Electrochemical Synthesis Of Hydrogen Peroxide Research Articles

Effects of porous structure and oxygen functionalities on electrochemical synthesis of hydrogen peroxide on ordered mesoporous carbon

Two-electron oxygen reduction reaction (2e− ORR) is a promising alternative to energy-intensive anthraquinone process for hydrogen peroxide (H2O2) production. Metal-free nanocarbon materials have garnered intensive attention as highly prospective electrocatalysts for H2O2 production, and an in-depth understanding of their porous structure and active sites have become a critical scientific challenge. The present research investigates a range of porous carbon catalysts, including non-porous, microporous, and mesoporous structures, to elucidate the impacts of porous structures on 2e− ORR activity. The results highlighted the superiority of mesoporous carbon over other porous materials, demonstrating remarkable H2O2 selectivity. Furthermore, integration of X-ray photoelectron spectroscopy (XPS) data analysis with electrochemical assessment results unravels the moderate surface oxygen content is the key to increase 2e− ORR activity. These results not only highlight the intricate interplay between pore structure and oxygen content in determining catalytic selectivity, but also enable the design of carbon catalysts for specific electrochemical reactions.

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.

S, N, and O tri-doped graphite nanosheets-based gas diffusion electrode boosts highly selective electrosynthesis of H2O2

Electrochemical synthesis of hydrogen peroxide (H2O2) via oxygen reduction reaction (ORR) is a promising environmentally friendly approach for on-site production of H2O2. The development of economically feasible cathodes with high activity and selectivity is of utmost importance to enable the large-scale application of the process of H2O2 electrosynthesis. Herein, a novel electrocatalyst of sulfur, nitrogen, and oxygen tri-doped graphite nanosheets (SNOGNSs) was developed, which exhibited the selectivity of up to 97.4 % for the electrosynthesis of H2O2, significantly higher than that of flake graphite (FG, 51.4 %), OGNSs (72.8 %) and NOGNSs (90.9 %). The gas diffusion electrode (GDE) was fabricated using SNOGNSs as catalysts, and the accumulation of H2O2 reached 732.8–1044.4 mg/Lh−1 at 0.3–0.5 A electrolytic current. The mechanism of the synergistic enhancement of two-electron ORR by S, N, and O tri-doping was revealed utilizing density functional theory (DFT) calculations. This work offers a suitable alternative for on-site clean production of H2O2 that can be applied in electrochemical advanced oxidation processes.

New and Revised Aspects of the Electrochemical Synthesis of Hydrogen Peroxide: From Model Electrocatalytic Systems to Scalable Materials

New and Revised Aspects of the Electrochemical Synthesis of Hydrogen Peroxide: From Model Electrocatalytic Systems to Scalable Materials

B, S co-doped mesoporous carbon as an efficient catalyst for H2O2 electrosynthesis in natural seawater

The small-scale electrochemical synthesis of hydrogen peroxide (H2O2) in marine environments is of great significance for environmental wastewater treatment, and the design of electrocatalysts for complicated marine conditions is the key for this technology. Although B-doped carbon materials have been demonstrated to be resistant to Cl− poisoning, the deposition of Ca2+ on the surface of catalyst in seawater and the sluggish reaction kinetics of non-metallic catalysts remain to be solved. Herein, B, S co-doped mesoporous carbon materials were synthesized by a simple NaCl template method. The H2O2 yield of the as-prepared sample was up to 3.66 mol/(gcat h) with a Faradaic Efficiency (FE) of 97.98 % at 100 mA/cm2 in natural seawater, and achieved 100 % inactivation of bacteria and Chlorella within 5 min at a low current density. Based on the structural characterization and electrochemical results, the S-containing structure on the carbon matrix suppresses Ca2+ deposition due to its excellent proton adsorption activity. Furthermore, the electron transfer process between the reactant and BC3 was enhanced by the abundant mesoporous structure, so as to optimize the sluggish oxygen reduction reaction (ORR) kinetics on BC3. This work offers a strategy for inactivation of marine microorganisms and the degradation of organic pollutants, which promotes the advancement of marine wastewater treatment technology, and also provides reference for the design of metal free catalysts used in marine environments.

