Removal Of Oxygen Research Articles

(2022-2023 ECS Toyota Young Investigator Fellowship) Enhanced Water Electrolysis Using Layered Coaxial Nanowire Electrodes

Novel electrocatalytic approaches are urgently needed to increase the energy efficiency and decrease the cost of hydrogen production by PEM water electrolyzers. Recently, we developed a novel catalytic platform, the layered coaxial nanowire electrode (LCANE), which enables PEM water electrolyzers with higher energy efficiency and reduced usage of precious metal catalysts. Electrolyzers based on the LCANE approach use a thin film of IrO2-decorated Pt that is intimately interfaced with an ionomer membrane in the form of vertically-aligned coaxial nanowires. Each nanowire consists of a Pt shell encapsulating an ionomer core, with the Pt shell further decorated by IrO2 clusters. The top region of each nanowire bends to form a layer of in-plane aligned Pt/IrO2 nanowires, providing excellent in-plane electronic conductivity. This unique catalyst/electrode geometry offers several key advantages. By localizing ionomer within the nanowire core, the exterior surface of the catalyst remains free from ionomer, eliminating thin-film transport barriers and preventing catalyst poisoning by ionomer adsorption. The vertically aligned sections of the nanowires provide non-tortuous transport of reactants and products, with abundant pore space for facile access of water and removal of oxygen. Close integration of catalyst and ionomer provides improved proton access and eliminates stranding of catalyst. By incorporating catalyst in the form of a thin film and replacing some of the Ir with Pt, lower Ir loading (as low as 0.1 mg/cm2) is achieved without sacrificing surface area or performance.AcknowledgmentThis work was supported by the ECS-Toyota Young Investigator Fellowship and by the Laboratory Directed Research and Development program at Los Alamos National Laboratory.

1D One-Phase Modeling of the Anode Catalyst Layer/Porous Transport Layer Interface Affecting Proton Exchange Membrane Water Electrolysis

Optimizing the structure of the porous transport layer (PTL) is crucial for improving the performance of proton exchange membrane water electrolysis (PEMWE), particularly for cells with low anode catalyst loadings. A growing number of studies reveal that catalysts are normally not entirely utilized in PEMWE, whereas the degree of catalyst utilization strongly depends on the structure of the PTL. As the oxygen evolution reaction (OER) at the anode is the limiting reaction step in PEMWE, inefficient use of the anode catalyst layer (aCL) would result in higher activation losses and, thus, cause a waste of unused catalysts [1–3]. This phenomenon becomes more serious when catalyst loading is reduced to meet the eco-friendly requirement of $2 per kgH2 while conserving noble material resources [4].Schuler et al. [1, 5] combined commercial CCMs with different PTL configurations, and found that with different aCL/PTL interface properties, the activation overpotential could have a maximum deviation of 20 mA at 0.1 A/cm2. Peng et al. [2] manufactured an ultra-low Ir loading CCM with 0.03 mgIr/cm2. Optimizing the aCL/PTL interface showed that the activation overpotential can have a maximum deviation of 40 mV at 0.75 A/cm2. Previous studies concluded that the aCL/PTL interface is crucial for improving the catalyst utilization. Consequently, the triple-phase boundary (TPB) site concept at the aCL/PTL interface is gaining more and more attention: the catalysts can only be entirely activated at reaction sites with sufficient water supply, ionic and electronic conductivities, and oxygen removal pathways [3]. According to TPB, not all reaction sites on the aCL meet these requirements. Figure 1 shows the corresponding physical picture. At the contact point of aCL and PTL (S) offers much greater electronic conductivity compared to the pore area (P), where electron removal is limited by the aCL in-plane conductivity (i.e., 1.85×106 S/m vs. 65.8 S/m) [3]. However, beneath the contact area (S), mass transport of oxygen is limited, indicating the necessity of optimizing the aCL/PTL interface.Figure 1: Illustration of physical picture at aCL/PTL interface.In our contribution, we implement a one-dimensional, one-phase model to investigate the interplay between PTL geometry at the aCL/PTL interface and catalyst utilization. The PTL transports water toward the aCL and electrons and oxygen toward the cathode and anode bipolar plates, respectively [6]. To simplify the physical conditions, we assume sufficient water supply and ion removal for the reaction sites on the aCL. Therefore, mass transport and electron transport limitations are only influenced by the aCL/PTL interface properties. Oxygen is assumed to dissolve in water only so that bubble formation does not disturb the reaction sites. Additionally, an ideal heat management condition is assumed in the model to achieve an isothermal condition. Our simulation results are in good agreement with literature, enabling the prediction of activation overpotentials corresponding to the PTL structure at aCL/PTL interface. Moreover, our results illustrate the local aCL behavior, which can be used to optimize the porous structure at the aCL/PTL interface, maximizing catalyst utilization. With our model, we aim to screen for an optimum PTL structure for a given aCL, allowing us to improve PEMWE cell performance by minimization of activation losses.

