退火处理对LaFeO_3/Pd复合薄膜微观结构和在碱液中电化学行为的影响  

Influences of Annealing on Micro-Structure and Electrochemical Properties in Alkaline Solution of LaFeO_3/Pd Composite Films

作　　者：张国庆[1] 王文旭[1] 李慷[1] 冯治棋[1] 罗永春[1,2] 

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,甘肃兰州730050

出　　处：《中国稀土学报》2013年第5期612-620,共9页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金项目(21063008)资助

摘　　要：采用射频磁控溅射装置在Si（111）衬底上分别制备了Pd单膜、LaFe03单膜和LaFe03／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，600oC退火1h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LaFe03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LaFe03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（3．9～19mAh·g-1），而LaFe03／Pd复合薄膜在退火前后的电极放电容量分别达到50和180．7mAh·g-1，LaFeO3单膜和LaFe03／Pd复合薄膜电极的交换电流密度，0分别为为3．36和590．51mA·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 film, LaFeO3 film and LaFeO3/Pd film were prepared by RF magnetron sputtering on Si （ 111 ） substrate. The influences of annealing on the phase structure, morphology, composition, combining states of oxygen in the lattice and electrochemical properties were investigated by XRD, XPS, SEM, EDS and electrochemical method. The results showed that the unannealed LaFeO3 film was amorphous state. As the annealing temperature increasing, the phase structures of LaFeO3 film annealed at 600℃ for 1 h transformed to perovskite-type orthorhombic structures, meanwhile grain size increased. As the annealing time increas- ing, the grain size of LaFeO3 film annealed at 800℃ had no significant change. The surface of the film was smooth and compact before annealing curred after annealing. The results of and crackle oc- XPS showed that the combination state of oxygen of LaFeO3 film includ- ed lattice oxygen, chemisorbed oxygen and physical absorbed oxygen. The chemisorbed oxygen turned to lattice oxygen after annealing. The results of electro- chemical measurement found that the discharge capac- ity of Pd film and LaFeO3 film was low （3.9 · 19 mAh.g-1）, the discharge capacity of LaFeO3/Pd film electrode before and after annealing was 50 and 180.7 mAh.g-1, respectively. The exchange current density of LaFeO3 film and LaFeOJPd film was 3. 36 and 590. 51 mA · g-1, respectively. The electrocatalytic activity of the surface of LaFeO3/Pd composite film e- lectrode and its electrochemical capacity were in- creased after the deposition of Pd film.

关 键 词：射频磁控溅射 LAFEO3 Pd薄膜 热处理 微观组织 电化学性能 稀土 

分 类 号：TQ139.2[化学工程—无机化工] TQ152