Electrochemical Generation Of Hydrogen Peroxide Research Articles

Electrochemical Hydrogen Peroxide Generation and Activation Using a Dual-Cathode Flow-Through Treatment System: Enhanced Selectivity for Contaminant Removal by Electrostatic Repulsion.

To oxidize trace concentrations of organic contaminants under conditions relevant to surface- and groundwater, air-diffusion cathodes were coupled to stainless-steel cathodes that convert atmospheric O2 into hydrogen peroxide (H2O2), which then was activated to produce hydroxyl radicals (·OH). By separating H2O2 generation from its activation and employing a flow-through electrode consisting of stainless-steel fibers, the two processes could be operated efficiently in a manner that overcame mass-transfer limitations for O2, H2O2, and trace organic contaminants. The flexibility resulting from separate control of the two processes made it possible to avoid both the accumulation of excess H2O2 and the energy losses that take place after H2O2 has been depleted. The decrease in treatment efficacy occurring in the presence of natural organic matter was substantially lower than that typically observed in homogeneous advanced oxidation processes. Experiments conducted with ionized and neutral compounds indicated that electrostatic repulsion prevented negatively charged ·OH scavengers from interfering with the oxidation of neutral contaminants. Energy consumption by the dual-cathode system was lower than values reported for other technologies intended for small-scale drinking water treatment systems. The coordinated operation of these two cathodes has the potential to provide a practical, inexpensive way for point-of-use drinking water treatment.

Surfactant-tolerant cathodes for electrochemical generation of hydrogen peroxide for wastewater treatment

Surfactant-tolerant cathodes for electrochemical generation of hydrogen peroxide for wastewater treatment

Influence of Water Hardness and Complexing Agents on Electrochemical Hydrogen Peroxide Generation.

Recently, many studies have been published regarding electrochemical oxygen reduction reaction for generating hydrogen peroxide (H2O2) using gas diffusion electrodes (GDEs) for various applications. Sodium salts solved in deionized water were usually used as supporting electrolytes. In technical applications, however, tap water-based electrolytes with hardeners are particularly relevant and have only been considered in a few studies to date. In this work, we investigated the influence of hardeners on H2O2-generation at 150mAcm‑2 and were able to show that scaling occurs predominantly on the GDE surface and not in its pore structure. With the novel method in electrochemical synthesis by using complexing agents to bind hardeners, we were able to significantly reduce the scaling. Even after 10h of operation, the reactor still achieves a faradaic efficiency (FE) of above 70% (> 67 mg h-1 cm-2), comparable to the experiments without hardeners and complexing agents in the electrolyte. Furthermore, we demonstrate that the complexing agents are not electrochemically converted at the carbon-based GDE and behave inertly. If the cell is operated with complexing agents and rinsed with acidic liquid (anolyte) between batches, scaling can be completely avoided.

Electrogenerated chemiluminescence from luminol-labelled microbeads triggered by in situ generation of hydrogen peroxide.

We developed a sensing strategy that mimics the bead-based electrogenerated chemiluminescence immunoassay. However, instead of the most common metal complexes, such as Ru or Ir, the luminophore is luminol. The electrogenerated chemiluminescence of luminol was promoted by in situ electrochemical generation of hydrogen peroxide at a boron-doped diamond electrode. The electrochemical production of hydrogen peroxide was achieved in a carbonate solution by an oxidation reaction, while at the same time, microbeads labelled with luminol were deposited on the electrode surface. For the first time, we proved that was possible to obtain light emission from luminol without its direct oxidation at the electrode. This new emission mechanism is obtained at higher potentials than the usual luminol electrogenerated chemiluminescence at 0.3-0.5V, in conjunction with hydrogen peroxide production on boron-doped diamond at around 2-2.5V (vs Ag/AgCl).

