Ni Ce0 Research Articles

Boosting oxygen vacancy formation and Ni dispersion by Ce0.9Y0.1O2 nanorod: Efficient water and hydrocarbon activation

Ni-based higher hydrocarbon steam reforming (SR) catalyst usually encounters low water dissociation rate and carbon deposition-induced inactivity and instability. Herein, we report a Ni–Ce0.9Y0.1O2-nanorod (Ni–CYO–NR) with a MgSiO3 postcoating that exhibits a TOF and conversion of 0.18·s−1 and 95% at 700 ℃ and carbon deposition amount and deactivation rate constant 2 orders of magnitude lower than those of Ni–Ce0.9Y0.1O2-nanoparticle (Ni–CYO–NP). Characterization results suggested that Ni–CYO–NR has a higher oxygen vacancy concentration and Ni dispersion than Ni–Ce0.9Zr0.1O2–NR and Ni–CYO–NP because of its CYO(110) nature. DFT calculations revealed that CYO(110) has the lowest formation energy of oxygen vacancies and energy barrier for H2O dissociation relative to CZO(110) and CYO(111). Additionally, MgSiO3 postcoating inhibited the deep sintering of Ni, which in turn suppressed carbon formation. This demonstrates that the superior n-dodecane SR performance of MgSi–Ni–CYO–NR can be attributed to the enhanced and stabilized O–H, C–C, and C–H bond dissociation and carbon formation resistance and removal.

Performance enhanced of Ni Ce0.8Sm0.2O1.9 hydrogen electrode for reversible solid oxide cells with cadmium substitution

Ni1-xCdxO-SDC composite materials are prepared and investigated as the hydrogen electrodes for reversible solid oxide cell (RSOC). XRD, SEM, XPS and Raman techniques have been used to characterize structural properties, textural and mobility of adsorbed oxygen and lattice oxygen. After reduction, Cd is incorporated into the lattice of Ni and formed NiCd alloy. The reduced Ni0.9Cd0.1O-SDC possesses the most oxygen vacancies, resulting in the highest catalytic activity for the electrochemical oxidation of H2 and the electrolysis of H2O. The electrochemical oxidation process of H2 on the hydrogen electrode in solid oxide fuel cell (SOFC) mode is investigated with a symmetric cell under various H2 partial pressures. The surface diffusion of adsorbed H atom on the reduced Ni1-xCdxO-SDC composite hydrogen electrodes is the rate-determining step (RDS) for H2 electrochemical oxidation reaction and the reduced Ni0.9Cd0.1O-SDC shows the highest electrochemical oxidation rates. The maximum power densities (Pmax) of the cells with reduced Ni0.9Cd0.1O-SDC as hydrogen electrode is 796.2 mW cm−2 when using H2 as the fuel at 700 °C. Furthermore, in solid oxide electrolysis cell (SOEC) mode, the cell with reduced Ni0.9Cd0.1O-SDC as hydrogen electrode exhibits the best electrolysis performance under various H2O concentrations and the current densities remain stable during the test at different voltages for a total period of 10 h under 47%H2O + 53%H2O atmosphere at 700 °C.

High-performance direct carbon dioxide-methane solid oxide fuel cell with a structure-engineered double-layer anode

Reduced La0.6Sr0.2Cr0.85Ni0.15O3 (LSCrN) contains exsolved Ni nanoparticles (LSCrN@Ni) and abundant oxygen vacancies. Thus, it is an excellent catalyst for CO2 dry reforming of CH4. To use CH4 directly in solid oxide fuel cells, Ni–Ce0.9Gd0.1O1.95 (GDC) anode-supported cells are fabricated with and without a layer of LSCrN@Ni-20 wt% GDC on top of the anode, which are defined as double anode supported cell (DASC) and conventional anode supported cell (CASC), respectively. They are investigated comparatively by X-ray diffraction, thermal expansion, thermogravimetry, scanning electron microscopy, and electrochemical performance measurement in H2 and 50%CO2–50%CH4 fuels. Both CASC and DASC demonstrate similarly high performance with H2 fuel, the maximum power density is 856 and 822 mW cm−2 at 750 °C, respectively. When 50%CO2–50%CH4 is used, DASC outperforms CASC significantly, showing a maximum power density of 758 mW cm−2 and an on-cell CH4 conversion of 85.5% at 750 °C. Also, DASC demonstrates a stable performance, and the cell voltage and CH4 conversion remain unchanged at 0.65 V and 84% without detectable carbon formation in the anode, while those of CASC decrease monotonously from the beginning with observable carbon formation during a test of 36 h under 400 mA cm−2 at 750 °C.