Structure–Property Relationships with Functionalized Subphthalocyanines: Toward Photovoltaic Devices More Stable to Photooxidative Degradation Mediated by Singlet Oxygen

AbstractIn this work, the overarching goal of improving the photooxidative stability of organic components used in photovoltaic devices is addressed, focusing on the common problem of degradation mediated by singlet molecular oxygen. Through a systematic exploration of boron subphthalocyanines (SubPcs), the influence of donor and acceptor substituents on the SubPc's redox properties has been examined, including the SubPc's ability to (1) act as a photosensitizer for singlet oxygen generation and (2) deactivate singlet oxygen are examined. How singlet oxygen formation and removal are influenced by linking together three SubPcs in a compact structure and by linking a SubPc to another molecular unit of relevance for organic photovoltaics (indenofluorene‐extended tetrathiafulvalene) is also examined. Synthetic protocols rooted in acetylenic scaffolding, experimental and computational structure–property relationships (optical and redox properties, singlet oxygen quantum yields, and removal kinetics), and characteristics of a functional photovoltaic device using a SubPc molecule are presented, demonstrating that cyano functionalization results in remarkably enhanced organic photovoltaic device stability.

Primary processes in photophysics and photochemistry of a potential light-activated anti-cancer dirhodium complex.

Photophysics and photochemistry of a potential light-activated cytotoxic dirhodium complex [Rh2(µ-O2CCH3)2(bpy)(dppz)](O2CCH3)2, where bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine (Complex 1 or Rh2) in aqueous solutions was studied by means of stationary photolysis and time-resolved methods in time range from hundreds of femtoseconds to microseconds. According to the literature, Complex 1 demonstrates both oxygen-dependent (due to singlet oxygen formation) and oxygen-independent cytotoxicity. Photoexchange of an acetate ligand to a water molecule was the only observed photochemical reaction, which rate was increased by oxygen removal from solutions. Photoexcitation of Complex 1 results in the formation of the lowest triplet electronic excited state, which lifetime is less than 10ns. This time is too short for diffusion-controlled quenching of the triplet state by dissolved oxygen resulting in 1O2 formation. We proposed that singlet oxygen is produced by photoexcitation of weakly bound van der Waals complexes [Rh2…O2], which are formed in solutions. If this is true, no oxygen-independent light-induced cytotoxicity of Complex 1 exists. Residual cytotoxicity deaerated solutions are caused by the remaining [Rh2…O2] complexes.

High-efficient removal of Oxygen(O2) impurity from H2 flow on nickel-manganese Oxide: Regulating the exposed crystal plane, structure-activity relationship and determination of active sites

The presence of oxygen (O2) impurity in hydrogen produced by water electrolysis can pose safety hazards when hydrogen is used as a power source. Therefore, oxygen (O2) impurities must be removed from H2 flow to meet the strict purity requirements. In this work, nickel manganese oxide is applied to remove oxygen from H2 flow. It is synthesized via the co-precipitation method using different precipitants, manganese and nickel precursors. The results of the oxygen removal test show that NiMn-4 catalyst, prepared using oxalic acid, manganese acetate and nickel nitrate as the precursors, has the best performance in removing oxygen impurities from the hydrogen flow. The catalyst could retain an oxygen removal efficiency of nearly 70 % at the reaction temperature of 80 °C. Also, XRD, Raman spectra and HRTEM analysis results show that the crystal phase of NiMn-4 (Ni6MnO8) exhibits much stronger crystallinity than the other catalysts and has (400) and (222) planes of Ni6MnO8. H2/O2-TPD and H2-TPR analysis results indicate that NiMn-4 catalyst has much more adsorbed oxygen species, overflow hydrogen and hydrogen consumption at per specific surface area compared to the other catalysts. The XPS results of Ni2p and O1s imply that there is much higher valence of Ni (Ni3+).