Electrochemical Hydrogen Peroxide Generation and Removal of Moxifloxacin by Electro-Fenton Process

In this study, the removal of moxifloxacin, an antibiotic of the fluoroquinolone group, from aqueous solutions was investigated using the electro-Fenton process. As the efficiency of the electro-Fenton process is highly dependent on the amount of H2O2 produced during process, the formation of H2O2 under acidic conditions was also investigated. In this context, the effects of applied current, cathode type and O2 flow rate on H2O2 production were investigated using boron-doped diamond anode. The highest H2O2 production was achieved using the boron-doped diamond anode and the graphite felt cathode. In addition, the optimum conditions for the applied current and oxygen flow rate for H2O2 production were determined to be 0.25 A and 0.1 L min−1, respectively. The effects of applied current and Fe2+ concentration in the electro-Fenton process on the removal of moxifloxacin were investigated. It was found that the moxifloxacin removal rate increased with increasing applied current. The highest H2O2 accumulation was observed at 0.25 A applied current, and moxifloxacin removal also reached 93.6% after 60 min. The moxifloxacin removal rate reached the highest value at Fe2+ concentration of 0.01 mM. This study provides promising results for the efficient treatment of moxifloxacin-containing wastewater by the electro-Fenton process without the addition of H2O2 using boron-doped diamond anode anode and graphite felt cathode.

Innovative carbon materials from lignocellulosic wastes for electrochemical hydrogen peroxide production: Bridging biomass conversion and material properties

This study aims to assess the electrochemical generation of hydrogen peroxide and hydroxyl radicals (*OH) using carbon cathodes synthesized from three different lignocellulosic residues, Phragmites australis (PA), Cladium mariscus (CM) and Typha domingensis (TD). These vegetal species are commonly used in natural wetlands and phytoremediation processes and can accumulate recalcitrant pollutants within these treatment processes, generating a waste that should be properly managed. To convert these residues into valuable carbon materials, they underwent hydrothermal carbonization (HTC) followed by either chemical activation with KOH or pyrolysis at 1000 ºC. The best results were obtained with chemically activated materials, yielding a maximum H2O2 concentration of 313 mg L−1 with the carbon cathode produced from PA. The specific surface area, oxygenated functional groups and presence of structural defects in carbonous structures, were key parameters related to a good performance as catalysts towards the 2e- Oxygen Reduction Reaction (ORR). It was also demonstrated, in comparison with previous studies, that the presence of heavy metals in the structure of the lignocellulosic residue enhanced the decomposition of H2O2 into *OH. However, in the study of the degradation of a model organic contaminant as methylene blue (MB), it was shown that these *OH were not the main contributors to degradation, as direct H2O2 chemical degradation and adsorption on the carbon materials played the most significant role. Therefore, the outstanding capacity of these lignocellulosic residues as catalysts for the electrogeneration of H2O2 was confirmed, suggesting their potential future application in advanced oxidation processes for water decontamination.

Easily scale 3D conductive gradient fiber membrane for contaminants removal and fouling mitigation under electrochemical assistance

An electrochemical membrane filtration system provides an innovative approach to enhance contaminant removal and mitigate membrane fouling. There is an urgent need to develop portable, versatile, and efficient electrochemical membranes for affordable wastewater treatment. Here, a 3D conductive gradient fiber membrane (CC/PVDF) with a gradient porous structure was prepared using a two-step phase inversion method. Methyl orange (MO) was utilized as model organic substance to investigate the electrochemical performance of the CC/PVDF membrane. At applied potentials of +2 V, +3 V, −2 V and −3 V, the removal efficiency of MO was 5.1, 5.3, 4.8, and 5.1 times higher than at 0 V. A dramatic flux loss of 35.02% occurred on the membrane without electrochemistry, interestingly, whereas the flux losses were only 23.59%–10.24% in the applied potential after 30 min of filtration, which were approximately 1.18, 1.28, 1.29 and 1.38 times as high as that without electrochemistry, respectively. The enhanced removal and anti-fouling performances of the membranes were attributed to the functions of electrochemical degradation, electrostatic repulsion, and electrically enhanced wettability. Electrochemical generation of Hydrogen peroxide, along with HO• radicals, was detected and direct electron transfer and HO• were proved to be the dominant oxidants responsible for MO degradation. The intermediate oxidation products were identified by mass spectrometry, and an electrochemical degradation pathway of MO was proposed based on bond-breaking oxidation, ring-opening reactions, and complete oxidation. All the findings emphasize that the ECMF system possesses superior efficiency and creative potential for water purification applications.

