热处理温度对钴卟啉负载碳黑电催化剂的结构及氧还原性能的影响

制备了钴卟啉负载碳黑催化剂(CoTMPP/BP2000)用于燃料电池阴极氧还原反应. 利用循环伏安法研究了200～900 ℃热处理温度对催化性能的影响. 研究结果表明, 热处理能够提高CoTMPP/BP2000的催化活性, 热处理温度为900 ℃时, 催化剂的氧还原能力最好. 利用紫外-可见光谱、透射电镜、红外光谱、热重分析及X射线光电子能谱等手段研究了热处理温度对催化剂结构的影响. 结果表明, 热处理改变了催化剂的活性中心结构, 400 ℃以上热处理使催化剂中钴卟啉环的结构坍塌, Co—N4键断裂; 900 ℃高温下形成了稳定的Co—Nx—C结构, 新的活性位使催化剂的氧还原能力得到提高.

Effect of Heated-treating Temperature on the Electrocatalysis of Oxygen Reduction for Carbon Black-supported CoTMPP/BP2000

Carbon black-supported cobalt tetramethoxyphenylporphyrin CoTMPP/BP2000 was prepared as cathode electrocatalyst for the oxygen reduction in proton exchange membrane fuel cell(PEMFC).The effect of various heated-treating temperature from 200 ℃ to 900 ℃ on the electrocatalytic activities for oxygen reduction of CoTMPP/BP2000 were investigated by cyclic voltammogram(CV) and Koutecky-Levich plot.Results show that the heat-treatment can enhance the catalytric activity and stability of the catalyst, 900 ℃ is found to be the most suitable temperature.The influence of heate-treating temperature of CoTMPP/BP2000 was analyzed by UV-Vis, TEM, IR, TG and XPS methods. Results reveal that heated-treatment can change the central structure of catalyst, the porphyrin ring and Co—N4 band of the catalyst can not exited with and after 400 ℃ heat-treatment.The most stable Co—Nx—C structure was formed with 900 ℃ heat-treatment, this new active site can efficiently improve the catalytic ability of oxygen reduction of CoTMPP/BP2000.