Ni-doped sites in yeast-derived catalysts for efficient electrochemical synthesis of hydrogen peroxide

The electrochemical synthesis of hydrogen peroxide (H2O2) via the 2-electron pathway of oxygen reduction reaction offers a green and on-site product. However, there remains an urgent need to develop cost-efficient electrocatalysts with H2O2 productivity that meets practical industrial-scale requirements. In this study, yeast-derived carbon material loaded with multiple Ni active sites achieved electrochemical synthesis of H2O2 at industrial current density. The precursor of heteroatom-doped carbon material was obtained through high-dispersed Ni(II) adsorption on yeast cells. By adjusting the pyrolysis temperature and Ni loading dosage, the carbon framework, pore structure, and Ni active sites within the obtained Ni/yeast were successfully regulated. Ni/yeast featured with highly active Ni single-atom sites, metallic Ni nanoparticles and Ni2P nanoparticles, enabling stable running for 10 h at 200 mA cm−2 in a flow cell. Ni/yeast exhibits remarkable H2O2 Faradaic efficiency of 94.6 % and a yield of 35.3 mol gcat−1h−1. The abundant pore structure and multiple Ni active sites within Ni/yeast provide promising avenues for manipulating heteroatom-doped carbon materials in H2O2 electrosynthesis.

Coordination engineering regulating metal single-atom anchored on n-doped carbon as a bifunctional catalyst for H2O2 production via dual channels

Electrochemical synthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e- ORR) or two-electron water oxidation reaction (2e- WOR), parades great prospects in substituting traditional anthraquinone process. However, the low efficiency and selectivity hinders its practical utilization. Exploration of a bifunctional catalyst capable of simultaneously driving the 2e- WOR and 2e- ORR is crucial for thoroughly improving H2O2 conversion efficiency. Herein, by means of first principles calculation, the 2e- ORR and 2e- WOR activities of metal-nitrogen doped carbon (M−NC, M = Mn, Fe, Co, Ni, Ru, In, and Pt) are investigated. Combining the pyrrole nitrogen coordination regulation, the best sample (RuN(Po)4) is screened from forty single atom configurations, which exhibits ultra-low overpotentials (0.02 V/0.04 V) and excellent inhibition on 4e- ORR/WOR side reactions. In-depth study further verifies its low reaction energy barrier and high thermodynamic stability for H2O2 synthesis in two pathways. Our work is expected to provide useful understanding for designing highly-efficient bifunctional catalysts for H2O2 production.

Perspectives on Carbon-Based Catalysts for the Two-Electron Oxygen Reduction Reaction for Electrochemical Synthesis of Hydrogen Peroxide: A Minireview

Perspectives on Carbon-Based Catalysts for the Two-Electron Oxygen Reduction Reaction for Electrochemical Synthesis of Hydrogen Peroxide: A Minireview

Platinum Single-Atom catalysts confined in NH2-UIO-66 for highly selective oxygen reduction reaction

The electrochemical synthesis of hydrogen peroxide via the two-electron oxygen reduction reaction (2e–ORR) offers a green and environment-friendly production method. Here, Pt single-atom catalyst confined in NH2-UIO-66 was successfully prepared by glow discharge plasma at room temperature, and it was used for the 2e–ORR. The plasma treated sample exhibited a high H2O2 selectivity of 99.86%, surpassing that of the samples prepared by calcination and chemical reduction methods. NH2-UIO-66 inhibits the growth of Pt particles and improves Pt dispersion. Plasma prevents Pt aggregation due to the low temperature and enhances the interaction between Pt and NH2-UIO-66 which leads to an outstanding electrocatalytic ORR. This work provides strategies towards single-atom catalysts through the confinement of metal–organic frameworks for electrocatalysis.

Mimicking Metalloenzyme Microenvironments in the Transition Metal-Single Atom Catalysts for Electrochemical Hydrogen Peroxide Synthesis in an Acidic Medium.

