Electrosynthesis Of Hydrogen Peroxide Research Articles

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.

Bifunctional Oxygen-Defect Bismuth Catalyst toward Concerted Production of H2O2 with over 150% Cell Faradaic Efficiency in Continuously Flowing Paired-Electrosynthesis System.

The electrosynthesis of hydrogen peroxide (H2O2) from O2 or H2O via the two-electron (2e-) oxygen reduction (2e- ORR) or water oxidation (2e- WOR) reaction provides a green and sustainable alternative to the traditional anthraquinone process. Herein, a paired-electrosynthesis tactic is reported for concerted H2O2 production at a high rate by coupling the 2e- ORR and 2e- WOR, in which the bifunctional oxygen-vacancy-enriched Bi2O3 nanorods (Ov-Bi2O3-EO), obtained through electrochemically oxidative reconstruction of Bi-based metal-organic framework (Bi-MOF) nanorod precursor, are used as both efficient anodic and cathodic electrocatalysts, achieving concurrent H2O2 production at both electrodes with high Faradaic efficiencies. Specifically, the coupled 2e- ORR//2e- WOR electrolysis system based on such distinctive oxygen-defect Bi catalyst displays excellent performance for the paired-electrosynthesis of H2O2, delivering a remarkable cell Faradaic efficiency of 154.8% and an ultrahigh H2O2 production rate of 4.3 mmol h-1 cm-2. Experiments combined with theoretical analysis reveal the crucial role of oxygen vacancies in optimizing the adsorption of intermediates associated with the selective two-electron reaction pathways, thereby improving the activity and selectivity of the 2e- reaction processes at both electrodes. This work establishes a new paradigm for developing advanced electrocatalysts and designing novel paired-electrolysis systems for scalable and sustainable H2O2 electrosynthesis.

A Generalized Coordination Engineering Strategy for Single-Atom Catalysts toward Efficient Hydrogen Peroxide Electrosynthesis.

Designing non-noble metal single-atom catalysts (M-SACs) for two-electron oxygen reduction reaction (2e-ORR) is attractive for the hydrogen peroxide (H2O2) electrosynthesis, in which the coordination configuration of the M-SACs essentially affects the reaction activity and product selectivity. Though extensively investigated, a generalized coordination engineering strategy has not yet been proposed, which fundamentally hinders the rational design of M-SACs with optimized catalytic capabilities. Herein, a generalized coordination engineering strategy is proposed for M-SACs toward H2O2 electrosynthesis via introducing heteroatoms (e.g., oxygen or sulfur atoms) with higher or lower electronegativity than nitrogen atoms into the first sphere of metal-N4 system to tailor their electronic structure and adjust the adsorption strength for *OOH intermediates, respectively, thus optimizing their electrocatalytic capability for 2e-ORR. Specifically, the (O, N)-coordinated Co SAC (Co-N3O) and (S, N)-coordinated Ni SAC (Ni-N3S) are precisely synthesized, and both present superior 2e-ORR activity (Eonset: ≈0.80V versus RHE) and selectivity (≈90%) in alkaline conditions compared with conventional Co-N4 and Ni-N4 sites. The high H2O2 yield rates of 14.2 and 17.5moLg-1h-1 and long-term stability over 12h are respectively achieved for Co-N3O and Ni-N3S. Such favorable 2e-ORR pathway of the catalysts is also theoretically confirmed by the kinetics simulations.

Efficient Neutral H2O2 Electrosynthesis from Favorable Reaction Microenvironments via Porous Carbon Carrier Engineering

AbstractThe efficient electrosynthesis of hydrogen peroxide (H2O2) via two‐electron oxygen reduction reaction (2e− ORR) in neutral media is undoubtedly a practical route, but the limited comprehension of electrocatalysts has hindered the system advancement. Herein, we present the design of model catalysts comprising mesoporous carbon spheres‐supported Pd nanoparticles for H2O2 electrosynthesis at near‐zero overpotential with approximately 95 % selectivity in a neutral electrolyte. Impressively, the optimized Pd/MCS‐8 electrocatalyst in a flow cell device achieves an exceptional H2O2 yield of 15.77 mol gcatalyst−1 h−1, generating a neutral H2O2 solution with an accumulated concentration of 6.43 wt %, a level sufficiently high for medical disinfection. Finite element simulation and experimental results suggest that mesoporous carbon carriers promote O2 enrichment and localized pH elevation, establishing a favorable microenvironment for 2e− ORR in neutral media. Density functional theory calculations reveal that the robust interaction between Pd nanoparticles and the carbon carriers optimized the adsorption of OOH* at the carbon edge, ensuring high active 2e− process. These findings offer new insights into carbon‐loaded electrocatalysts for efficient 2e− ORR in neutral media, emphasizing the role of carrier engineering in constructing favorable microenvironments and synergizing active sites.