The role of Ce addition in catalytic activity enhancement of TiO2-supported Ni for CO2 methanation reaction.

In this work, various amounts of Ce were added to TiO2 to form a mixed oxide support; CexTi1−xO2 (x = 0, 0.003, 0.05, 0.10 and 0.15) and then those synthesized supports were impregnated by 10 wt% Ni to produce a catalysts. The 10 wt% Ni–CexTi1−xO2 (x = 0, 0.003, 0.05, 0.10 and 0.15) catalysts were tested for CO2 methanation reaction by using a fixed-bed reactor in the temperature range of 100–500 °C. The sample was pretreated at 450 °C under H2 and then a mixed feed gas of CO2 and H2 was switched into the reactor to start the reaction. The results showed that 10 wt% Ni–Ce0.003Ti0.997O2 catalyst (the lowest Ce content) exhibited the highest CO2 conversion and CH4 yield. Moreover, 10 wt% Ni–Ce0.003Ti0.997O2 showed highly stable during the stability test (50 h.). The results indicated that upon addition of small amount of Ce into TiO2-supported Ni, the surface, structural, electrical and redox properties of the catalyst were improved to the extent that these properties can promote the catalytic activities for CO2 methanation. The Ce addition can improve the CO2 methanation catalytic activity by several ways. First, higher dispersion of Ni on catalysts surface upon addition of Ce was observed which resulted in higher adsorption rate of H2 on this metal active site. Second, formation of a larger amounts of oxygen vacancies as well as basicity improvement upon addition of Ce were occurred which can increase the CO2 adsorption on catalyst surface. Third, incorporation of Ce resulted in improving of a starting reduction temperature of Ni2+ to Ni0 for TiO2-supported Ni catalyst which can indicate that the reducibility of Ce-doped TiO2-supported Ni catalyst was enhanced and then alter its catalytic activity. However, increasing of Ce content led to lowering of CO2 methanation activities which resulted from increasing of basicity by Ce addition. The excess amounts of adsorbed CO2 would lead to competitive adsorption to H2 and then lead to a decrease of catalytic activity. Therefore, an appropriate amount of H2 and CO2 adsorption ability on catalyst surface was a prominent factor to dominate the catalytic activity.

Synthesis and characterization of Pt-, Pd-, and Ru-promoted Ni–Ce0.6Zr0.4O2 catalysts for efficient biodiesel production by deoxygenation of oleic acid

Herein, we prepared Pt-, Pd-, and Ru-promoted Ni–Ce0.6Zr0.4O2 catalysts with improved oleic acid deoxygenation performance and investigated their physicochemical properties by N2 adsorption-desorption, X-ray diffraction (XRD), NH3 temperature-programmed desorption (NH3-TPD), and X-ray photoelectron spectroscopy (XPS). Among the above catalysts, the highest oleic acid conversion, C9–C17 selectivity, and oxygen removal efficiency were observed for Pt/Ni–Ce0.6Zr0.4O2, which was mainly ascribed to its highest surface defect oxygen fraction and acidity.

Influence of Calcination Temperature on Activity and Selectivity of Ni–CeO2 and Ni–Ce0.8Zr0.2O2 Catalysts for CO2 Methanation

Herein, we studied the influence of calcination temperature (500–800 °C) of Ni/CeO2 and Ni/Ce0.8Zr0.2O2 catalysts on the specific surface area, pore volume, crystalline size, lattice parameter, chemical bonding and oxidation states, nickel dispersion and CH4/CO production rate in CO2 methanation. In general, the catalytic performance revealed that Zr doping catalysts could increase the CH4 production rate. Combined with the production rate and the characterizations results, we found that the combination of nickel dispersion, peak area of CO2–TPD and OII/(OII + OI)) play the critical role in increasing the CH4 production rate. It is well to be mentioned that the CO production rate is strongly influenced by the nickel dispersion. Furthermore, the in-situ DRIFTS confirmed that the CO originates from the decomposition of H-assisted formate species.

