Synergistic effects of advanced oxidization reactions in a combination of TiO2 photocatalysis for hydrogen production and wastewater treatment applications

In this paper, the synergistic effects of advanced oxidization reactions in a combination of TiO₂ photocatalysis are comparatively investigated for hydrogen production and wastewater treatment applications. An experimental study is conducted with a photoelectrochemical reactor under a UV-light source. TiO₂ is selected as the photocatalyst due to the high corrosion resistant nature and ability to form hydroxyl radicals with the interaction with photons. The synergetic effects of advanced oxidization processes (AOPs) such as Fenton, Fenton-like, photocatalysis (TiO₂/UV) and UV photolysis (H₂O₂/UV) are investigated individually and in a combination of each other. The Fenton type reagent in the reactor is formed by anodic sacrificial of stainless-steel electrode with the presence of H₂O₂. The influences of various parameters, including pH level, type of the electrode and electrolyte and the UV light, on the performance of the combined system are also investigated experimentally. The highest chemical oxygen demand (COD) removal efficiency is observed as 97.9% for the experimental condition which combines UV/TiO₂, UV/H₂O₂ and photo-electro Fenton type processes. The maximum hydrogen production rate from the photoelectrolysis of wastewater is obtained as 7.0 mg/Wh for the experimental condition which has the highest rate of photo-electro Fenton type processes. The average enhancement with the presence of UV light on hydrogen production rates and COD removal efficiencies are further calculated to be 3% and 20%, respectively.     

Treatment of textile wastewaters by solar-driven advanced oxidation processes

Heterogeneous (TiO₂/UV, TiO₂/H₂O₂/UV) and homogenous (H₂O₂/UV, Fe²⁺/H₂O₂/UV) solar advanced oxidation processes (AOPs) are proposed for the treatment of recalcitrant textile wastewater at pilot-plant scale with compound parabolic collectors (CPCs). The textile wastewater presents a lilac colour, with a maximum absorbance peak at 516 nm, high pH (pH = 11), moderate organic content (DOC = 382 mg C L⁻¹, COD = 1020 mg O₂ L⁻¹) and high conductivity (13.6 mS cm⁻¹), associated with a high concentration of chloride (4.7 g Cl⁻ L⁻¹). The DOC abatement is similar for the H₂O₂/UV and TiO₂/UV processes, corresponding only to 30% and 36% mineralization after 190 kJ_UV L⁻¹. The addition of H₂O₂ to TiO₂/UV system increased the initial degradation rate more than seven times, leading to 90% mineralization after exposure to 100 kJ_UV L⁻¹. All the processes using H₂O₂ contributed to an effective decolourisation, but the most efficient process for decolourisation and mineralization was the solar-photo-Fenton with an optimum catalyst concentration of 100 mg Fe²⁺ L⁻¹, leading to 98% decolourisation and 89% mineralization after 7.2 and 49.1 kJ_UV L⁻¹, respectively. According to the Zahn-Wellens test, the energy dose necessary to achieve a biodegradable effluent after the solar-photo-Fenton process with 100 mg Fe²⁺ L⁻¹ is 12 kJ_UV L⁻¹.     

Optimal performance assessment for a photo‐Fenton degradation pilot plant driven by solar energy using artificial neural networks

Artificial neural networks (ANN) were proposed as a multivariate experimental design tool for monitoring a photo‐Fenton treatment of wastewaters containing a synthetic mixture of pesticides. ANN and Nelder‐Mead simplex methods were used to find out the optimum operating parameters of a photo‐Fenton pilot plant. ANN was developed to predict the most important operating parameters (e.g., the total organic carbon and the initial mineralization kinetic rate constants of the reactions), which determine the photo‐catalytic degradation efficiency in photo‐Fenton processes. Experimental measurements of temperature, pH, hydrogen peroxide (H₂O₂) consumption, initial concentration of Fe²⁺, and the AE were used as input data for the ANN learning. A feed‐forward with one hidden layer, a Levenberg–Marquardt learning algorithm, a hyperbolic tangent sigmoidal transfer function and a linear transfer function were used to develop the ANN model. The best fitting of the training database was obtained with an ANN architecture constituted by seven neurons in the hidden layer. The simulated results were validated with experimental measurements, showing an acceptable agreement (R² > 0.99). The ANN was subsequently coupled with a Nelder–Mead simplex method to obtain the optimum operating parameters of the photo‐Fenton pilot plant. The H₂O₂ consumption was used as key variable for evaluating the optimization procedure. Errors less than 1% between simulated and experimental data were found. The obtained results showed that the use of ANN provides an excellent predictive performance tool with the additional capability to assess the influence of each operating parameter on the removal process of water pollutants. Copyright © 2011 John Wiley & Sons, Ltd.     