Electrochemical Peroxide Generation for in Situ Disinfection

Among the numerous technological advances sought in order to facilitate human exploration and habitation outside of earth’s atmosphere, solutions and innovations are needed for processing resources locally to support sustainable and long duration space missions. Such in-situ resource utilization (ISRU) is aimed at reducing the payload mass during launch and eliminate the need for ground support for long-term missions and ultimately space colonization. Disinfection needs is an area of particular need, which is currently accomplished through the use of pre-packaged, disposable, wetted disinfection wipes. These items represent an appreciable carry-along mass and disposal/replacement burden requiring ground support. Therefore, a system is desired that could utilize onboard utilities to create disinfecting solutions to eliminate storage/disposable problems of the wetted wipes and further reduce the astronaut’s dependence on earth-based supplies.Faraday Technology Inc. is addressing this challenge by demonstrating an in-situ approach, which utilizes on-board supplies of air and water for on demand electrochemical generation of hydrogen peroxide. Hydrogen peroxide is well-established disinfectant with non-toxic decomposition products (viz., O2 and H2O), that is safe enough for human contact to be sold commercially as a 1-5 w/w% solution, which makes it an ideal disinfecting solution for closed space environments. Faraday has continued to improve the TRL by scaling the electrochemical peroxide generation system from a sub-scale to alpha-scale process in order to deliver 1 L per day of ~2 w/w% hydrogen peroxide for disinfectant applications from DI water feed-stream with air as a feed source[1],[2],[3],[4]. These electrolytes were then sent to NASA for microbial control property characterization.This system eliminates the need to ferry disinfectant wipes to manned space capsules and is a critical enabling technology for future moon-based missions and beyond. Specifically, this talk will discuss the results of these advancements. Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, 80NSSC20C0070, and 80NSSC23CA036 is acknowledged.

Algal Removal from Water by Electrochemical Generation of Hydrogen Peroxide and Persulfate

Algal Removal from Water by Electrochemical Generation of Hydrogen Peroxide and Persulfate

Electrochemical generation of hydrogen peroxide from a zinc gallium oxide anode with dual active sites

Electrochemical water oxidation enables the conversion of H2O to H2O2. It holds distinct advantages to the O2 reduction reaction, which is restricted by the inefficient mass transfer and limited solubility of O2 in aqueous media. Nonetheless, most reported anodes suffer from high overpotentials (usually >1000 mV) and low selectivity. Electrolysis at high overpotentials often causes serious decomposition of peroxides and leads to declined selectivity. Herein, we report a ZnGa2O4 anode with dual active sites to improve the selectivity and resist the decomposition of peroxides. Its faradaic efficiency reaches 82% at 2.3 V versus RHE for H2O2 generation through both direct (via OH−) and indirect (via HCO3−) pathways. The percarbonate is the critical species generated through the conversion of bicarbonate at Ga-Ga dual sites. The peroxy bond is stable on the surface of the ZnGa2O4 anode, significantly improving faradaic efficiency.

Polarity reversal for enhanced in-situ electrochemical synthesis of H2O2 over banana-peel derived biochar cathode for water remediation

