of contact points in solid–solid interactions. This investigation studies the impact of three distinct ZnCo2O4 catalyst morphologies and their redox property on soot oxidation. The formation of the cubic phase of ZnCo2O4 via three distinct methods was revealed during XRD analysis. SEM analysis unveiled varying morphologies, including rod-shaped, rose petal-shaped, and bead-like structures. Notably, ZnCo2O4 exhibiting bead-like morphology demonstrated heightened levels of chemisorbed oxygen species which was observed during XPS analysis. The presence of Co2+ and Co3+ occupied at octahedral site ZnCo2O4 acted as the active sites for soot oxidation. With continuous redox property (Co 3+ → Co 2+) leading to the generation of active oxygen species and with an added advantage of surface morphology, the M2 sample (with bead-like morphology) exhibited superior soot oxidation activity, which is evident by its T50% value of 402 °C. This study underscores the essential role of catalyst morphology in influencing soot oxidation activity. Through a comprehensive array of structural, morphological, and catalytic analyses, this work sheds light on the correlation between catalyst architecture and enhanced soot oxidation performance.

Visible light driven generation of dual active oxygen species on Zr-MOF/g-C3N4 photocatalyst for highly selective photocatalytic oxidation of sulfides to sulfoxides

The efficient synthesis of valuable compounds using visible light catalytic conversion method has great application prospects. Herein, Zr-MOF/g-C3N4 composite material was synthesized through a simple solvothermal method, which presented effective photocatalytic activity for oxidation of sulfides to sulfoxides under visible light irradiation, higher than that of pure Zr-MOF and g-C3N4. This is attributed to the Zr-MOF/g-C3N4 composite exhibit wide visible-light absorption, large pore volume, and the promotion photogenerated carriers’ separation. Mechanism studies revealed that singlet oxygen (1O2) and superoxide radical (O2–) are the main active oxygen species in this photocatalytic process, which improve the photocatalytic conversion and selectivity of sulfides to sulfoxides. More importantly, this work will provide meaningful references for constructing catalysts that can be used for visible light catalytic synthesis of sulfoxides.

Effect of interferon lambda on the generation of active oxygen species in mice under conditions of oxidative stress induced by Mitomycin C

This research was aimed at studying the effect of species-specific recombinant bovine interferon lambda (IFN-λ) on the generation of reactive oxygen species (ROS) in mouse liver and bone marrow cells under conditions of mitomycin Cinduced oxidative stress. The experiment included female white laboratory mice. There were formed four groups of 6 animals each: the negative control group (group I); the group of mice that received a three-fold injection of IFN-λ at a dose of 0.1 ml/kg (group II) and mice that, in addition to IFN-λ, were administered a cytotoxic drug that induced free radical oxidation processes - mitomycin C at a dose of 10 mg/kg (group III), as well as the animals receiving only mitomycin C (group IV). We studied the concentration and viability of a cell suspension obtained from the liver of mice, as well as the relative content of intracellular ROS in the liver and bone marrow cells of animals, assessed by the fluorescence intensity of the oxidized form of 2',7'-dichlorodihydrofluorescein diacetate. The concentration and viability of cells in the liver suspension of healthy mice did not change with the introduction of IFN-λ (group II), indicating the absence of a toxic effect of IFN-λ on these cells. An increase in the level of ROS in the studied cells was detected when IFN-λ was administered to mice of group II (an increase in the level of ROS by 1.3 times in liver cells and by 2.9 times in bone marrow cells, relative to the mice of group I) and a decrease in the level of ROS in the mice under conditions of oxidative stress induced by mitomycin C (reduction in the content of intracellular ROS by 1.9 and 7.2 times in liver and bone marrow cells in the animals of group III, relative to the mice of group IV). The presented changes may indicate the normalization of IFN-λ redox balance in the body and, probably, appear in connection with the immunomodulatory activity of IFN-λ.

