脉冲电流促进(La,Sr)(Ti,Ni)O3原位溶出金属纳米颗粒的研究

Study on the metal particles exsolution in situ of(La,Sr)(Ti,Ni)O3 perovskite oxides via pulsed electric current technology

表界面是纳米催化的核心。设计表界面的活性位点并应用到实际工业催化领域一直是研究热点。在这里我们采用(La,Sr)(Ti,Ni)O3钙钛矿型氧化物作为基体活性材料,采用脉冲电流技术(PEC),在500 V-3 Hz-30 s脉冲参数处理下,成功制备出基体原位溶出金属间化合物纳米颗粒的活性物质。利用X射线衍射仪(XRD)分析了作用后的微观结构,即Ni-Ti及La-Ni析出相,扫描电子显微镜(SEM)观察了脉冲作用后材料的表面形貌,脉冲电压在400 V,500 V时,形貌发生明显变化,说明一定脉冲能量的注入会改变部分基体的形貌,且在500 V时会明显观察到溶出纳米颗粒,且分布均匀。电化学测试显示脉冲处理后材料具有良好的电荷传递能力。最后,分析认为基体本身存在的氧空位及脉冲发生器造成的氧分压梯度共同作用使粒子得到机会由体内晶格扩散到表面造成钙钛矿型氧化物的原位溶出。

Surface/interface is the core of nanocatalysis.The design of the active sites onto the surface/interface and applying it to the field of industrial catalysis have been shown a tremendous research hotspot.Herein,the nanoparticles exsolved in situ was obtained successfully with the perovskite substrate as the active matrix via pulsed electric current(PEC)technology at 500 V-3 Hz-30 s.The microstructure was analyzed by XRD.The pattern showed a few new precipitated phases that was Ni-Ti and La-Ni intermetallic compounds.The morphology of the samples was observed by SEM.It was obvious that the morphology had changed apparently when the pulsed voltage was 400 V and 500 V.The result meant that the injection of certain pulsed energy would change the morphology of the matrix,and the exsolved nanoparticles would appear and distribute homogeneously at 500 V.Electrochemical tests showed that the powder had good charge transfer resistance.Finally,orrelation analysis suggested that the oxygen vacancy of the matrix itself and oxygen partial pressure gradient caused by the pulsed generator made joint efforts to allow the particles diffusing from the lattice to the surface,and resulting in the exsolution.