Rate Of H2O2 Generation Research Articles

Efficient photosynthesis of H2O2 via two-electron oxygen reduction reaction by defective g-C3N4 with terminal cyano groups and nitrogen vacancies

The development of photocatalysts for the efficient generation of hydrogen peroxide (H2O2) and degradation of antibiotic pollutants is a mutual-beneficial solution to the chemical resource demands and environmental remediation. Herein, efficient visible-light-driven H2O2 production and antibiotic degradation are achieved by using nitrogen-deficient modified polymeric carbon nitride (g-C3N4) to facilitate the reduction of dioxygen. The N defects modified g-C3N4 reached an excellent H2O2 generation rate of 623.5 μmol g−1h−1 without O2 bubbling. The structural features and entire photocatalytic conversion process were systematically studied via experiments and theoretical calculations. It was found that the N defects in the framework constructed a giant internal electric field (IEF), which effectively inhibited carrier recombination. Revealed the neglected H2O2 production via 1O2 pathway, which effectively promoting the selective 2e− oxygen reduction reaction (ORR). More interestingly, the N defects structure greatly improved the O2 adsorption ability and O2 production ability of the material, while inhibiting the in situ generated H2O2 from being decomposed and maintaining high efficiency of H2O2 production under air conditions. This study thoroughly revealed the synergistic effects of the terminal cyano group and nitrogen vacancies over g-C3N4 for efficient H2O2 photogeneration photosynthesis.

Construction of a Novel Cascade Electrolysis-Heterocatalysis System by Using Zeolite-Encaged Ultrasmall Palladium Catalysts for H2 O2 Generation.

In situ generation of hydrogen peroxide (H2 O2 ) has attracted extensive attention, especially in water treatment. However, traditional anthraquinones can only produce high-concentration H2 O2 and its transportation and storage are not convenient and dangerous. Herein, an in situ and on-demand strategy to produce H2 O2 by using a cascade water electrolysis together with a heterocatalysis system is provided. Beginning with water, H2, and O2 can be generated via electrolysis and then react with each other to produce H2 O2 immediately on efficient zeolite-encaged ultrasmall Pd catalysts. Significantly, the H2 O2 generation rate in the optimized cascade system reaches up to 0.85mol L-1 h-1 gPd -1 , overcoming most of the state-of-the-art catalysts in previous literature. The confinement effect of zeolites is not only beneficial to the formation of highly dispersed metal species, promoting the H2 O2 generation, but also inhibits the H2 O2 decomposition, enhancing the production yield of H2 O2 . In addition, the effect of electrolytes, sizes of Pd species, as well as zeolite acidity are also systematically studied. This work provides a new avenue for H2 O2 generation via a highly efficient cascade electrolysis-heterocatalysis system by using zeolite-supported metal catalysts. The high catalytic efficiency and green process for H2 O2 generation make it very promising for further practical applications.

Highly efficient heterogeneous electro-Fenton degradation of organic pollutants using a FeNi-OH/NF cathode

The electro-Fenton (EF) technology provided a promising way to degrade organic pollutants by in-situ producing H2O2 and decomposing it into hydroxyl radicals (OH). However, the degradation rate is restricted by the two-electron oxygen reduction reaction (ORR) rate of H2O2 generation and the production efficiency of OH, and the efficient EF cathode is important. Herein, we designed an efficient heterogeneous EF system with a Fe-doped β-Ni(OH)2 nanosheets/nickel foam (FeNi-OH/NF) cathode for phenol removal in water. FeNi-OH enhanced the electrochemically active area for H2O2 production and produced OH for pollutant degradation. The FeNi-OH/NF cathode demonstrates excellent heterogeneous EF catalytic activity with a degradation efficiency of phenol (99.4%) and total organic carbon (67.4%) in 2 h. The experiments and density functional theory (DFT) calculations further confirmed that the Fe-doped β-Ni(OH)2 on the nickel foam enhanced H2O2 adsorption and accelerated Fe3+/Fe2+ circulation, promoting the reaction of H2O2 with Fe2+ to produce OH for phenol degradation. This study provides a novel and efficient heterogeneous EF cathode for accelerating pollutant degradation securely and quickly.

