张蓉,柳璐,马飞,张晶,王文洋,李瑞丰.过渡金属/氮掺杂石墨的制备及电催化氧还原[J].分子催化,2014,(6):553-563
过渡金属/氮掺杂石墨的制备及电催化氧还原
Preparation and Electrocatalytic Activity of Transition Metal/Nitrogen doped Carbon catalysts for Oxygen Reduction Reaction
投稿时间:2014-05-29  修订日期:2014-09-13
DOI:
中文关键词:  过渡金属/氮掺杂石墨  电催化  氧还原  动力学  催化活化位
英文关键词:transition metal and nitrogen doped graphite  Electrocatalysis  Oxygen reduction reaction  Kinetics  Catalytic active sites
基金项目:
作者单位E-mail
张蓉* 太原理工大学 zhangrong@tyut.edu.cn 
柳璐 太原理工大学 liulu2013@link.tyut.edu.com 
马飞 太原理工大学 mafei5073@qq.com 
张晶 太原理工大学 zj5073@163.com 
王文洋 太原理工大学 wwy420@163.com 
李瑞丰 太原理工大学 rfli@tyut.edu.cn 
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中文摘要:
      用简单的化学方法制备了过渡金属(TM)壳聚糖水杨醛席夫碱配合物,然后以此配合物为金属源和N源、以硝酸预处理石墨为载体,经热处理后制备了过渡金属/氮掺杂石墨催化剂TM-N-C-t (TM=Co, Ni, Cu; t=200, 400, 600, 800,1000℃)。以此催化剂为修饰剂制备了玻碳修饰电极,并用循环伏安法(CV)研究了催化剂TM-N-C-t的电化学行为和电催化氧还原(ORR)的催化性能,催化剂的组成和结构采用TG,FT-IR,XRD,XPS等技术进行了表征。研究结果表明,催化剂TM-N-C-t对ORR均显示不同程度的催化活性,其中以1000℃热处理的钴基催化剂Co-N-C-1000的催化活性最好,其活性已接近相同条件下的商用催化剂JM 20%Pt/C,催化活性位主要为Co-N-C。根据扩散控制的不可逆反应的循环伏安行为,计算得到了TM-N-C-t催化剂电催化ORR的动力学参数,并以此提出了氧还原催化反应的机理,在活性最好的催化剂Co-N-C-1000修饰电极上,氧气以4e转移途径被还原为水。
英文摘要:
      Non-noble transition metal and nitrogen doped carbon catalysts for oxygen reduction reaction (ORR) were recognized as one of the most promising to replace the traditional Pt-based catalyst with the high cost and scarcity. In this paper, graphite-supported transition metal (TM=Co, Ni Cu) complexes of chitosan-salicyiclaldehyde Schiff base (TM-CS-Sal) were synthesized by a simple chemical method, then heat-treated at 200, 400, 600, 800 and 1000℃ to optimize their activity for ORR. The effects of heat treatment temperature and the nature of metal on the electrocatalytic properties of the resulting catalysts TM-N-C-t (t=200, 400, 600, 800, 1000℃) was surveyed using cyclic voltammetry (CV). The catalysts TM-N-C-t all showed strong catalytic activity toward the ORR, but the Co-based catalyst at heat temperature of 1000 ◦C (Co-N-C-1000) yielded the best ORR activity, which has been close to that of the commercial JM 20% Pt/C. Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric and differential thermal analysis (TG-DTA) were used to characterize these catalysts in terms of their structure and composition. The characterizing results combined with catalytic activities showed that Co-N-C potentially may be the main catalytic active sites of the best electrocatalyst Co-N-C -1000 and responsible for the ORR catalytic activity in alkaline electrolyte. In addition, cyclic voltammetry also was used to obtain the important kinetic parameters: overall ORR electron transfer number and electron transfer coefficiency. The overall electron transfer number for ORR catalyzed by the catalysts heat-treated at 800 and 1000 ◦C of Co-N-C-t (800, 1000◦C) was determined to be 3.44 and 4.03, suggesting that the ORR catalyzed by Co-N-C-t (800, 1000◦C) is a mixture of 2- and 4-electron transfer pathways, dominated by a 4-electron transfer process. Based on these measurements, a mechanism of ORR occurring in Co-N-C-t (t=800, 1000◦C) /GC electrode is proposed to facilitate further investigation.
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