The fabrication of a cost-efficient cathode is critical for in-situ electrochemical generation of hydrogen peroxide (H2O2) to remove persistent organic pollutants from groundwater. Herein, we tested a stainless-steel (SS) mesh wrapped banana-peel derived biochar (BB) cathode for in-situ H2O2 electrogeneration to degrade bromophenol blue (BPB) and Congo red (CR) dyes. Furthermore, polarity reversal is evaluated for the activation of BB surface via introduction of various oxygen containing functionalities that serve as active sites for the oxygen reduction reaction (ORR) to generate H2O2. Various parameters including the BB mass, current, as well as the solution pH have been optimized to evaluate the cathode performance for efficient H2O2 generation. The results reveal formation of up to 9.4 mg/L H2O2 using 2.0 g BB and 100 mA current in neutral pH with no external oxygen supply with a manganese doped tin oxide deposited nickel foam (Mn-SnO2@NF) anode to facilitate the oxygen evolution reaction (OER). This iron-free electrofenton (EF) like process enabled by the SSBB cathode facilitates efficient degradation of BPB and CR dyes with 87.44 and 83.63% removal efficiency, respectively after 60 min. A prolonged stability test over 10 cycles demonstrates the effectiveness of polarity reversal toward continued removal efficiency as an added advantage. Moreover, Mn-SnO2@NF anode used for the OER was also replaced with stainless steel (SS) mesh anode to investigate the effect of oxygen evolution on H2O2 generation. Although Mn-SnO2@NF anode exhibits better oxygen evolution potential with reduced Tafel slope, SS mesh anode is discussed to be more cost-efficient for further studies.

Electrochemical generation of hydrogen peroxide during cathodic polarization of metallic orthopedic biomaterials

Electrochemical generation of hydrogen peroxide during cathodic polarization of metallic orthopedic biomaterials

Mo-Based Heterogeneous Interface and Sulfur Vacancy Synergistic Effect Enhances the Fenton-like Catalytic Performance for Organic Pollutant Degradation.

Heterogeneous Fenton-like reactions (HFLRs) based on the in situ electrochemical generation of hydrogen peroxide (H2O2) are one of the green methods to remediate organic pollutants in wastewater. However, the design of Fenton-like catalysts with specific active sites and high pollutant degradation rate is still challenging. Here, MoS2-MoC and MoS2-Mo2N catalytic cathodes with heterojunctions were successfully prepared, and the mechanism by which hydroxyl radicals and singlet oxygen (1O2) were generated cleanly without adding chemical additives other than oxygen was clarified. The composite catalysts contained more sulfur vacancies, and the catalytic cathode achieved a high paracetamol pollutant degradation efficiency with 0.17 kWh g-1 TOC specific energy consumption. And almost 5 times higher activity was achieved compared to a pure MoS2 catalytic cathode. Experimental studies confirmed that the production of 1O2 was based on the transformation of superoxide radicals by Mo6+, and 1O2 accounted for approximately 66% of the total degradation and enhanced the nonradical behavior in the reaction. This work provides a sustainable strategy for pollutant utilization, which is valuable for solving the difficult problems of HFLRs and developing new environmental remediation technologies.

Polytetrafluoroethylene-based gas diffusion electrode for electrochemical generation of hydrogen peroxide

Hydrogen peroxide (H2O2) is a versatile oxidizing agent with numerous applications in various industries. One application of H2O2 is for water treatment, where it is combined with an ultraviolet (UV) radiation source to produce hydroxyl radicals. For point-of-use water treatment devices, the in-situ electrochemical generation of H2O2 is a more attractive solution compared with the external addition of chemicals. One common electrode for H2O2 production is gas diffusion electrode (GDE), which facilitates oxygen transport to the reaction zone. In our study, a GDE was developed based on an expanded polytetrafluoroethylene (ePTFE) substrate for the in-situ cathodic production of H2O2. The GDE characterization indicated its longevity and tolerance to a pressure difference of more than 70 psi, which is typical in residential water distribution systems. The performance of the GDE was evaluated in an electrochemical cell based on various parameters. The cell generated ∼0.6 mM H2O2 at a catalyst loading of 0.22 mg cm–2, flow rate of 40 mL min–1, and current density of ∼200 A m–2. When coupled with a UV-LED array, the ePTFE-based cell was able to oxidize >60% of methylene blue. To the best of our knowledge, this is the first study in which an ePTFE-based GDE has been applied to the electrochemical generation of H2O2, with the ePTFE network as the gas diffusion layer (GDL), thus making the system practically leak-free. The air-breathing electrochemical cell with the ePTFE-based GDE is a reliable means of generating H2O2.