Patient-Related Factors Associated with Adverse Outcomes Following Weaning from Veno-Arterial Extracorporeal Membrane Oxygenation

Background: Veno-arterial extracorporeal membrane oxygenation (vaECMO) removal reflects a critical moment and factors of adverse outcomes are incompletely understood. Thus, we studied various patient-related factors during vaECMO removal to determine their association with outcomes. Methods: A total of 58 patients from a university hospital were included retrospectively. Demographic, clinical, and echocardiographic parameters were recorded while under vaECMO support, as well as the need for inotropic and vasoactive-inotropic scores (VIS). Successful weaning was defined as 28-day survival without reinitiation of vaECMO. Results: Patient age differed significantly between patients with a successful and a failed vaECMO weaning (54 ± 14 vs. 62 ± 12 years, p = 0.029). In univariable logistic regression, age (OR 0.952 (0.909–0.997), p = 0.038), the necessities for inotropic agents at the time of echocardiography (OR 0.333 (0.113–0.981), p = 0.046), and vaECMO removal (OR 0.266 (0.081–0.877), p = 0.030) as well as the dobutamine dose during removal (OR 0.649 (0.473–0.890), p = 0.007), were significantly associated with a successful weaning from vaECMO. Age (HR 1.048 (1.006–1.091), p = 0.024) and the VIS (HR 1.030 (1.004–1.056), p = 0.025) at the time of vaECMO removal were independently associated with survival in bivariable Cox regression. In Kaplan–Meier analysis, a VIS of >5.1 at vaECMO removal was associated with impaired survival (log-rank p = 0.025). Conclusions: In this cohort, age and the extent of vasoactive-inotropic agents were associated with adverse outcomes following vaECMO, whereas echocardiographic biventricular function during vaECMO support was not.

Heterogeneous single-atom doped 2D-layered graphitic carbon nitride electrocatalyst for oxygen evolution reaction and removal of toxic heavy metal ion Cr from Wastewater

The 2D-layered graphitic carbon nitride (gCN) has been a well-known electro-photocatalyst to have wide applications in energy storage, energy evolution, and environmental remediation. The physicochemical properties of the bulk, O-doped (O-gCN), and hetero atom are compared, which is further utilized as an electrocatalyst for the oxygen evolution reactions (OER) process. The prepared nanosheets exhibited a layered structure with a uniform porous nature. Moreover, the forbidden energy bandgap (Eg) of 1.7 eV is observed, which is lower than bulk and O-doped gCN. The heteroatom BO-gCN nanosheets have higher OER activity compared to other samples and benchmark catalysts. The BO-gCN nanosheets exhibit a lower overpotential and Tafel potential of 240 mV and 207 mV/dec, respectively. Effects of various operating parameters such as photocatalyst dosage and solution pH are investigated. The photocatalytic removal results exhibited BO-gCN can be a robust and effective catalyst for the removal of Cr ions in environmental remediation.

H2-O2 재결합 반응을 통한 M/γ-Al2O3 촉매의 산소 제거 성능과 산소 결손이 촉매에 미치는 영향

H2-O2 재결합 반응을 통한 M/γ-Al2O3 촉매의 산소 제거 성능과 산소 결손이 촉매에 미치는 영향

Analysis of Carbon Functional Groups through FTIR Patterns in The Preparation of Reduced Graphene Oxide (RGO)

The preparation of Reduced Graphene Oxide (RGO) through oil palm fiber biomass using a strong acid activation method with sulfuric acid (H2SO4) media, followed by application of microwave waves, is an interesting approach to obtain RGO. The study primarily focused on using the Fourier Transform Infrared (FTIR) spectroscopy technique to detect the formation of RGO based on changes in functional groups. The success of the formation of this RGO was confirmed by the presence of sharp and widening peak in the range of wave numbers 3254-3399 cm-1 which was OH-stretching. the longer the microwave wave is applied, the narrower the OH-stretching peak due to the removal of oxygen due to the application of microwave wave.

Regulating reconstruction of oxide-derived Cu for electrochemical CO2 reduction toward n-propanol.