Regulation of eg orbital occupancy in Ni-based metal-organic frameworks for efficient hydrogen peroxide electrosynthesis

Subject to the binding strength between the cathode and the oxo-intermediates, the hydrogen peroxide (H2O2) electrosynthesis with high productivity and high selectivity in oxygen reduction reaction (ORR) cannot be achieved simultaneously. In this work, the dual-metal-organic frameworks (NiFe-MOFs) is designed and synthesized, in which the eg orbital occupancy of Ni nodes is regulated by the super-exchange effect of Ni(2+σ)+-O-Fe(3-σ)+ bond. As a result, the binding strength between the cathode and the oxo-intermediates (*O2, *OOH) is optimized, which efficiently promotes oxygen reduction kinetics and inhibits O-O bond breakage. The H2O2 yield of NiFe-MOFs cathode reaches 1.83mol·g-1·h-1 with a Faraday efficiency of 96.3% at 0.5V vs. RHE, which is far superior to Ni-MOFs (0.21mol·g-1·h-1, 65.4%), Fe-MOFs (0.65mol·g-1·h-1, 57.5%). This work offers a new strategy to design and develop cathodic catalysts for H2O2 electrosynthesis with high productivity and high selectivity.

Highly Efficient Acidic Electrosynthesis of Hydrogen Peroxide at Industrial-Level Current Densities Promoted by Alkali Metal Cations.

Acidic H2O2 synthesis through electrocatalytic 2e- oxygen reduction presents a sustainable alternative to the energy-intensive anthraquinone oxidation technology. Nevertheless, acidic H2O2 electrosynthesis suffers from low H2O2 Faradaic efficiencies primarily due to the competing reactions of 4e- oxygen reduction to H2O and hydrogen evolution in environments with high H+ concentrations. Here, we demonstrate the significant effect of alkali metal cations, acting as competing ions with H+, in promoting acidic H2O2 electrosynthesis at industrial-level currents, resulting in an effective current densities of 50-421 mA cm-2 with 84-100 % Faradaic efficiency and a production rate of 856-7842 μmol cm-2 h-1 that far exceeds the performance observed in pure acidic electrolytes or low-current electrolysis. Finite-element simulations indicate that high interfacial pH near the electrode surface formed at high currents is crucial for activating the promotional effect of K+. In situ attenuated total reflection Fourier transform infrared spectroscopy and ab initio molecular dynamics simulations reveal the central role of alkali metal cations in stabilizing the key *OOH intermediate to suppress 4e- oxygen reduction through interacting with coordinated H2O.

Highly Efficient Acidic Electrosynthesis of Hydrogen Peroxide at Industrial‐Level Current Densities Promoted by Alkali Metal Cations

AbstractAcidic H2O2 synthesis through electrocatalytic 2e− oxygen reduction presents a sustainable alternative to the energy‐intensive anthraquinone oxidation technology. Nevertheless, acidic H2O2 electrosynthesis suffers from low H2O2 Faradaic efficiencies primarily due to the competing reactions of 4e− oxygen reduction to H2O and hydrogen evolution in environments with high H+ concentrations. Here, we demonstrate the significant effect of alkali metal cations, acting as competing ions with H+, in promoting acidic H2O2 electrosynthesis at industrial‐level currents, resulting in an effective current densities of 50–421 mA cm−2 with 84–100 % Faradaic efficiency and a production rate of 856–7842 μmol cm−2 h−1 that far exceeds the performance observed in pure acidic electrolytes or low‐current electrolysis. Finite‐element simulations indicate that high interfacial pH near the electrode surface formed at high currents is crucial for activating the promotional effect of K+. In situ attenuated total reflection Fourier transform infrared spectroscopy and ab initio molecular dynamics simulations reveal the central role of alkali metal cations in stabilizing the key *OOH intermediate to suppress 4e− oxygen reduction through interacting with coordinated H2O.

Stable Pentagonal Layered Palladium Diselenide Enables Rapid Electrosynthesis of Hydrogen Peroxide.