Stabilization of Urea in Urine through the Electrochemical Generation of Hydrogen Peroxide

Urine represents a small fraction, usually 1-2%, of the total volume of a typical wastewater stream, but contributes over half of the nitrogen. This nitrogen, which is predominantly ammonium, must be removed prior to discharging the treated wastewater into the environment. Traditional nitrogen removal processes are often energy intensive and operationally sensitive. Source separation of urine presents an opportunity to divert most of the nitrogen received by a traditional wastewater treatment plant and allow direct treatment of this highly concentrated waste stream. Source separation of urine is not without its own operational difficulties though; flushless urinals often succumb to clogging and foul odors. This is in part due to the hydrolysis of urea by the urease enzyme which converts urea, the principal nitrogen compound in urine, to ammonia. This in turn produces odors and precipitates minerals which lead to mineral scaling. Source separated urine is also susceptible to biological growth, which along with scaling, are the primary causes of plumbing fixture failures in source separation installations. Source separated urine has been identified as a potential candidate for resource recovery, but the instability of fresh urine presents operational hurdles that must be overcome. The hydrolysis of urea by urease may be inhibited by dosing fresh urine with a sufficient volume of strong acid or base, or by strong oxidants such as hydrogen peroxide. These stabilizers are hazardous materials, and bulk storage of these chemicals presents inherent danger. We have investigated the use of electrochemical cells capable of producing hydrogen peroxide in-situ in fresh urine to determine the feasibility of this technology for urine stabilization. Urine is fed to the cathode chamber where a gas diffusion electrode reduces atmospheric oxygen to hydrogen peroxide, which deactivates any urease present in the urine. An added benefit to using hydrogen peroxide is its biocidal properties; urine samples treated with this approach displayed no biological growth after extended storage. Previous experiments have utilized exogenously added jack bean urease to simulate conditions present in source separated urine collection systems; control samples with no hydrogen peroxide present exhibited complete disappearance of urea, while samples with electrochemically synthesized hydrogen peroxide remained stable. Current experiments are exploring the long-term stability of treated urine after exposure to ureolytic bacteria to better simulate real world applications of this treatment approach.

Black Phosphorous Mediates Surface Charge Redistribution of CoSe2 for Electrochemical H2 O2 Production in Acidic Electrolytes.

Electrochemical generation of hydrogen peroxide (H2 O2 ) by two-electron oxygen reduction offers a green method to mitigate the current dependence on the energy-intensive anthraquinone process, promising its on-site applications. Unfortunately, in alkaline environments, H2 O2 is not stable and undergoes rapid decomposition. Making H2 O2 in acidic electrolytes can prevent its decomposition, but choices of active, stable, and selective electrocatalysts are significantly limited. Here, the selective and efficient two-electron reduction of oxygen toward H2 O2 in acid by a composite catalyst that is composed of black phosphorus (BP) nailed chemically on the metallic cobalt diselenide (CoSe2 ) surface is reported. It is found that this catalyst exhibits a 91% Faradic efficiency for H2 O2 product at an overpotential of 300 mV. Moreover, it can mediate oxygen to H2 O2 with a high production rate of ≈1530mg L-1 h-1 cm-2 in a flow-cell reactor. Spectroscopic and computational studies together uncover a BP-induced surface charge redistribution in CoSe2 , which leads to a favorable surface electronic structure that weakens the HOO* adsorption, thus enhancing the kinetics toward H2 O2 formation.

