Enhanced H2O2 Production Research Articles

Spatial Specific Janus S-Scheme Photocatalyst with Enhanced H2 O2 Production Performance.

Photocatalytic oxygen reduction reaction (ORR) for H2 O2 production in the absence of sacrificing agents is a green approach and of great significance, where the design of photocatalysts with high performance is the central task. Herein, a spatial specific S-scheme heterojunction design by introducing a novel semiconducting pair with a S-scheme mechanism in a purpose-designed Janus core-shell-structured hollow morphology is reported. In this design, TiO2 nanocrystals are grown inside the inner wall of resorcinol-formaldehyde (RF) resin hollow nanocakes with a reverse bumpy ball morphology (TiO2 @RF). The S-scheme heterojunction preserves the high redox ability of the TiO2 and RF pair, the spatial specific Janus design enhances the charge separation, promotes active site exposure, and reduces the H2 O2 decomposition to a large extent. The TiO2 @RF photocatalyst shows a high H2 O2 yield of 66.6mMg-1 h-1 and solar-to-chemical conversion efficiency of 1.11%, superior to another Janus structure (RF@TiO2 ) with the same heterojunction but a reversed Janus spatial arrangement, and most reported photocatalysts under similar reaction conditions. The work has paved the way toward the design of next-generation photocatalysts for green synthesis of H2 O2 production.

Coral-shaped Mn-CuS with hierarchical pores and crystalline defects for high-efficiency H2O2 production via electrocatalytic two-electron reduction

We report the development of non-noble transition metal sulfide catalysts Mn-CuS-x for high-efficiency and selective H2O2 production. In this study, we synthesized Mn-CuS-x with coral-shaped hierarchical porous structure through one-pot hydrothermal reaction. The Mn-CuS-x possesses large specific surface area with plenty of crystalline defects via heteroatom doping of Mn. The Mn-CuS-x kinetically favored 2e− pathway over 4e− pathway, resulting in high selectivity (>92%) to H2O2 production and high H2O2 concentration (∼24.5 mM at 0.6 V vs. RHE) within 3 h for the optimized Mn-CuS-2 catalysts (synthesized with a molar ratio of 1:3:8 (MnCl2·4 H2O: CuCl2·2 H2O: C2H5NS)). The Mn-CuS-2 showed excellent stability, indicating that the Mn-CuS electrocatalysts can simultaneously achieve both high stability and enhanced H2O2 production. Our first-principles calculations further confirmed that the heteroatom Mn doping to CuS thermodynamically makes the 2e–-ORR pathway more favorable. This study provides a green, low-cost, and efficient route to produce H2O2, which is very promising for generating chemicals and liquid fuels.

Abstract 2837: A novel radiosensitizer of titanium peroxide nanoparticles (TiOxNPs) through continuous ROS generation