Boosting photocarrier collection in semiconductors by synergizing photothermoelectric and photoelectric

Efficient generation and collection of photocarriers is a contradiction for most metal oxide semiconductors. An approach to better understanding and controlling photocarriers’ special collection is critical for solar-fuel conversation. Herein, p-type BiFeO3 was chosen to reveal the diffusion length (∼34 nm) limited performance and to develop an approach to boosting photocarrier collection by synergizing photothermoelectric and photoelectric. In this approach, efficient photocarrier collection was realized by two processes: 1) an inner photothermoelectric voltage as the carriers’ driving force to promote drift in the flat band region; 2) the accumulated electrons in the cooling interface consumed photogenerated holes and inhibited recombination. As a result, the composite photocathode shows a state-of-the-art photocurrent of − 0.49 mA·cm−2 and an H2O2 generation rate of 695 mmol/(L·m2). This work aims to provide a broader understanding of photocarrier collection's limited performance of metal oxide photoelectrode and explore a universal approach to improving it without extra power input.

Phase regulation of WO3 for highly selective oxygen reduction to hydrogen peroxide

Hydrogen peroxide (H2O2), as one of the most important chemicals, is widely applied in many industries. Electrocatalytic oxygen reduction provides a safe and on-site method for H2O2 synthesis. The research of transition metal oxides (TMOs) for H2O2 synthesis is mainly focused on the modification of transition metal elements and graphene. Few studies directly control pure TMOs without changing supporting materials or introducing other elements. Here, we demonstrate for the first time a phase regulation strategy to develop highly selective and stable tungsten trioxide catalysts for H2O2 generation through 2e− oxygen reduction reaction (2e− ORR). DFT calculations show that the kinetic energy barrier (0.08 eV) of the 2e− ORR pathway on the cubic tungsten trioxide (c-WO3) surface is much lower than that of the 4e− ORR pathway (0.76 eV). As a result, a selectivity of 90 % and H2O2 production rate of 179 mmol gcat−1h−1 are achieved at 0.1 V vs RHE under alkaline conditions, outperforming all catalysts previously reported under the same conditions. Moreover, after continuous testing for more than 24 h at a constant potential of 0.1 V vs RHE, the H2O2 generation rate has not been diminished, indicating an excellent stability of c-WO3 in practical applications.

Efficient hydrogen peroxide electrosynthesis using anthraquinone covalently bonded CNT on superhydrophobic air breathing cathode

Electrochemical H2O2 production through two-electron oxygen reduction (ORR) is an environmentally friendly process with high energy efficiency. The low catalysts’ activity, low oxygen transfer rate and less device demonstration restrict the ORR development. In this study, a superhydrophobic air breathing cathode (ABC) was constructed, which consisted of anthraquinone covalently linked CNT-NH2 (NCNT-AQ) and PTFE modified carbon felt. This ABC could keep stable liquid-gas-solid three phase interfaces and efficiently utilize O2 through natural air diffusion, and the H2O2 generation rate could arrive at 2.09 M gcatalyst−1 h−1 at current density of 50 mA cm−2, which was 4.45 times higher than traditional electrode. A flow cell was designed with this ABC, the concentration of produced H2O2 could reach 0.26 M (8.84 g L−1) within 7 h, while the energy consumption was only 44.88 kWh kg−1 and the cost was estimated as 4.20 $ kg−1. The application of this device was demonstrated by the treatment of organic polluted water and soil. This work presents a highly selective, durable, and low-cost H2O2 electrosynthesis cell, providing a promising approach for the in-situ production and utilization of H2O2.

