MOFs衍生物电催化剂的制备及其氧还原性能研究

【作者】 张艳；

【导师】 王宗花； 周瑜；

【作者基本信息】 青岛大学 ， 分析化学， 2019， 硕士

【摘要】 高效的催化剂材料是提高新型能源转化反应效率的关键。像铂（Pt）等贵金属有着高效的催化性能,但成本高和稳定性差阻碍了它们实际的应用。因此,寻找合适的催化剂材料显得尤为重要。金属有机骨架材料（Metal-organic frameworks,MOFs）通常由金属节点离子和有机配体通过配位键形成的多孔功能性材料,具有合成方法简单且结构可控等优势,在气体储存、光致发光、载药、催化等方面有着极强的应用性。在本论文中我们使用MOFs材料作为前驱体,通过高温碳化及酸处理后得到MOFs的衍生物,具有较好的导电性并将其应用于电催化方面的研究。具体研究内容如下:我们以胺官能化的Al-MOFs（NH₂-MIL-53（Al））作为氮源和碳的前驱体,提供一种用于氧还原反应的氮掺杂多孔碳（NPC-MILs）的简便合成方法。制备的NPC-MIL作为一种非金属催化剂具有良好的ORR（氧还原反应）催化潜力。优化的NPC-MIL-900（在900℃碳化）表现出ORR催化活性可与商业Pt/C相媲美。此外,计时电流测试,NPC-MIL-900催化剂材料显示出来优于Pt/C的稳定性。计时电流测试也表明NPC-MIL-900催化剂在碱性电解液中对甲醇的耐受性高于Pt/C。这些结果表明NPC-MIL-900在燃料电池中具有潜在的应用前景。在溶液法制备ZIF-67（Zeolitic imidazolate framework-67）材料的基础上,通过原位替代金属镍的方法合成双金属MOFs（ZIF-67（NiCo））,然后通过直接碳化得到其MOFs的衍生物,并对其电化学性能进行了探究。通过调控双金属掺杂比例以及碳化温度,寻找性能最优的非贵金属电催化剂。ZIF-67（NiCo-40%）-C-800的ORR催化性能稍优于商业Pt/C,并且表现出理想的四电子过程。此外,ZIF-67（NiCo-40%）-C-800催化剂还具有更好的稳定性和更高的甲醇耐受性。本工作为制备可调控金属比例掺杂多孔非贵金属碳材料提供了一种简单、可扩展的途径,具有广阔的应用前景。同时为下一步设计更高效的催化剂材料提供了设计思路。更多还原

【Abstract】 Efficient catalyst materials are key to improving new energy conversion equipment.Precious metals such as platinum（Pt）have high catalytic performance,but their high cost and poor stability hinder practical applications.Therefore,it is particularly important to find a suitable catalyst material.Metal-organic frameworks（MOFs）are porous functional materials formed by the interactions of metal-node ions and organic ligands through coordination bonds.The synthesis method is simple and the structure is controllable,which has widely application in gas storage,photoluminescence,drug loading and catalysis.However,the conductivity of MOFs is poor.In this work,MOFs were used as the precursors.After high-temperature carbonization and acid treatment,the derivatives of MOFs have good conductivity and can apply for electrocatalysis.The specific research contents are as follows:Here,we use amine-functionalized Al-MOFs（NH₂-MIL-53（Al））as a nitrogen source and carbon’s precursor to provide a simple synthesis of nitrogen-doped porous carbon（NPC-MILs）for oxygen reduction reaction.NPC-MIL has good ORR catalytic potential as a non-metallic catalyst.The optimized NPC-MIL-900（carbonized at 900℃）exhibits a ORR catalytic activity to comparable with commercial Pt/C.In addition,the chrono-current measurement shows that the stability of NPC-MIL-900 catalyst is better than Pt/C.The chronoamperometry also indicates that the NPC-MIL-900 catalyst is more resistant to methanol in alkaline electrolytes than Pt/C.These indicate that NPC-MIL-900 has potential applications in fuel cells.Based on the preparation of ZIF-67（Zeolitic imidazolate framework-67）by solution method,bimetallic MOFs（ZIF-67（NiCo））were synthesized by in situ replacement of metallic nickel.Then ZIF-67（NiCo）were directly carbonized to obtain derivatives of MOFs and the electrochemical properties of derivatives were explored.By controlling the doping ratio of the materials and the carbonization temperature,it can be found the non-precious metal electrocatalysts have the best ORR catalytic activity.In addition,the ZIF-67（NiCo-40%）-C-800 catalyst has better stability and higher methanol tolerance in an alkaline system.This work provides a simple and scalable approach for the preparation of tunable metal proportion doped porous non-precious metal carbon materials,and has broad application prospects.At the same time,it provides a design idea for the next step to design a more efficient catalyst material.更多还原