Ultrasonic spray pyrolysis synthesis of Ag/TiO2 nanocomposite photocatalysts for simultaneous H2 production and CO2 reduction

Simultaneous photocatalytic hydrogen production and CO₂ reduction (to form CO and CH₄) from water using methanol as a hole scavenger were investigated using silver-modified TiO₂ (Ag/TiO₂) nanocomposite catalysts. A simple ultrasonic spray pyrolysis (SP) method was used to prepare mesoporous Ag/TiO₂ composite particles using TiO₂ (P25) and AgNO₃ as the precursors. The material properties and photocatalytic activities were compared with those prepared by a conventional wet-impregnation (WI) method. It was found that the samples prepared by the SP method had a larger specific surface area and a better dispersion of Ag nanoparticles on TiO₂ than those prepared by the WI method, and as a result, the SP samples showed much higher photocatalytic activities toward H₂ production and CO₂ reduction. The optimal Ag concentration on TiO₂ was found to be 2 wt%. The H₂ production rate of the 2% Ag/TiO₂–SP sample exhibited a six-fold enhancement compared with the 2% Ag/TiO₂–WI sample and a sixty-fold enhancement compared with bare TiO₂. The molar ratio of H₂ and CO in the final products can be tuned in the range from 2 to 10 by varying the reaction gas composition, suggesting a viable way of producing syngas (a mixture of H₂ and CO) from CO₂ and water using the prepared Ag/TiO₂ catalysts with energy input from the sun.     

Electrochemical reduction of CO2 in solid oxide electrolysis cells

This paper describes results on the electrochemical reduction of carbon dioxide using the same device as the typical planar nickel-YSZ cermet electrode supported solid oxide fuel cells (H₂-CO₂, Ni-YSZ|YSZ|LSCF-GDC, LSCF, air). Operation in both the fuel cell and the electrolysis mode indicates that the electrodes could work reversibly for the charge transfer processes. An electrolysis current density of ≈1 A cm⁻² is observed at 800 °C and 1.3 V for an inlet mixtures of 25% H₂-75% CO₂. Mass spectra measurement suggests that the nickel-YSZ cermet electrode is highly effective for reduction of CO₂ to CO. Analysis of the gas transport in the porous electrode and the adsorption/desorption process over the nickel surface indicates that the cathodic reactions are probably dominated by the reduction of steam to hydrogen, whereas carbon monoxide is mainly produced via the reverse water gas shift reaction.     

Effect of SiO2 additives on the PEM fuel cell electrode performance

The Nafion membrane used as an electrolyte in the Polymer Electrolyte Membrane Fuel Cell (PEMFC) needs hydration to retain the proton conductivity. In PEMFC operation the reactant gas needs to be humidified either externally or internally. To reduce the cost, weight and complexities of the PEMFC system, it is beneficial to operate the PMEFC without humidification of the reactant gases because it eliminates the need for a complex gas-humidification sub-system. In recent years, worldwide R&D efforts have been made to remove the external humidifying unit from the PEMFC system by endowing the membrane electrode assembly (MEA) with self-humidifying ability. Efforts have been made to minimize humidification of the ionic polymer by introducing SiO₂ either in the catalyst layer or on the gas diffusion layer or on the membrane directly. In-house has made two silica powders, 1. Aerogel silica, surface area is 582 m²/g and 2. Silica powder with surface area of 45 m²/g is incorporated in the fuel cell electrode. This improves the hydrophilic and protonation properties of the SiO₂ powders when treated with H₂SO₄. Initial experiments under humidified conditions showed that the Silica powder, which was not treated with H₂SO_4, gave marginally lower performance compared to the H₂SO₄ treated sample. The polarization behaviors of the electrode with and without SiO₂ in the catalyst layer were studied. The PEMFC was also studied under different humidity conditions. The electrodes and the PEMFC were characterized by different electrochemical techniques like cyclic voltammetry and Electrochemical Impedance Spectroscopy (EIS). The results are presented in this paper.     