Oxide-derived copper (OD-Cu) is the most efficient and likely practical electrocatalyst for CO2 reduction toward multicarbon products. However, the inevitable but poorly understood reconstruction from the pristine state to the working state of OD-Cu under strong reduction conditions largely hinders the rational construction of catalysts toward multicarbon products, especially C3 products like n-propanol. Here, we simulate the reconstruction of CuO and Cu2O into their derived Cu by molecular dynamics, revealing that CuO-derived Cu (CuOD-Cu) intrinsically has a richer population of undercoordinated Cu sites and higher surficial Cu atom density than the counterpart Cu2O-derived Cu (Cu2OD-Cu) because of the vigorous oxygen removal. In situ spectroscopes disclose that the coordination number of CuOD-Cu is considerably lower than that of Cu2OD-Cu, enabling the fast kinetics of CO2 reaction and strengthened binding of *C2 intermediate(s). Benefiting from the rich undercoordinated Cu sites, CuOD-Cu achieves remarkable n-propanol faradaic efficiency up to ~17.9%, whereas the Cu2OD-Cu dominantly generates formate.

Atomic-Scale Insights into Carbon Dioxide Hydrogenation over Bimetallic Iron–Cobalt Catalysts: A Density Functional Theory Study

The conversion of carbon dioxide to fuels and chemicals is a promising long-term approach for mitigating CO2 emissions. Despite extensive experimental efforts, a fundamental understanding of the bimetallic catalytic structures that selectively produce the desired products is still lacking. Here, we report on a computational surface science approach into the effect of the Fe doping of Co(111) surfaces in relation to CO2 hydrogenation to C1 products. Our results indicate that Fe doping increases the binding strength of surface species but slightly decreases the overall catalytic activity due to an increase in the rate-limiting step of CO dissociation. FeCo(111) surfaces hinder hydrogenation reactions due to lower H coverages and higher activation energies. These effects are linked to the Lewis basic character of the Fe atoms in FeCo(111), leading to an increased charge on the adsorbates. The main effect of Fe doping is identified as the inhibition of oxygen removal from cobalt surfaces, which can be expected to lead to the formation of oxidic phases on bimetallic FeCo catalysts. Overall, our study provides comprehensive mechanistic insights related to the effect of Fe doping on the catalytic behavior and structural evolution of FeCo bimetallic catalysts, which can contribute to the rational design of bimetallic catalysts.

Hydrodeoxygenation of guaiacol over halloysite nanotubes decorated with Ru nanoparticles: Effect of alumina acid etching on catalytic behavior and reaction pathways

Halloysite nanotubes (HNTs) is a promising support for liquid-phase hydrodeoxygenation (HDO) catalysts due to a wide abundance, low cost and tunable properties. Acid etching of halloysite by sulfuric acid was found to enlarge lumen diameter (24.3 nm), enhance specific surface area (154 m2/g) and acidity (0.343 mmol/g). Based on pristine and dealuminated HNTs, Ru-containing catalysts were synthesized via impregnation under microwave irradiation. The catalytic properties of synthesized catalysts in HDO of guaiacol were studied in batch reactors at 120–180 °C, under hydrogen pressure of 3 MPa, with guaiacol/Ru molar ratio of 200 in water as a solvent. Comparing the results of catalytic tests, we have concluded that the catalysts based on etched halloysite enhanced greater activity (TOF – 211 h−1) in the HDO of guaiacol compared their analogue supported on pristine HNTs. Moreover, the Ru-catalyst based on etched HNTs contributed to an increase selectivity to hydrogenolysis with effective oxygen removal.

Research on the impact of rotor wear on the effectiveness of the aluminium refining process

Physical modelling is successfully used to understand mechanisms involved in the aluminium refining process by injecting inert gas into the liquid metal through rotors. Two types of industrial impellers, which are extremely different in construction, were tested in the research. The aim of the research was to determine the effectiveness of their operation depending on their degree of wear. This type of research has not been tested on water models so far. During the process, the parameters were changed, such as the gas flow rate from 13 to 19 L/min, the rotor speed from 325 to 400 rpm and the height of the rotor from the bottom of the refining reactor. Tests were carried out for new and worn rotors. Oxygen removal rate curves were prepared on the basis of tests determining changes in oxygen content in the model liquid as a function of time for changing rotor speed values. It was found that the efficiency of hydrogen removal from the model liquid was higher when worn impellers were used in the model. In order to verify results of model tests, a metallographic analysis of samples obtained in industrial conditions and using the analysed process parameters was carried out.