Lanthanum-doped magnetic biochar activating persulfate in the degradation of florfenicol

In this study, lanthanum-doped magnetic biochar (LaMBC) was synthesized from bagasse by co-doping iron salt and lanthanum salt, and it was characterized for its application in the activation of persulfate (PS) in the degradation of Florfenicol (FLO). The results indicated that the LaMBC/PS system consistently achieved a degradation efficiency of over 99.5 %, with a reaction rate constant 4.71 times as that of MBC. The mechanism of FLO degradation suggested that O2•- and •OH played dominant roles, contributing 40.92 % and 36.96 %, respectively, during FLO degradation. Through physicochemical characterization and quenching experiments, it can be concluded that the key reasons for the enhancement of MBC activation performance are as follows: (1) Lanthanum doping in magnetized biochar increased the Fe(II) content in MBC. (2) Lanthanum doping significantly improved the adsorption capacity of LaMBC, increased the concentration of pollutants on the catalyst surface and effectively enhancing the reaction rate. (3) Lanthanum doping effectively increased the surface Fe(II) content during the reaction process in LaMBC, promoted the generation of active oxygen species in PS. This study delves into synthesizing and applying LaMBC for PS activation and FLO removal. The emphasis is on comprehensively characterizing and experimenting to elucidate the mechanism, proposing an innovative approach for efficiently degrading antibiotic wastewater.

Poly(Lysine)-Derived Carbon Quantum Dots Conquer Enterococcus faecalis Biofilm-Induced Persistent Endodontic Infections.

Persistent endodontic infections (PEIs) mediated by bacterial biofilm mainly cause persistent periapical inflammation, resulting in recurrent periapical abscesses and progressive bone destruction. However, conventional root canal disinfectants are highly damaging to the tooth and periodontal tissue and ineffective in treating persistent root canal infections. Antimicrobial materials that are biocompatible with apical tissues and can eliminate PEIs-associated bacteria are urgently needed. Here, ε-poly (L-lysine) derived carbon quantum dots (PL-CQDs) are fabricated using pyrolysis to remove PEIs-associated bacterial biofilms. Due to their ultra-small size, high positive charge, and active reactive oxygen species (ROS) generation capacity, PL-CQDs exhibit highly effective antibacterial activity against Enterococcus faecalis (E. faecalis), which is greatly dependent on PL-CQDs concentrations. 100 µg/mL PL-CQDs could kill E. faecalis in 5 min. Importantly, PL-CQDs effectively achieved a reduction of biofilms in the isolated teeth model, disrupting the dense structure of biofilms. PL-CQDs have acceptable cytocompatibility and hemocompatibility in vitro and good biosafety in vivo. Thus, PL-CQDs provide a new strategy for treating E. faecalis-associated PEIs.

Architecting multi-active center on 3DOM La0.76Ce0.19Ag0.05Mn0.9Co0.1O3-δ perovskite for soot oxidation

Precise construction of multiple active centers on perovskite oxides is recognized as a feasible and promising strategy to cooperatively promote the catalytic performances. Herein, 3DOM La0.76Ce0.19Ag0.05Mn0.9Co0.1O3-δ perovskite was designed and further treated within H2/N2 flow. High-temperature reduction did not destroy the original structure of perovskite, while the lattice Ag and Co were exsolved on perovskite surfaces to form Ag/Ag2O and Co@Co3O4. Compared with the traditional impregnation method, this strategy provided the active nanoparticles with smaller size, higher dispersion, and stronger interaction with perovskite matrix. XPS and O2-TPD indicated that the exsolved Ag and Co components could not only act as the O2 activation sites to accelerate the generation of active oxygen species on surfaces, but also offered the electrons to the oxygen vacancy on the perovskite. In addition, the vacancy formed after A-site and B-site cations exsolution could also adsorb and activate O2, ultimately boosting the catalytic combustion of soot. As a result, the developed perovskite exhibited a competitive catalytic activity with the T50 of 364 ℃ under the condition of 500 ppm NO + 5 % O2/N2. This work offered a facile and effective pathway to assemble high-performance perovskite-type oxides for heterogeneous catalysis.