Abstract Background: Metal nanoparticles have been proposed as potential radiosensitizers. Among those, titanium nanoparticles are attractive candidates for application as radiosensitizers. We have newly established and evaluated titanium peroxide nanoparticles (TiOxNPs). The TiOxNPs are generated from titanium dioxide nanoparticles (TiO2NPs), manufactured via direct reaction of TiO2NPs with hydrogen peroxide. Distinguished characteristics of the TiOxNPs are continuous generation of reactive oxygen species (ROS) by X-ray irradiation. Bio-availabilities and safety was previously reported (Nanoparticles, 2020; 10(6): 1125). Materials and Methods: Characteristics of TiOxNPs were determined following experiments. Dynamic light scattering analysis was used to measure the diameter and Z-potential of the NPs. Transmission electron microscope (TEM) observation revealed the detailed topology of the NPs. X-ray irradiation was performed using the X-ray generator at a voltage of 150 kV and a current of 5 mA with a 1-mm thick aluminum filter in vitro and in vivo. Reactive oxygen species (ROS) generation was evaluated using human pancreatic cancer cells, named MIAPaCa-2. The cells were stained with 50 μM carboxy-20,70-dichlorofluorescein (C-H2DCF) incubated for 45 min, and then stained with Hoechst for nuclear staining. The degree of fluorescence of C-H2DCF was detected using the fluorescence microscope. To evaluate cytotoxic effects of TiOxNPs, a colony-formation assay was performed. For xenograft experiments, the MIAPaCa-2 cells (2 x 106 cells) were injected subcutaneously into the hind legs of the BALB/cAJcl nude mice. Once the tumor volume reached 100-200 mm3, mice were randomly assigned into six groups: the control group, TiOxNPs alone, 5 Gy alone, and TiOxNPs combined with 5 Gy. Tumor size, body weight, and health condition of all mice were followed every two to three days for 55 days post-treatment. Results: Primary particles smaller than 10 nm gathered and formed secondary particles that were approximately 50 nm in diameter, and their Z-potential was -30 mV. TEM observation revealed the detailed topology of the NPs. The TiOxNPs enhanced H2O2 production more than 7-folds compared to X-ray irradiation alone in MIA PaCa-2 cells. In xenografts, combination effects of the TiOxNPs and X-ray irradiation were significantly greater than X-ray irradiation (5 Gy) alone. Conclusions: The TiOxNPs revealed to be powerful radiosensitizers in pancreatic cancer model. Clinical tests are warranted to clarify the application of TiOxNPs in the nearest future. Citation Format: Ryohei Sasaki, Hiroaki Akasaka, Masao Nakayama, Yoshiko Fujita, Hikaru Kubota, Kenta Morita, Mennaallah Hassan, Mohammed Salah, Yuya Nishimura, Naritoshi Mukumoto, Takeaki Ishihara, Daisuke Miyawaki, Chiaki Ogino. A novel radiosensitizer of titanium peroxide nanoparticles (TiOxNPs) through continuous ROS generation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2837.

A CsEIL3-CsARN6.1 module promotes waterlogging-triggered adventitious root formation in cucumber by activating the expression of CsPrx5.

The formation of adventitious roots (ARs) derived from hypocotyl is the most important morphological adaptation to waterlogging stress in Cucumis sativus (cucumber). Our previous study showed that cucumbers with the gene CsARN6.1, encoding an AAA ATPase domain-containing protein, were more tolerant to waterlogging through increased AR formation. However, the apparent function of CsARN6.1 remained unknown. Here, we showed that the CsARN6.1 signal was predominantly observed throughout the cambium of hypocotyls, where denovo AR primordia are formed upon waterlogging treatment. The silencing of CsARN6.1 expression by virus-induced gene silencing and CRISPR/Cas9 technologies adversely affects the formation of ARs under conditions of waterlogging. Waterlogging treatment significantly induced ethylene production, thus upregulating CsEIL3 expression, which encodes a putative transcription factor involved in ethylene signaling. Furthermore, yeast one-hybrid, electrophoretic mobility assay and transient expression analyses showed that CsEIL3 binds directly to the CsARN6.1 promoter to initiate its expression. CsARN6.1 was found to interact with CsPrx5, a waterlogging-responsive class-III peroxidase that enhanced H2 O2 production and increased AR formation. These data provide insights into understanding the molecular mechanisms of AAA ATPase domain-containing protein and uncover a molecular mechanism that links ethylene signaling with the formation of ARs triggered by waterlogging.

Novel BiOBr/Bi2S3 high-low junction prepared by molten salt method for boosting photocatalytic degradation and H2O2 production

The molten salt method focuses on improving the crystallinity of synthetic materials and avoiding the high energy consumption of traditional synthesis processes. In this work, a novel BiOBr/Bi2S3 high-low junction with large contact area was constructed by the molten salt method combined with the ion exchange strategy. Its unique energy band structure and new charge transfer mechanism realize the rapid migration of photogenerated charges between different components. Specifically, Bi2S3 was grown on BiOBr in situ by a high-temperature molten salt reaction. Due to the deep valence band position of BiOBr and the narrow band gap of Bi2S3, an intrinsic internal electric field and band bending are produced at the interface, forming a high-low junction photocatalyst with an intimate interface. In addition, the BiOBr/Bi2S3 composite maintains a high oxidation potential and produces high and robust photocatalytic oxidation activity. In the molten state, the close binding of BiOBr and Bi2S3 can be promoted through the ion-exchange strategy, resulting in excellent photocatalytic degradation rates of bisphenol A and tetracycline and in-situ generation of H2O2. Finally, the mechanism of carriers separation and transfer in BiOBr/Bi2S3 high-low junction is also discussed. Density functional theory (DFT) results found that the improvement of O2 adsorption ability would promote the occurrence of oxygen reduction reaction (ORR), and make positive contributions to the enhanced H2O2 production activity. This study will provide a new perspective for broadening the spectral response range of Bi-based photocatalytic materials and preparing high-low junction photocatalysts with dense interface by the molten salt method.