High performance intermediate temperature solid oxide fuel cells with Ba0.5Sr0.5Co0.8Fe0.1Nb0.1O3−δ as cathode

Ba0.5Sr0.5Co0.8Fe0.1Nb0.1O3−δ (BSCFN) perovskite oxides have been synthesized and studied as the cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). XRD and SEM testing results demonstrate that BSCFN is chemical and physical compatible with La0.8Sr0.2Ga0.83Mg0.17O3−δ(LSGM) electrolyte. The BSCFN cathodes exhibit excellent catalytic activity for oxygen reduction and mobility. High maximum power densities of 0.22, 0.41 and 0.63Wcm−2 have been obtained for the Ni–Ce0.9Gd0.1O2−δ(GDC)/La0.4Ce0.6O2−δ(LDC)/LSGM/BSCFN electrolyte supported single cell at 600, 650 and 700°C, respectively. Further, the cell exhibits a stable performance under a constant current load of 0.6Acm−2 for over 100h at 650°C, indicating the BSCFN is an excellent cathode material for IT-SOFCs.

Ceria catalyst for inert-substrate-supported tubular solid oxide fuel cells running on methane fuel

A ceria catalyst is applied to an inert-substrate supported tubular single cell for direct operation on methane fuel. The tubular single cell comprises a porous yttria-stabilized zirconia (YSZ) supporter, a Ni–Ce0.8Sm0.2O1.9 anode, a YSZ/Ce0.8Sm0.2O1.9 bi-layer electrolyte, and a La0.6Sr0.4Co0.2Fe0.8O3−δ cathode. The ceria catalyst is incorporated into the porous YSZ supporter layer by a cerium nitrate impregnation. The effects of ceria on the microstructure and electrochemical performance of the tubular single cell are investigated with respect to the number of impregnations. The optimum number of impregnations is determined to be four based on the maximum power density and polarization property of the tubular single cell in hydrogen and methane fuels. At 700 °C, the tubular single cell shows similar maximum power densities of ∼260 mW cm−2 in hydrogen and methane fuels, respectively. Moreover, the ceria catalyst significantly improves the performance stability of the cell running on methane fuel. At a current density of 350 mA cm−2, the single cell shows a low degradation rate of 2.5 mV h−1 during the 13 h test in methane fuel. These results suggest the feasibility of applying the ceria catalyst to the inert-substrate supported tubular single cell for direct operation on methane fuel.

Stable direct-methane solid oxide fuel cells with calcium-oxide-modified nickel-based anodes operating at reduced temperatures

In this study, some basic oxide additives are introduced into the conventional Ni–Ce0.8Sm0.2O1.9 (SDC) cermet anodes of solid oxide fuel cells (SOFCs) for using methane as the fuel. The effects of incorporating basic oxides on the phase composition, electrical conductivity, microstructure, coking tolerance and catalytic/electrocatalytic activity of the anodes are systematically studied. The basic oxide content and the possible phase reactions in the composite anode have considerable effects on the chemical interactions, electrical conductivities and coking resistances of the cermet anodes. The CaO-modified Ni–SDC anode exhibits higher catalytic performance and/or superior coking tolerance than the Ni–SDC and BaO, SrO, MgO, La2O3-modified Ni–SDC anodes under methane steam reforming conditions. The SOFC with a CaO-modified Ni–SDC anode delivers a much higher power generation than the cells composed of the pristine and BaO-modified Ni–SDC anodes using humidified methane fuel at intermediate temperatures. The improved coking resistance of the CaO-modified Ni–SDC anode results in a more stable voltage in the durability test using methane fuel than the cell with a Ni–SDC anode under the same test conditions. In summary, the CaO-modified Ni–SDC composite is a potential coking-resistant and active anode material for SOFCs that use methane as fuel.

