氮掺杂炭层包覆碳纳米管的组织结构调控及其氧还原催化活性  

Nitrogen-doped carbon coatings on carbon nanotubes as efficient oxygen reduction catalysts

作　　者：李莉香[1,2] 赵宏伟[1] 邢天宇[1] 耿新[1,2] 宋仁峰[3] 安百钢[1,2] LI Li-xiang;ZHAO Hong-wei;XING Tian-yu;GENG Xin;SONG Ren-feng;AN Bai-gang(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China;Institute of Materials Electrochemistry Research, University of Science and Technology Liaoning, Anshan 114051, China;Ansteel Mining Engineering Corporation, Anhsan 114004, China)

机构地区：[1]辽宁科技大学化学工程学院,辽宁鞍山114051 [2]辽宁科技大学材料电化学研究所,辽宁鞍山114051 [3]鞍钢集团矿业设计研究院,辽宁鞍山114004

出　　处：《新型炭材料》2017年第5期419-426,共8页New Carbon Materials

基　　金：国家自然科学基金(51672117;50801035);辽宁省高校创新团队(LT2014007);辽宁省自然科学基金(201502063);辽宁省教育厅资助项目(2016TSZD01)~~

摘　　要：采用化学原位聚合合成聚吡咯涂覆碳纳米管,之后将其在氮气氛下热处理制备氮掺杂炭层包覆碳纳米管NCCNTs。利用该工艺,通过改变热处理温度,调控NC-CNTs组织结构和表面化学组成。比表面和孔结构分析显示,600,800和1 000℃热处理制备的氮掺杂碳纳米管NC-CNT600,NC-CNT800和NC-CNT1000的比表面积和孔体积依次显著增加,NC-CNT1000的比表面积和孔体积分别约是NC-CNT600的3倍和1.7倍。这是因碳纳米管表面聚吡咯层向氮掺杂炭层转化过程导致更多的微孔形成。然而,制备温度升高使NC-CNTs的氮含量降低,表面含氮官能团由吡咯型氮向吡啶型氮和石墨氮转化,NC-CNT1000含最高比例的石墨氮。作为无金属催化剂,NC-CNTs在碱性电解质条件下展现了明显的氧还原催化活性,但其氧还原活性并不与样品氮含量成正比。NC-CNT600和NC-CNT800的氧还原反应为两电子转移机制,而NCCNT1000表现为两电子和四电子转移混合机制,其展现出最高的氧还原催化活性和催化稳定性,这可能是其具有高的比表面积和孔体积,结合含氮官能团中高比例石墨氮的缘故。Polypyrrole coated carbon nanotubes(PPy CNTs)synthesized by an in situ chemical polymerization approach were heat treated at600,800and1000℃in N2to prepare N doped carbon coatings on CNTs(NC CNTs).The specific surface area(SSA)and pore volume of the NC CNTs increase significantly with heat treatment temperature and the nitrogen content decreases.Also,as the temperature increases the content of pyrrolic N decreases while that of the graphitic N increases.The SSA and pore volume of the NC CNT1000are3and1.7times higher than those of the NC CNT600.As metal free electrocatalysts,the NC CNTs show significant ORR activity in a basic electrolyte,but it is not proportional to their total nitrogen content.The ORR mechanism of the NC CNT600and NC CNT800belongs to a two electron transfer reaction while that of the NC CNT1000to a mixture of the two electron and four electron transfer reactions.The NC CNT1000exhibits the best ORR activity and durability among the samples owing to its highest SSA and pore volume as well as having the largest amount of graphitic N.

关 键 词：氮掺杂 碳纳米管 氧还原 氮官能团 

分 类 号：O643.36[理学—物理化学] TB383.1[理学—化学]