Highly efficient electro-Fenton process on hollow porous carbon spheres enabled by enhanced H2O2 production and Fe2+ regeneration

Electro-Fenton (e-Fenton) is a promising method for wastewater treatment that relies on powerful ·OH generated via the decomposition of electro-generated H2O2 catalyzed by Fe2+. In this regard, developing a catalyst capable of simultaneously producing H2O2 and accelerating Fe2+ regeneration is of considerable importance; however, this remains a challenge because of the difficulty in modulating the electronic microenvironment. Herein, a hollow porous carbon sphere catalyst (HPCS) is developed to synchronously enhance H2O2 generation and accelerate Fe3+/Fe2+ cycling by constructing an electron-rich microenvironment via surface curvature regulation. The Fe2+ regeneration efficiency reaches 35.5% on HPCS featuring a larger curvature structure (HPCS-TPOS), which is 1.6 times higher than the smaller curvature HPCS-S catalyst (22.8%). Density functional theory reveals that the electron-rich microenvironment on the outer surface of high curvature structure promotes Fe2+ regeneration. The H2O2 production rate on HPCS-TPOS is 47.2 mmol L−1 h−1, exceeding the state-of-the-art e-Fenton catalysts reported. Benefiting from the concurrent high-efficiency of H2O2 production and Fe2+ regeneration, HPCS-TPOS e-Fenton is demonstrated to be efficient for sulfamethoxazole removal with the kinetic rate of 0.30–0.72 min−1 at pH 3–7. This work offers new insight into the design of efficient catalysts by rationally regulating curvature structures for wastewater treatment.

Modification of g-C3N4 with hydroxyethyl cellulose as solid proton donor via hydrogen bond to enhance H2O2 production

Hydroxyethyl cellulose (HEC) is used as a solid proton donor to modify graphitic carbon nitride (g-C3N4) via non-covalent bonds to improve H2O2 production performance. The modified g-C3N4 (CN/HEC) is prepared by stirring the suspension of g-C3N4 and HEC at room temperature and drying. The H2O2 production efficiency of CN/HEC is 3.89 times that of g-C3N4. Both experimental results and density functional theory calculations (DFT) suggest charge transfer from HEC to g-C3N4 and hydrogen bond formation between HEC and g-C3N4. CN/HEC possesses higher charge separation efficiency than g-C3N4. Stability test, XPS, FTIR, and DFT analyses suggest that HEC acts as a proton donor. The synergy of charge separation enhancer and proton donor from HEC promotes the sequential two-step single-electron O2 reduction for H2O2 production. This study explores a way to utilize cellulose material as solid proton donors to modify g-C3N4 via hydrogen bonds under mild conditions for increased H2O2 production performance.

Efficient degradation of organic compounds in landfill leachate via developing bio-electro-Fenton process

Efficient and harmless disposal of landfill leachate has attracted increasing attention. In this study, the bio-electro-Fenton method was investigated and developed to degrade the organic compounds in landfill leachate by hydroxyl radical oxidation. The optimal operational parameters (i.e., pH and external voltage) of the bio-electro-Fenton system were detected. Under the conditions of pH 2, 0.6 V, the highest total chemical oxygen demand (COD) decrement efficiency was obtained (about 70%), with apparent removal constant at 6 h (kapp-6h) of about 0.12 h−1. Subsequently, to further increase the degradation efficiency, functionalized carbon black and functionalized carbon nanotube (FCNT) were prepared as catalysts for the cathode electrode modification. With 0.4 mg/cm2 FCNT coated on the cathode electrode, 91.3% of the organic compounds were degraded, remaining only 84 mg/L COD (kapp-6h = 0.24 h−1). In all the reactors, the COD was mainly decreased in 0–6 h, contributing to over 68% of the total degradation efficiency. In the bio-electro-Fenton system, the bio-anode electrode could enhance H2O2 production and the conversion between Fe2+ and Fe3+ by strengthening electrons generation and transportation via the oxidation of organics by biofilms (dominant with Geobacter) covered on the carbon brush.