1D/2D CoNi-LDH/ZnIn2S4 S-scheme heterojunction for effectively tetracycline degradation under photocatalytic-peroxymonosulfate activation system: DFT calculations and mechanism insights

The coupling of photocatalysis and peroxymonosulfate (PMS) induced advanced oxidation processes can be realized as an efficient strategy for antibiotics-contaminated water purification. However, developing a suitable catalyst with both visible light photo-response and high PMS activation efficiency remains challenging. Here, we employed the simple hydrothermal process to synthesis CoNi-LDH/ZnIn2S4 S-scheme heterojunction, which combines the benefits of visible photocatalysis and massive generation of active oxygen species generated by activating PMS. The results exhibited that the removal efficiency of optimized heterojunction under Light/PMS system reached 90.1 % within 15 min, which were nearly 8.8 and 1.31 times those of single ZIS and CoNi-LDH, respectively. Mechanistic analysis and density functional theory (DFT) calculation indicated that the satisfactory catalytic activity of heterojunction resulted from the synergistic effect between photocatalysis and PMS activation, which facilitates the separation of photogenerated carriers and accelerates the activation of PMS to generate abundant reactive species. Additionally, CoNi-LDH/ZIS heterojunction possess good ant-interference ability, excellent reusability over four cycles, acceptable adaptability in real water environments. Moreover, the toxicity of intermediates and degradation pathways are also investigated. Overall, this work provides new insights into the fabrication of S-scheme photocatalyst in photocatalytic-PMS activation system, which can realize high-efficient purification of antibiotics wastewater.

Generation of active oxygen species by CO2 dissociation over defect-rich Ni-Pt/CeO2 catalyst for boosting methane activation in low-temperature dry reforming: Experimental and theoretical study

Herein, we demonstrated a one-pot complex combustion method to synthesize defect-rich Ni-Pt/CeO2 catalyst having oxygen vacancy sites (Vo) by incorporating Ni and Pt species into the ceria lattice. These Vo sites are highly active for dissociating CO2 into reactive oxygen species and CO at low temperature. CH4-TPSR demonstrated that surface reactive oxygen species are more selective than lattice oxygen toward the formation of syngas. The catalytic properties and activity of the synthesized catalysts were also compared with the conventionally impregnated catalyst. In-situ DRIFT and Raman study revealed reactive oxygen-assisted CH4 activation via the formation of CHxO intermediate. DFT calculation also showed the facile formation of CH3O and CH2O species over the bimetallic NiPt-CeO2(111) catalyst surface. The Ni-Pt/CeO2 (0.5 wt%Pt-2 wt%Ni) catalyst showed superior activity and stability with ∼86% conversion of CH4 and CO2 at 675 °C, where the H2/CO ratio is one. The catalyst was stable up to 700 h time-on-stream.

Fabrication of highly dispersed Pd-Mn3O4 catalyst for efficient catalytic propane total oxidation

Adjusting the interaction between dual active components for enhancing volatile organic compounds (VOCs) degradation is an effective but still challenging means of air pollution control. Herein, a limited pyrolysis oxidation strategy was adopted to prepare Pd-Mn3O4 spinel catalysts with uniform morphology and active component dispersion. Among these, 1.08Pd-Mn3O4 presented the highest catalytic efficiency with a T90 value of 240 °C, which was 94 °C lower than that of Mn3O4. Characterization and density functional theory (DFT) calculation results revealed that the strong metal-support interaction (SMSI) effect between Pd and Mn3O4 promoted the redistribution of surface charges, thus strengthening the oxidation-reduction ability of the active sites. Moreover, the SMSI effect led to a better migration of surface oxygen species, and boosted the generation of active surface oxygen species. Simultaneously, the Pd catalyst further reduced the energy barrier in the initial stage of the dehydrogenation of propane. Overall, this study provided a novel design strategy for dual active components catalysts with SMSI effect and extended the application of these catalysts in the important field of VOCs elimination.