High performance composite hollow fiber membranes for CO2/H2 and CO2/N2 separation

The search for a clean energy source as well as the reduction of CO₂ emissions to the atmosphere are important strategies to resolve the current energy shortage and global warming issues. We have demonstrated, for the first time, a Pebax/poly(dimethylsiloxane)/polyacrylonitrile (Pebax/PDMS/PAN) composite hollow fiber membrane not only can be used for flue gas treatment but also for hydrogen purification. The composite membranes display attractive gas separation performance with a CO₂ permeance of 481.5 GPU, CO₂/H₂ and CO₂/N₂ selectivity of 8.1 and 42.0, respectively. Minimizing the solution intrusion using the PDMS gutter layer is the key to achieving the high gas permeance while the interaction between poly(ethylene oxide) (PEO) and CO₂ accounts for the high selectivity. Effects of coating solution concentration and coating time on gas separation performance have been investigated and the results have been optimized. To the best of our knowledge, this is the first polymeric composite hollow fiber membrane for hydrogen purification. The attractive gas separation performance of the newly developed membranes may indicate good potential for industrial applications.     

Promotional effect of alkaline earth over Ni-La2O3 catalyst for CO2 reforming of CH4: Role of surface oxygen species on H2 production and carbon suppression

Alkaline earth elements (Mg, Ca and Sr) on Ni-La₂O₃ catalyst have been investigated as promoters for syngas production from dry CO₂ reforming of methane (DRM). The catalysis results of DRM performance at 600 °C show that the Sr-doped Ni-La₂O₃ catalyst not only yields the highest CH₄ and CO₂ conversions (∼78% and ∼60%) and highest H₂ production (∼42% by vol.) but also has the lowest carbon deposition over the catalyst surface. The XPS, O₂-TPD, H₂-TPR and FTIR results show that the excellent performance over the Sr-doped Ni-La₂O₃ catalyst is attributed to the presence of a high amount of lattice oxygen surface species which promotes C-H activation in DRM reaction, resulting in high H₂ production. Moreover, these surface oxygen species on the Ni-SDL catalyst can adsorb CO₂ molecules to form bidentate carbonate species, which can then react with the surface carbon species formed during DRM, resulting in higher CO₂ conversion and lower carbon formation.     

Anodic behavior of 8Y2O3-ZrO2/NiO cermet using an anode-supported electrode

8Y₂O₃-ZrO₂ (8YSZ)/NiO cermet anode-supported symmetric cell is introduced and fabricated using a tape casting process to analyze the anodic behavior of an anode-supported cell. An anode-supported symmetric cell helps us understand the complex anode structure of cermets. The anodic behavior of 8YSZ/NiO is compared to a MIEC electrode of Sm_0.2Ce_0.8O_1.9 (SDC)/NiO. The anodic behavior of a 8YSZ/NiO cermet electrode is investigated and discussed with respect to the hydrogen partial pressure (p(H₂)), water partial pressure (p(H₂O)), area specific resistance (ASR), activation energy (E_a), thermal cycle, and redox process. Based on these studies, an empirical reaction model of 8YSZ/NiO is established, and the related reaction processes are discussed. On impedance spectra diagram, high and medium frequency arcs are associated with the charge transfer process and the H₂O formation reaction, while the low frequency arc corresponds to the dissociative adsorption and the surface diffusion/gas phase diffusion process. Changes in microstructure by redox and thermal cycling have a significant effect on the electrochemical properties and structural stability of a thick anode-supported cermet structure.     

Synthesis, characterization and electrocatalytical behavior of Nb-TiO2/Pt nanocatalyst for oxygen reduction reaction

In order to point out the effect of the support to the catalyst for oxygen reduction reaction nano-crystalline Nb-doped TiO₂ was synthesized through a modified sol-gel route procedure. The specific surface area of the support, S_BET, and pore size distribution, were calculated from the adsorption isotherms using the gravimetric McBain method. The support was characterized by X-ray diffraction (XRD) technique.The borohydride reduction method was used to prepare Nb-TiO₂ supported Pt (20 wt.%) catalyst. The synthesized catalyst was analyzed by TEM technique.Finally, the catalytic activity of this new catalyst for oxygen reduction reaction was investigated in acid solution, in the absence and the presence of methanol, and its activity was compared towards the results on C/Pt catalysts.Kinetic analysis reveals that the oxygen reduction reaction on Nb-TiO₂/Pt catalyst follows four-electron process leading to water, as in the case of C/Pt electrode, but the Tafel plots normalized to the electrochemically active surface area show very remarkable enhancement in activity of Nb-TiO₂/Pt expressed through the value of the current density at the constant potential.Moreover, Nb-TiO₂/Pt catalyst exhibits higher methanol tolerance during the oxygen reduction reaction than the C/Pt catalyst.The enhancement in the activity of Nb-TiO₂/Pt is consequence of both: the interactions of Pt nanoparticles with the support and the energy shift of the surface d-states with respect to the Fermi level what changes the surface reactivity.     

