利用含氮碳源合成B,N分离共掺杂晶态纳米碳及其氧还原反应催化性能研究

Development the non-precious metal catalyst with low-cost and high activity towards oxygen reduction reactions (ORR) is the key of the commercialization for proton exchange membrane fuel cells. B,N-codoped carbon nanostructure materials are as a kind of promising catalysts for ORR. However, the BN covalent easily formed between B and N atoms during the synthesis, which is not favorable for ORR. Based on the group coordination principle, this project employs the nitrogen-containing biomass and polymer with polar groups as the carbon resources to synthesize B,N-codoped crystalline carbon nanostructures. In the synthesis, the graphitization catalyst metal ions are introduced into the backbone of carbon resources, and then the B resources are introduced. After carbonization and treating with acid, B,N-codoped crystalline carbon nanostructures will be obtained. The introduced metal ions play the role of saving N, which could avoid the direct contact between B and N atoms, and also could avoid the formation of BN covalent. Finally, the B,N-separated codoped crystalline carbon nanostructures will be synthesized. By controlling the synthetic conditions, the structures of the B,N-separated codoped crystalline carbon nanostructures will be tuned, including the B,N doped types and content, and the crystalline degree and micro-morphology of carbon nanostructures. Studying the electrocatalytic activites of the synthetic B,N-separated codoped crystalline carbon nanostructures towards ORR. By combining the theoretical calculation with experiments, the relation between the structure and ORR performance of the materials performance are explored.

发展低成本、高活性的非贵金属阴极氧还原反应催化剂是质子交换膜燃料电池商业化的关键。B,N共掺杂纳米碳材料是很有前景的催化剂，但是在材料制备过程中B原子与N原子容易形成BN共价键，这对于氧还原反应是不利的。针对以上问题，本项研究拟采用具有极性基团的含N生物质或聚合物作为碳源，基于基团配位原理，先后分别引入具有石墨化催化剂的金属离子及B源。经过碳化和酸处理后，合成B,N分离共掺杂晶态纳米碳。先引入的金属离子对N原子有固定作用，避免N原子与后引入的B原子直接接触，从而防止在碳化过程中生成BN共价键，从而制备B,N分离共掺杂晶态纳米碳。控制合成条件，实现对材料结构（B,N的掺杂类型和含量、以及碳的晶化程度和形貌结构等）的调控。研究这类材料对氧还原反应的电催化活性，理论计算结合实验表征，明晰材料结构与性能之间的关系。

本项目以含有极性基团的含N物质三聚氰胺为碳源，硝酸铁作为催化剂，基于基团相互作用合成了B,N分离共掺杂石墨化纳米碳包裹的Fe/Fe3C纳米粒子复合材料。在合成过程中，通过控制实现了三聚氰胺中的N原子先与硝酸铁中的Fe3+离子配位，这能够阻止在随后的热解过程中的BN共价键的生成，形成有效的B,N分离共掺杂石墨化纳米碳包裹的Fe/Fe3C纳米粒子复合材料，从而提高复合材料的催化性能。研究表明，这种材料的氧还原催化活性与Pt/C催化剂相接近，并具有优异抗甲醇性能及循环稳定性。此外，设计合成了N-掺杂CNTs/石墨烯、CrN/N-掺杂纳米碳以及Co-VN/N-掺杂竹节状碳纳米管等材料用于非贵金属氧还原催化剂。针对碳材料的储能性能差及稳定性差等问题，采用原位同步活化法制备了多孔碳材料以及类石墨烯片层材料用于储能领域。为了进一步提高碳基材料的储能性质，构筑了过渡金属化合物（氮化物、氧化物等）与三维碳结构的复合材料、自支撑电极材料用于锂电负极材料，并利用原位X-射线吸收精细谱技术探究了嵌锂/脱锂过程中各种金属原子的配位环境及价态的变化，揭示出材料的储锂机制。在本项目的支持下，共发表SCI论文23篇，出版专著1部。申请中国发明专利5项，其中4项已授权。