Evaluation of Ca3(Co,M)2O6 (M=Co, Fe, Mn, Ni) as new cathode materials for solid-oxide fuel cells

Series compounds Ca3(Co0.9M0.1)2O6 (M=Co, Fe, Mn, Ni) with hexagonal crystal structure were prepared by sol–gel route as the cathode materials for solid oxide fuel cells (SOFCs). Effects of the varied atomic compositions on the structure, electrical conductivity, thermal expansion and electrochemical performance were systematically evaluated. Experimental results showed that the lattice parameters of Ca3(Co0.9Fe0.1)2O6 and Ca3(Co0.9Mn0.1)2O6 were both expanded to certain degree. Electron-doping and hole-doping effects were expected in Ca3(Co0.9Mn0.1)2O6 and Ca3(Co0.9Ni0.1)2O6 respectively according to the chemical states of constituent elements and thermal-activated behavior of electrical conductivity. Thermal expansion coefficients (TEC) of Ca3(Co0.9M0.1)2O6 were measured to be distributed around 16×10−6K−1, and compositional elements of Fe, Mn, and Ni were especially beneficial for alleviation of the thermal expansion problem of cathode materials. By using Ca3(Co0.9M0.1)2O6 as the cathodes operated at 800°C, the interfacial area-specific resistance varied in the order of M=Co<M=Fe<M=Ni<M=Mn, and the over-potential increased in the order of M=Fe≈M=Co<M=Mn<M=Ni. Among all of these compounds, Ca3(Co0.9Fe0.1)2O6 showed the best electrochemical performance and the power density as high as ca. 500mWcm−2 at 800°C achieved in the single cell with La0.8Sr0.2Ga0.83Mg0.17O2.815 as electrolyte and Ni–Ce0.8Sm0.2O1.9 as anode. Ca3(Co0.9M0.1)2O6 (M=Co, Fe, Mn, Ni) can be used as the cost-effective cathode materials for SOFCs.

Long-term stability of metal-supported solid oxide fuel cells employing infiltrated electrodes

Here, stability of the metal-supported solid oxide fuel cell (MS-SOFC) with Ni–Ce0.8Sm0.2O2−δ (SDC) infiltrated 430L anode and La0.6Sr0.4Fe0.9Sc0.1O3−δ (LSFSc) infiltrated scandia-stabilized zirconia (SSZ) cathode is evaluated. It is found that the degradation rate defined as the voltage loss during a fixed period is faster at higher operation temperatures and larger current densities. Scanning electron microscopy (SEM) and energy dispersive X-ray spectra (EDS) analysis indicate that the degradation is mainly caused by the morphological change of the anode while metal element diffusion between Ni catalyst and 430L substrate contributes little. A 1500 h durability test measured at 650 °C and 0.9 A cm−2 shows a degradation rate of 1.3% kh−1 and the voltage decrease is mainly found in the initial 500 h.

Enhanced electrochemical activity in Ca3Co2O6 cathode for solid-oxide fuel cells by Cu substitution

Cu-substituted Ca3(Co1−xCux)2O6 (x = 0, 0.05, 0.1, 0.15) are prepared and evaluated as cathode materials for solid-oxide fuel cells (SOFCs). Effects of Cu substitution for Co on structure, electrical conductivity, thermal expansion and electrochemical performance have been investigated. Pure hexagonal structure can be attained, but a small amount of impurity phase Ca0.828CuO2 appears if x is high. Ca3Co2O6 behaves as a thermal-activated semiconductor in the temperature range between 300 and 800 °C; its electrical conductivity is remarkably enhanced by Cu substitution. Experimental results show coexistence of mixed valent Co ions and disordered state of oxygen vacancies in the Cu-substituted samples. Meanwhile, Cu substitution leads to slightly enlarged thermal expansion coefficient, reduced area specific resistance and improved electrochemical performance. For x = 0.05, the power density as high as ca. 550 mW cm−2 at 800 °C is achieved in the single cell with La0.8Sr0.2Ga0.83Mg0.17O2.815 as electrolyte and Ni–Ce0.8Sm0.2O1.9 as anode. Cu substitution can effectively enhance the electronic and ionic transport properties of Ca3Co2O6 cathode for SOFCs.

Hydrocarbon-fueled solid oxide fuel cells with surface-modified, hydroxylated Sn/Ni–Ce0.8Gd0.2O1.9heterogeneous catalyst anode