Defects controlling, elements doping, and crystallinity improving triple-strategy modified carbon nitride for efficient photocatalytic diclofenac degradation and H2O2 production

The development of an effective dual-function photocatalyst for refractory contaminant abatement and sacrificial-free in-situ H2O2 generation is a major challenge. Herein, defects controlling, elements doping, and crystallinity improving triple-strategy is established to synthesize modified g-C3N4 (SCBCN0.4). The triple-strategy of modification reconciles crystallinity improvement and the decoration of moderate cyano-group defects and B and O co-dopants. Characterization experiments and theoretical calculations reveal microstructure and electronic structure optimization, improved light-harvesting capability, and enhanced carrier separation efficiency. SCBCN0.4 performs admirably in the degradation of diclofenac and a variety of other pharmaceuticals. Through synchronous oxygen reduction and water oxidation processes, SCBCN0.4 has an excellent in-situ photocatalytic H2O2 generation rate of 620 μmol/g/h (309 μmol/g/h without sacrificial agents). SCBCN0.4's detoxification, reusability, and stability were validated in several experiments. Hence, this research offers a ground-breaking approach to manufacturing triple-strategy modified g-C3N4 for environmental remediation and (sacrificial-free) in-situ H2O2 production.

(1 0 0)-Oriented tetragonal zircon BiVO4 single crystal film

Single crystal films can advance the basic understanding of material. In this work, the tetragonal zircon BiVO4 (t-z BVO) films were prepared on YSZ (111) substrates by magnetron sputtering. The samples deposited within 30 min are pure phase, and the t-z BVO films were grown along the (100) orientation on YSZ (111). With the increase of deposition time, the morphology of samples gradually widened, growing from a rod-like shape to a dense and continuous sheet-like shape. In situ growth of two-layer structure of t-z BVO and V2O5 in the sample deposited for 120 min can be vividly seen. The photocatalytic degradation rate of rhodamine B (RhB) of the sample deposited for 30 min was as high as 1.3-fold than that of TiO2. And the H2O2 generation rate of the sample deposited for 30 min was higher than that of the other two samples.

Biomimetic O2-carrying and highly in-situ H2O2 generation using Ti3C2 MXene/MIL-100(Fe) hybrid via Fe-Protoporphyrin bridging for photo-fenton synergistic degradation of thiacloprid

Efficient and deep degradation for organic contaminants in the absence of externally supplied H2O2 is still a challenge and research hotspot for photo-Fenton catalysis. In this work, a novel Ti3C2 MXene/MIL-100(Fe) hybrid via Fe-protoporphyrin bridging was proposed to in-situ generate H2O2 for photo-Fenton catalytic degradation of thiacloprid (TCL). The generated Schottky junction between MXene and MIL-100(Fe) and biomimetic oxygen-carrying from Fe-protoporphyrin constructed a synergistic system to promote H2O2 generation and photo-Fenton reaction. As expected, MXene/MIL-100(Fe) exhibited 12 times higher of H2O2 generation rate (reaching 1175.2 μmol/L under air-bubble), and 24 times of degradation rate and 3.7 times of mineralization rate for TCL compared to MIL-100(Fe). In addition, MXene/MIL-100(Fe) possessed 21–60 times higher TCL degradation rate than many of reported photo-Fenton catalysts in H2O2-free system. MXene/MIL-100(Fe) realized > 80 % TOC removal of TCL (80 mg/L) within 120 min, and exhibited excellent catalytic stability (>97 % TCL degradation) for 10 successive reuses.

Insights into the role of reactive oxygen species in photocatalytic H2O2 generation and OTC removal over a novel BN/Zn3In2S6 heterojunction

Developing photocatalysts with superior performance to generate hydrogen peroxide (H2O2) and degrade oxytetracycline (OTC) is an effective strategy for the treatment of energy crisis and water purification. Herein, BN nanosheets were anchored onto the Zn3In2S6 microspheres for the research. Experimental and density functional theory (DFT) results demonstrate that due to different work functions and unique 2D/2D contact, the electron is spatially separated in BN/Zn3In2S6 nanocomposite, which increases the electron transfer efficiency from 43.7% (Zn3In2S6) to 55.6% (BN/ZIS-4). As a result, BN/ZIS-4 with optimal ratio of BN and Zn3In2S6 exhibits the highest OTC degradation efficiency (84.5%) and H2O2 generation rate (115.5 μmol L−1) under visible light illumination, which is 2.2 and 2.9 times than that of pristine Zn3In2S6. H2O2 generation is dominated by two pathways: two-step single-electron process (O2 → ∙O2- → H2O2) and another way (O2 → ∙O2- → 1O2 → H2O2). In the process of degrading OTC, ∙O2-, 1O2 and ∙OH are regarded as the main active species. This work offers a new insight for designing efficient, stable and reusable photocatalysts to solve current environmental conundrums.

