基于单分散石墨化碳球的制备及其应用研究

A novel method for the synthesis of discrete and highly dispersible carbon spheres (DCS) is proposed in this project by using dual templates. Firstly, monodisperse crosslinked polymer spheres with core-shell or homogeneous structures are synthesized by emulsion polymerization or perception polymerization, respectively. The as-prepared polymer spheres are composed of two components: one is the carbon source, and the other is the cavity source, namely soft template 1. Secondly, the prepared monodisperse polymer spheres are dispersed in monomers containing initiator. After polymerization, the spheres are homogenously immobilized into the crosslinked polymer matrix (soft template 2), which is crucial for obtaining DCS. The soft template 2 provides a confined space for the high temperature pyrolysis of the polymer spheres and thus prevents polymer/carbon conglutination during high-temperature treatment. In this way, each single polymer sphere can be converted to carbon within the isolated space during pyrolysis. Meanwhile, soft template 1 as well as core for core-shell sphere decomposes to leave void and hollow part, respectively, while soft template 2 decomposes gradually to leave porous or hollow carbon spheres separately. Finally, DCSs are obtained after pyrolysis of the sphere/polymer (soft template 2) composites. The scientific merits of the proposal include: a) the conglutination during high-temperature treatment can be solved simply and conveniently; b) the porosity of monodisperse carbon sphere can be tuned; c) the carbon sphere doping can be realized by screening of the carbon source. The prepared monodisperse porous or hollow carbon spheres will show promising applications in many fields such as fuel cell catalysis, energy storage, and gas sensors etc.

本申请项目拟采用双模板法制备单分散石墨化碳球，并开展其应用研究。首先采用沉淀聚合和乳液聚合分别合成单分散聚合物球以及具有核/壳结构的聚合物球，要求聚合物球的组分之一在热处理过程中碳化成碳，另一组分热解致孔，热解致孔组分称之为软模板1。然后将制备的单分散聚合物球嵌入交联聚合物基体（称之为软模板2）中，经程序升温碳化处理得到单分散多孔或中空石墨化碳球（软模板2完全热解）；其中中空碳球由核壳结构聚合物球制备，壳为碳源，核热解；同时探索所制备的单分散多孔或中空碳球在电化学催化及储能等领域的应用。本申请项目采用软模板方法，可解决碳球高温碳化制备过程中存在的团聚问题，所制备的碳球具有单分散性且孔径在介孔范围内可调；同时可以实现碳球掺杂，赋予碳球新功能，具有较强的理论意义和实际应用价值。

本项目研究围绕碳球(中空和实心)、杂原子掺杂多孔碳材料的制备及电化学应用等方面展开，主要研究结果包括（1）采用模板热解法制备单分散中空碳球(HCSs),而后以HCSs为载体负载PtRu双金属纳米粒子，PtRu负载量为15.75 wt%，粒径为2-4 nm。该催化剂用于直接甲醇燃料电池(DMFCs)，其甲醇氧化电流可达到650 mA/mgPt。（2）采用聚合物包埋热解法制备出单分散B掺杂中空碳球(BHCS)。在碱性电解质中(下同)，BHCS表现出较高的氧还原(ORR)电催化活性，其ORR起始电位为-0.025 V (vs.Ag/AgCl，下同)，电子转移数为3.89，接近商业Pt/C催化剂水平。（3）采用Friedel-Crafts烷基化反应制备出超交联聚(三吡咯-三嗪)微球(PTPT)和共聚(三吡咯-三嗪/吡咯)微球(P(TPT-Py)，再将其分别与醋酸亚铁混合经热解制备得到Fe/N共掺杂碳球催化剂(Fe-N/C和Fe-NTP/C)。对于Fe-N/C催化剂，其ORR起始电位为0.041 V，半波电位为-0.07 V；对于Fe-NTP/C催化剂，其ORR起始电位为0.051 V，半波电位为-0.055 V，均远优于商业Pt/C催化剂(0.001 V和-0.115 V)。此外，采用氧化聚合反应制备了聚(三吡咯-三嗪)微球(TPN)，经热解得到“真正”不含金属的N掺杂碳球催化剂(NC)，其ORR起始电位为0.008 V，半波电位为-0.111 V，略高于商业Pt/C催化剂。(4)采用直接共混热解法制备了氮掺杂和硫掺杂碳纳米管(NCNTs和SCNTs),二者ORR起始电位分别为-0.038 V和-0.082 V，均低于商业Pt/C催化剂。（5）采用聚合物纳米球自组装法和互穿网络(IPN)聚合物碳化法分别制备出2种多孔碳材料，其比电容分别为319 F/g和221 F/g(电流密度为0.5 A/g，下同)。此外，采用水热碳化及KOH活化法制备出氮掺杂多孔碳材料，其比电容高达365 F/g。（6）分别以龙须草、莲蓬壳、紫苏叶和构树皮为原料，经碳化制备出4种生物质多孔碳材料，其比电容分别为373 F/g、402 F/g、287 F/cm3和 320 F/g。（7）构筑了2种基于碳纳米管的葡萄糖电化学传感器，其葡萄糖检测限分别为56 nM和 2.5 nM。