Electrosynthesis of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e- ORR) is promising for various practical applications, such as wastewater treatment. However, few electrocatalysts are active and selective for 2e- ORR yet are also resistant to catalyst leaching under realistic operating conditions. Here, a joint experimental and computational study reveals active and stable 2e- ORR catalysis in neutral media over layered PdSe2 with a unique pentagonal puckered ring structure type. Computations predict active and selective 2e- ORR on the basal plane and edge of PdSe2, but with distinct kinetic behaviors. Electrochemical measurements of hydrothermally synthesized PdSe2 nanoplates show a higher 2e- ORR activity than other Pd-Se compounds (Pd4Se and Pd17Se15). PdSe2 on a gas diffusion electrode can rapidly accumulate H2O2 in buffered neutral solution under a high current density. The electrochemical stability of PdSe2 is further confirmed by long device operational stability, elemental analysis of the catalyst and electrolyte, and synchrotron X-ray absorption spectroscopy. This work establishes a new efficient and stable 2e- ORR catalyst at practical current densities and opens catalyst designs utilizing the unique layered pentagonal structure motif.

Enhanced hydrogen peroxide electrosynthesis and prolonged lifespan by preparing gas diffusion electrode via electrodeposition of CB on Ni foam

In-situ hydrogen peroxide (H2O2) production is pivotal for the effective implementation of the electro-Fenton reaction. However, challenges such as low H2O2 yields and a short electrode lifespan have hindered its application. This study introduced a novel gas diffusion electrode (GDE), the CB(E)-Ni foam(GDE), fabricated through a combination of carbon black (CB) electrodeposition and polytetrafluoroethylene (PTFE) impregnation techniques. Comprehensive physicochemical characterizations and electrochemical evaluations indicated that CB was more uniformly dispersed across the Ni foam, enhancing its electrochemical activity. When employed as a cathode, the CB(E)-Ni foam(GDE) demonstrated superior two-electron oxygen reduction reaction (2e− ORR) capabilities, marked by increased oxygen utilization and reduced energy demands, achieving a remarkable H2O2 concentration of 897.73 mg/L after 120 min. This performance significantly outpaces that of traditional GDEs. The unique structure of the CB(E)-Ni foam(GDE) not only prolonged electrode life by preventing rapid deactivation but also boosted H2O2 production and oxygen efficiency by 31.78% and 31.79%, respectively, when compared to a standard non-GDE configuration. In practical applications, the CB(E)-Ni foam(GDE) demonstrated utility by facilitating an 84.1% degradation rate of fulvic acid over 120 min within a homogeneous electro-Fenton system, highlighting its potential for environmental remediation.

Hydrogen peroxide electrosynthesis using commercial carbon blacks as catalysts: the influence of surface properties and adsorption performance

AbstractBACKGROUNDSurface properties and adsorption performance of carbon materials play a crucial role in the electrochemical two‐electron oxygen reduction to produce H2O2. However, there is still a lack of in‐depth research on commercial carbon blacks in this area. Herein, four typical commercial carbon blacks (Acetylene black (AB), Ketjen black EC 600JD, Vulcan XC 72 and Black Pearls 2000) were used as cathode catalysts to generate H2O2. Surface chemistry and pore structure of electrodes of the four carbon blacks were systematically characterized, and their effects on H2O2 adsorption, electrochemical generation and degradation were investigated.RESULTSAmong the four carbon blacks, AB has the highest content of C–O–C/COOH and CO, which are active groups catalyzing the two‐electron oxygen reduction reaction to generate H2O2. AB has the lowest level of defects and highest degree of graphitization, and AB‐modified graphite felt electrode (AB‐Ele) has the largest average pore diameter, smallest specific surface area and smaller charge transfer resistance. H2O2 production using AB‐Ele is the largest and reaches 567.7 mg L−1 at 180 min under a current density of 5 mA cm−2, and only decreases by 17.6% after 10 repeated uses.CONCLUSIONOverall, rich oxygen‐containing functional groups such as C–O–C, COOH and CO, high degree of graphitization, suitable surface area and porosity as well as weak H2O2 adsorption performance are beneficial for the two‐electron oxygen reduction reaction to generate H2O2. AB‐modified graphite felt electrode exhibits good catalytic activity and reusability in H2O2 electrosynthesis, demonstrating promising application prospects. © 2024 Society of Chemical Industry (SCI).

Low-Coordinated Conductive ZnCu Metal-Organic Frameworks for Highly Selective H2O2 Electrosynthesis.

Direct electrosynthesis of hydrogen peroxide (H2O2) with high production rate and high selectivity through the two-electron oxygen reduction reaction (2e-ORR) offers a sustainable alternative to the energy-intensive anthraquinone technology but remains a challenge. Herein, a low-coordinated, 2Dconductive Zn/Cu metal-organic framework supported on hollow nanocube structures (ZnCu-MOF (H)) is rationally designed and synthesized. The as-prepared ZnCu-MOF (H) catalyst exhibits substantially boosted electrocatalytic kinetics, enhanced H2O2 selectivity, and ultra-high Faradaic efficiency for 2e-ORR process in both alkaline and neutral conditions. Electrochemical measurements, operando/quasi in situ spectroscopy, and theoretical calculation demonstrate that the introduction of Cu atoms with low-coordinated structures induces the transformation of active sites, resulting in the beneficial electron transfer and the optimized energy barrier, thereby improving the electrocatalytic activity and selectivity.