Influence of the Geometry of the Oxygen Removal Chamber on the Oxygen Concentration in a PEM Water Electrolysis System

In this paper, we investigate the optimization of an oxygen removal system for water electrolysis plants because high oxygen concentrations can be dangerous and compromise the quality of the hydrogen produced. The design of an oxygen removal system was investigated using numerical analysis. The results showed that the diameter of the chamber had a significant effect on the oxygen removal efficiency, and a diameter twice the size of the gas inlet was found to be optimal. The porosity of the catalyst layer also played a crucial role in the efficiency, with a lower porosity resulting in higher removal rates. Additionally, the optimal chamber length was found to be 76.8 D to achieve an oxygen mole fraction of 2.4 ppm after the chamber, which satisfied the safety criterion of 4.0 ppm. These results can aid in the design of oxygen removal systems for water electrolysis plants, providing a more efficient and safer operation.

A comparative analysis of integrating thermochemical oxygen pumping in water-splitting redox cycles for hydrogen production

Solar thermochemical hydrogen (STCH) is a promising route for renewable fuel production, but efficiency and cost concerns must be addressed before it can contribute meaningfully to decarbonization efforts. The oxygen removal (reduction) step of two-step STCH redox cycles needs high temperature (1300–1500 °C) and low oxygen partial pressure (10-5-10-3 bar). This consumes significant energy by way of redox reheating, re-radiation losses and pumping work. Thermochemical oxygen pumping (TcOP) has been shown to be more efficient than mechanical pumps in the medium vacuum range, enabling higher heat-to-fuel efficiency and potentially lower reduction temperatures. We have previously proposed a novel Reactor Train System for STCH and reported significant efficiency and productivity improvements by replacing mechanical pumps with TcOP. The current work is a comparative analysis of different implementations of TcOP and its hybridization with conventional oxygen removal schemes like mechanical vacuum pumps and inert gas sweep. The integration of these hybrid TcOP systems with different STCH reactor systems using redox monoliths or particles is analyzed in terms of energy use along with mass and heat transfer considerations. Our results show that direct oxygen transfer between STCH and TcOP reactors results in the best performance for reduction oxygen partial pressures below 10 Pa. Furthermore, we show that achieving reduction pressures of 1 Pa and lower is challenging with existing reactor systems due to a combination of low gas density and relatively high molar flowrates. This challenge also applies to other oxygen removal systems like vacuum pumps and inert sweep.

The role of stress release in shaping iron whisker morphology during oxygen removal process

Metal growth in materials manufacturing or applications can significantly impact the efficiency and performance of processes. Despite extensive research efforts to understand dendrite and whisker growth mechanisms in various processes like battery charging and metal powder production, the growth of metal during the removal of oxygen from its oxides remains poorly understood. In this study, we investigated the role of stress release in the formation of iron whiskers. Our findings emphasized the significance of the oxygen removal process from hematite (Fe2O3) to wüstite (FeO), as a crucial step in initiating the structure for subsequent iron growth. We observed that, compared to carbon monoxide (CO), hydrogen (H2) exhibited superior stress release capabilities, leading to rapid volume shrinkage in the Fe2O3 to FeO stage. This preferential stress reduction by H2 was attributed to the development of a larger-sized nanoscale hole structure on the surface of iron oxides, effectively inhibiting the growth of filament-shaped whiskers.

Effect of tamoxifen treatment on catalase (CAT) and superoxide dismutase (SOD) expression and localization in the hen oviduct

The imbalance between free reactive oxygen species (ROS) generation and removal (e.g., by antioxidative enzymes) leads to the damage of important biomolecules and cells. Earlier studies in hens showed that treatment with tamoxifen (TMX; estrogen receptor inhibitor) modulates oxidative stress and causes the reproductive system regression realized by cell apoptosis. The aim of the present study was, therefore, to examine the expression and immunolocalization of the key enzymatic antioxidants, i.e. catalase (CAT) and superoxide dismutase (SOD), in the chicken oviduct following TMX treatment. Laying hens were treated daily with TMX until a pause in egg-laying occurred and then euthanized on day 8 of the experiment. Quantitative real-time PCR and western blot analyses showed the presence of CAT and SOD transcripts and proteins, respectively, in all oviductal segments, i.e., the infundibulum, magnum, isthmus, shell gland and vagina. In control hens (laying), the mRNA expression of CAT was the highest in the shell gland, lower in the isthmus and the lowest in other oviductal parts, whereas protein expression was the highest in the magnum, lower in the isthmus and the lowest in other segments. The SOD transcript and protein abundances only were lower in the magnum than in other segments. Immunoreactive CAT and SOD products were localized in all layers of the oviductal wall, but the intensity of staining depended on the cell type. TMX treatment affected CAT and SOD expression and the effect of TMX depended on gene, protein, cell type and oviductal part. Generally, CAT expression was elevated, while SOD expression was decreased under TMX treatment. These results point to the importance of CAT and SOD in the maintenance of proper oviduct health and function. Changes in ROS scavenging enzymes after estrogen receptor blockage indicate the significance of estrogen in the regulation of oxidative status in the avian oviduct.