Ni-catalyst-based anode-supported solid oxide fuel cells (SOFCs) operating with H2 fuel are highly efficient, low-emission, electrochemical energy conversion devices. However, the economical production of hydrogen is a challenge, and there is immense interest to use hydrocarbon fuels directly with SOFC. Unfortunately, the solid-carbon generated continuously by hydrocarbon cracking accumulates on the Ni-metal surface and leads to rapid decline in performance. We show here that 1 atom% Sn (with respect to Ni) incorporated onto a surface-modified Ni–Ce0.8Gd0.2O1.9 (GDC) cermet anode with extended three-phase boundaries, where O2− ions, electrons, and fuels get together, acts as an excellent decoking agent. The hydrophilic Sn doped on the surface of Ni is hydrated and hydroxylated by reacting with the water vapour produced by the electrochemical oxidation of the fuel, and the hydroxyl groups aid the oxidation of neighbouring carbon and drive off as CO2. Moreover, the enlarged three-phase boundaries of the anode allow O2− ions to rapidly reach the deposited carbon as well as the hydrocarbon gas and electrochemically oxidize them. With this modified Sn/Ni–GDC catalyst anode, GDC electrolyte, and La0.6Sr0.4Co0.2Fe0.8O3−δ cathode, more than 200 h of operation with a methane-fueled SOFC is demonstrated here.

Performance Comparison between Ni–SDC and Ni–YSZ Cermet Electrodes for Carbon Dioxide Electrolysis on Solid Oxide Electrolysis Cell

Solid oxide electrolysis cells (SOECs) have already proven their ability to electrolyze steam (H2O). Recently, the attention has been drawn towards the electrolysis of carbon dioxide (CO2). In this paper, the electrochemical reduction of CO2 over Ni–Ce0.8Sm0.2O1.9 (SDC) and Ni–8 mol% Y2O3–ZrO2(YSZ) electrodes was studied on SOEC device.Cells used in this work consist of Ni–SDC or Ni–YSZ cermet electrodes, YSZ electrolyte, and (La0.8Sr0.2)0.97MnO3 (LSM) electrode. Electrochemical properties of SOEC were evaluated by impedance spectroscopy and current–voltage (I–V) curves with a supply of CO2/H2 and pure O2 gases to the cathode and anode sides, respectively, at 1000 oC.The results of preliminary experiments indicated that in CO2/H2 mixture, CO2 reduction proceeds indirectly via kinetically fast reverse water-gas shift reaction (RWGSR, CO2 + H2 ⇌ CO + H2O). The impact of cathode material on CO2 reduction was studied as depicted in Fig. 1 (a) and (b), which shows I–V curves of single button cells employing Ni–SDC and Ni–YSZ electrodes, respectively. The cell with Ni–SDC electrode exhibited relatively high current density compared with Ni–YSZ electrode. The better performance of Ni–SDC electrode depends on the conductivity of doped ceria; it exhibits higher ionic conductivity than YSZ and shows electronic conductivity under a reducing atmosphere. These two factors are most likely extended the effective triple phase boundary (TPB) region and improved the electrochemical reactions at electrode/electrolyte interface.

Metal supported solid oxide fuel cells with infiltrated nanoelectrodes

Novel metal supported solid oxide fuel cells (SOFCs) containing porous 430L support, yttria stabilised zirconia (YSZ) electrolyte and porous YSZ layer are fabricated by tape casting, tape lamination and subsequent cofiring in a reduced atmosphere. Nano Ni–Ce0·8Sm0·2O2−δ (SDC) and La0·8Sr0·2FeO3−δ (LSF) particles, which act as anode and cathode catalysts, individually, are infiltrated onto the internal surfaces of porous 430L and YSZ respectively. Maximum power density of the single cell is 850 mW cm−2 at 800°C. Encouraging performances of the infiltrated electrodes are also achieved, e.g. 0·06 Ω cm2 for the LSF infiltrated YSZ composite cathode and 0·075 Ω cm2 for the Ni-SDC infiltrated 430L composite anode at 800°C. Additionally, oxygen reduction kinetics over infiltrated LSF–YSZ composite cathodes is also studied.

Evaluation of Ni and Ni–Ce0.8Sm0.2O2−δ (SDC) impregnated 430L anodes for metal-supported solid oxide fuel cells

Ni impregnated 430L anodes used for metal-supported solid oxide fuel cells are prepared and evaluated. The effects of catalysts loadings and heat treatment temperatures on the anode polarization resistances are investigated. The stabilities of the Ni impregnated 430L anodes are also measured and increasing the calcination temperature can enable a much more stable anode performance. Furthermore, by applying the Ni–Ce0.8Sm0.2O2−δ (SDC) impregnated 430L composite anode, a low polarization resistance of 0.12 Ω cm2 at 650 °C is obtained. The 1200 h durability test shows that the polarization resistance of the composite anode increases from 0.12 Ω cm2 to 0.3 Ω cm2 during the initial 500 h while no degradation is found during the subsequent measurement.