Fenton法预活化污泥制备磁性活性炭的实验研究

利用Fenton法预活化二沉池剩余污泥能够有效改善污泥活性炭的性质,制备性能良好的污泥磁性活性炭.通过考察H_2O_2投加量、H_2O_2/Fe~(2+)投加质量比、活化pH、预活化时间对污泥前驱体和污泥磁性活性炭的影响,探索Fenton法预活化污泥的作用机理.结果表明:Fenton试剂在酸性pH条件下产生羟基自由基,具有强氧化性的·OH破坏污泥胞外聚合物,同时将大分子有机物氧化成中间体和小分子有机物,少量孔隙随着CO_2和H_2O的逸出而形成;Fenton试剂的使用引入了铁,而铁盐是污泥热解的催化剂,能够促进焦油的裂解,加快有机物大分子键的断裂,从而促使更多孔隙的生成.     

Green synthesis of Ag/Fe3O4/RGO nanocomposites by Punica Granatum peel extract: Catalytic activity for reduction of organic pollutants

The magnetically separable Ag/Fe₃O₄/RGO nanocomposites (NCs) were synthesized through a green method using Punica Granatum peel extract as a reducing and stabilizing agent. The total phenolic content (TPC) in the Punica Granatum peel extract and the ability of extract to scavenge the DPPH radical were measured and the results proved that the extract has the ability of reduction of Ag⁺ ions and graphene oxide (GO) to Ag nanoparticles (NPs) and reduced graphene oxide (RGO), respectively. Furthermore, the presence of phenolic compounds in the extract was confirmed using UV–Vis and FT-IR techniques. Deposition of Ag NPs on the surface of Fe₃O₄/RGO NCs was confirmed by color change from transparent to brown with maximum absorption at 418 nm which is due to surface plasmon resonance of Ag NPs. The crystalline nature of the Ag/Fe₃O₄/RGO NCs was identified utilizing XRD analysis. The catalytic activity of the green synthesized Ag/Fe₃O₄/RGO NCs was evaluated in the reduction of organic pollutants such as 4-nitrophenol (4-NP), methylene blue (MB), methyl green (MG) and methyl orange (MO) in water at mild conditions. The results indicated that the biosynthesized NCs have very high and effective catalytic activity for the different types of dyes within few seconds. The morphology and catalytic activity of the Ag/Fe₃O₄/RGO NCs was compared with Ag/RGO and Ag/Fe₃O₄ NCs, which were synthesized using Punica Granatum peel extract. The results revealed that the unique synergistic effect of Ag NPs and immobilization over supporters of RGO and Fe₃O₄ magnetite composite assisted in the reduction of 4-NP, MB, MG and MO.     

Enhanced heterogeneous ferrioxalate photo-fenton degradation of reactive orange 4 by solar light

A combined homogeneous and heterogeneous photocatalytic decolourisation and degradation of a chlorotriazine Reactive azo dye Reactive Orange 4 (RO4) have been carried out using ferrous sulphate/ ferrioxalate with H₂O₂ and TiO₂-P25 particles. Solar/ferrous/H₂O₂/TiO₂-P25 and solar/ferrioxalate/H₂O₂/TiO₂-P25 processes are found to be more efficient than the individual photo-Fenton and solar/TiO₂-P25 processes. A comparison of these two processes with UV/ferrous/H₂O₂/TiO₂-P25 and UV/ferrioxalate/H₂O₂/TiO₂-P25 reveals that ferrioxalate is more efficient in solar light whereas ferrous ion is more efficient in UV light. The experimental parameters such as pH, initial H₂O₂, Fe²⁺, ferrioxalate and TiO₂-P25 concentration strongly influenced the dye removal rate in solar processes. The optimum operating conditions of these two combined processes are reported.     

