纳米碳纤维的表面性质和微结构对氧还原催化活性的影响

Effects of Surface Properties and Microstructures of Carbon Nanofibers on Their Electrocatalytic Activity for Oxygen Reduction Reaction

采用超声处理的方法分别对管式纳米碳纤维(t-CNF)和鱼骨式纳米碳纤维(f-CNF)进行了表面化学处理.XPS结果表明,在混酸(浓硫酸+浓硝酸)和氨水中进行超声化学处理可以在CNF表面分别引入含氧官能团和含氮官能团.电化学测试结果表明,2种不同微结构CNF的氧还原催化活性都遵循相同的趋势,即CNF-P<CNF-O<CNF-ON,且鱼骨式CNF的催化活性好于相应的管式CNF.这说明纳米碳纤维的表面性质和微结构都会影响其在碱性溶液中的氧还原催化活性,而前者的影响可能更大些.另外,t-CNF-ON和f-CNF-ON均表现出了很高的氧还原催化活性.

Two types of carbon nanofibers（CNFs）,tubular CNFs（t-CNFs） and fish-bone CNFs（f-CNFs） were synthesized and the effects of surface properties of CNFs on their electrocatalytic activity for oxygen reduction reaction（ORR） in alkaline media were investigated.Oxygen- and nitrogen-containing functional groups were introduced onto the CNF surface by sonochemical oxidation in mixed acids（concentrated sulfuric acid and nitric acid） and ammonia,respectively.The ORR activities of the CNF catalyst were measured in an oxygen-saturated 0.1 mol/L KOH electrolyte solution by rotating disk electrode（RDE） technique.The RDE results show that the electrocatalytic activities of the two types of CNFs increase in the same sequence untreated CNFs oxygen-containing CNFs nitrogen-containing CNFs,while the f-CNFs-based catalysts have higher electrocatalytic activities for ORR than t-CNFs-based counterparts.The results indicate that both the surface properties and the microstructures of CNFs have effects on the electrocatalytic activity of CNFs for ORR,although the former may have a dominant effect.