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通过沉淀法,以炭黑为载体、氯化镧和四甲基氢氧化铵(TMAH)为原料制备了炭载纳米氧化镧催化剂。采用扫描电镜(SEM)和X射线衍射(XRD)对所获产物的组织结构进行表征,采用循环伏安法和旋转圆盘测试对产物的催化活性进行研究。结果表明:当纳米La2O3微粒负载到炭黑上时,沉淀剂(四甲基氢氧化铵)的加入量和热处理温度都会对其组织结构产生影响。当沉淀剂用量为6 mmol,热处理温度为750℃时可以得到粒径小、分散性好的氧化镧粒子,其平均粒径约为20 nm。电化学测试确定了该催化剂对氧气还原反应的催化活性,并得出氧气还原反应是以二电子和四电子反应共同进行的。
Carbon supported lanthanum oxide catalysts were prepared by precipitation method using carbon black as carrier, lanthanum chloride and tetramethylammonium hydroxide (TMAH) as raw materials. The structure of the obtained product was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The catalytic activity of the product was investigated by cyclic voltammetry and spin disk test. The results show that the addition of precipitating agent (tetramethylammonium hydroxide) and the heat treatment temperature all affect the microstructure of nano-La2O3 particles. When the amount of the precipitating agent is 6 mmol and the heat treatment temperature is 750 ℃, lanthanum oxide particles with small particle size and good dispersibility can be obtained with the average particle size of about 20 nm. The electrochemical tests confirmed the catalytic activity of the catalyst for the oxygen reduction reaction and concluded that the oxygen reduction reaction was carried out by two-electron and four-electron reactions.