Cycle analysis of low and high H2 utilization SOFC/gas turbine combined cycle for CO2 recovery

A major factor in global warming is CO₂ emission from thermal power plants, which burn fossil fuels. One technology proposed to prevent global warming is CO₂ recovery from combustion flue gas and the sequestration of CO₂ underground or near the ocean bed. Solid oxide fuel cell (SOFC) can produce highly concentrated CO₂, because the reformed fuel gas reacts with oxygen electrochemically without being mixed with air in the SOFC. We therefore propose to operate multi-staged SOFCs with high utilization of reformed fuel to obtain highly concentrated CO₂. In this study, we estimated the performance of multi-staged SOFCs considering H₂ diffusion and the combined cycle efficiency of a multi-staged SOFC/gas turbine/CO₂ recovery power plant. The power generation efficiency of our CO₂ recovery combined cycle is 68.5%, whereas the efficiency of a conventional SOFC/GT cycle with the CO₂ recovery amine process is 57.8%.     

Highly efficient CO2 bubble removal on carbon nanotube supported nanocatalysts for direct methanol fuel cell

In this paper, we investigate the CO₂ microbubble removal on carbon nanotube (CNT)-supported Pt catalysts in direct methanol fuel cells (DMFCs). The experiments involve the incorporation of near-catalyst-layer bubble visualization and simultaneous electrochemical measurements in a DMFC anodic half cell system, in which CH₃OH electro-oxidation generate carbon dioxide (CO₂) microbubbles. We observe rapid removal of smaller CO₂ bubble sizes and less bubble accumulation on a Pt-coated CNT/CC (Pt/CNT/CC, CC means carbon cloth) electrode. The improved half cell performances of the high CO₂ microbubble removal efficiency on the CNT-modified electrode (Pt/CNT/CC) were 34% and 32% higher than on Pt/CC and Pt/CP electrodes, respectively.     

Reinforced photocatalytic reduction of CO2 to fuel by efficient S-TiO2: Significance of sulfur doping

The photocatalytic reduction of CO₂ to valuable chemicals and fuels is an efficient approach to control the ever-rising CO₂ level in the atmosphere. The present paper describes a significant improvement in photoreduction of carbon dioxide (CO₂) using sulfur (S) doped titania (S-TiO₂) nanoparticles as a photocatalyst under UV-A and visible light irradiation. The sulfur doping was done by following a simple sonothermal method, and a series of photocatalysts were synthesized with the varied amount of S doping. Various characterization techniques were employed for the photocatalysts such as XRD, surface area, UV–Visible, SEM, TEM, and XPS. The XPS reveals that S is predominantly present as S⁴⁺ in S-TiO₂. The electronic structure for S-TiO₂ anatase was calculated with the Vienna ab initio simulation package (VASP) code in the framework of spin-polarized density functional theory. Additional states closer to the valence band are produced inside the band gap as a result of doping. In situ reductive reaction conditions can partially reduce the catalyst, and results in the shift of Fermi level into the conduction band. It is suggested that S-doping increases catalyst surface conductivity, improves the charge transfer rate and the rate of photocatalytic reactions. The prepared series of catalysts have shown excellent activity under UV-A and visible light for photocatalytic reduction of CO₂. The effect of the different base including K₂CO₃, Na₂CO₃, NaOH and KOH; catalyst amount; sulfur doping amount; and light wavelength were monitored. Methane, ethylene, propylene, and propane were observed as reaction products. In 24 h, S-TiO₂ exhibited the highest photoactivity in KOH aqueous solution with a maximum yield of 6.25 μmol g^?1 methane, 2.74 μmol g^?1 of ethylene, 0.074 μmol g^?1 of propylene and 0.030 μmol g^?1 of propane under UV-A irradiation. The catalysts were active in visible light and able to generate methane and methanol in acetonitrile-H₂O mixture with/without TEOA as sacrificial donor producing 846.5 μmol g^?1 of methane and 4030 μmol g^?1 of methanol for the former and 167.6 μmol g^?1 of methane and 12828.4 μmol g^?1 of methanol for the latter case. An estimate demonstrates that mass transfer does not limit the CO₂ reaction.     

