【摘要】 采用溶液共混和高温热解两步法,以聚苯并咪唑(PyPBI)和三聚氰胺(Mela)为复合氮源,中度氧化的碳纳米管(moCNTs)为碳源,醋酸钴为金属源,制备出一系列moCNTs/PyPBI/Mela(Co)催化剂,对其进行TEM、TGA、XRD、XPS表征和电化学活性测试,结果表明:当moCNTs/PyPBI(Co)前驱体与三聚氰胺的质量比为1∶2,热解温度为800℃时,催化剂的起始还原电位可达到0.87V(vs.RHE),接近于商业Pt20%/C催化剂。moCNTs/PyPBI/Mela(Co)催化剂催化性能的提高归因于其结构中的吡啶氮与钴结合形成Co-N活性位点,增加对O2的吸附能力,弱化了O—O键,促进氧分子的还原反应,促使ORR反应通过4e-途径进行。更多还原

【Abstract】 Using mildly oxidized carbon nanotubes( mo CNTs) as the carbon source,and pyridyl-linked polybenzimidazole( Py PBI) and melamine as a binary nitrogen source mo CNTs/Py PBI/Mela( Co) electrocatalysts have been prepared by a two-step method involving solution blending and pyrolysis.The results showed that the electrocatalysts prepared using binary nitrogen sources had a higher electrocatalytic activity than the electrocatalysts prepared using single nitrogen sources.The electrocatalysts prepared at 800 ℃ had the highest electrocatalytic activity,with a maximum ORR onset potential of 0.87 V( vs.RHE),which is only 0.07 V lower than that of Pt 20%/C( JM).We conclude that the nitrogen sources are decomposed and N atoms enter into the carbon lattice to product more pyridinic nitrogen and form Co-N active sites during the pyrolysis process.Pyridinic N atoms at Co-N active sites can increase charge delocalization degree and enable the carbon around the pyridinic N atoms to adsorb molecular oxygen.Furthermore Co- N active sites can weaken the O—O bonds,and enhance the reduction of oxygen,and then complete the ORR through the 4e-reduction pathway,which provides a good explanation for the high electrocatalytic activity of our material.更多还原