Electrochemical reduction of oxygen into hydrogen peroxide in an acidic medium offers an energy-efficient and green H2 O2 synthesis as an alternative to the energy-intensive anthraquinone process. Unfortunately, high overpotential, low production rates, and fierce competition from traditional four-electron reduction limit it. In this study, a metalloenzyme-like active structure is mimicked in carbon-based single-atom electrocatalysts for oxygen reduction to H2 O2 . Using a carbonization strategy, the primary electronic structure of the metal center with nitrogen and oxygen coordination is modulated, followed by epoxy oxygen functionalities close to the metal active sites. In an acidic medium, CoNOC active structures proceed with greater than 98% H2 O2 selectivity (2e- /2H+ ) rather than CoNC active sites that are selective to H2 O (4e- /4H+ ). Among all MNOC (M=Fe, Co, Mn, and Ni) single-atom electrocatalysts, the CoNOC is the most selective (> 98%) for H2 O2 production, with a mass activity of 10Ag-1 at 0.60V vs. RHE. X-ray absorption spectroscopy is used to identify the formation of unsymmetrical MNOC active structures. Experimental results are also compared to density functional theory calculations, which revealed that the structure-activity relationship of the epoxy-surrounded CoNOC active structure reaches optimum (ΔG*OOH ) binding energies for high selectivity.

Coherent Sub-Nanometer Interface between Crystalline and Amorphous Materials Boosts Electrochemical Synthesis of Hydrogen Peroxide.

There are enormous yet largely underexplored exotic phenomena and properties emerging from interfaces constructed by diverse types of components that may differ in composition, shape, or crystal structure. It remains poorly understood the unique properties a coherent interface between crystalline and amorphous materials may evoke, and there lacks a general strategy to fabricate such interfaces. It is demonstrated that by topotactic partial oxidation heterostructures composed of coherently registered crystalline and amorphous materials can be constructed. As a proof-of-concept study, heterostructures consisting of crystalline P3 N5 and amorphous P3 N5 Ox can be synthesized by creating amorphous P3 N5 Ox from crystalline P3 N5 without interrupting the covalent bonding across the coherent interface. The heterostructure is dictated by nanometer-sized short-range-ordered P3 N5 domains enclosed by amorphous P3 N5 Ox matrix, which entails simultaneously fast charge transfer across the interface and bicomponent synergistic effect in catalysis. Such a P3 N5 /P3 N5 Ox heterostructure attains an optimal adsorption energy for *OOH intermediates and exhibits superior electrocatalytic performance toward H2 O2 production by adopting a selectivity of 96.68% at 0.4 VRHE and a production rate of 321.5 mmol h-1 gcatalyst -1 at -0.3 VRHE . The current study provides new insights into the synthetic strategy, chemical structure, and catalytic property of a sub-nanometer coherent interface formed between crystalline and amorphous materials.

Electrosynthesis of Hydrogen Peroxide through Selective Oxygen Reduction: A Carbon Innovation from Active Site Engineering to Device Design.

Electrochemical synthesis of hydrogen peroxide (H2 O2 ) through the selective oxygen reduction reaction (ORR) offers a promising alternative to the energy-intensive anthraquinone method, while its success relies largely on the development of efficient electrocatalyst. Currently, carbon-based materials (CMs) are the most widely studied electrocatalysts for electrosynthesis of H2 O2 via ORR due to their low cost, earth abundance, and tunable catalytic properties. To achieve a high 2e- ORR selectivity, great progress is made in promoting the performance of carbon-based electrocatalysts and unveiling their underlying catalytic mechanisms. Here, a comprehensive review in the field is presented by summarizing the recent advances in CMs for H2 O2 production, focusing on the design, fabrication, and mechanism investigations over the catalytic active moieties, where an enhancement effect of defect engineering or heteroatom doping on H2 O2 selectivity is discussed thoroughly. Particularly, the influence of functional groups on CMs for a 2e- -pathway is highlighted. Further, for commercial perspectives, the significance of reactor design for decentralized H2 O2 production is emphasized, bridging the gap between intrinsic catalytic properties and apparent productivity in electrochemical devices. Finally, major challenges and opportunities for the practical electrosynthesis of H2 O2 and future research directions are proposed.

Spectroscopic Identification of Active Sites of Oxygen-Doped Carbon for Selective Oxygen Reduction to Hydrogen Peroxide.

The electrochemical synthesis of hydrogen peroxide (H2 O2 ) via a two-electron (2 e- ) oxygen reduction reaction (ORR) process provides a promising alternative to replace the energy-intensive anthraquinone process. Herein, we develop a facile template-protected strategy to synthesize a highly active quinone-rich porous carbon catalyst for H2 O2 electrochemical production. The optimized PCC900 material exhibits remarkable activity and selectivity, of which the onset potential reaches 0.83 V vs. reversible hydrogen electrode in 0.1 M KOH and the H2 O2 selectivity is over 95 % in a wide potential range. Comprehensive synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy combined with electrocatalytic characterizations reveals the positive correlation between quinone content and 2 e- ORR performance. The effectiveness of chair-form quinone groups as the most efficient active sites is highlighted by the molecule-mimic strategy and theoretical analysis.