Impact of powder properties on deoxidation and densification of carbon steels during powder bed fusion – Laser beam

This work examined the influence of powder properties on deoxidation and densification of carbon steels during powder bed fusion-laser beam (PBF-LB) at compositions between 0.06 and 1.1 wt% C. Analysis revealed that deoxidation was greatest in alloys with high carbon content, reaching losses of up to 440–600 ppm at compositions of 0.75 and 1.1 wt% C. This behavior was not due to enhanced oxygen removal by spatter, as spatter in high carbon alloys had less oxygen pickup (∼4% vs. ∼27%) and formed smaller oxide layers (∼42 nm vs. ∼82 nm). Instead, it was due to the high oxygen affinity of carbon at elevated temperature, which resulted in formation of gaseous carbon oxides that were subsequently removed by the process atmosphere. Regarding densification, powders with high avalanche energy (>7.75 mJ/kg), break energy (>4.75 mJ/kg), and particle size distribution (D10 > 25 μm) were more likely to form lack of fusion porosity at low energy input.

Fabrication of PANI supported magnesium/cobalt spinel ternary oxide as an efficient oxygen evolution reaction and removal of organic pollutant

The advancement of potent, highly efficient and reasonably priced catalysts is necessary for the production of hydrogen from a renewable source and removal of organic contaminants from waste water. In this study, we demonstrated the dynamic proportion capability of the hydrothermally condensed polymorphic electrocatalyst MgCo2O4/PANI nanocomposite. The composite material has higher surface area of 264 m2 g-1 and electrochemical active surface area of 299.5 cm2. The MgCo2O4/PANI nanocomposite exhibits 201 mV of lower overpotential to attain at 10 mA cm-2 of current density and 66 mV dec-1 of reduced Tafel value. The long-term viability for 50 h is demonstrated using MgCo2O4/PANI at 10 mA cm-2 for O2 production. The findings of this study demonstrated that MgCo2O4/PANI nanocomposite is an affordable, non-precious material, which can be utilized to generate H2 on a large scale. On the other hand, the resultant material was then applied for the Congo Red (CR) dye photodegradation irradiated with visible light with degradation efficiency of 98%. The comparison of nanostructured MgCo2O4/PANI demonstrates that the electrochemical performance for water oxidation processes as well as degradation process is significantly higher than the pure form. The exceptional catalytic performance of MgCo2O4/PANI nanocomposite is due to the large quantity of active sites, some immense oxygen vacancies, and a fast electron transfer rate, with a steady oxygen generating stability of 1500 cycles confirm the endurance of MgCo2O4/PANI nanoarrays, which is beneficial for future industrial application.

Properties of a Soluble Lead Flow Battery Recycled with Hydrogen Peroxide

AbstractThe service life of soluble lead flow batteries can be extended by periodic addition of H2O2, especially when it failed. However in first few cycles after H2O2 treatment, its coulombic efficiency is very low. To clarify it, the properties of electrode and electrolyte, and cycle performance have been systematically analyzed. It has been found that the negative/positive electrode reactions have serious overpotentials during early charging due to oxygen, which are produced and dissolved into the electrolyte during H2O2 treatment. With increasing the cycle number, the polarization degree decreases to the normal level of the battery. To solve it, oxygen is removed using argon after H2O2 treatment. The flow cell is normally recovered in the cycling performance. The average coulomb efficiency is 94.5±5.8 % for 500 times. After H2O2 treatment and oxygen removal, it exhibits a good cycling performance at the average coulomb efficiency of 93.9±4.2 % for another 500 times.