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采用射频磁控溅射装置在Si(111)衬底上分别制备了Pd单膜、LaFeO3单膜和LaFeO3/Pd复合薄膜,利用XRD,SEM,EDS,XPS和电化学测试方法研究了退火处理对LaFeO3/Pd薄膜材料的相结构、形貌、化学组成以及电化学性能的影响。研究结果表明:未退火的溅态LaFeO3薄膜呈无序非晶态结构,随退火温度升高,600℃退火1 h后LaFeO3薄膜晶化为钙钛矿型正交结构,此时薄膜晶粒尺寸呈增大趋势;800℃退火时,随退火时间增加,薄膜晶粒尺寸变化不明显,退火前LaFeO3薄膜表面平整、致密,退火后薄膜表面出现裂纹。XPS分析表明,LaFeO3薄膜中的氧以晶格氧、化学吸附氧和物理吸附氧三种结合状态形式存在,退火后LaFeO3薄膜中化学吸附氧转变为晶格氧。电化学测试结果表明,Pd膜电极和LaFeO3膜电极放电容量很低(3.9~19 mAh·g-1),而LaFeO3/Pd复合薄膜在退火前后的电极放电容量分别达到50和180.7 mAh·g-1,LaFeO3单膜和LaFeO3/Pd复合薄膜电极的交换电流密度I0分别为为3.36和590.51 mA·g-1。镀Pd后能极大改善和提高LaFeO3/Pd复合膜电极的电催化活性和电化学放电容量。
Pd single film, LaFeO3 single film and LaFeO3 / Pd composite film were prepared on Si (111) substrates by RF magnetron sputtering. The effects of annealing treatment on the properties of the films were investigated by XRD, SEM, EDS, XPS and electrochemical measurements Effect of Phase Structure, Morphology, Chemical Composition and Electrochemical Properties of LaFeO3 / Pd Thin Films. The results show that the un-annealed LaFeO3 thin film has a disordered amorphous structure. With the annealing temperature increasing, the LaFeO3 thin film crystallizes into a perovskite orthorhombic structure after annealed at 600 ℃ for 1 h. At this time, the grain size With the annealing time increasing at 800 ℃, the grain size of the films did not change obviously. The surface of LaFeO3 thin films was smooth and dense before annealing, and the cracks appeared on the surface of the films after annealing. XPS analysis showed that the oxygen in the LaFeO3 thin film existed in the form of lattice oxygen, chemisorbed oxygen and physicadsorbed oxygen, and the chemisorbed oxygen in the LaFeO3 thin film was transformed into the lattice oxygen after annealing. The results of electrochemical tests showed that the discharge capacity of the LaFeO3 / Pd composite electrode was very low (3.9-19 mAh · g-1), while the discharge capacity of the LaFeO3 / Pd composite film was 50 and 180.7 mAh · g- 1, the exchange current density I0 of LaFeO3 single film and LaFeO3 / Pd composite film electrode is 3.36 and 590.51 mA · g-1, respectively. Pd plating can greatly improve and improve the electrocatalytic activity and electrochemical discharge capacity of LaFeO3 / Pd composite membrane electrode.