Spectroscopic Identification of Active Sites of Oxygen‐Doped Carbon for Selective Oxygen Reduction to Hydrogen Peroxide

AbstractThe electrochemical synthesis of hydrogen peroxide (H2O2) via a two‐electron (2 e−) oxygen reduction reaction (ORR) process provides a promising alternative to replace the energy‐intensive anthraquinone process. Herein, we develop a facile template‐protected strategy to synthesize a highly active quinone‐rich porous carbon catalyst for H2O2 electrochemical production. The optimized PCC900 material exhibits remarkable activity and selectivity, of which the onset potential reaches 0.83 V vs. reversible hydrogen electrode in 0.1 M KOH and the H2O2 selectivity is over 95 % in a wide potential range. Comprehensive synchrotron‐based near‐edge X‐ray absorption fine structure (NEXAFS) spectroscopy combined with electrocatalytic characterizations reveals the positive correlation between quinone content and 2 e− ORR performance. The effectiveness of chair‐form quinone groups as the most efficient active sites is highlighted by the molecule‐mimic strategy and theoretical analysis.

Urotropine-triggered multi-reactive sites in carbon nanotubes towards efficient electrochemical hydrogen peroxide synthesis

The production of hydrogen peroxide (H2O2) by electrochemical oxygen reduction is a clean and convenient route. Here, we develop a universal urotropine (hexamethylenetetramine) modified carbon-based catalyst strategy. Both experimental results and theoretical calculations proved that the introduction of urotropine not only provides the isolating O2 active sites to protect OOH* from being further split, but also excites carbon nanotube matrix to produce rich secondary O2 active sites. More importantly, the end-on type of adsorption of O2 on excited secondary reactive sites can be stabilized by the hydrogen bond effect, which greatly increases the productivity of H2O2. As a result, the urotropine (hexamethylenetetramine) modified commercial carbon nanotubes (denoted as H-CNTs) catalyst achieved 95% selectivity and 748 mmol·gcatalyst·h−1 yield of H2O2 at 0.7 V vs. RHE. Therefore, this work provides a highly potential urotropine modification strategy towards efficient electrochemical H2O2 synthesis.

Electrochemical synthesis of hydrogen peroxide on BiNiOx−4 and in situ disinfection

The BiNiOx−4 catalyst prepared by sol–gel method has high selectivity for electrocatalytic production of H2O2 (93.2% at 0.4 VRHE), as well as a yield of 223 mmol L−1 in 2 h, and favourable bactericidal effect. The mechanism involved was demonstrated by DFT calculations.

Efficient and durable electrochemical oxygen reduction to H2O2 in acidic media assisted through catalyst layer design

Electrochemical synthesis of hydrogen peroxide (H2O2) through 2-electron oxygen reduction reaction (ORR) is a sustainable alternative to the industrialized anthraquinone oxidation process. Gas-diffusion electrode (GDE) is employed to overcome the mass transport limitation of O2 to deliver high current density. However, long-term stability in practical electrolyzer with GDE is still challenging due to electrode flooding. Here, we propose a double catalyst layer (CL) strategy with gradient Nafion distribution to balance the mass transport of O2 and H+ and improve the flood-proof ability. Our design achieved H2O2 production rate up to 2.16 mmol h−1 cm−2 with a selectivity of about 90% and enabled 48 h stable electrolysis at 100 mA cm−2. Compared to the state-of-the-art H2O2 electrosynthesis system in acidic media, the full-cell voltage improved significantly to 2.3 V at 100 mA cm−2, indicating its potential for practical production and utilization.

Electrochemical Synthesis of Hydrogen Peroxide Catalyzed by Carbon Nanotubes with Surface Co-NX Sites and Encapsulated Co Nanoparticles.