Landfill leachate treatment by solar-driven AOPs

Sanitary landfill leachate resulting from the rainwater percolation through the landfill layers and waste material decomposition is a complex mixture of high-strength organic and inorganic compounds which constitutes serious environmental problems. In this study, different heterogeneous (TiO₂/UV, TiO₂/H₂O₂/UV) and homogenous (H₂O₂/UV, Fe²⁺/H₂O₂/UV) photocatalytic processes were investigated as an alternative for the treatment of a mature landfill leachate. The addition of H₂O₂ to TiO₂/UV system increased the reduction of the aromatic compounds from 15% to 61%, although mineralization was almost the same. The DOC and aromatic content abatement is similar for the H₂O₂/UV and TiO₂/H₂O₂/UV processes, although the H₂O₂ consumption is three times higher in the H₂O₂/UV system. The low efficiency of TiO₂/H₂O₂/UV system is presumably due to the alkaline leachate solution, for which the H₂O₂ becomes highly unstable and self-decomposition of H₂O₂ occurs. The efficiency of the TiO₂/H₂O₂/UV system increased 10 times after a preliminary pH correction to 4. The photo-Fenton process is much more efficient than heterogeneous (TiO₂, TiO₂/H₂O₂/UV) or homogeneous (H₂O₂/UV) photocatalysis, showing an initial reaction rate more than 20 times higher, and leading to almost complete mineralization of the wastewater. However, when compared with TiO₂/H₂O₂/UV with acidification, the photo-Fenton reaction is only two times faster.The optimal initial iron dose for the photo-Fenton treatment of the leachate is 60 mg Fe²⁺ L⁻¹, which is in agreement with path length of 5 cm in the photoreactor. The kinetic behaviour of the process (60 mg Fe²⁺ L⁻¹) comprises a slow initial reaction, followed by a first-order kinetics (k = 0.020 , r₀ = 12.5 mg ), with H₂O₂ consumption rate of k_H2O2 = 3.0 mmol H₂O₂, and finally, the third reaction period, characterized by a lower DOC degradation and H₂O₂ consumption until the end of the experiment, presumably due to the formation of low-molecular-weight carboxylic groups. A total of 306 mM of H₂O₂ was consumed for achieving 86% mineralization (DOC_final = 134 mg L⁻¹) and 94% aromatic content reduction after 110 kJ_UV L⁻¹, using an initial iron concentration of 60 mg Fe²⁺ L⁻¹.     

Enhancing oxygen reduction reaction performance in acidic media via bimetal Fe and Cr synergistic effects

Currently, it is a great challenge to improve the stability of Fe-based oxygen reduction reaction (ORR) catalysts in acidic medium, because the Fenton reaction between Fe-based catalyst and H₂O₂ will reduce the stability of the catalyst. In this study, Fe, Cr and nitrogen-doped carbon (FeCr-N-C) was synthesized via co-impregnation of biomass walnut shells with metal precursor solutions. The FeCr-N-C catalyst has an onset potential of 0.88 V vs. RHE and outperforms the Fe-N-C catalyst in acidic media. Moreover, FeCr-N-C shows negligible activity decay (ΔE_1/2 = 14 mV) in 0.1 M HClO₄ after 20 000 cycles. The experimental results proved that the bimetal synergism can produce low yield of H₂O₂ (<2%), which might attribute to variations of local electronic structure. The reactive oxygen species of the catalyst were analyzed by Ultraviolet-visible (UV-Vis) absorption spectra. It was proved that the presence of bimetal inhibited the Fenton reaction between Fe²⁺/Fe³⁺ and H₂O₂, and further improved the stability of the catalysts. Hence, this study proposes an efficient strategy to facilitate the practical application of Fe-based catalysts in acidic media.     

Phosphorus-doped Fe3O4 nanoflowers grown on 3D porous graphene for robust pH-Universal hydrogen evolution reaction

It is extremely necessary to develop highly efficient and low-cost non-noble metal electrocatalysts for hydrogen evolution reaction (HER) under a pH-universal condition in the realm of sustainable energy. Herein, we have successfully prepared phosphorus doped Fe₃O₄ nanoflowers on three-dimensional porous graphene (denoted as P–Fe₃O₄@3DG) via a simple hydrothermal and low-temperature phosphating reaction. The P–Fe₃O₄@3DG hybrid composite not only demonstrates superior performance for HER in 1.0 M KOH with low overpotential (123 mV at 10 mA/cm²), small Tafel slope (65 mV/dec), and outstanding durability exceeding 50 h, but also exhibits satisfying performances under neutral and acidic medium as well. The 3D graphene foam with large porosity, high conductivity, and robust skeleton conduces to more active sites, and faster electron and ion transportation. The phosphorus dopant provides low Gibbs free energy and ability of binging H⁺. The synergistic effect of 3DG substrate and P–Fe₃O₄ active material both accelerates the catalytic activity of Fe-based hybrid composite for HER.     

