Mn-N-C催化剂的制备及其在碱性介质中对氧还原反应的电催化性能  

Preparation of Mn-N-C catalyst and its electrocatalytic activity for the oxygen reduction reaction in alkaline medium

作　　者：张蓉[1] 张晶[1] 马飞[1] 王文洋[1] 李瑞丰[1] 

机构地区：[1]太原理工大学化学化工学院,山西太原030024

出　　处：《燃料化学学报》2014年第4期467-475,共9页Journal of Fuel Chemistry and Technology

基　　金：山西省自然科学基金(2013011012-1)

摘　　要：选用壳聚糖(CS)为原料制备了壳聚糖水杨醛席夫碱锰配合物(Mn-CS-sal)。将Mn-CS-sal配合物负载于石墨碳上得到碳载配合物(Mn-CS-sal/C),后经高温热处理得到Mn-N-C目标催化剂(Mn-N-C-t,t=200、400、600、800、1 000℃)。采用FT-IR、XRD、XPS和电化学等方法对催化剂的组成和结构进行了表征,对其在氧还原反应中的电催化性能进行了研究。结果表明,所得到的Mn-N-C催化剂对氧还原反应(ORR)具有很好的催化作用,但以600℃热处理制备的催化剂其活性最好。催化剂中Mn-N-C结构是催化ORR的活性位。采用循环伏安法获得了Mn-N-C-t催化ORR的动力学参数,即总的转移电子数n和电子传递系数αnα;具有最佳活性的Mn-N-C-600催化剂的总转移电子数为3.63,说明在此条件下,Mn-N-C-600催化ORR主要以4e转移途径为主,由此提出了可能的氧还原反应的机理。Chitosan salicylaldehyde Schiff-base manganese complex （ Mn-CS-sal） was synthesized by a simple chemical method and then supported on graphite carbon;the graphite-supported Mn-CS-sal （ Mn-CS-sal/C） was heat-treated at different temperatures （t） to obtain the Mn-N-C catalysts （Mn-N-C-t, t = 200, 400, 600, 800, 1 000 ℃） . The electrocatalytic activity of Mn-N-C catalysts in the oxygen reduction reaction （ ORR ） was investigated and their structure and composition were characterized by Fourier Transform Infrared （ FT-IR ） spectrum, X-ray diffraction （ XRD） and X-ray photoelectron spectroscopy （ XPS） . The results indicated that all the Mn-N-C catalysts are highly active in ORR, whereas the Mn-N-C-600 catalyst heat-treated at 600℃ exhibits the highest ORR activity. The excellent ORR activity of the Mn-N-C catalysts in alkaline media should be attributed to their Mn-N-C configuration. Two important kinetic parameters, i. e. the overall ORR electron transfer number （ n ） and electron transfer coefficiency （αnα） , were determined by the cyclic voltammetry method. The Mn-N-C-600 catalyst shows an overall electron transfer number of 3. 63 for ORR, suggesting that the catalytic ORR is via a mixture of 2-and 4-electron transfer pathways, but dominated by the 4-electron transfer process. Based on these observations, a possible mechanism for ORR over the surface of Mn-N-C modified electrode is proposed.

关 键 词：壳聚糖 非贵金属催化剂 电催化 Mn-N-C 氧还原 热处理 

分 类 号：O646[理学—物理化学]