Nickel single atoms anchored on ultrathin carbon nitride for selective hydrogen peroxide generation with enhanced photocatalytic activity

Photocatalysis technology provides a promising and effective method for hydrogen peroxide (H2O2) production. Nevertheless, the photocatalytic H2O2 production activity is greatly regulated by the two-electron oxygen reduction reaction (2e− O2RR). Herein, we demonstrate a robust single atom photocatalyst (NiCN-x, Ni single atoms anchored on ultrathin g-C3N4) for artificial H2O2 production under visible light irradiation. A high H2O2 generation rate of 27.11 mmol g−1h−1 and an apparent quantum yield (AQY) of 8.56 % at 400 nm are both obtained in the optimal NiCN-4 photocatalytic system. Furthermore, NiCN-4 catalyst shows relatively high selectivity of H2O2 with 87.3 % through using a rotating ring-disk electrode (RRDE) measurement. Furthermore, NiCN-4 shows enhanced photocatalytic TC decomposition with degradation efficiency of 89.4 %. Based on DFT calculation, experimental results and advanced characterizations, we find that the high photocatalytic performance is attributed to the boosting 2e−O2RR process with the formation of Ni-μ-peroxide (Ni-OOH) and the unique electronic feature of Ni-Nx coordination sites. This study offers a new blueprint for the fabrication of single atom catalysts (SACs) to achieve artificial photosynthesis of H2O2 with high selectivity and degradation of organic pollutants.

Reprint of: Production of Superoxide Radicals and Hydrogen Peroxide by NADH- Ubiquinone Reductase and Ubiquinol-Cytochrome c Reductase from Beef-Heart Mitochondria

Complex I (NADH-ubiquinone reductase) and Complex III (ubiquinol-cytochrome c reductase) supplemented with NADH generated O2−at maximum rates of 9.8 and 6.5 nmol/min/mg of protein, respectively, while, in the presence of superoxide dismutase, the same systems generated H2O2 at maximum rates of 5.1 and 4.2 nmol/min/mg of protein, respectively. H2O2 was essentially produced by disproportionation of O2−, which constitutes the precursor of H2O2. The effectiveness of the generation of oxygen intermediates by Complex I in the absence of other specific electron acceptors was 0.95 mol of O2− and 0.63 mol of H2O2/mol of NADH. A reduced form of ubiquinone appeared to be responsible for the reduction of O2 to O2−, since (a) ubiquinone constituted the sole common major component of Complexes I and III, (b) H202 generation by Complex I was inhibited by rotenone, and (c) supplementation of Complex I with exogenous ubiquinones increased the rate of H2O2 generation. The efficiency of added quinones as peroxide generators decreased in the order Q1 > Q0 > Q2 > Q6 = Q10, in agreement with the quinone capacity of acting as electron acceptor for Complex I. In the supplemented systems, the exogenous quinone was reduced by Complex I and oxidized nonenzymati- cally by molecular oxygen. Additional evidence for the role of ubiquinone as peroxide generator is provided by the generation of O2− and H2O2 during autoxidation of quinols. In oxygenated buffers, ubiquinol (Q0H2), benzoquinol, duroquinol and menadiol generated O2−with k3 values of 0.1 to 1.4 M-1 s-1 and H2O2 with k4 values of 0.009 to 4.3 m-1·s-1

AQ-coupled few-layered g-C3N4 nanoplates obtained by one-step mechanochemical treatment for efficient visible-light photocatalytic H2O2 production

Solar-driven photocatalytic H2O2 production is a sustainable and clean technique with respect to the traditional route. Here, the efficient H2O2 generation was accomplished by π−π coupling of AQ onto the few-layered graphitic carbon nitride (g-C3N4) nanoplates through one-step mechanochemical treatment. A H2O2 generation rate of 231 μM h−1 was obtained using AQ-coupled g-C3N4 nanoplates under visible light illumination, exceeding that of the g-C3N4 nanoplates and bulk g-C3N4 by 7-time and 14-time, respectively. Experimental results showed that the high oxygen reduction efficiency could be ascribed to the enhanced surface area, more exposed active sites and the distinct AQ roles of the electrons storage and restraining the charge recombination. This work inspired future work in synthesizing H2O2 through a sustainable and green route.

