ZIF-67衍生的Ag/Co@NC材料及其氧还原性能的研究

ZIF-67-Derived Ag/Co-Embedded N-Enriched Mesoporous Carbon for Oxygen Reduction Reaction

氮掺杂的多孔碳材料可作为氧还原反应的催化剂,本文借助ZIF-67富氮多孔的特殊结构,采用湿式逐步还原法将Ag嵌入ZIF-67孔腔内,然后在Ar中碳化成功地制备了Ag/Co双金属嵌入的氮掺杂的多孔碳复合材料(Ag/Co@NC)作为氧还原反应的催化剂.为了证明Ag的突出作用,同时在Ar中碳化了ZIF-67制备了Co嵌入的氮掺杂的多孔碳材料(Co@NC).利用扫描电子显微镜、透射电子显微镜、X射线衍射、X射线光电子能谱以及比表面积分析对材料的显微形貌、物相组成、结构进行分析,采用循环伏安和线性扫描极化曲线对材料的氧还原催化活性和催化稳定性进行研究.结果表明,Ag的嵌入未改变ZIF-67的晶体结构,但是大大提高了材料的氧还原催化活性.Ag/Co@NC材料的半波电位和起始电位均高于Co@NC材料,且其在1000次循环伏安测试前后的半波电位变化仅为30 mV,显示出很好的催化稳定性和甲醇耐受性,可作为燃料电池和金属-空气电池的阴极催化剂.

Nitrogen-doped porous carbon materials are considered as one of the most promising catalysts for oxygen reduction reaction(ORR).Herein,in order to further improve the activity of the nitrogen-doped porous carbon,Ag/Co bimetal is embedded into nitrogendoped porous carbon to form Ag/Co-embedded nitrogen-doped porous carbon material(AgC o@NC).The AgC o@NC was derived by the wet impregnation of Ag+into ZIF-67 precursor,followed by chemical reduction and a subsequent pyrolysis process under Ar atmosphere at different temperatures(500 oC,600 oC,700 oC).The morphologic characterization shows that the Ag/Co nanoparticles were successfully embedded in the mesoporous carbon framework with abundant nitrogen atoms.The electrochemical test results indicate that the AgC o@NC-600 catalyst exhibited the higher onset potential and half-wave potential than thods of others and Pt/C in alkaline media.Furthermore,the AgC o@NC and Co@NC also displayed the higher methanol-tolerance performance than commercial Pt/C.