Electrochemical H2O2 Research Articles

Room temperature oxygenated groups addition in carbon materials via ozone oxidation for boosting electrochemical H2O2 production

The crucial yet delicate 2e− oxygen reduction reaction (ORR) for producing the green chemical H2O2 relies on the uniform coordination environment of the active sites, such as oxygenated groups in metal-free carbon material catalysts. However, conventional harsh carbon material synthesis methods inevitably introduce structural defects and alter morphology, hindering the precise control of active site formation. Herein, we developed the ozone oxidation method under controlled reaction conditions to precisely modify carbon materials at room temperature. Through controlling the ozonation of reaction time, concentration, temperature, and relative humidity, we find the mild method allows us to precisely add active carboxyl group (–COOH) without forming structural defects. Electrochemical tests reveal that the optimal catalyst with the highest –COOH content exhibits the most outstanding mass activity of 164 A/g at 0.65 V and the highest H2O2 selectivity of 91 %. The density functional theory calculations demonstrate that the carbon sites directly connected to –COOH possess the optimized binding strength of *OOH intermediate to favor the two-electron oxygen reduction process. This work offers a novel approach to precisely and gently control carbon surface groups while preserving the structural morphology through ozone gas treatment, which can be readily applied to other material designs.

Modulating Core Polarity in Metal-free Covalent Organic Frameworks for Selective Electrocatalytic Hydrogen Peroxide Production.

Tuning the charge density at the active site to balance the adsorption ability and reactivity of oxygen is extremely significant for driving a two-electron oxygen reduction reaction (ORR) to produce hydrogen peroxide (H2O2). Herein, we have highlighted the influence of intermolecular polarity in covalent organic frameworks (COFs) on the efficiency and selectivity of electrochemical H2O2 production. Different C3 symmetric building blocks have been utilized to regulate the charge density at the active sites. The benzene-cored COF, which exhibits reduced polarity than the triazine-cored COF, displayed enhanced performance in H2O2 production, achieving 93.1% selectivity for H₂O₂ at 0.4 V with almost two-electron transfer and a faradaic efficiency of 90.5%. In-situ electrochemical Raman spectroscopy and scanning electrochemical microscopy (SECM) were employed to confirm H₂O₂ generation and analyze spatial reactivity patterns. These techniques provided detailed insights into localized catalytic behavior, emphasizing the influence of core polarity.

Modulating Core Polarity in Metal‐free Covalent Organic Frameworks for Selective Electrocatalytic Hydrogen Peroxide Production

Tuning the charge density at the active site to balance the adsorption ability and reactivity of oxygen is extremely significant for driving a two‐electron oxygen reduction reaction (ORR) to produce hydrogen peroxide (H2O2). Herein, we have highlighted the influence of intermolecular polarity in covalent organic frameworks (COFs) on the efficiency and selectivity of electrochemical H2O2 production. Different C3 symmetric building blocks have been utilized to regulate the charge density at the active sites. The benzene‐cored COF, which exhibits reduced polarity than the triazine‐cored COF, displayed enhanced performance in H2O2 production, achieving 93.1% selectivity for H₂O₂ at 0.4 V with almost two‐electron transfer and a faradaic efficiency of 90.5%. In‐situ electrochemical Raman spectroscopy and scanning electrochemical microscopy (SECM) were employed to confirm H₂O₂ generation and analyze spatial reactivity patterns. These techniques provided detailed insights into localized catalytic behavior, emphasizing the influence of core polarity.

Robust and washable silk fiber-based electrochemical biosensor for high-performance sensing of hydrogen peroxide