A Polyimide-Based Photocatalyst for Continuous Hydrogen Peroxide Production Using Air and Water under Solar Light

A Polyimide-Based Photocatalyst for Continuous Hydrogen Peroxide Production Using Air and Water under Solar Light

Scavenging mitochondrial hydrogen peroxide by peroxiredoxin 3 overexpression attenuates contractile dysfunction and muscle atrophy in a murine model of accelerated sarcopenia.

Age‐related muscle atrophy and weakness, or sarcopenia, are significant contributors to compromised health and quality of life in the elderly. While the mechanisms driving this pathology are not fully defined, reactive oxygen species, neuromuscular junction (NMJ) disruption, and loss of innervation are important risk factors. The goal of this study is to determine the impact of mitochondrial hydrogen peroxide on neurogenic atrophy and contractile dysfunction. Mice with muscle‐specific overexpression of the mitochondrial H2O2 scavenger peroxiredoxin3 (mPRDX3) were crossed to Sod1KO mice, an established mouse model of sarcopenia, to determine whether reduced mitochondrial H2O2 can prevent or delay the redox‐dependent sarcopenia. Basal rates of H2O2 generation were elevated in isolated muscle mitochondria from Sod1KO, but normalized by mPRDX3 overexpression. The mPRDX3 overexpression prevented the declines in maximum mitochondrial oxygen consumption rate and calcium retention capacity in Sod1KO. Muscle atrophy in Sod1KO was mitigated by ~20% by mPRDX3 overexpression, which was associated with an increase in myofiber cross‐sectional area. With direct muscle stimulation, maximum isometric specific force was reduced by ~20% in Sod1KO mice, and mPRDX3 overexpression preserved specific force at wild‐type levels. The force deficit with nerve stimulation was exacerbated in Sod1KO compared to direct muscle stimulation, suggesting NMJ disruption in Sod1KO. Notably, this defect was not resolved by overexpression of mPRDX3. Our findings demonstrate that muscle‐specific PRDX3 overexpression reduces mitochondrial H2O2 generation, improves mitochondrial function, and mitigates loss of muscle quantity and quality, despite persisting NMJ impairment in a murine model of redox‐dependent sarcopenia.

Iodide ions as invisible chemical scissors tailoring carbon nitride for highly efficient photocatalytic H2O2 evolution

The obtained TCN/NaI possesses Na+ and –OH co-modification, which shows the highest H2O2 generation rate. DFT calculations further reveal that the electron of β spin-orbital in TCN/NaI can transfer to the π* orbital of O2 more facile than BCN.

The impact of reductants on the catalytic efficiency of a lytic polysaccharide monooxygenase and the special role of dehydroascorbic acid.

Monocopper lytic polysaccharide monooxygenases (LPMOs) catalyse oxidative cleavage of glycosidic bonds in a reductant-dependent reaction. Recent studies indicate that LPMOs, rather than being O2 -dependent monooxygenases, are H2 O2 -dependent peroxygenases. Here, we describe SscLPMO10B, a novel LPMO from the phytopathogenic bacterium Streptomyces scabies and address links between this enzyme's catalytic rate and in situ hydrogen peroxide production in the presence of ascorbic acid, gallic acid and l-cysteine. Studies of Avicel degradation showed a clear correlation between the catalytic rate of SscLPMO10B and the rate of H2 O2 generation in the reaction mixture. We also assessed the impact of oxidised ascorbic acid, dehydroascorbic acid (DHA), on LPMO activity, since DHA, which is not considered a reductant, was recently reported to drive LPMO reactions. Kinetic studies, combined with NMR analysis, showed that DHA is unstable and converts into multiple derivatives, some of which are redox active and can fuel the LPMO reaction by reducing the active site copper and promoting H2 O2 production. These results show that the apparent monooxygenase activity observed in SscLPMO10B reactions without exogenously added H2 O2 reflects a peroxygenase reaction.