Solar thermochemical process for hydrogen production using ferrites

A two-step water splitting process using the ZnFe₂O₄/Zn/Fe₃O₄ reaction system was proposed for H₂ generation utilizing concentrated solar heat. The mixture of Zn and Fe₃O₄ was heated to 873 K in flowing steam with an Ar carrier gas, and the H₂ gas was generated at 93.4% of the theoretical yield for the reaction of 3Zn+2Fe₃O₄+4H₂O=3ZnFe₂O₄+4H₂ (H₂ generation step). The XRD and Mössbauer spectroscopy showed that the Zn‐submitted ferrite (Zn_xFe_3−xO₄; 0.2≤x≤1) (main solid product) and ZnO (minor) were formed in the solid products after the H₂ generation reaction. The ZnFe₂O₄ product, which was formed after the H₂ generation step during the two-step water splitting process with the ZnFe₂O₄/Zn/Fe₃O₄ system, could be decomposed into Zn (and ZnO) and Fe₃O₄ by the Xe beam irradiation at 1900 K after 3 min with a 67.8% yield for the reaction of 3ZnFe₂O₄=3Zn+2Fe₃O₄+2O₂ (O₂ releasing step=solar thermal step).     

Kinetic study of Nafion degradation by Fenton reaction

To predict the durability of polymer electrolyte membranes in fuel cells, the degradation reactions of Nafion 117 films were studied as oxidation reactions with hydroxyl radicals as oxidation accelerators. The radical species were generated by the Fenton reaction between hydrogen peroxide (H₂O₂) and iron ions (Fe²⁺). The Nafion degradation kinetics were estimated by fluorine ion (F⁻) generation. The H₂O₂ and Nafion degradation reactions fit a pseudo-first-order rate constant. The values of the activation energy and frequency factor are 85 kJ mol⁻¹ and 3.97 × 10⁸ s⁻¹ for H₂O₂ decomposition in the presence of a Nafion film and 97 kJ mol⁻¹ and 9.88 × 10⁸ s⁻¹ for F⁻ generation. The Nafion surface morphology became rough after reaction for 12 h; small cracks, approximately 100 μm in length, were observed at temperatures below 60 °C. These cracks connected to make larger gaps of approximately 1 mm at temperatures above 70 °C. We also found a linear relationship between H₂O₂ consumption and F⁻ generation. The rate constant is temperature dependent and expressed as ln(d[F⁻]/d[decomposed H₂O₂]) = −19.5 × 10³ K⁻¹ + 42.8. F⁻ generated and H₂O₂ consumed along with the Nafion degradation conditions can be predicted using this relation.     

The Fe3+ role in decreasing the activity of Nafion-bonded IrO2 catalyst for proton exchange membrane water electrolyser

Fe³⁺ is a common ion contaminant for the proton exchange membrane water electrolyser (PEMWE). In this work, three-electrode-system was employed to study the effect of Fe³⁺ on Nafion-bonded IrO₂ catalyst which is conventional anode catalyst for PEMWE. Study results showed that Fe³⁺ contamination decreased IrO₂ catalytic activity significantly only when the following two conditions were both satisfied: 1) Nafion resin exists in working electrode; 2) working electrode potential was over 1.471 V (vs. NHE) which is around the initial voltage of oxygen evolution reaction (OER). Besides, the contaminated working electrode activity was recovered to about 16% by being immersed into 3 M H₂SO₄ solution, but it was recovered to about 59% by ethanol washing method. These study results revealed that Fe³⁺ plays a role of catalyst for H₂O₂ production during OER process, which leads to Nafion resin decomposition. The degradation products covered working electrode surface, and thus decreased effective active sites of IrO₂. Nafion degradation was further confirmed by analyzing 1) F⁻ content in anode water and 2) FTIR of contaminated Nafion membrane.     