The effect of preparation method on the catalytic performance over superior MgO-promoted Ni–Ce0.8Zr0.2O2 catalyst for CO2 reforming of CH4

The effect of preparation method on MgO-promoted Ni–Ce0.8Zr0.2O2 catalysts was investigated in CO2 reforming of CH4. Co-precipitated Ni–MgO–Ce0.8Zr0.2O2 exhibited very high activity as well as stability (XCH4 > 95% at 800 °C for 200 h) due to high surface area, high dispersion of Ni, small Ni crystallite size, and easier reducibility. Four elements (Ni, Mg, Ce, and Zr) are located at the same position for the co-precipitated catalyst, resulting in easier reducibility.

Preparation of nano-structured Ni–Ce0.8Gd0.2O1.9 anode materials for solid oxide fuel cells via the water-in-oil (W/O) micro-emulsion route

Highly dispersed nano-crystalline NiO–Ce0.8Gd0.2O1.9 (GDC) anode powders were synthesized through a novel water-in-oil (W/O) micro-emulsion route, that has not been previously reported. The spherical-shaped NiO–Ce0.8Gd0.2O1.9 nano-powders exhibited a high degree of dispersion, and the morphology of the NiO–Ce0.8Gd0.2O1.9 particles was controlled by varying the aqueous to oil phase ratio. The polarization resistance at 800 °C with humidified H2 fuel and the activation energy of ME10 anode synthesized by the micro-emulsion method with the aqueous to oil phase volume ratios of 1:12 were 0.02 Ω cm2 and 0.55 eV, respectively, which were significantly lower than those of other Ni–ceria-based anodes. These properties contributed to a smaller particle size and better dispersion compared to conventional anode materials, leading to an increased number of reaction sites. In accordance with the polarization resistance results, single cells containing ME10 anodes exhibited a high maximum power density of 0.36 W cm−2 at 800 °C with humidified H2 fuel.

H2 and CO production over a stable Ni–MgO–Ce0.8Zr0.2O2 catalyst from CO2 reforming of CH4

Ni–Ce0.8Zr0.2O2 and Ni–MgO–Ce0.8Zr0.2O2 catalysts were investigated for H2 production from CO2 reforming of CH4 reaction at a very high gas hourly space velocity of 480,000 h−1. Ni–MgO–Ce0.8Zr0.2O2 exhibited higher catalytic activity and stability (CH4 conversion >95% at 800 °C for 200 h). The outstanding catalytic performance is mainly due to the basic nature of MgO and an intimate interaction between Ni and MgO.

Sol–gel auto-combustion synthesis of Ni–CexZr1−xO2 catalysts for carbon dioxide reforming of methane

Carbon dioxide reforming of methane (methane dry reforming) over Ni–Ce0.8Zr0.2O2 catalysts prepared by a sol–gel auto-combustion method and a conventional co-precipitation method were comparatively studied. We show that sol–gel auto-combustion is very promising for preparing thermal stable homogeneous mixed metal oxide catalysts. The auto-combustion synthesized catalyst exhibited higher initial activity and stability due to its smaller Ni crystalline size and intimate interaction between Ni and Ce0.8Zr0.2O2. In contrast, the co-precipitated catalyst showed poor activity and deactivated rapidly. The rapid deactivation was caused by a higher graphitization degree of the deposited carbon over co-precipitated catalyst with larger Ni crystalline size. We also found that the physico-chemical properties and catalytic activity of sol–gel auto-combustion synthesized catalysts were closely related to the metal nitrate (MN)/citric acid (CA) ratio. High MN/CA ratio led to more violent combustion behaviour and an accordingly higher degree of crystallization of the synthesized catalyst. In contrast, a low MN/CA ratio resulted in more carbon species residues and poor catalytic performance. The Ce/Zr ratio also had a profound influence on the phase structure, reducibility, oxygen vacancies and catalytic performance of Ni–Ce0.8Zr0.2O2 catalysts. Ni–Ce0.8Zr0.2O2 catalyst with cubic phase exhibited the best catalytic performance because of high reducibility, high Ni dispersion and strong Ni-CexZr1−xO2 interaction, and considerable amounts of oxygen vacancies.