Novel layered double hydroxide-based passive NOx adsorber: Synergistic effects of Co and Mn on low-temperature NOx storage and regeneration

Passive NOx adsorber (PNA) is an efficient strategy for reducing vehicular NOx emission during cold-start period, and current studies on PNA development are limited to materials containing precious metals (Pt, Pd, and Ag, etc.). Herein, Co–Mn–Mg–Al mixed metal oxides were prepared from layered double hydroxides (LDHs) and utilized as a new type of PNA. Although Co–Mg–Al oxides exhibited excellent NOx adsorption capabilities because Co species promoted the generation of active oxygen species, their NOx adsorption performance deteriorated substantially with decreasing adsorption temperature below 150 °C and they required high temperatures over 400 °C to release the adsorbed NOx. Conversely, Mn–Mg–Al oxides retained their adsorption performance regardless of adsorption temperature and allowed for NOx desorption at relatively low temperatures by decreasing the thermal stability of the adsorbed NOx species. Notably, Co–Mn–Mg–Al mixed oxides exhibited high NOx adsorption performance at low temperatures between 50 and 150 °C and were passively regenerated via thermal treatment within a temperature range of 200–350 °C owing to the synergistic effects of Co and Mn. The developed LDH-based PNA materials presented excellent cyclic NOx adsorption performances for long-term operation, and dynamic tests indicated that NOx adsorbed onto Co–Mn–Mg–Al mixed oxides was effectively released with increasing temperature even in the presence of NO and O2.

One-Pot Synthesis of Bismuth Basic Nitrate-Bi2MoO6 Photocatalyst for Selective Oxidation of Toluene

The key issues to improve the performance of photocatalysts for selective oxidation of toluene are promoting the migration and separation of charge carrier, and enhancing the generation of active oxygen species. It is known that the construction of compact heterojunction is an efficient protocol to inhibit photogenerated electron-hole recombination. In this work, a 2D-2D [Bi6O6(OH)3](NO3)3·1.5H2O-Bi2MoO6 (denoted as BBN-BMO) composite heterojunction has been prepared by one-step hydrothermal method for the first time. The tetragonal phase BBN in the composite plays the role of transferring electrons from the visible light activated orthorhombic phase BMO and promoting the generation of active •O2−, the holes left in BMO are used to activate toluene and produce benzyl radical, thus greatly improving the photocatalytic performance for selective oxidation of toluene. The toluene conversion rate of BBN-BMO is 3466 µmol·g−1·h−1, which is three times that of pure BMO. The selectivity to benzaldehyde is 94.2%. In addition, reasonable mechanism has been speculated based on a series of control experiments.

Effects of impure ions in precursors on the formation of active oxygen in MnO2 for promoting VOCs oxidation

Impure ions in the precursor can cause the structural transition of prepared MnO2 catalysts and influence their activity in toluene catalytic oxidation. Here, the effects of K+ and SO42- on the catalytic activity of MnO2 are examined. Removing absorbed SO42- by repeating water washing facilitates the exposure of active sites on the surface of MnO2. The temperature for toluene conversion reaches 90% (T90) of catalysts decreases from 247 ºC to 238 ºC. While the loss of K+ during the water washing leads to the inferior performance of MnO2. Re-impregnating of K+ can stimulate the generation of active oxygen species on the surface of catalysts (K/MnO2), which showed elevated catalytic activity in toluene conversion (T90, 229 ºC). In addition, K/MnO2 performs good stability for toluene combustion in long-term operation. Density Function Theory calculations reveal that the formation energy of oxygen vacancy and the adsorption energy of toluene on the surface of catalyst decrease from 6.996 eV and − 0.079 to 5.482 eV and − 0.468 eV as the introduction of K+, respectively. Our results provide a complete understanding of the effects of impurity ions on the performance of manganese oxide for catalytic oxidation of toluene.