Wearable electronics, especially fiber-based biosensors, show promise in large-scale production and reusability compared with conventional wafer-based electronics. However, it is challenging to use wearable electronics, with less intensity and non-wash ability, to produce fiber-based biosensors for textiles. Here, a robust and washable Prussian blue (PB)-functionalized silk fiber (PB-SF) flexible electrode is reported. Modified cyanotype is successfully employed to immobilize PB nanoparticles (∼18.32 nm) onto silk fibers for hydrogen peroxide (H2O2) detection. The intrinsic mechanical properties of silk fibers are well maintained with slight increases in stress (∼10 %) and strain (∼16 %). Furthermore, the PB-SF electrode displays good electrochemical H2O2 sensing performance with a sensitivity of 716.54 μA/mM·cm2, a linear range of 0.01–0.6 mM and a low detection limit of 10 μM (S/N = 3). Notably, the hybrid PB-SF electrode adapts to mechanical deformations with a series of angles and the electrical signals are not compromised obviously even after 100 home laundry washing cycles. PB modified silk fibers is simple, easy-operating and cost-effective electrode that is suitable for large-scale production as it can be integrated into e-textiles through typical textile processing methods.

Shape-controllable synthesis of lignin-derived boron-doped nanoporous carbons for dye adsorption and electrochemical H2O2 production

Lignin-derived nanocarbon materials (LNCMs) have attracted intense attention due to their excellent properties and promising applications in renewable energy technologies. However, lignins tend to melt and agglomerate during pyrolysis, make it difficult to control the morphology and pore structure of the resulting carbon. In this study, boron-doped porous nanocarbon (BFC) in various shapes (sphere, band, and sheet) were synthesized using ammonium borate as a crosslinking agent to prevent lignin melting, assisted by liquid nitrogen freeze-drying and potassium phosphate (KP) templating. The effects of BFC structure on methylene blue adsorption and electrochemical generation of H2O2 were investigated. The results show that KP-1/1-8BFC exhibits a high specific surface area (912.89 m2/g) and a hierarchical micro-mesoporous structure, achieving a remarkable adsorption capacity of 473.9 mg/g for methylene blue and rapid kinetics. The selectivity of KP-1/20-8BFC for electrochemical production of H2O2 reaches 85 %. This study offers theoretical guidance for the controllable synthesis of LNCMs, contributing to the advancement of sustainable energy solutions.

Platinum nanoparticles-based electrochemical H2O2 sensor for rapid antibiotic susceptibility testing

With the increase of antimicrobial resistance, rapid antibiotic susceptibility testing (AST) to guide precise antibiotic administration has become increasingly important. However, current gold standard AST approaches tend to take up to 24–48 h. In this work, based on the nature of catalase-positive bacteria decomposing H2O2, we developed a rapid, portable, straightforward, and cost-effective phenotypic AST approach by detecting residual H2O2 using a Pt nanoparticles-based electrochemical sensor. The pulse current of the sensor exhibited a linear increase with rising H2O2 concentration, demonstrating a high sensitivity of ∼382.2 μA cm−2 mM−1. This approach showed superb diagnostic performance, with an area under the curve of 1 for 24 clinical samples of Escherichia coli and Staphylococcus aureus, with a total detection time of 60 and 45 min, respectively. Furthermore, the performance of the sensor showed no degradation even after 100 detections, promising a substantial reduction in AST costs. Overall, the proposed approach exhibited immense potential for diagnosing bacterial antibiotic resistance.

First-principles study of electrochemical H2O2 production on Pd-B40 single-atom catalyst

Hydrogen peroxide (H2O2), a versatile green compound, is increasingly in demand. The electrochemical two-electron oxygen reduction reaction (2e− ORR) is a simple and environmentally friendly substitute method to the traditional anthraquinone oxidation method for H2O2 production. This study systematically investigates the 2e− ORR process on single transition metal atom-loaded boron fullerene (M − B40) using density functional theory calculations. In evaluating the stability of the catalysts, we found that Au, Pd, Pt, Rh, and Ir atoms adsorbed on hexagonal or heptagonal sites of B40 exhibit good stability. Among these, Pd-modified B40 heptagonal cavity (Pd-B40-heptagonal) demonstrates an ideal Gibbs free energy change for OOH* (4.49 eV) and efficiently catalyzes H2O2 production at a low overpotential (0.27 V). Electronic structure analysis reveals that electron transfer between Pd-B40-heptagonal and adsorbed O2 facilitates O2 activation. Additionally, the high 2e− ORR activity of Pd-B40-heptagonal is attributed to electron transfer from the Pd-d orbitals to the π* anti-bonding of p orbitals of OOH*, moderately activating the O-O bond. This study offers valuable understanding designing high-performance electrocatalysts for 2e− ORR.

