炭载金属钴卟啉催化剂氧还原性质的研究

Study on oxygen reduction electrochemical characteristics of heat-treated catalysts based on cobalt-porphyrin complexes

以金属钴卟啉(CoTMPP)负载在炭黑Black Pearls 2000(BP2000)上作氧还原电催化剂,对质子交换膜燃料电池阴极氧还原进行电催化.采用旋转圆盘电极(RDE)研究了BP2000炭载体经φ=30%H2O2或c=6 mol/LHNO3化学预处理后对催化剂氧还原催化活性的影响,并且测试了不同CoTMPP/BP催化剂的单电池性能.采用Koutevky-Levich关系式评价了电子转移数目,分析了反应过程催化剂的催化机理.结果表明,炭载体经过预处理后催化性能明显提高,且CoTMPP负载于H2O2处理过的炭载体BP2000上活性最好,焙烧的最佳温度是900℃,电催化还原过程的电子转移数介于2～4 e,反应机理符合催化还原的混合机理.

To obtain cathode electrocatalysts for the oxygen reduction in proton exchange membrane （PEM） fuel cell, cobalt tetramethoxy phenyl porphyrins adsorbed on pretreated black pearls 2000 （BP2000） have been investigated in detail. The influence of chemical pretreatment of carbon supports by 6 mol/L HNO3 orφ=30% H202 on the activity of electrocatalysts for oxygen reduction in acid medium has been investigated by the rotating disc electrode （RDE） technique, and the fuel cell performance of single cells with the different CoTMPP/BP electrocatalysts was examined under actual PEM fuel cell conditions. Koutevky-Levich plot shows that the number of transferred electrons during oxygen reduction on CoTMPP/BP is found to be between 2 and 4. The most active and stable catalysts were obtained at a high temperature （900℃）, The oxygen reduction activity of CoTMPP/BP was improved significantly after pretreats of carbon support, furthermore, pretreatment with φ=30% H2O2 was better than with 6 mol/L HNO3. The most active and stable catalysts were obtained at high temperature（900℃）.