Cobalt and Titanium substituted SrFeO_(3) based perovskite as efficient symmetrical electrode for solid oxide fuel cell

One of the key tasks in solid oxide fuel cell research is to develop cost-competitive electrodes that work efficiently in wide range of air and fuel utilizations.Herein,we promote our study to a series of Cobalt and Titanium substituted La_(0.4)Sr_(0.6)Fe_(0.7)Ti_(0.3-x)Co_(x)O_(3-δ)(LSFTC,x=0,0.05,0.1,0.2)perovskite oxides.It is shown that Cobalt doping effectively improves the electrical conductivity and oxygen electrochemical reduction activity,yielding decreased cathode polarization resistance and lower dependence of pO_(2) change.For example,σ_(600℃)=81 S/cm and R_(p,C750℃)=0.1 Ω cm^(2) for LSFTC-5 are obtained in pO_(2)=0.21 atm.In anode conditions of wet H2,the LSFTC cubic perovskites are partially reduced to hybrid structure of ABO_(3)-A_(2)BO_(4)-metal with Cobalt doping amount less than 10% and are fully decomposed to A_(2)BO_(4)-metal with 20% doping.The higher Cobalt substitution generates more nano particles exsolution,which promotes anode processes at low temperatures.However,the generated AO-rich compositions are shown detrimental to anode performance in both conducting property and anode catalytic activity under low H_(2) partial pressures.In current study,the electrodes are evaluated under practical working conditions with broad pO_(2) and pH_(2),which provides guidelines for industrial-applicable SrFeO_(3) based symmetrical electrode development.

Evaluation of La_(0.7)Ca_(0.3)Cr_(0.95)Zn_(0.05)O_(3-δ)-Gd_(0.1)Ce_(0.9)O_(2-δ) Dual-phase Material and its Potential Application in Oxygen Transport Membrane

In this work, a dual-phase material consisting Gd0.1Ce0.9O2-δ （GDC, 60 wt%） was synthesized. of La0.7Ca0.3Cr0.95Zn0.05O3-δ （LCCZ, 40 wt%） and Properties including phase structure, sintering behavior, electrical conductivity and oxygen permeability for LCCZ-GDC were evaluated. The results show that dense LCCZ-GDC dual-phase disks were obtained at the sintering temperature of 1250, 1300, 1350 and 1400 ℃ by tape casting and high temperature sintering method. The grain sizes of both GDC and LCCZ grew up with the increasing of sintering temperature. The average grain size of GDC was about 0.5, 0.8, 1.4, 1.8 μm while the average grain size of LCCZ was about 0.8, 1.5, 1.8 and 2 pm after sintering at 1250, 1300, 1350 and 1400℃, respectively. Oxygen flux of LCCZ-GDC decreased with the increase of sintering temperature from 1250 to 1400 ℃. The oxygen flux of LCCZ-GDC sintered at 1250 ℃ reached 0.079 mL/min/cm2 at 975℃ with a membrane thickness of 800 μm. Dual-phase material of LCCZ-GDC will be a promising oxygen transport membrane material for its low sintering temperature and good microstructure.

Electrochemical property of multi-layer anode supported solid oxide fuel cell fabricated through sequential tape-casting and co-firing

In this work, a multi-layer anode supported solid oxide fuel cell(SOFC) is designed and successfully prepared through sequential tape casting and co-firing. The single cell is consisted of NiO-3 YSZ(3 YSZ: 3 mol.% yttria doped zirconia) anode support, NiO-8 YSZ(8 YSZ: 8 mol.% yttria stabilized zirconia) anode functional layer, dense 8 YSZ electrolyte layer, and porous 3 YSZ cathode scaffold layer with infiltrated La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) cathode. The clear interfaces and good contacts between each layer, without element inter-diffusion being observed, suggest that this sequential tape casting and co-firing is a feasible and successful route for anode supported single cell fabrication. This cell exhibits remarkable high open circuit voltage of 1.097 V at 800?C under room temperature humidified hydrogen, with highly dense and gastight electrolyte layer. It provides a power density of 360 mW/cm^2 under operation voltage of0.75 V at 800?C and a stable operation of ～110 h at 750?C under current density of-300 mA/cm^2. Furthermore, this cell also presents encouraging electrochemical responses under various anode hydrogen partial pressures and maintains high power output at low fuel concentrations.

Inducing the SnO2-based electron transport layer into NiFe LDH/NF as efficient catalyst for OER and methanol oxidation reaction

In an electrocatalyst with a heterointerface structure,the different interfaces can efficiently adjust the catalyst’s conductivity and electron arrangement,thereby enhancing the activity of the electrocatalyst.Ultrathin and smaller Ni Fe LDH was successfully constructed on the surface of SnOnanosheet supported NF by layer by layer assembly,and exhibits lower overpotential of 234 mV at a current density of 10 m A cm,which only increases by 6.4%even at a high current density of 100 mA cm.The excellent OER activity of catalyst is attributed to the contribution of the semiconductor SnOelectron transport layer.Through experiments and characterization,3d structure SnOnanosheets control the growth of ultra-thin nickel-iron,the hierarchical interface between SnOand Ni Fe LDH can change the electron arrangement around the iron and nickel active centers at the interface,resulting the valence states of iron slightly increased and Nicontent increased.The result will promote the oxidation of water.Meanwhile,the SnOsemiconductor as electron transport layer is conducive to trapping electrons generated in oxidation reaction,promoting electrons transferring from the Ni Fe LDH active center to the Ni substrate more quickly,and enhance the activity of Ni Fe LDH.It also shows excellent activity in an electrolyte solution containing 0.5 M methanol and 1 M KOH,and only 1.396 V(vs.RHE)is required to drive a current density of 10 mA cm.

Fabrication and optimization of La_(0.4)Sr_(0.6)Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ) electrode for symmetric solid oxide fuel cell with zirconia based electrolyte

La（0.4）Sr（0.6）Co（0.2）Fe（0.7）Nb（0.1）O（3-δ）（LSCFN）was applied as both anode and cathode for symmetrical solid oxide fuel cells（SSOFCs）with zirconia based electrolyte.The cell with LSCFN electrode was fabricated by tape-casting and screen printing.Fabrication process was optimized firstly by comparing co-sintering and separate-sintering of electrode and electrolyte.To further improve the LSCFN electrode properties,oxygen ionic conductor of Gd（0.1）Ce（0.9）O（2-δ）（GDC）was added into the LSCFN electrode.The preferred composition of LSCFN-GDC composite electrode was found to be 1：1 in weight ratio with polarization resistance of 0.16Ωcm^2at 800~℃.The maximum power densities of LSCFN-GDC｜｜GDC/YSZ/GDC｜｜LSCFN-GDC tested in H2and CH4with 3%H2O were 395 m W cm^（-2）and 124 m W cm^（-2）at 850~？C,respectively,which were much higher than that of LSCFN｜｜GDC/YSZ/GDC｜｜LSCFN cells at same condition,possibly due to the extension of the triple phase boundary induced by the addition of GDC.The cell showed reasonable stability using H2and CH4with 3%H2O as fuels and no significant power output degradation was observed after total 200 h operation.