20-Fold Increased Limiting Currents in Oxygen Reduction with Cu-tmpa by Replacing Flow-By with Flow-Through Electrodes.

Electrochemical oxygen reduction is a promising and sustainable alternative to the current industrial production method for hydrogen peroxide (H2O2), which is a green oxidant in many (emerging) applications in the chemical industry, water treatment, and fuel cells. Low solubility of O2 in water causes severe mass transfer limitations and loss of H2O2 selectivity at industrially relevant current densities, complicating the development of practical-scale electrochemical H2O2 synthesis systems. We tested a flow-by and flow-through configuration and suspension electrodes in an electrochemical flow cell to investigate the influence of electrode configuration and flow conditions on mass transfer and H2O2 production. We monitored the H2O2 production using Cu-tmpa (tmpa = tris(2-pyridylmethyl)amine) as a homogeneous copper-based catalyst in a pH-neutral phosphate buffer during 1 h of catalysis and estimated the limiting current density from CV scans. We achieve the highest H2O2 production and a 15-20 times higher geometrical limiting current density in the flow-through configuration compared to the flow-by configuration due to the increased surface area and foam structure that improved mass transfer. The activated carbon (AC) material in suspension electrodes, which have an even larger surface area, decomposes all produced H2O2 and proves unsuitable for H2O2 synthesis. Although the mass transfer limitations seem to be alleviated on the microscale in the flow-through system, the high O2 consumption and H2O2 production cause challenges in maintaining the initially reached current density and Faradaic efficiency (FE). The decreasing ratio between the concentrations of the O2 and H2O2 in the bulk electrolyte will likely pose a challenge when proceeding to larger systems with longer electrodes. Tuning the reactor design and operating conditions will be essential in maximizing the FE and current density.

Modelling Anodic H2O2 Accumulation in Alkaline Water Electrolysis with Experimental Validation

Hydrogen peroxide (H2O2) is a high value commodity chemical used as a green oxidant in industries such as paper milling and textile bleaching, and is currently produced by the anthraquinone oxidation process. The anodic co-production of H2O2 during alkaline water electrolysis has gained interest as a sustainable alternative for anthraquinone oxidation. However, electrochemical H2O2 production is often studied with idealized laboratory setups to determine the H2O2 formation kinetics. In this work, we perform the reaction using a flow cell with separately recirculating anolyte and catholyte. We then fit the H2O2 accumulation data to an analytical model that we derive based on mole balances that accounts for anodic generation, anodic oxidation, and bulk disproportionation of H2O2, as well as anolyte reservoir volume and anode chamber volume. We performed experiments to derive values for maximum H2O2 production at 300 mA cm-2, with values of 0.540 mmol s-1 for anodic generation of H2O2 (FEH2O2 = 58%) and 0.416 min-1 for anodic oxidation of H2O2, with a bulk disproportionation rate constant of 1.85 × 10−3 min-1. We successfully applied our model to two sources in literature to derive values for their systems as well. In all cases, the contribution of anodic oxidation of H2O2 was found to be the larger loss mechanism in comparison to bulk disproportionation. Figure 1

Metal Atom-Support Interaction in Single Atom Catalysts toward Hydrogen Peroxide Electrosynthesis.

Single metal atom catalysts (SACs) have garnered considerable attention as promising agents for catalyzing important industrial reactions, particularly the electrochemical synthesis of hydrogen peroxide (H2O2) through the two-electron oxygen reduction reaction (ORR). Within this field, the metal atom-support interaction (MASI) assumes a decisive role, profoundly influencing the catalytic activity and selectivity exhibited by SACs, and triggers a decade-long surge dedicated to unraveling the modulation of MASI as a means to enhance the catalytic performance of SACs. In this comprehensive review, we present a systematic summary and categorization of recent advancements pertaining to MASI modulation for achieving efficient electrochemical H2O2 synthesis. We start by introducing the fundamental concept of the MASI, followed by a detailed and comprehensive analysis of the correlation between the MASI and catalytic performance. We describe how this knowledge can be harnessed to design SACs with optimized MASI to increase the efficiency of H2O2 electrosynthesis. Finally, we distill the challenges that lay ahead in this field and provide a forward-looking perspective on the future research directions that can be pursued.