Efficient Neutral H2O2 Electrosynthesis from Favorable Reaction Microenvironments via Porous Carbon Carrier Engineering.

The efficient electrosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e- ORR) in neutral media is undoubtedly a practical route, but the limited comprehension of electrocatalysts has hindered the system advancement. Herein, we present the design of model catalysts comprising mesoporous carbon spheres-supported Pd nanoparticles for H2O2 electrosynthesis at near-zero overpotential with approximately 95% selectivity in a neutral electrolyte. Impressively, the optimized Pd/MCS-8 electrocatalyst in a flow cell device achieves an exceptional H2O2 yield of 15.77 mol gcatalyst-1 h-1, generating a neutral H2O2 solution with an accumulated concentration of 6.43 wt.%, a level sufficiently high for medical disinfection. Finite element simulation and experimental results suggest that mesoporous carbon carriers promote O2 enrichment and localized pH elevation, establishing a favorable microenvironment for 2e- ORR in neutral media. Density functional theory calculations reveal that the robust interaction between Pd nanoparticles and the carbon carriers optimized the adsorption of OOH* at the carbon edge, ensuring high active 2e- process. These findings offer new insights into carbon-loaded electrocatalysts for efficient 2e- ORR in neutral media, emphasizing the role of carrier engineering in constructing favorable microenvironments and synergizing active sites.

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.

Interfaces Engineering of Ultrafine Ni@Ni2P/C Core-Shell Heterostructure for High Yield Hydrogen Peroxide Electrosynthesis.

Developing cost-effective and sustainable catalysts with exceptional activity and selectivity is essential for the practical implementation of on-site H2O2 electrosynthesis, yet it remains a formidable challenge. Metal phosphide core-shell heterostructures anchored in carbon nanosheets (denoted as Ni@Ni2P/C NSs) are designed and synthesized via carbonization and phosphidation of the 2D Ni-BDC precursor. This core-shell nanostructure provides more accessible active sites and enhanced durability, while the 2D carbon nanosheet substrate prevents heterostructure aggregation and facilitates mass transfer. Theoretical calculations further reveal that the Ni/Ni2P heterostructure-induced optimization of geometric and electronic structures enables the favored adsorption of OOH* intermediate. All these features endow the Ni@Ni2P/C NSs with remarkable performance in 2e ORR for H2O2 synthesis, achieving a top yield rate of 95.6mgL-1h-1 with both selectivity and Faradaic efficiency exceeding 90% under a wide range of applied potentials. Furthermore, when utilized as the anode of an assembled gas diffusion electrode (GDE) device, the Ni@Ni2P/C NSs achieve in situ H2O2 production with excellent long-term durability (>32h). Evidently, this work provides a unique insight into the origin of 2e ORR and proposes optimization of H2O2 production through nano-interface manipulation.

Sulfur poisoned PtNi/C catalysts toward two-electron oxygen reduction reaction for acidic electrosynthesis of hydrogen peroxide

Selective electrocatalysis of two-electron oxygen reduction reaction (2e– ORR) has been recognized as a sustainable and on-site process for hydrogen peroxide (H2O2) production. Great progress has been achieved for 2e– ORR in alkaline media. However, it is challenged by insufficient activity and selectivity of the catalysts in acidic electrolytes. Herein, we report sulfur-poisoned PtNi/C catalysts (PtNiSx/C) that could regulate ORR from the 4e– to 2e– pathway. The identified PtNiS0.6/C offers high activity in terms of onset potential of ∼0.69 V (vs. RHE) and ∼80 % selectivity. The mass activity is also comparable and outperforms representative Pt-based precious and transition-metal-based catalysts. In addition, it is interestingly found that the Faradaic efficiency further increased to 95 % during the long-term electrolysis test due to Ni atom surface migration. The electrochemical production of the H2O2 system was applied to the electro-Fenton process, which has realized the effective degradation of organic pollutants. This work offers a strategy by sulfur poisoning PtNi/C catalyst to realize Pt-based 2e– ORR active catalysts to electrolysis of H2O2 in acidic media.

Efficient Electrosynthesis of Hydrogen Peroxide Using Oxygen-Doped Porous Carbon Catalysts at Industrial Current Densities.