Ozonative epoxidation of ethylene: A novel process for production of ethylene oxide

Here we report a novel reaction for ethylene oxide production using catalytic reaction of ethylene with ozone at room temperature. A key aspect of this path is boosting selective oxygen coverage on the surface of the catalyst which enables achieving high ethylene oxide selectivity and maintaining high conversion. Comparing the structural changes of the catalyst before and after the reaction suggested that the process allows facile generation of the catalytic active sites and selective oxygen species on the Ag/Al2O3 catalyst. With this novel process and under kinetically controlled regime, single-pass ethylene conversion of 98% and selectivity of 56% were achieved at room temperature. The low apparent activation energy of 22.1 kJmol-1 indicated the feasibility and high rate of this reaction at room temperature. This approach is believed to deliver a new class of processes for other oxygen insertion reactions.

Activation of Co-O bond in (110) facet exposed Co3O4 by Cu doping for the boost of propane catalytic oxidation

Defects engineering in metal oxide is an important avenue for the promotion of VOCs catalytic oxidation. Herein, the influence of crystal facet of Co3O4 is first investigated for the propane oxidation. An intelligent Cu doping is subsequently performed in the most active (110) facet exposed Co3O4 catalyst. The optimized Cu-Co3O4-110–3 catalyst exhibits a prominently enhanced activity with propane conversion rate of 1.9 μmol g−1 s−1 at reaction temperature of 192 °C and the propane mass space velocity of 60,000 mL g−1 h−1, about 2.4 times that of the pristine Co3O4. Systematic experimental characterizations (XAS, EPR, Raman, TPR, XPS, etc.) combined with density functional theory calculations point out that the incorporated Cu could increase the electrophilicity of nearby O atom and implant beneficial defect structures (lattice distortion, coordination unsaturation, abundant oxygen vacancies, etc.), which could significantly activate Co-O bond in Co3O4, leading to the facilitated generation of active oxygen species as well as promoted oxidation ability. This study could set an illuminating paradigm for the boost of the intrinsic oxidation activity by the precise defect construction in Co3O4 catalyst, which will help drive ahead the pursuit of non-precious metal catalyst for VOCs abatement.

The pro-apoptotic activity of sinueracasbanone D isolated from Sinularia Leptoclados in hepatocellular carcinoma cells.

The soft-bodied corals of the genera Sarcophyton and Sinularia (Alcyoniidae) are known as a warehouse of casbane and cembranoid diterpenoids with remarkable antitumor effects. Two casbane-type diterpenoids (1, 2) along with four cembrane-type diterpenoids (3-6) were isolated from the diethyl ether soluble fraction of the organic extracts of the Red Sea soft corals Sinularia leptoclados and Sarcophyton glaucum, respectively. The antiproliferative activity of all isolated compounds (1-6) against three hepatocellular carcinoma cells, namely, Huh-7, SNU 499, and HepG2, along with the normal cells EA.hy 926, was evaluated. Sinueracabanone D (1) displayed a remarkable antiproliferative effect against the examined cancer cell lines, especially HepG2 cells with IC50 of 4.0 ± 0.37µM. Cell cycle analysis indicated compound 1 caused the accumulation of HepG2 cells in the G2/M-phase. Further, compound 1 exhibited significant pro-apoptotic activities in HepG2 cells as evidenced by annexin V staining, enhanced mRNA expression of Bax, cytochrome C, and caspase 3, as well as inhibition of Bcl2 expression. Also, challenging HepG2 cells with sinueracabanone D (1) enhanced the active oxygen species generation and decreased mitochondrial membrane potential. In conclusion, compound 1 possesses potent antiproliferative activities against HepG2 cells. These antiproliferative activities are mediated, at least partly, by their ability to induce apoptosis, mitochondrial dysfunction, and oxidative stress.