An Efficient Electrochemical Sensing of Hydrogen Peroxide on Zn-Based Coordination Polymer Decorated Carbon Paste Electrode

Due to the important role of hydrogen peroxide (H2O2) in biological systems and its wide range of practical applications, the development of efficient electrochemical H2O2 sensors has become a highly attractive research area. Herein, we reports the synthesis and fabrication of zinc-based coordination polymer [Zn(bim)(L1)(Cl)]n (CP-a): [bim = 1-benzylimidazole, L1 = terephthalic acid] on modified carbon paste electrode (CP-a/CPE) for the electrochemical detection of H2O2. The surface morphology of CP-a/CPE was confirmed by field emission scanning electron microscopy. Electrochemical sensing features were evaluated by cyclic voltammetry and chrono-amperometry. The linear range at the potential of −0.5 V based on CP-a/CPE for H2O2 was 0.001 mM–60 mM, with a low detection limit (LOD) of 0.0004 mM. The effect of interfering species on the reduction peak current response shows a minor change of signals (>5%). The as-synthesized CP-a/CPE sensor exhibited efficient reproducibility and stability. The electrocatalytic activity and good performance imply that the metal-based coordination polymers are potential candidates for fabricating electrochemical sensors.

Selective electrochemical H2O2 production by a molecular copper catalyst: A crucial relation between reaction rate and mass transport

Selective electrochemical H2O2 production by a molecular copper catalyst: A crucial relation between reaction rate and mass transport

Monodispersed Au nanoparticles decorated MoS2 nanosheets with enhanced peroxidase-like activity based electrochemical H2O2 sensing for anticancer drug evaluations

BackgroundThe unique size, physical and chemical properties, and ultra-high stability of nanozymes have attracted extensive attentions in sensing, but improvement of catalytic activity of the nanozymes is still an urgent issue. Given the ultra-high simulated enzyme activity of metal nanoparticles and the advantage of multi-enzyme catalysis, an Au-decorated MoS2 nanosheets (MoS2/Au NS) integrating the double peroxidase-like (POD) activity is developed. ResultsBy optimizing and adjusting the density of AuNPs, as well as its morphology and other parameters, a monodisperse and high-density distribution of AuNPs on MoS2 nanosheets was obtained, which can greatly improve the POD-like activity of MoS2/Au NS. Nafion solution was applied to assist the modification of MoS2/Au NS on the electrode surface so as to improved its stability. An electrochemical H2O2 detection platform was constructed by modifying MoS2/Au NS nanozyme on the SPCE using the conductive Nafion solution. And the negatively charged sulfonic acid group can eliminate negatively charged electroactive substances to improve the specificity. Then ascorbic acid was used to stimulate tumor cells to produce H2O2 as therapeutic model, an ultrasensitive chronocoulometry detection for H2O2 in cell lysate was established. The logarithmically of ΔQ and the logarithmically of H2O2 concentration showed a good linear relationship between 1 μM and 500 mM, with a LOD value of 0.3 μM. SignificanceThe developed H2O2 sensor has excellent stability, reproducibility (RSD = 2.3 %, n = 6) and selectivity, realized the quantitative detection of H2O2 in cell lysate. Compared with commercial fluorescence detection kits for H2O2 in cell lysate, it is worth mentioning that the electrochemical H2O2 sensor developed in this study is simpler and faster, with higher sensitivity and lower cost. This provides a potential substitute for disease diagnosis and treatment evaluation based on accurate detection of H2O2.