(Digital Presentation) On Demand Electrochemical Peroxide Generation for Disinfection

Novel technologies with limited earth support are required to enable habitation in microgravity spacecraft habitats such as International Space Station (ISS). Disinfection needs is an area of particular need, which is currently accomplished through the use of pre-packaged, disposable, wetted disinfection wipes. These items represent an appreciable carry-along mass and disposal/replacement burden requiring ground support. Therefore, a system is desired that could utilize onboard utilities to create disinfecting solutions to eliminate storage/disposable problems of the wetted wipes and further reduce the astronaut’s dependence on earth-based supplies.Faraday Technology Inc. is addressing this challenge by demonstrating an in-situ approach, which utilizes on-board supplies of air and water for on demand electrochemical generation of hydrogen peroxide. Hydrogen peroxide is well-established disinfectant with non-toxic decomposition products (viz., O2 and H2O), that is safe enough for human contact to be sold commercially as a 1-5 w/w% solution, which makes it an ideal disinfecting solution for closed space environments. Faraday has continued to improve the TRL by scaling the electrochemical peroxide generation system from a sub-scale to alpha-scale process in order to deliver 1 L per day of ~2 w/w% hydrogen peroxide for disinfectant applications from DI water feed-stream with air as a feed source [1],[2],[3],[4] . These electrolytes were then sent to NASA for microbial control property characterization. Specifically, this talk will discuss the results of these advancements. Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, and 80NSSC20C0070 is acknowledged.

Novel electrochemical advanced oxidation processes with H2O2 generation cathode for water treatment: A review

Recently, electrochemical generation of hydrogen peroxide (H2O2) using cathodic oxygen reduction reaction (ORR) has been conventionally implemented in electrochemical advanced oxidation processes (EAOPs) for water treatment. H2O2 could be activated using reagents like Fe2+ and O3 to produce the hydroxyl radicals (•OH), and further reduce organics. The conventional Fenton, Peroxone and Electro-Oxidation (EO) processes were enhanced using H2O2 generation cathode to execute Electro-Fenton, Electro-Peroxone and ORR-EO processes. In this study, the carbon-based materials as catalysts for H2O2 generation cathode were generally investigated. The development of cutting-edge EAOPs based on H2O2 generation cathode was introduced using three stories. The future viewpoint of EAOPs based on H2O2 generation cathode was discussed.

Nanoporous Graphene via a Pressing Organization Calcination Strategy for Highly Efficient Electrocatalytic Hydrogen Peroxide Generation.

Nanoporous graphenes (NPGs) have recently attracted huge attention owing to their designable structures and diverse properties. Many important properties of NPGs are determined by their structural regularity and homogeneity. The mass production of NPGs with periodic well-defined pore structures under a solvent-free green synthesis poses a great challenge and is largely unexplored. A facile synthetic strategy of NPGs via pressing organization calcination (POC) of readily available halogenated polycyclic aromatic hydrocarbons is developed. The gram-scale synthesized NPGs have ordered structures and possess well-defined nanopores, which can be easily exfoliated to few layers and oxidized in controllable approaches. After being decorated with oxygen species, the oxidized NPGs with tunable catalytic centers exhibit high activity, selectivity, and stability toward electrochemical hydrogen peroxide generation.

Selective Electrochemical Generation of Hydrogen Peroxide from Oxygen Reduction on Atomically Dispersed Platinum

A catalyst with an atomically dispersed metal center may provide an ideal structure for the electrochemical synthesis of H2O2 due to the distinct chemoselectivity. Herein, we report a simple electrochemical method to prepare atomically dispersed Pt catalyst on a sulfur-doped carbon structure (Pt1-meso-S-C) by underpotential deposition (UPD) of copper atoms followed by a galvanic replacement reaction under ambient conditions. Sulfur doping in the carbon structure shows a strong affinity to metal atoms, resulting in underpotential deposition (UPD) of a single copper adatom at a potential positive to its thermodynamic equilibrium potential. Galvanic replacement of the UPD Cu by platinum precursor leads to the formation of a single-atom Pt catalyst on a sulfur-doped carbon structure. This Pt1-meso-S-C acts as a highly selective catalyst for the electrochemical reduction of O2 into H2O2 without promoting consecutive H2O2 decomposition. However, the catalysts (Ptn-meso-S-C and Pt/C) with the platinum ensemble sites exhibit a four-electron pathway for oxygen reduction reaction (ORR) and the consecutive H2O2 decomposition. This work demonstrates that the reaction mechanism can be adjusted by the dispersion of metal catalysts.