Fe-N共掺杂纳米碳材料的形貌对电化学还原反应的影响（英文）

Effect of Morphology of Fe-N Codoped Carbon Nanomaterial on Electrochemical Reduction Reactions

众所周知,石墨烯片(GS)和碳纳米管是能源转化和储存应用中有效的催化剂.然而,过渡金属基氮(N)掺杂的体系中经常形成GS和碳纳米管的复合物,使得该体系内的构效关系研究变得十分困难.为了可控制备出含有理想物种的催化剂,作者尝试通过利用氮对碳纳米管生长的效应调节生成产物的形貌.本文中,作者采用一步法制备了一系列Fe-N共掺杂的GS、GS/竹节碳纳米管(BCNTs)复合物及BCNTs催化剂.为了评估碳形貌对催化剂性能的影响,作者采用氧气还原反应(ORR)及二氧化碳还原反应(CO2RR)作为模型反应.电化学测试结果表明,所有的样品当中仅含BCNTs的催化剂表现出最好的ORR活性(起始电位Eonset=1.02 VRHE)及CO2RR活性(CO生成法拉第效率FECO=91.1%,-0.6 VRHE).进一步的研究表明,优异的活性与独特的BCNTs中存在的缺陷、较大的比表面积、高含量的吡啶N及FeNx相关.该工作加深了作者对形貌相关的ORR及CO2RR过程的认识和理解.

Graphene nanosheets(GS)and carbon nanotubes have been considered as good catalysts candidates for applications in energy conversion and storage.However,hybrids of GS and carbon nanotubes are always formed in transition metal-based nitrogen-doped system,making the system quite complex for exploring the structure-activity relationship.To prepare the catalysts with desired species controllably,we try to adjust the outcomes with the effect of nitrogen on the growth of carbon nanotubes.In this work,a series of Fe-N co-doped carbon hybrid catalysts containing N-doped GS or hybrids of GS/bamboo carbon nanotubes(BCNTs)or BCNTs were obtained with one-step pyrolyzed method.To evaluate the effect of carbon morphology on performance of catalysts,oxygen reduction reaction(ORR)and CO2 reduction reaction(CO2RR)were used as model reactions.Electrochemical studies revealed that the catalysts containing only BCNTs showed the best performance of ORR(Eonset,1.02 VRHE)and CO2RR(FECO,91.1%at-0.6 VRHE)among the tested samples.Further investigations displayed that the remarkable activity is closely related to the defects,large specific surface area and high content of pyridinic N,and existence of FeNxin the unique BCNTs.Such work deepens fundamental understanding in the morphology-dependent catalysis for both ORR and CO2RR processes.