Bioinspired Tetranuclear Manganese Cubane Complex as an Efficient Molecular Electrocatalyst for Two‐Electron Water Oxidation Towards Hydrogen Peroxide

AbstractStable homogeneous two‐electron water oxidation electrocatalysts are highly demanded to understand the precise mechanism and reaction intermediates of electrochemical H2O2 production. Here we report a tetranuclear manganese complex with a cubane structure which can electrocatalyze water oxidation to hydrogen peroxide under alkaline and neutral conditions. Such a complex demonstrates an optimal Faradaic efficiency (FE) of 87 %, which is amongst (if not) the highest FE(H2O2) of reported homogeneous and heterogeneous electrocatalysts. In addition, active species were identified and co‐catalysts were excluded through ESI‐MS characterization. Furthermore, we identified water binding sites and isolated one‐electron oxidation intermediate by chemical oxidation of the catalyst in the presence of water substrates. It is evident that efficient proton‐accepting electrolytes avoid rapid proton building‐up at electrode and substantially improve reaction rate and selectivity. Accordingly, we propose a two‐electron catalytic cycle model for water oxidation to hydrogen peroxide with the bioinspired molecular electrocatalyst. The present work is expected to provide an ideal platform to elucidate the two‐electron WOR mechanism at the atomic level.

Bioinspired Tetranuclear Manganese Cubane Complex as an Efficient Molecular Electrocatalyst for Two-Electron Water Oxidation Towards Hydrogen Peroxide.

Stable homogeneous two-electron water oxidation electrocatalysts are highly demanded to understand the precise mechanism and reaction intermediates of electrochemical H2O2 production. Here we report a tetranuclear manganese complex with a cubane structure which can electrocatalyze water oxidation to hydrogen peroxide under alkaline and neutral conditions. Such a complex demonstrates an optimal Faradaic efficiency (FE) of 87 %, which is amongst (if not) the highest FE(H2O2) of reported homogeneous and heterogeneous electrocatalysts. In addition, active species were identified and co-catalysts were excluded through ESI-MS characterization. Furthermore, we identified water binding sites and isolated one-electron oxidation intermediate by chemical oxidation of the catalyst in the presence of water substrates. It is evident that efficient proton-accepting electrolytes avoid rapid proton building-up at electrode and substantially improve reaction rate and selectivity. Accordingly, we propose a two-electron catalytic cycle model for water oxidation to hydrogen peroxide with the bioinspired molecular electrocatalyst. The present work is expected to provide an ideal platform to elucidate the two-electron WOR mechanism at the atomic level.

Enhanced electroproduction of hydrogen peroxide with oxidized boron-doped carbon catalysts synthesized from gaseous CO2

As an eco-friendly alternative to the conventional anthraquinone process, electrochemical production of hydrogen peroxide (H2O2) through the oxygen reduction reaction has been attracting attention. The goal of this work is to derive a carbon-based material from carbon dioxide (CO2) to achieve high performance in electrochemical H2O2 production. Doping heterogeneous element such as oxygen on a carbon catalyst has been mainly explored to increase the selectivity and activity, but little research has been conducted on enhancing catalytic activity with oxidized boron insertion. This study proposes porous carbon materials synthesized from CO2 as electrocatalysts. Polyethylene oxide (PEO) was thermally treated together to increase the boron-oxygen bonding sites. As a result, the synthesized carbon materials having oxidized boron functional groups of BC2O and BCO2 showed high activity (1.25 mA cm−2) and selectivity (∼90 %) over a wide voltage range in two-electron ORR (Oxygen Reduction Reaction) at alkaline media. Furthermore, in an H-cell where 0.4 V vs. RHE was applied, the average H2O2 production rate was maintained at 452.96 mmol g−1 h−1 for four hours with a high faraday efficiency of 90 %.

