The emphases of discussion are on the preparation of pt / c electrocatalysts with freeze - drying method . the freeze - drying method is first investigated at first . and then the comparison of the freeze - drying method and heat - drying method is carried out 主要對(duì)冷凍干燥法制備pt / c催化劑展開研究,對(duì)冷凍干燥法制備pt / c催化劑的工藝進(jìn)行了初步探索,并且與加熱干燥法制備的pt / c催化劑進(jìn)行了比較。
Through the comparison between freeze - drying and heat - drying , the agglomeration and the desorption of the precursor on carbon support can be alleviated with freeze - drying method . the effects on the electrocatalysts by pretreatments of carbon support , dispersant and precursor are studied . the result shows that pretreatment of the carbon support by kmno _ 4 can add oxygen - containing functional groups on the surface of carbon , which can reduce the hydrophobicity of the carbon support , and then make it much easier for carbon to dissolve in water to form suspension ; isopropyl alcohol can make the carbon support in high dispersion in the precursor solution , which can make the precursor absorbed on the surface of the carbon 采用高錳酸鉀氧化預(yù)處理的碳載體比表面積較大,表面含氧官能團(tuán)數(shù)量較多,親水性較好,有利于前軀體在碳載體表面的吸附;選取異丙醇作為預(yù)凍液中的分散劑,有利于碳載體在前軀體溶液中的分散,容易實(shí)現(xiàn)前軀體離子在碳載體表面的穩(wěn)定吸附和分散;使用酸性pt ( no _ 2 ) _ 2 ( nh _ 3 ) _ 2作為前軀體,可以使前軀體離子和碳載體表面的酸性含氧官能團(tuán)發(fā)生離子交換反應(yīng),使得前軀體離子吸附量增大,分散更加均勻,以上三種因素的選取都可以得到催化活性更高的pt / c催化劑。