High light stress induces H2O2 production and accelerates fruit ripening in tomato

Increased synthesis of H2O2 is observed during the initiation of fruit ripening. However, its association with plant cell processes triggering the maturation of fruit has not yet been demonstrated. The aim of this work is to investigate whether H2O2 participates in the tomato ripening process and particularly through its association with the ethylene signaling pathway. The experiments were carried out with two ethyl methanesulfonate mutant lines of Micro-Tom tomato deficient in GDP-L-galactose phosphorylase activity and displaying lower ascorbic acid content than the corresponding parental genotype (i.e. wild type). Plants were subjected to a high irradiance (HI) treatment to stimulate H2O2 synthesis. HI treatment enhanced H2O2 production and reduced the timing of fruit ripening in both mutants and wild-type fruits. These results could be linked to an increase of the expression of H2O2-related genes and changes in the expression of ethylene-related genes. The fruit H2O2 production increased or decreased after applying the treatments that induced ethylene synthesis or blocked its action, respectively. The results presented in this work give an evidence of the association of redox and hormonal components during fruit ripening in which H2O2 participates downstream in the events regulated by ethylene.

Oxygen-containing surface functional groups, mesoporous structure and photothermal effect co-modulated highly-efficient H2O2 production and pollutant degradation

Carbon-based nanomaterials are well-recognized catalysts for H2O2 production though remain insufficient for practical applications, and their photothermal effect is usually ignored. Herein, two typical carbon nanomaterials, mesoporous carbon hollow spheres (MCHS) and carbon hollow spheres (CHS), are selectively synthesized to explore the influence of oxygen-containing surface functional groups, mesoporous structure and photothermal effect on their electrocatalytic and application ability. It was found that the abundant oxygen-containing surface functional groups in MCHS can optimize the adsorption energy of *OOH while the mesoporous structure of MCHS provides plenty of electrochemical active sites, both of which significantly enhance H2O2 production selectivity of the MCHS (96.0% versus 87.0% for the CHS counterpart). Furthermore, the notable photothermal effect of the MCHS can promote the generation of more ·OH radicals and accelerate related reaction kinetics (3.5 times higher than those without NIR light irradiation) under the in-situ electro-Fenton degradation of methyl orange. As a result, remarkable degradation efficiency of 98.1% was achieved for the MCHS under the illumination of near infrared (NIR) light, outperforming those without NIR light irradiation (70.1% for MCHS and 54.7% for CHS). By integrating oxygen-containing surface functional groups, mesoporous structure and photothermal effect, this work achieves remarkable H2O2 production ability and pollutant degradation application simultaneously, providing a new avenue for the design of advanced electrocatalysts and may promote their energy related applications.

Mechanism of Cadmium Exposure Induced Hepatotoxicity in the Mud Crab (Scylla paramamosain): Activation of Oxidative Stress and Nrf2 Signaling Pathway.

