电化学氧还原氮掺杂碳基催化剂合成及其催化性能研究

The electrocatalytic activity and durality of nitrogen-doped carbon based catalysts depend on their structures. The improvement of electrocatalytic activity and durality are rely on the beter understanding of active site structures. In this proposal, we will address structure-reactivity relationships of high-surface-area nitrogen-doped carbon based catalysts for the electroreduction of oxygen. Our work is based on the hypothesis that a utilizing high-surface-area nitrogen-doped carbon based catalysts for higher acitive site utilization, choosing high-nitrogen containing chemicals as nitrogen prcursors to increase the nitroge contents of active site for achieving high active sites density (SD) on nitrogen doped carbon based catalysts;a careful tuning contents and ratios of precursors including (nitrogen, transition metal salt, carbon),and optimizing heat-treatment procedures to fabricate Fe-N2+2 structures, and pyridinic or graphitic nitrgen-doped carbon to catalyze oxygen reduction via 4e path and increase turnover rate of the catalyst. The electrochemical activity of catalysts will be correlated with their synthesis procedure and structure.The mechansim for oxygen redution will be studied. At the end of this project is a deeper understanding of how structure affects activity and durabity of nitrogen-doped carbon electrocatalyts for oxygen reduction, which will propel the development of non-precious metal based catalysts for proton-membrane exchange fuel cell.

本项目针对氮掺杂碳基氧还原催化剂存在活性位点密度低、催化活性较差和稳定性不佳等问题，提出高比表面积的氮掺杂碳基氧还原催化剂合成及其性能研究的课题，旨在制备具有高催化活性和高稳定性的氮掺杂碳基电化学氧还原催化剂。拟开发新的氮源，设计合成一系列高比表面积的氮掺杂碳基氧还原催化剂,增加活性位点处的氮含量和容积比表面积，实现增加催化剂的活性位点密度和催化剂利用率的目的；拟优化氮源、过渡金属的含量和成分、及高温热解的升温程序，制备具有Fe-N2+2、吡啶型或石墨型氮掺杂结构的氮掺杂碳基催化剂，研究促进氧还原的四电子催化过程的策略，实现提高催化剂的氧还原转化率的目的。系统研究合成材料和方法对催化剂结构、催化性能和稳定性的影响；探索氮掺杂碳催化剂的活性位点结构，揭示催化剂结构与其氧还原催化性能和稳定性之间的构效关系。本研究成果将促进氮掺杂碳基氧还原催化剂开发及其在质子交换膜燃料电池中的应用。

本项目针对氮掺杂碳基氧还原催化剂存在活性位点密度低、催化活性较差和稳定性不佳等问题，提出高比表面积的氮磷掺杂碳基氧还原催化剂合成及其性能研究的课题，旨在制备具有高催化活性和高稳定性的氮掺杂碳基电化学氧还原催化剂。我们采用硬模板技术合成一系列高比表面积（639 -1117 cm2 g-1）的，氮磷掺杂碳基氧还原催化剂, 通过优化活性位点处的氮含量（3.2-6.8％）和磷含量（0.1-0.6％），实现增加催化剂的活性位点密度和催化剂利用率的目的，并采用XPS光电能谱结合电化学性能测试以及电化学毒性测试，对氮磷掺杂碳基氧还原催化剂催化活性位点结构进行了初步探讨，我们认为所制备的2类磷氮掺杂催化剂具有较高吡啶型或吡咯石墨氮掺杂形态，该类氮掺杂形态对氧还原催化性能有较好的促进作用；在氧还原催化机理方面，以CoMn2O4钴锰尖晶石氧化物作为一种模型催化剂，提出利用该类催化剂具有氧还原和氧析出双功能催化特性和降解氧还原中间产物过氧化氢特性，制备具有高稳定CoMn2O4/CNTs复合物催化剂。