Using chemical looping gasification with Fe2O3/Al2O3 oxygen carrier to produce syngas (H2+CO) from rice straw

The chemical looping gasification of rice straw using Fe₂O₃/Al₂O₃ as oxygen carrier was studied at reaction time of 5–25 min, steam-to-biomass (S/B) ratio of 2.0–4.8, reaction temperature of 750–950 °C, and oxygen carrier-to-biomass of 1.0. The gasification can be regarded completed in 20-min reaction. There exist an optimal S/B ratio of 2.8 and reaction temperature of 900 °C leading to maximum performances yielded are 1.22 Nm³/kg gas yield at 54.6% H₂+24.2% CO. The studied Fe₂O₃ oxygen carrier/rice straw is a feasible platform for syngas production from an agricultural waste.     

V2O5 nanoribbons/N-deficient g-C3N4 heterostructure for enhanced visible-light photocatalytic performance

Visible-light-induced heterostructure photocatalysts have been regarded as promising candidates in clean energy production and environmental treatment of organic pollutants. In this study, we have prepared nanocomposites of V₂O₅/N-deficient g-C₃N₄ (VO/Ndef-CN), which have been characterized by a variety of techniques. The as-synthesized nanocomposites show efficient bifunctional photocatalytic properties toward hydrogen generation and pollutants degradation (dye and antibiotic). The optimized 5VO/Ndef-CN photocatalyst exhibits improved photoactivity for H₂ production (5892 μmol g^?1 h^?1), with a high quantum yield of 6.5%, and fast degradation of organic pollutants, as well as high photocatalytic stability under visible light irradiation. The high photocatalytic efficiency is due to the presence of N defects and S-scheme heterojunction formation, which leads to rapid charge separation, enhanced visible-light absorption, and increased active sites. Furthermore, the possible activity-enhanced mechanism and the photodegradation pathway are proposed based on the experimental and density functional theory (DFT) investigations.     

Effect of H2O2 on Nafion properties and conductivity at fuel cell conditions

During PEM fuel cell operation, formation of H₂O₂ and material corrosion occurs, generating trace amounts of metal cations (i.e., Fe²⁺, Pt²⁺) and subsequently initiating the deterioration of cell components and, in particular, PFSA membranes (e.g., Nafion). However, most previous studies of this have been performed using conditions not relevant to fuel cell environments, and very few investigations have studied the effect of Nafion decomposition on conductivity, one of the most crucial factors governing PEMFC performance. In this study, a quantitative examination of properties and conductivities of degraded Nafion membranes at conditions relevant to fuel cell environments (30-100%RH and 80 °C) was performed. Nafion membranes were pre-ion-exchanged with small amounts of Fe²⁺ ions prior to H₂O₂ exposure. The degradation degree (defined as loss of ion-exchange capacity, weight, and fluoride content), water uptake, and conductivity of H₂O₂-exposed membranes were found to strongly depend on Fe content and H₂O₂ treatment time. SEM cross-sections showed that the degradation initially took place in the center of the membrane, while FTIR analysis revealed that Nafion degradation preferentially proceeds at the sulfonic end group and at the ether linkage located in the pendant side chain and that the H-bond of water is weakened after prolonged H₂O₂ exposure.     

Simultaneous production of H2 and C2 hydrocarbons by using a novel configuration solid-electrolyte + fixed bed reactor

A novel combined single chamber solid electrolyte plus fixed bed reactor configuration was developed for the simultaneous production of H₂ and C₂ hydrocarbons from a humidified CH₄ atmosphere. Hence, a Pt/YSZ/Ag solid electrolyte cell was placed on the top of an active oxidative coupling catalyst powder bed Ce–Na₂WO₄/SiO₂. H₂ was produced via steam electrolysis in a Pt cathode of the solid electrolyte cell (H₂O + 2e⁻ → H₂ + O²⁻). Simultaneously, the produced O²⁻ ions were electrochemically pumped to the Ag anode, leading to the C_2s production, via oxidative coupling of CH₄ (4CH₄ + 3O²⁻ → C₂H₄ + C₂H₆ + 3H₂O + 6e⁻). Additionally, non-reacted O²⁻ molecules desorbed to the gas phase (2O²⁻ → O₂+4e⁻) and reacted with CH₄ in the catalyst bed leading to an increase of C_2s yield. The influence of different reaction parameters was investigated together with long-term reaction experiments, confirming the stability of this configuration for its practical application. The obtained results demonstrated that the addition of an active catalyst bed strongly enhances both: the efficiency of the single chamber steam electrolysis and the oxidative coupling process.     