Cadmium, one of the most toxic heavy metals, can cause severe oxidative damage to aquatic animals. However, the mechanism whereby the mud crabs respond to cadmium exposure remains unclear. This study investigated the effects of cadmium exposure on oxidative stress and histopathology changes and evaluated the role of the Nrf2 signaling pathway in regulating responses to cadmium-induced hepatotoxicity were investigated in mud crabs. Mud crabs were exposed to 0, 0.01, 0.05, and 0.125 mg/L cadmium for 21 d. The present results indicated that cadmium exposure increased hydrogen peroxide (H2O2) production, lipid peroxidation and tissue damage, but decreased the activity of superoxide dismutase (SOD) and catalase (CAT), and caused lipid peroxidation and tissue damage. The results of an integrated biomarker index analysis suggested that the toxicity of cadmium was positively related to cadmium concentration. The expression levels of the Nrf2 signaling pathway (Nrf2, metallothionein, and cytochrome P450 enzymes) were up-regulated after cadmium exposure. Silencing of Nrf2 in vivo decreased antioxidant gene (SOD, CAT, and glutathione S-transferase) expression, suggesting that Nrf2 can regulate antioxidant genes. Knocking down Nrf2 in vivo also significantly decreased the activity of SOD and CAT after cadmium exposure. Moreover, silencing of Nrf2 in vivo enhanced H2O2 production and the mortality rates of mud crabs after cadmium exposure. The present study indicated that cadmium exposure induced hepatotoxicity in the mud crab by increasing H2O2 content, which decreased the antioxidant capacity, leading to cell injury. In addition, the Nrf2 is activated to bound with antioxidant response element, initiating the expression of antioxidant enzyme genes during cadmium induced hepatotoxicity in the mud crabs.

Fluorine-doped carbon: A metal-free electrocatalyst for oxygen reduction to peroxide

Electrochemical synthesis in-situ of hydrogen peroxide (H2O2) is an alternative to the anthraquinone oxidation (AO) process. The catalyst with high performance and excellent stability is the key part of oxygen reduction reaction (ORR). Fluorine (F) has high electronegativity, which can induce the polarization of adjacent carbon, produce active centers and increase the force between oxygen and carbon. In this work, we used a simple synthesis method to prepare F-doped carbon electrocatalyst in F2 atmosphere. The F-doped carbon as cathode was used to generate H2O2 via the two-electron pathway. The H2O2 concentration and selectivity of catalyst can reach 2837.5 mg L−1 and 95.7% after electrolyzing three hours, respectively. The linear sweep voltammetry shows that the onset potential of F-doped carbon is 37 mV more positive than that of pristine carbon, and its limited current density of catalyst reach 5.882 mA cm−2. The density functional theory (DFT) calculation demonstrates the covalent bonds CF2 can activate O2 and promote desorption of intermediate OOH to enhance H2O2 production. The prepared F-doped carbon with excellent performance and outstanding cycle durability is a promising electrocatalyst.

Effects of g-C3N4 Heterogenization into Intrinsically Microporous Polymers on the Photocatalytic Generation of Hydrogen Peroxide.

Graphitic carbon nitride (g-C3N4) is known to photogenerate hydrogen peroxide in the presence of hole quenchers in aqueous environments. Here, the g-C3N4 photocatalyst is embedded into a host polymer of intrinsic microporosity (PIM-1) to provide recoverable heterogenized photocatalysts without loss of activity. Different types of g-C3N4 (including Pt@g-C3N4, Pd@g-C3N4, and Au@g-C3N4) and different quenchers are investigated. Exploratory experiments yield data that suggest binding of the quencher either (i) directly by adsorption onto the g-C3N4 (as shown for α-glucose) or (ii) indirectly by absorption into the microporous polymer host environment (as shown for Triton X-100) enhances the overall photochemical H2O2 production process. The amphiphilic molecule Triton X-100 is shown to interact only weakly with g-C3N4 but strongly with PIM-1, resulting in accumulation and enhanced H2O2 production due to the microporous polymer host.

Plasma-induced hierarchical amorphous carbon nitride nanostructure with two N2C-site vacancies for photocatalytic H2O2 production

Carbon nitride (CN) with nitrogen vacancy is a robust photocatalyst with proven enhancing H2O2 production ability. However, nitrogen vacancy control is extremely challenging with the majority of reports representing it as a few vacancies. Herein, for the first time, the amorphous CN (ACN) with two N2C-site vacancies in one CN unit is prepared by a one-step H2 plasma approach. First-principles calculations and experimental results provide consistent evidence that two N2C vacancies are located in one CN unit structure after amorphous transformation. Plasma-induced ACN is stable with a hierarchical continuous nanosheet network structure and exhibits an ultrahigh specific surface area of ~405.76 m2g−1, which is 83 times higher than that of pristine CN (4.89 m2g−1) and significantly enhanced photocatalytic H2O2 production, yielding 1874 μmolg−1h−1. Besides, the existence potential drop of 2.61 eV for the electrostatic potential in ACN is key to charge carrier separation. Moreover, the amorphous transformation leads to a new strong band tail, which remarkably enhances the absorbance edge of ACN up to 593 nm, resulting in a wider range of visible-light absorption to enhance H2O2 production. The results have provided an effective approach for promoting the practical application of ACN in photocatalytic H2O2 production.

