Houfu Lv,Yingjie Zhou,Xiaomin Zhang,Yuefeng Song,Qingxue Liu,Guoxiong Wang,Xinhe Bao
Solid oxide electrolysis cell (SOEC) can electrochemically convert CO 2 to CO at the gas-solid interface with a high current density and Faradaic efficiency, which has attracted increasing attentions in recent years. Exploring efficient catalyst for electrochemical CO 2 reduction reaction (CO 2 RR) at the cathode is a grand challenge for the research and development of SOEC. Sr 2 Fe 1.5 Mo 0.5 O 6- δ (SFM) is one kind of promising cathode materials for SOEC, but suffers from insufficient activity for CO 2 RR. Herein, Gd 0.2 Ce 0.8 O 1.9 (GDC) nanoparticles were infiltrated onto the SFM surface to construct a composite GDC-SFM cathode and improve the CO 2 RR performance in SOEC. The current density over the GDC infiltrated SFM cathode with a GDC loading of 12.8 wt% reaches 0.446 A cm −2 at 1.6 V and 800 °C, which is much higher than that over the SFM cathode (0.283 A cm −2 ). Temperature-programmed desorption of CO 2 measurements suggest that the infiltration of GDC nanoparticles significantly increases the density of surface active sites and three phase boundaries (TPBs), which are beneficial for CO 2 adsorption and subsequent conversion. Electrochemical impedance spectroscopy results indicate that the polarization resistance of 12.8 wt% GDC-SFM cathode was obviously decreased from 0.46 to 0.30 Ω cm 2 after the infiltration of GDC nanoparticles.
Yanli Zhang,Jiale Zhao,Simeng Zeng,Zixuan Liu,Bo Wang,Fuhua Lin
In this paper, a novel Cu/F co-doping strategy is proposed to modify the electrochemical performance of Sr 2 Fe 1.5 Mo 0.5 O 6– δ (SFM) cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The pristine SFM, Cu-doped Sr 2 Fe 1.4 Cu 0.1 Mo 0.5 O 6− δ (SFCM) and Cu/F co-doped Sr 2 Fe 1.4 Cu 0.1 Mo 0.5 O 5.9− δ F 0.1 (SFCMF) powders were synthesized by acid-glycine combustion method, and the impacts of Cu/F co-doping on the performance of SFM cathode were investigated systematically. It's found that Cu-doped SFCM has higher oxygen vacancy content and electrical conductivity than the pristine SFM and Cu/F co-doped SFCMF cathodes. While the Coulombic force between B-sites metallic ions and oxygen ions are significantly weaken for SFCMF, enhancing the mobility of lattice oxygen. Due to the combined effects of Cu and F doping, SFCMF cathode exhibits the best electrochemical performance among all investigated samples. At 600 °C, the polarization resistant for SFCMF cathode is 1.79 Ω cm 2 , decreased by 43.71 % in contrast to the parent SFM cathode. These results indicate that Cu/F co-doping is an effective strategy to improve the electrochemical properties of perovskite cathode materials.
Yanli Zhang,Zongchao Zhu,Yiheng Gu,Han Chen,Yifeng Zheng,Lin Ge
In this paper, a novel Cl − anion doping strategy is proposed to modify the electrochemical performance of Sr 2 Fe 1.5 Mo 0.5 O 6− δ (SFM) cathode for solid oxide fuel cells. A series of Cl-doped Sr 2 Fe 1.5 Mo 0.5 O 6− x − δ Cl x (SFMCl x , x = 0, 0.1, 0.2, 0.3, 0.4) materials is synthesized by the citric acid–glycine combustion method, and the effect of Cl doping on the crystal structure and electrochemical performance is systemically investigated. The doping of Cl into the SFM leads to the lattice expansion, and the electrochemical performance of Cl-doped SFMCl x cathodes is effectively improved as a result of the enhanced mobility of lattice oxygen introduced by Cl doping. The optimal composition with x = 0.2 (sample Sr 2 Fe 1.5 Mo 0.5 O 5.8− δ Cl 0.2 , noted as SFMCl0.2) exhibits a minimum polarization resistance R p value of 1.987 Ω cm 2 at 600 °C, reduced by 38.04% compared with the SFM cathode. These results suggest that Cl doping is an effective strategy to improve the electrochemical properties of cathode for solid oxide fuel cells.
Houfu Lv,Le Lin,Xiaomin Zhang,Dunfeng Gao,Yuefeng Song,Yingjie Zhou,Qingxue Liu,Guoxiong Wang,Xinhe Bao
Solid oxide electrolysis cells (SOECs) have attracted increasing attention as a promising device for the electrochemical CO2 reduction reaction (CO2RR) due to their high efficiency and fast kinetics. Exploring active cathode catalysts for the CO2RR is highly desirable for the research and development of SOECs. Herein, in situ exsolved FeNi3 nanoparticles on a Sr2Fe1.35Mo0.45Ni0.2O6−δ (SFMN) double perovskite substrate (FeNi3@SFMN) is developed to efficiently catalyze the CO2RR in SOECs. The SOEC with the FeNi3@SFMN–GDC (Gd0.2Ce0.8O1.9) cathode shows a current density of 0.934 A cm−2 at 1.6 V and 800 °C, as well as high stability and no coke deposition for 40 h at 1.2 V. CO2-temperature programmed desorption and quasi in situ Fourier-transform infrared spectroscopy measurements verify the intensive adsorption of CO2 on the FeNi3@SFMN–GDC cathode. Distribution of relaxation time analysis combined with density functional theory calculations discloses the stimulative activation of CO2 at the interface between the exsolved FeNi3 nanoparticles and the SFMN substrate with abundant oxygen vacancies, which improves the CO2RR performance at the FeNi3@SFMN–GDC cathode.
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