Metal-free carbon catalysts (MFCCs) are one of the commonly used catalysts for electrocatalytic two-electron oxygen reduction (2e- ORR) synthesis of hydrogen peroxide (H2O2). Oxygen doping is an effective means to improve the performance of MFCCs, but the performance of oxygen-doped carbon catalysts is still not high enough, and the contribution of different oxygen functional groups (OFGs) to the catalytic performance is still inconclusive. In this paper, carbon-based catalysts with different oxygen contents and ratios of OFGs were prepared, and the high 2e- ORR activity of COOH + C-OH was demonstrated by combining the results of experiments and theoretical calculations. The prepared oxygen-doped carbon-based catalyst C-0.1M80 achieved an onset potential of 0.795 V (vs RHE), a selectivity of up to 98.2% (0.6 V vs RHE), and a H2O2 oxidation current of 1.33 mA cm-2 (0.5 V vs RHE) in a rotating ring-disk electrode test (0.1 M KOH solution), which was an outstanding performance in MFCCs. In a solid electrolyte flow cell, C-0.1M80 achieved a Faraday efficiency of 97.5% at 200 mA cm-2 with a corresponding H2O2 production rate of 123.7 mg cm-2 h-1. In addition, a flow cell stability test was performed at an industrial current density (100 mA cm-2) with an astounding 200 h of uninterrupted operation, also achieving an outstanding average Faradaic efficiency (95.8%).

Coupling Ni Single Atomic Sites with Metallic Aggregates at Adjacent Geometry on Carbon Support for Efficient Hydrogen Peroxide Electrosynthesis.

Single atomic catalysts have shown great potential in efficiently electro-converting O2 to H2O2 with high selectivity. However, the impact of coordination environment and introduction of extra metallic aggregates on catalytic performance still remains unclear. Herein, first a series of carbon-based catalysts with embedded coupling Ni single atomic sites and corresponding metallic nanoparticles at adjacent geometry is synthesized. Careful performance evaluation reveals NiSA/NiNP-NSCNT catalyst with precisely controlled active centers of synergetic adjacent Ni-N4S single sites and crystalline Ni nanoparticles exhibits a high H2O2 selectivity over 92.7% within a wide potential range (maximum selectivity can reach 98.4%). Theoretical studies uncover that spatially coupling single atomic NiN4S sites with metallic Ni aggregates in close proximity can optimize the adsorption behavior of key intermediates *OOH to achieve a nearly ideal binding strength, which thus affording a kinetically favorable pathway for H2O2 production. This strategy of manipulating the interaction between single atoms and metallic aggregates offers a promising direction to design new high-performance catalysts for practical H2O2 electrosynthesis.

Inhibiting Joule Heating to Enhance the Hydrogen Peroxide Electrosynthesis Efficiency at Industrial Level Current Density

Inhibiting Joule Heating to Enhance the Hydrogen Peroxide Electrosynthesis Efficiency at Industrial Level Current Density

Hydrogen Peroxide Electrosynthesis in a Strong Acidic Environment Using Cationic Surfactants

Hydrogen Peroxide Electrosynthesis in a Strong Acidic Environment Using Cationic Surfactants

Carboxylated Hexagonal Boron Nitride/Graphene Configuration for Electrosynthesis of High-Concentration Neutral Hydrogen Peroxide.

The electrosynthesis of hydrogen peroxide (H2 O2 ) via two-electron (2e- ) oxygen (O2 ) reduction reaction (ORR) has great potential to replace the traditional energy-intensive anthraquinone process, but the design of low-cost and highly active and selective catalysts is greatly challenging for the long-term H2 O2 production under industrial relevant current density, especially under neutral electrolytes. To address this issue, this work constructed a carboxylated hexagonal boron nitride/graphene (h-BN/G) heterojunction on the commercial activated carbon through the coupling of B, N co-doping with surface oxygen groups functionalization. The champion catalyst exhibited a high 2e- ORR selectivity (>95 %), production rate (up to 13.4 mol g-1 h-1 ), and Faradaic efficiency (FE, >95 %). The long-term H2 O2 production under the high current density of 100 mA cm-2 caused the cumulative concentration as high as 2.1 wt %. The combination of in situ Raman spectra and theoretical calculation indicated that the carboxylated h-BN/G configuration promotes the adsorption of O2 and the stabilization of the key intermediates, allowing a low energy barrier for the rate-determining step of HOOH* release from the active site and thus improving the 2e- ORR performance. The fast dye degradation by using this electrochemical synthesized H2 O2 further illustrated the promising practical application.