Porous carbon-doped g-C3N4 with tunable band structure for boosting photocatalytic H2O2 production with simultaneous pollutants removal

Photocatalytic H2O2 production with simultaneous organic pollutants degradation is intriguing, but has challenges in achieving economic practicality, efficient pollutants degradation, and suppressing the decomposition of generated H2O2. Herein, porous carbon-doped g-C3N4 (PCCN) was prepared using natural dead leaves as a morphology regulator and carbon source, resulting in nanopores and doping levels on g-C3N4 framework. Under visible-light irradiation for 1 h, optimal PCCN showed a superior H2O2 yield of 37.44 μmol·L−1 with simultaneous bisphenol-A (BPA) degradation of 96%, which is 4.44 and 3.84 times greater than those of pristine g-C3N4, respectively. The significantly enhanced H2O2 production is attributed to nanopores with more reactive sites and doping levels that extend lightabsorption· H2O2 is generated by the 2e-oxygen reduction reaction, and BPA is simultaneously mineralized by h+ and •O2− . This work proposes a promising pragmatic synthesis of high-photocatalytic materials and provides new insights into energy conversion coupled with wastewater recycling.

CuBi2O4 photocathode with integrated electric field for enhanced H2O2 production

Metal oxide semiconductors are promising for photosynthetic H2O2 production, provided the issue of excessive charge recombination can be adequately addressed. Inducing internal electric field is a common remedial strategy to inhibit carrier recombination but challenging to accomplish without external power input. To overcome this drawback, a novel photocathode was designed and fabricated by combing photothermoelectricity and photoelectricity by adding a NaCo2O4 film under the CuBi2O4 film to generate an internal electric field from photoinduced temperature gradients. Our results show the significantly enhanced photoelectrochemical activity for the composite photocathode with an H2O2 production concentration of 192.9 µmol/L, 2.4 times higher than CuBi2O4. Photocurrent under controlled temperature gradients and COMSOL simulation defined that the enhancement comes from the synergy of photothermoelectricity and photoelectricity. This work demonstrates a feasible strategy to inhibit carrier recombination in photoelectrode with internal thermoelectric potential, which can significantly enhance the energy conversion efficiency without extra energy consumption.

Activatable Biomineralized Nanoplatform Remodels the Intracellular Environment of Multidrug-Resistant Tumors for Enhanced Ferroptosis/Apoptosis Therapy.

Ferroptosis is a new form of regulated cell death with significant therapeutic prospect, but its application against drug-resistant tumor cells is challenging due to their ability to effuse antitumor agents via p-glycoprotein (P-gp) and anti-lipid peroxidation alkaline intracellular environment. Herein, an amorphous calcium phosphate (ACP)-based nanoplatform is reported for the targeted combinational ferroptosis/apoptosis therapy of drug resistant tumor cells by blocking the MCT4-mediated efflux of lactic acid (LA). The nanoplatform is fabricated through the biomineralization of doxorubicin-Fe2+ (DOX-Fe2+ ) complex and MCT4-inhibiting siRNAs (siMCT4) and can release them to the tumor cytoplasm after the hydrolysis of ACP and dissociation of DOX-Fe2+ in the acidic lysosomes. siMCT4 can inhibit MCT4 expression and force the glycolysis-generated lactic acid (LA) to remain in cytoplasm for rapid acidification. The nanoplatform-induced remodeling of the tumor intracellular environment can not only interrupt the ATP supply required for P-gp-dependent DOX effusion to enhance H2 O2 production, but also increase the overall catalytic efficiency of Fe2+ for the initiation and propagation of lipid peroxidation. These features could act in concert to enhance the efficacy of the combinational ferroptosis/chemotherapy and prolong the survival of tumor-bearing mice. This study may provide new avenues for the treatment of multidrug-resistant tumors.