Visualization study on the dynamics of CO2 bubbles in anode channels and performance of a DMFC

The present study reports on experimental investigations of the dynamic behavior of CO₂ gas bubbles and the performance of a 9 cm² transparent direct methanol fuel cell (DMFC). The movement of CO₂ gas bubbles in the anode channel subjected to a flow of aqueous methanol solution was visualized. A series of parametric studies was carried out to evaluate the effects on the CO₂ gas bubbles dynamics as well as the cell performance. It was observed that the pores around the corner of the channel ribs and the intersection of the carbon cloth fibres were favorable sites for the emergence of CO₂ gas bubbles. The growth and coalescence of CO₂ gas bubbles resulted in gas slugs blocking the channel and the pores in porous diffusion layer as well. Then the gas slugs were pushed by the aqueous methanol solution flow to detach and sweep downstream, clearing all the existing small bubbles on the porous diffusion layer surface. The processes of emergence, growth, coalescence, detachment, and sweeping of the gas bubbles were found to occur periodically. High flow rates of the aqueous methanol solution resulted in small discrete CO₂ gas bubbles and short gas slugs. Increasing temperature of the methanol solution increased the quantity of CO₂ gas bubbles. More CO₂ gas bubbles and large gas slugs appeared in the channels with increasing pressure difference between the anode and the cathode. The cell performance was improved with increasing aqueous methanol flow rates, feed temperature, feed concentration, and the pressure difference between the anode and the cathode.     

Surface modification of solution combustion synthesized Ni/Al2O3 catalyst for aqueous-phase reforming of ethanol

The effect of surface modification of an alumina powder supported nano-scale nickel catalyst used in aqueous-phase reforming of ethanol has been explored in this paper. The Al₂O₃ powder was prepared by a solution combustion synthesis (SCS) route and the surface of the powder was modified by a non-thermal RF plasma treatment using nitrogen gas. Catalysts were coated by an impregnation method. The performances of the unmodified and modified Ni/Al₂O₃ catalysts have been compared from a catalytic activity, selectivity, and microstructural point of view. The catalytic activity results showed that while nature, relative ratio and selectivity of the products both in gas and liquid effluents did not change, catalytic activity (in terms of EtOH conversion and H₂ yield per g) of the sample increased after plasma modification. Microstructural (XRD, surface area) analysis showed that phase content and surface area of unmodified and modified catalysts are similar, while TEM and H₂-chemisorption showed higher metal surface area, higher metal dispersion and lower active metal particle size for the modified sample compared to the unmodified sample. The temperature programmed reduction (TPR) analysis demonstrated stronger support-metal interaction and smaller NiO particles for the modified catalyst at lower heat treatment temperature. The temperature programmed desorption (TPD) of ammonia analysis showed stronger acidity for the modified support, which can explain better dispersion of the metal particles on the modified catalyst compared to the unmodified sample.     

Cathodic H2 gas production through Pd alloy membrane electrodes

The object of this study was to develop a high performance hydrogen-metal oxide cell. A hydrogen permeable membrane electrode (HPME)-H₂-NiOOH rechargeable cell was tested for this purpose and the performance of the cathodic hydrogen gas production through the membrane electrode was investigated. A Pd 66.6 wt%-Ag 13.4 wt%-Au 20 wt% alloy membrane electrode, of which one surface was covered with PdPt black catalyst and the other with Pd black, was used to make one of the walls of the hydrogen gas containing vessel. When the PdPt catalysed electrolyte-facing surface is cathodically polarized in concentrated KOH solutions, hydrogen atoms dissolve in the membrane by penetrating it and leave the other palladized surface as free hydrogen gas, which passes into the gas chamber. The influence of electrode potential, hydrogen pressure in the gas chamber, membrane thickness, electrolyte concentration and temperature on the hydrogen production rate and yield into the gas chamber was investigated and a refined analysis on the said phenomena was carried out.     

