Enhancing The Electro-catalytic Activity Of Electrodes For Solid Oxide Fuel Cells By Surface And Interface Engineering

Solid oxide fuel cells have been regarded as one of the"idealest power generation devices of the 21st century"because of its high energy conversion efficiency,no pollution,and flexible fuel use.The main bottleneck in its large-scale commercial development is the fast material degradation at extreme high operating temperatures?800-1000oC?.Therefore,reducing the operating temperature?500-700oC?of solid oxide fuel cells has become the focus of scientific research.Electrode material is an essential part of SOFC,and the catalytic activity of the electrode plays a crucial role in determining the overall performance and durability of the cell.Aiming at improving the catalytic activity of the electrodes at intermediate operating temperature,we have carried out the following research on the regulation of surface and interface properties of the electrodes:?1?Highly textured Nd₂NiO_4+?thin films with different strain states were prepared on?110?-and?100?-oriented single crystal Yttrium stabilized Zirconium?YSZ?substrates using pulsed laser deposition?PLD?.We fabricated two different strain state NNO thin film model systems,while the NNO?100?film on YSZ?110?substrate exhibited 5.37%tensile strain along the a-b plane and-3.82%compressive strain along c axis,the NNO?110?film on YSZ?100?substrate presented 4.05%tensile strain along the a-b plane and-2.7%compressive strain along c axis.The assembled cell was subjected to electrochemical analysis test.The results showed that the NNO?100?film with large compressive strain along the c-axis has a HOR activity about 7 times higher than that of the NNO?110?film.The high-resolution XRD results show that the difference in performance is mainly due to the difference in the concentration of oxygen defects caused by the introduction of strain.?2?By reducing the Pr_0.4Sr_0.6Co_0.2Fe_0.7Mo_0.1O_3-?material in H₂ atmosphere at high-temperature.we synthesized Co-Fe alloy nanoparticle-modified double-layered perovskite(Pr_0.4Sr_0.6)₃(Fe_0.85Mo_0.15)₂O₇?DLP-PSFM?material by in-situ exsolution.The Co-Fe alloy nanoparticles were uniformed distributed on the matrix with a average size of 20nm.The obtained DLP-PSFM were used as the anode material of proton-conducting solid oxide fuel cell.The peak power density of the single cell was 78 mW/cm² at 750°C,and the cell showed stable power output without observable degradation,which is mainly due to the uniformly distributed catalyst nanoparticles.?3?A PBSCF powder-nanofiber composite electrode was prepared as cathode material for proton-conducting solid oxide fuel cell.Three types of the cells using PBSCF powder,PBSCF nanofiber and powder-nanofiber composite as electrodes were tested in this work.The cell with composite electrode showed significantly better performance than that of the ones with single powder and nanowire electrode.Specifically,the polarization resistence was reduced from 1.46?·cm² for PBSCF powder to 0.57?·cm² for powder-nanofiber composite at 600°C.The characterization results showed that the performance improvement is mainly due to the larger specific surface area and the improved interface contact between the electrode material and the electrolyte.