Thermal reduced graphene oxide enhanced in-situ H2O2 generation and electrochemical advanced oxidation performance of air-breathing cathode

Developing highly efficient catalysts with high ORR activity and H2O2 selectivity is an important challenge for producing H2O2 through 2e− oxygen reduction reaction (ORR). In this work, we tuned the reduction degree of graphene oxide by controlling reducing temperature and prepared graphite-TRGO hybrid air breathing cathodes (ABCs). The H2O2 production rate of TRGO-1100 (with highest reduction degree) modified ABC exhibits highest H2O2 generation rate of 20.4 ± 0.8 mg/cm2/h and current efficiency of 94 ± 2%. The charge transfer resistance of TRGO-1100 decreases by 2.5-fold compared with pure graphite cathode. Unreduced GO shows high H2O2 selectivity and low ORR activity, while TRGO shows lower H2O2 selectivity but higher ORR activity. Though the 2e− ORR selectivity of TRGO decreased TRGO with all reduction degrees, the H2O2 production increased in all forming electrodes. Superior performance of TRGO modified ABCs is attributed to high oxygen adsorption and low charge transfer resistance. TRGO possesses super-hydrophobicity and large surface area for oxygen adsorption. Besides, TRGO provides abundant electrochemically active sites to facilitate the electron transfer and formed more mesopores for H2O2 release. Electro-Fenton using TRGO-1100-ABC exhibited great performance for Persistent Organic Pollutants (POPs) degradation, which removed 66% of tetracycline in 5 min.

ZnO nanoparticles embedded in hollow carbon fiber membrane for electrochemical H2O2 production by two-electron water oxidation reaction

Electrochemical two-electron water oxidation reaction (2e-WOR) provides a promising alternative route for hydrogen peroxide (H2O2) production, where the design of earth abundant and environmentally friendly electrocatalysts with both high selectivity and production rate is crucial. Here we report the synthesis of ZnO nanoparticles embedded in hollow carbon fiber membrane as efficient 2e-WOR electrocatalyst by a metal-organic framework engaged electrospinning-pyrolysis method. The resultant ZnO@carbon composite fiber exhibits a foam-like hierarchical structure composed of interconnected hollow carbon nanocubes encapsulated with oxygen vacancy rich ZnO nanocrystals. Owing to the improved selectivity of ZnO, excellent conductivity of carbon fiber, promoted active site exposure and mass transfer of hollow structure, the free-standing membrane electrode shows superior 2e-WOR performances with high selectivity (83.8% at 2.8 V vs. RHE), H2O2 generation rate (19.7 μmol cm−2 min−1) and robust stability.

Enhanced electrochemical advanced oxidation on boride activated carbon: The influences of boron groups

Exploring an efficient electro-catalyst is fundamentally important to enhance degradation of persistent organic pollutants during electrochemical advanced oxidation process. In this work, boride activated carbon (BAC) containing different boron group content was prepared as low-cost and efficient catalysts. BAC possessed a more positive onset potential of oxygen reduction reaction (0.458 V vs. RHE) and a faster rate of H2O2 generation (365 mg/L pH=3), compared with activated carbon (0.425 V vs. RHE, 138 mg/L pH=3). DFT calculations and XPS results revealed that -BC3 and -BC2O active groups enhanced oxygen adsorption, and small electronegativity difference between B and O facilitated the desorption of •OOH. The rate of in-situ phenol degradation (0.193 min−1) increased by an order of magnitude as compared to activated carbon (0.018 min−1), because BAC promoted the in-situ conversion of H2O2 to •OH. Therefore, it provided a theoretical base for the further application of boron catalyst in two-electron oxygen reduction process.