Aqueous-phase reforming of n-BuOH over Ni/Al2O3 and Ni/CeO2 catalysts

The aqueous-phase reforming (APR) of n-butanol (n-BuOH) over Ni(20 wt%) loaded Al₂O₃ and CeO₂ catalysts has been studied in this paper. Over 100 h of run time, the Ni/Al₂O₃ catalyst showed significant deactivation compared to the Ni/CeO₂ catalyst, both in terms of production rates and the selectivity to H₂ and CO₂. The Ni/CeO₂ catalyst demonstrated higher selectivity for H₂ and CO₂, lower selectivity to alkanes, and a lower amount of C in the liquid phase compared to the Ni/Al₂O₃ sample. For the Ni/Al₂O₃ catalyst, the selectivity to CO increased with temperature, while the Ni/CeO₂ catalyst produced no CO. For the Ni/CeO₂ catalyst, the activation energies for H₂ and CO₂ production were 146 and 169 kJ mol⁻¹, while for the Ni/Al₂O₃ catalyst these activation energies were 158 and 175 kJ mol⁻¹, respectively. The difference of the active metal dispersion on Al₂O₃ and CeO₂ supports, as measured from H₂-pulse chemisorption was not significant. This indicates deposition of carbon on the catalyst as a likely cause of lower activity of the Ni/Al₂O₃ catalyst. It is unlikely that carbon would build up on the Ni/CeO₂ catalyst due to higher oxygen mobility in the Ni doped non-stoichiometric CeO₂ lattice. Based on the products formed, the proposed primary reaction pathway is the dehydrogenation of n-BuOH to butaldehyde followed by decarbonylation to propane. The propane then partially breaks down to hydrogen and carbon monoxide through steam reforming, while CO converts to CO₂ mostly through water gas shift. Ethane and methane are formed via Fischer-Tropsch reactions of CO/CO₂ with H₂.     

Combined air partial oxidation and CO2 reforming of coal bed methane to synthesis gas over co-precipitated Ni-Mg-ZrO2 catalyst

The present study aims at exploring a concept which can convert coal-bed methane (containing methane, air and carbon dioxide) to synthesis gas. Without pre-separation and purification, the low-cost synthesis gas can be produced by coupling air partial oxidation and CO₂ reforming of coal bed methane. For this purpose, the co-precipitated Ni-Mg-ZrO₂ catalyst was prepared. It was found that the co-precipitated Ni-Mg-ZrO₂ catalyst exhibited the best activity and stability at 800 °C during the reaction. The conversions of CH₄ and CO₂ maintained at 94.8% and 82.1% respectively after 100 h of reaction. The effect of reaction temperature was investigated. The H₂/CO ratio in the product was mainly dependent on the feed gas composition. By changing O₂/CO₂ ratio of the feed gases, the H₂/CO ratio in the off-gas varied between 0.8 and 1.8. The experimental results showed that the high thermal stability and basic properties of the catalyst, and the strong metal-support interaction played important roles in improving the activity and stability of the catalyst. With the combined reactions and the Ni-Mg-ZrO₂ catalyst, the coal bed methane could be converted to synthesis gas, which can meet the need of the subsequent synthesis processes.     

Synthesis of nanocrystalline mesoporous Ni/Al2O3SiO2 catalysts for CO2 methanation reaction

A series of nanocrystalline mesoporous Ni/Al₂O₃SiO₂ catalysts with various SiO₂/Al₂O₃ molar ratios were prepared by the sol-gel method for the carbon dioxide methanation reaction. The synthesized catalysts were evaluated in terms of catalytic performance and stability. The catalysts were studied using XRD, BET, TPR and SEM. The BET results indicated that the specific surface area of the samples with composite oxide support changed from 254 to 163.3 m²/g, and an increase in the nickel crystallite size from 3.53 to 5.14 nm with an increment of Si/Al molar ratio was visible. The TPR results showed a shift towards lower temperatures, indicating a better reducibility and easier reduction of the nickel oxide phase into the nickel metallic phase. Furthermore, the catalyst with SiO₂/Al₂O₃ molar ratio of 0.5 was selected as the optimal catalyst, which showed 82.38% CO₂ conversion and 98.19% CH₄ selectivity at 350 °C, high stability, and resistivity toward sintering. Eventually, the optimal operation conditions were specified by investigating the effect of H₂/CO₂ molar ratio and gas hourly space velocity (GHSV) on the catalytic behavior of the denoted catalyst.     