Fenton degradation of 4-chlorophenol contaminated water promoted by solar irradiation

The degradation of 4-chlorophenol (4-CP) contaminated water by Fenton process with or without solar irradiation assistance were investigated. It was found that the COD degradation and mineralization efficiency of 4-CP were more than 90% when a 30 min treatment of solar photo-Fenton oxidation process was applied and under an optimum [H₂O₂]₀/[Fe²⁺]₀ ratio of 40, the COD degradation and mineralization efficiency increased 65% as compared to Fenton oxidation. Meanwhile, the AOS values increased from −0.33 to 2.13 in solar photo-Fenton process while no significant improvement for AOS values was found in Fenton process, implying a higher degree of oxidation for 4-CP in solar photo-Fenton process. In addition, increasing the intensity of solar irradiation seemed to be beneficial for treatment of 4-CP contaminated water. Formation of chloride ion as a result of mineralization of organically bounded chlorine was identified during the treatment of 4-CP solution. Near-stoichiometric accumulation of chlorine was observed during the degradation of 4-CP in both Fenton and solar photo-Fenton processes. However, accumulation rate of chloride ions were much faster in solar photo-Fenton process. The degradation of 4-CP was found to obey a pseudo-first-order reaction kinetics. As compared to Fenton process, the presence of solar light in photo-Fenton process increases the reaction rate by a factor of 6.5 and 15.8 for COD and TOC degradation, respectively. In other words, during the treatment of 4-CP contaminated water, solar photo-Fenton process possesses notably higher mineralization efficiency in a relatively short radiation time as compared to Fenton process, and could enhance the degradation treatment of refractory organic wastewater such as 4-CP in a cost-effective approach.     

Hydrogen production by redox of bimetal cation-modified iron oxide

Pure hydrogen can be stored and supplied directly to polymer electrolyte fuel cell by the redox of iron oxide: Fe₃O₄ + 4H₂ → 3Fe + 4H₂O and 4H₂O + 3Fe → Fe₃O₄ + 4H₂. Four bimetal-modified samples were prepared by impregnation. The hydrogen storage properties of the samples were investigated. The result shows that the Fe₂O₃–Mo–Al sample presented the most excellent catalytic activity and cyclic stability. H₂ forming temperature and H₂ forming rate could be surprisingly decreased and enhanced, respectively. The average H₂ forming temperature at the rate of 250 μmol min⁻¹·Fe-g⁻¹ for Fe₂O₃–Mo–Al in the first 4 cycles could be decreased from 469 °C before the addition of Mo–Al to 273 °C after the addition of Mo–Al. The reason for it may be that the Mo–Al additive in the sample can prevent from the sintering of the particles and accelerate the H₂O decomposition due to Mo taking part in the redox reaction. The average storage capacity of Fe₂O₃–Mo–Al was up to 4.68 wt%.     

Hydrogen permeation through dual-phase ceramic membrane derived from automatic phase-separation of SrCe0.50Fe0.50O3-δ precursor

Dense ceramic membranes with mixed protonic-electronic conductivity have been widely studied because of their 100% H₂ selectivity and directly integrated advantage with high-temperature chemical reactions. In this study, Sr-based dual-phase ceramic membrane SrCe_0.95Fe_0.05O_3-δ-SrFe_0.95Ce_0.05O_3-δ (SCF-SFC) with mixed protonic-electronic conductivity was obtained by automatic phase-separation of SrCe_0.5Fe_0.5O_3-δ (SCF55) precursor. After calcination at 1350 °C, the rationally designed SCF55 precursor auto-decomposed into two thermodynamically stable oxides: Ce-rich phase SrCe_0.95Fe_0.05O_3-δ and Fe-rich phase SrFe_0.95Ce_0.05O_3-δ that functioned as protonic and electronic conductors, respectively. The compositions and microstructures of the auto-formed phases were studied via XRD and SEM analyses. The dual-phase SCF-SFC membrane shows a high hydrogen permeation flux of 0.38 mL min⁻¹ cm⁻² at 940 °C. Stability tests indicated that the SCF-SFC membrane exhibited higher and more stable hydrogen permeation flux with less degradation under CO₂-containing atmospheres compared with the BaCe_0.15Fe_0.85O_3-δ-BaCe_0.85Fe_0.15O_3-δ (BCF-BFC) membrane. This significant improvement can be attributed to the lower CO₂ adsorption and reduced carbonate formation which is indicated by thermogravimetric analysis.