钴/氮掺杂碳催化剂及其氧还原催化机理研究

doi:10.13208/j.electrochem.170105

摘要/Abstract

摘要：

以尿素做氮源、醋酸钴做金属源，用湿法合并高温热处理法合成了钴/氮共掺杂碳的非贵金属氧还原催化剂Co-N/C-T. 采用循环伏安（CV）法和线性扫描法（LSV）探究了氮源和金属源用量以及热处理温度对氧还原反应电催化活性的影响，活性最好的催化剂Co_0.13-N_0.3/C-800的峰电位达到0.829 V（vs.RHE），接近商用Pt/C的活性，但比商用Pt/C有更好的耐甲醇性和稳定性. 同时，采用SEM，TEM，BET，XRD和XPS方法表征了催化剂结构和组分特征，并提出催化剂可能的电催化活性氧还原反应机理.

关键词: 钴/氮共掺杂碳催化剂, 氧还原, 电催化作用, 活性位, 热处理

Abstract: Transition metal-nitrogen co-doped carbon catalysts have attracted significant attention because of their reasonable activity and remarkable selectivity toward oxygen reduction reaction (ORR) as cathodic reaction in fuel cells. However, the role of transition metal in the active sites of the catalysts still is uncertain. In this work, the Co_x-N_y/C-T catalysts were prepared with BP2000 as a carbon source, urea (Ur) as a nitrogen source and Co(OAc)₂•4H₂O as a metal precursor by a simple chemical method. Meanwhile, in order to optimize the ORR activity, the catalysts were synthesized with different amounts of Co and urea, and heat-treated at different temperatures from 600-1000 ℃. SEM, TEM, BET, XRD and XPS techniques were used to characterize the catalysts in terms of structures and compositions, as well as the catalytic active sites. CV and LSV were measured to compare the ORR activity and to obtain the electron transfer number. The peak potential for oxygen reduction was approximately 0.829 V (vs. RHE) on the optimum Co_0.13-N_0.3/C-800 catalyst in an alkaline electrolyte. The results indicated that Co-N-C was potentially catalytic active site and responsible for the ORR catalytic activity in an alkaline electrolyte. The overall electron transfer number for ORR catalyzed by the optimum Co-N/C catalyst was determined to be 3.7, suggesting that the ORR catalyzed by Co-N/C was a mixture of 2- and 4-electron transfer pathways, dominated by a 4-electron transfer process. Furthermore, the Co_x-N_y/C-T catalysts also exhibited excellent methanol tolerance and stability.

Key words: Cobalt-based nitrogen-doped carbon catalyst, electrocatalysis；oxygen reduction reaction, catalytic active site, heat-treatment

中图分类号:

O646

姜孟秀，张晶，李月华，张蓉. 钴/氮掺杂碳催化剂及其氧还原催化机理研究[J]. 电化学（中英文）, 2017, 23(6): 627-637.

JIANG Meng-xiu, ZHANG Jing, LI Yue-hua, ZHANG Rong. Cobalt-Based Nitrogen-Doped Carbon Non-Noble Metal Catalysts for Oxygen Reduction Reaction[J]. Journal of Electrochemistry, 2017, 23(6): 627-637.

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