Pt/ZrO2 catalyst for a single-stage water-gas shift reaction: Ti addition effect

Ti modified Pt/ZrO₂ catalysts were prepared to improve the catalytic activity of Pt/ZrO₂ catalyst for a single-stage WGS reaction and the Ti addition effect on ZrO₂ was discussed based on its characterization and WGS reaction test. Ti impregnation into ZrO₂ increased the surface area of the support and the Pt dispersion. The reducibility of the catalyst was enhanced in the controlled Ti impregnation (∼20 wt.%) over Pt/ZrO₂ by the Pt-catalysed reduction of supports, particularly, at the interface between ZrO₂ and TiO₂. The significant CO₂ gas band in the DRIFTS results of Pt/Ti[20]/ZrO₂ indicated that the Ti addition made the formate decomposition rate faster than the Pt/ZrO₂ catalyst, linked with the enhanced Pt dispersion and reducibility of the catalyst. Consequently, Ti impregnation over the ZrO₂ support led to a remarkably enhanced CO conversion and the reaction rate of Pt/Ti[20]/ZrO₂ increased by a factor of about 3 from the bare Pt/ZrO₂ catalyst.     

On the activity and stability of Sr3NiPtO6 and Sr3CuPtO6 as electrocatalysts for the oxygen reduction reaction in a polymer electrolyte fuel cell

Sr₃NiPtO₆ and Sr₃CuPtO₆ were evaluated as low-platinum alternative oxygen reduction catalysts in a solid polymer electrolyte fuel cell at 80 °C. The oxides were synthesised using a new method based on an organometallic precursor route. The electrochemical evaluation showed similar oxygen reduction performance for Sr₃NiPtO₆ and Sr₃CuPtO₆, with a slightly higher activity for Sr₃NiPtO₆. In comparison with the oxides, the oxygen reduction activity for a commercial Pt/C catalyst was approximately 10 times higher. XRD analysis of the used electrodes revealed that the oxides were not stable in the PEMFC environment, and converted into platinum during operation. Elemental analysis of the used electrodes also showed a difference in platinum formation, where the platinum content on the surface of the electrode facing the gas diffusion layer was several times higher for Sr₃NiPtO₆ than Sr₃CuPtO₆. This indicates that the Sr₃NiPtO₆ electrode may be more susceptible to platinum migration.     

Photo-induced CO2 reduction by hydrogen for selective CO evolution in a dynamic monolith photoreactor loaded with Ag-modified TiO2 nanocatalyst

Ag-promoted TiO₂ nanoparticles immobilized over the cordierite monolithic support for dynamic and selective photo-reduction of CO₂ to CO by the use of hydrogen has been investigated. Ag-loaded TiO₂ NPs synthesized by a facile sol–gel method were coated over the monolith channels by dip-coating method. The samples were characterized by XRD, Raman, FTIR, SEM, TEM, XPS, N₂ adsorption–desorption, UV–Vis and PL spectroscopy. The photo-activity test of Ag-modified TiO₂ NPs was conducted for dynamic photocatalytic CO₂ reduction with H₂ as a reductant via a reverse water gas shift (RWGS) reaction in a cell type and monolith photo-reactors. Using 5 wt. % Ag/TO₂ NPs, CO₂ was energetically converted to CO with a yield rate 1335 μmole g-catal.^?1 h^?1, a 111 fold-higher than the amount of CO produced over the pure TiO₂ catalyst. More importantly, photo-activity of Ag/TiO₂ catalyst for CO evolution can be improved by 209 fold using monolith photo-reactor than the cell type reactor under the same operating conditions. This enactment was evidently due to the efficient light harvesting with larger illuminated surface area inside monolith micro-channels and efficient charges separation in the presence of Ag-metal. The reusability of Ag/TiO₂ NPs loaded over the monolithic support showed favorable recycling capability than the catalyst dispersed in a cell reactor. A possible reaction mechanism for this observation has been discussed in detail.     

Deposited RuO2–IrO2/Pt electrocatalyst for the regenerative fuel cell

A bifunctional RuO₂–IrO₂/Pt electrocatalyst for the unitized regenerative fuel cell (URFC) was synthesized by colloid deposition and characterized by analytical methods like TEM, XRD, etc. The result reveals that RuO₂–IrO₂ was well dispersed and deposited on the surface of Pt black. With deposited RuO₂–IrO₂/Pt as the catalyst of oxygen electrode, the performance of fuel cell/water electrolysis of unitized regenerative fuel cell (URFC) was studied in detail. URFC with deposited RuO₂–IrO₂/Pt shows better performance than that of URFC with mixed RuO₂–IrO₂/Pt catalyst. Cyclic performance of URFC with deposited RuO₂–IrO₂/Pt is very stable during 10 cyclic tests.