The exploitation of M-NX sites, where M is a transition metal atom, is widely regarded as an effective catalytic strategy to promote the oxygen reduction reaction (ORR). In addition, some studies have shown that transition metal nanoparticles (M-NPs) coated with carbon layers can improve the reactivity of ORR and ameliorate the overpotential of the reaction. In this study, we synthesized carbon nanotubes with single-atom Co-NX active sites, Co-NPs outside the tube, and Co-NPs wrapped in the tube by the complexation-pyrolysis synthesis method and explored the role of the particles and Co-NX sites through different pickling steps. The catalyst synthesized with the new stratagem in this study shows outstanding selectivity and also ORR activity. Furthermore, a natural air diffusion electrode fabricated using this material can produce H2O2 at 323 mg L-1 h-1 under neutral conditions without oxygen aeration.

Water Oxidation to Hydrogen Peroxide on Carbonaceous Materials

Hydrogen peroxide (H2O2) is one of the most important chemicals used in the chemical industry. It has been widely utilized in pulp and paper manufacturing, chemical synthesis, wastewater management, and disinfection.1 The primary industrial approach to producing H2O2 is via the fossil-based anthraquinone process - an energy-demanding multi-step process requiring high-cost catalysts and generating substantial volumes of waste. Another route to the classic anthraquinone process is the electrochemical production of H2O2 from oxygen (O2) and water (H2O). This electrochemical route based on renewable energy is an appealing “green” alternative.Our research group has been extensively working on the electrochemical production of H2O2 through anodic water oxidation using various electrode materials, including metal oxides, commercial carbon materials, and boron-doped diamond (BDD). Besides the electrode material, a suitable electrolyte is equally essential to achieve high H2O2 concentrations and production rates. The role of carbonate ions (HCO3 - and CO3 2-) for producing H2O2 has been investigated using commercial carbon fiber paper (CFP). The electrolyte pH was correlated with the activity of CO3 2- ions in enhancing H2O2 production. Thereby, a cyclic mechanism of H2O2 generation involving the oxidation of CO3 2- ions to peroxodicarbonate (C2O6 2-) species has been proposed.2 The role of the CO3 2- ions in enhancing the anodic H2O2 production was further studied in a continuous flow reactor using BDD anodes. The flow rate and setup configuration for 2e- water oxidation to H2O2 have been optimized at current densities up to 700 mA cm-2, with an impressive H2O2 production rate and faradaic efficiency. Additionally, the role of a chemical stabilizer in avoiding the H2O2 decomposition in the flow system has been addressed. The importance of electrolyte composition, pH, operating parameters, and cell setup to enhance the production of H2O2 at the anode was shown. Finally, outstanding H2O2 yields were obtained in continuous flow for at least 30 hours. References Perry, S. C.; Pangotra, D.; Vieira, L.; Csepei, L.-I.; Sieber, V.; Wang, L.; Ponce de León, C.; Walsh, F. C., Electrochemical synthesis of hydrogen peroxide from water and oxygen. Nat. Rev. Chem. 2019, 3 (7), 442-458.Pangotra, D.; Csepei, L.-I.; Roth, A.; Ponce de León, C.; Sieber, V.; Vieira, L., Anodic production of hydrogen peroxide using commercial carbon materials. Appl. Catal. B Environ. 2022, 303, 120848.

Charge state modulation on boron site by carbon and nitrogen localized bonding microenvironment for two-electron electrocatalytic H2O2 production

Design of electrochemical active boron (B) site at solid materials to understand the relationships between the localized structure, charge state at the B site and electrocatalytic activity plays a crucial role in boosting the green electrochemical synthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction (2eORR) pathway. Herein, we demonstrate a carbon (C) and nitrogen (N) localized bonding microenvironment to modulate the charge state of B site at the boron-carbon nitride solid (BCNs) to realize the efficient selective electrocatalytic H2O2 production. The localized chemical structure of N-B-N, N-B-C and C-B-C bonds at B site can be regulated through solid-state reaction between boron nitride (BN) and porous carbon (C) at variable temperatures. The optimized BCN-1100 achieves an outstanding H2O2 selectivity of 89% and electron transfer number of 2.2 (at 0.55 V vs. RHE), with the production of 10.55 mmol/L during 2.5 h and the catalytic stability duration for 15000 cycles. Further first-principles calculations identified the dependency of localized bonding microenvironment on the OOH* adsorption energies and relevant charge states at the boron site. The localized structure of B site with BNC2-Gr configuration is predicted to be the highest 2eORR activity.