A novel naturally aspirated cathode for efficient electrosynthesis of hydrogen peroxide and wastewater purification in electro-Fenton systems

Electrochemical synthesis of hydrogen peroxide (H2O2) has developed rapidly in recent years as an alternative process to the anthraquinone method. However, the low H2O2 production and high energy consumption limit its further application. In this study, we propose a simple method to fabricate a naturally aspirated cathode (NAC), which significantly reduces the mass transfer resistance of oxygen and achieves a high oxygen diffusion coefficient (7.11 × 10-6 m2 s−1) and oxygen utilization efficiency (39.6 %). Additionally, the NAC provides a high density of reaction sites to achieve efficient production of H2O2 (0–84.33 mg h−1 cm−2) at near industrial current densities (0–240 mA cm−2) without external aeration. Meanwhile, the prepared NAC can degrade over 97.5 % of dyes within 10 min during the electro-Fenton process. The NAC exhibits excellent H2O2 production performance and great stability during long-term operation, which offers huge potential for industrial-scale electrochemical H2O2 production and the advanced oxidation processes (AOP) derived from it.

A Non‐Enzymatic Electrochemical Sensor Based on Cerium Oxide Nanocubes for the Rapid Detection of Hydrogen Peroxide Residues in Food Samples†

The rapid and simple detection methods of hydrogen peroxide (H2O2) residues is highly required for food safety. Herein, an electrochemical H2O2 sensor is developed with cerium oxide nanocubes as highly active non‐enzymatic catalyst. Combined with carbon black to improve conductivity, the disposable sensor can determine H2O2 in the range from 100 to 100 μM with a limit of detection (LOD) of 100 nM. This sensor also shows good selectivity and reproducibility, which is enabled to detect H2O2 in real food samples without any pretreatment in 100 s, providing a new solution for the direct quantitative measurement of H2O2 residues for food safety. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Flexible Co-Ni nanocomposites in situ synthesized on carbon fibers for highly sensitive electrochemical detection of H2O2

In this study, Co-Ni nanomaterials were in situ synthesized on carbon fiber paper substrates, termed Co-Ni paper. Scanning electron microscopy characterization demonstrates fabricated flake-like Co-Ni nanocomposites uniformly distribute on carbon fibers, forming three-dimensional continuous network structure. The fabricated sample is determined to be a mixture of Co, Ni and C elements according to energy-dispersive X-ray spectrometer analysis. Without any pretreatments, Co-Ni paper exhibits excellent electro-oxidation capabilities towards H2O2, such as an excellent detecting performance in a wide linear range of 0‒11.5 mM of H2O2, fast amperometric responses within 1 s, and a low detection limit of 2.53 µM. Along with these intriguing properties, the in situ-synthesized Co-Ni paper has a good anti-interference towards Na2SO4, ZnCl2, glucose and NaCl during H2O2 detection. Moreover, the H2O2 electro-chemical sensor on Co-Ni paper also possesses excellent reproducibility, long-term stability and high mechanical stability. This Co-Ni-paper-based sensor is effective to determine H2O2 in blood samples, thus it is promising for electrochemical H2O2 sensing.

TCE degradation of modified graphite felt cathode in a flow-through electro-Fenton system and its H2O2 production ability in a real contaminated field

A modified graphite felt (MGF) was prepared with carbon black (CB) and polytetrafluoron (PTFE) for cathodic electrochemical H2O2 production, which was used in a flow-through cathodic electro-Fenton reactor to degrade chlorinated hydrocarbons. Cathode electrode was floating on aqueous surface and 369.1 mg/L H2O2 could be produced after 1 h 150 mA power applied without O2 aeration. The main O2 source for H2O2 production was confirmed from air with this floating position. In a 2.0 L flow-through cathodic electro-Fenton system, 95.97 % degradation efficiency for 5.0 mg/L trichloroethylene (TCE) was achieved in 90 min with 13.4 mL/min influent rate. Reducing the reactor volume to 0.14 L, 5.0 mg/L TCE could be degraded completely in 10 min with continuous 4 L influent. The mixed chlorinated hydrocarbons (TCE, cis-1,1-dichloroethylene, 1,2-dichloroethane, and dichloromethane) were also rapidly degraded in 20 min. The flow-through cathodic electro-Fenton reactor presented excellent degradation ability for chlorinated hydrocarbons with a smaller volume. In the simulated sand tank system, after continuously operated 27 days, H2O2 concentration in electrode well was still remained at 80 mg/L. In the contaminated field in Tianjin, China, H2O2 yield of MGF in groundwater could keep at about 60 mg/L after 220 min operating.