碳载体预处理对燃料电池Co-N/C非铂催化剂氧还原性能的影响

Effect of carbon carrier pretreatment on oxygen reduction performance of Co-N/C non-platinum catalyst for fuel cell

钴(Co)基氧还原催化剂以价格低、储量高、易获得等优势成为代替铂基氧还原催化剂重要选择之一。本工作先对科琴黑进行硝酸酸化预处理,与四水合乙酸钴混合后在氨气气氛下800℃热解制备出Co-N/C氧还原催化剂。由红外光谱测试、联碱中和滴定与比表面积测定可知,经硝酸酸化预处理后,科琴黑表面含氧官能团数量增多,科琴黑孔径不变,中孔比例增加。XRD和TEM测试表明科琴黑和四水合乙酸钴经氨气热处理后,生成了分散均匀无团聚的Co_(5.47)-N/C催化剂。电化学测试表明载体经预处理后,制备的Co-N/C催化剂的氧还原反应(ORR)的电催化性能更好,在碱性条件下电流密度达到了预处理前的4.2倍,在催化动力学中属于四电子转移。

Cobalt(Co)based oxygen reduction catalysts have become one of the important choices to replace platinum based oxygen reduction catalysts because of their low price,high reserves and easy availability.ECP600 JD was pretreated with nitric acid,mixed with cobalt acetate tetrahydrate,and then pyrolyzed at 800℃in ammonia atmosphere to prepare Co-N/C oxygen reduction catalyst.The infrared spectrum test,alkali neutralization titration and specific surface area measurement show that the number of oxygen-containing functional groups on the surface of ECP600 JD increases,the pore size of ECP600 JD remains unchanged,but the proportion of mesopores increases after nitric acid acidification pretreatment.XRD and TEM tests show that Co_(5.47)N is formed from ECP600 JD and cobalt acetate tetrahydrate after ammonia heat treatment,the Co-N/C catalyst is dispersed evenly without agglomeration.Electrochemical tests show that after pretreatment,the electrocatalytic performance of the prepared Co-N/C catalyst for oxygen reduction reaction(ORR)is better.Under alkaline conditions,the current density reaches 4.2 times that before pretreatment,and belongs to four electron transfer in catalytic kinetics.