Cost-efficient microbial electrosynthesis of hydrogen peroxide on a facile-prepared floating electrode by entrapping oxygen

Microbial electrosynthesis of hydrogen peroxide is receiving growing interest for a green substitute for anthraquinone process.However, poor oxygen transmission of electrode remains an obstacle to enhance H2O2 production rate without aeration. Here, a superhydrophobic natural air diffusion floating electrode (NADFE), which naturally and efficiently entraps O2 in the air, was proposed for the first time to improve microbial electrosynthesis of H2O2. Furthermore, a one-step calcined electrode preparation method was developed to reduce energy consumption further. In the microbial electrolysis cell with the NADFE, a high H2O2 production rate of 39 mg/L/h and current efficiency of 86% were achieved without aeration. The production rate of H2O2 was 2.2 times that of a gas diffusion electrode. Importantly, the energy consumption was 34.3 times lower than an electrochemical system. Therefore, the high H2O2 production rate and current efficiency, and low energy consumption of the process provide a superior alternative for environmental remediation.

Enhancement of hydrogen peroxide production by electrochemical reduction of oxygen on carbon nanotubes modified with fluorine

It is vital to synthesis hydrogen peroxide via electrochemical reduction of oxygen since it is a green process to produce oxidant with wide applications including water/wastewater treatment. In this work, fluorine (F) was employed to modify carbon nanotube (CNT), and the obtained F doped CNT (F-CNT) catalyst was used to fabricate gas diffusion electrode (GDE). It was found that F doping could improve oxygen reduction activity and H2O2 selectivity, and then enhanced the H2O2 production. After modification, F-CNT prepared with 0.6 M HF (CNT-F-0.6) had much higher H2O2 production (47.6 mg L−1) and current efficiency (89.5%) than that of CNT (29.6 mg L−1, 70.1%) at bias voltage of −1.3 V (vs SCE) and pH 7. Moreover, the high catalytic activity of CNT-F-0.6 could maintain in 5 consecutive reaction cycles. The material characterization and electrochemical test indicated that F doping had no significant effects on the surface area of CNT, but improved the defect degree of CNT. The enhanced H2O2 production performance could be ascribed to the formation of CF2 and CF3 on the surface of F-doped CNT, which rendered the potential for practical application of novel carbon catalyst for GDE.

Effect of betulin and betulonic acid on isolated rat liver mitochondria and liposomes

The paper considers the effects of plant triterpenoid betulin and its derivative betulonic acid on rat liver mitochondria and liposomes. It was found that betulonic acid and, to a lesser extent, betulin, activate mitochondrial respiration in states 2 and 4 and inhibit ADP- and DNP-stimulated (uncoupled) respiration. The effect of betulonic acid resulted in a significant decrease of the respiratory control and ADP/O ratios and decrease in Δψ. The effects of both compounds were most pronounced in the case of succinate-fueled mitochondrial respiration. This may include both the possible protonophore effect of betulonic acid and the inhibition of respiratory chain complexes by both compounds. Both agents enhanced H2O2 production in succinate-fueled mitochondria, while betulonic acid exerted an antioxidant effect with NAD-dependent substrates. Betulin was found to induce mitochondrial aggregation, but had no effect on membrane permeability. A similar pattern was found on liposomes. As revealed by the laurdan generalized polarization (GP) technique, betulin increased laurdan GP in lecithin liposomes, indicating a decrease in membrane fluidity. Measurements of GP as a function of fluorescence excitation wavelength gave an ascending line for high concentrations of betulin, which can be interpreted as phase heterogeneity of the lipid/betulin system. High concentrations of betulin (> 60 mol%) was also demonstrated to cause permeabilization of lecithin liposomes. Betulonic acid was much less effective in inducing the aggregation of mitochondria and liposomes and had no effect on membrane permeability. The possible mechanisms of betulin and betulonic acid effect on rat liver mitochondria and liposomes are discussed.