一步单模板法调控制备氮掺杂介孔碳球及其负载Pt基催化剂的电催化性能研究

The expensive price and easily poisoning of Pt electrocatalyst still remain the biggest hurdles to the commercial applications of the direct methanol fuel cells (DMFC). Our preliminary results show that the mesoporous carbon spheres-supported Pt catalyst has significantly enhanced electrocatalytic performance, better electrocatalytic stability and poisoning tolerance compared with the carbon black-supported Pt, which may be due to its unique hierarchical nanostructure that ensure fast mass transport during the reactions. Aiming to study the effects of the structures of the carbon spheres on the electrocatalytic performance of catalyst, N-doped mesoporous carbon spheres (N-MCS) with controllable mesopores will be prepared by using silica nanospheres as template and polypyrrole as carbon sources. And they will be explored to support Pt nanoparticles as electrocatalysts (Pt/N-MCS) for the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). The mathematic model of the relationship of the structure (such as mesopore size, the diameter of carbon spheres, the content of nitrogen) of N-MCS with regard to the electrochemical performance of the Pt/N-MCS catalyst will be established. Furthermore, to lower the cost of DMFC, the transition metals (such as Ni, Co, Fe) will be added to form Pt-based alloy nanoparticles, and the interaction effects of the component of the Pt-based alloy with regard to the electrochemical performance of the Pt-alloy/N-MCS catalyst will be revealed. The implementation of this proposed project will be expected to provide the experimental foundation and theoretical basis for the development of the DMFC electrocatalyst.

铂碳催化剂的高成本、易中毒是制约甲醇燃料电池（DMFC）大规模商业化的瓶颈。申请者前期工作发现，介孔碳球材料负载Pt催化剂具有较高的催化活性、抗毒性和稳定性，这可能归因于介孔碳球的可快速传质的多级孔结构。为探明碳材料的多级孔结构对催化剂催化性能的影响机理，本项目拟以聚吡咯为碳源，以SiO2纳米球为介孔导向剂，一步模板法制备氮掺杂介孔碳球（N-MCS）作为支撑材料负载Pt催化剂（Pt/N-MCS），并研究其电催化性能。通过对N-MCS的微观结构（介孔尺寸、碳球直径、氮含量等）的调控，揭示N-MCS的多级孔结构对Pt/N-MCS电催化性能的影响规律。为进一步降低Pt含量、提高抗毒性，本项目拟在Pt颗粒中添加非贵金属元素（Ni、Co、Fe），通过调整Pt基合金的元素组分和含量，明确Pt基合金元素组分和含量对催化剂抗毒性和稳定性的影响规律。本项目的研究可为设计DMFC催化剂提供研究基础和理论依据。

铂碳催化剂的高成本、易中毒是制约甲醇燃料电池（DMFC）大规模商业化的瓶颈。然而，Pt催化剂仍然是目前发现的催化活性最好的催化剂之一。因此，提高Pt催化剂的利用效率，延长其寿命可以降低燃料电池成本。其中最有效的方法之一，是发展高比表面积，强导电性的碳材料作为催化剂载体。该项目首先以聚吡咯为碳源，以SiO2球为模板，制备氮掺杂多级孔碳材料（三维有序多级孔碳以及有序介孔碳球）作为支撑材料负载Pt催化剂。研究了SiO2球的球径，HF腐蚀条件对氮掺杂介孔碳材料的结构形貌影响。确定了最优的形成介孔碳球的合成条件，以及最优的载Pt方式。以MOR和ORR为基础，考察不同多级孔结构碳载体对催化剂电化学性能的影响。结果表明，相较于商业Pt/C催化剂和氮掺杂介孔碳球载Pt催化剂（Pt/N-OMCS），氢气还原法制备的氮掺杂三维有序多级孔碳载Pt（Pt/N-OHPC）催化剂具有较高的电化学活性比表面积，较好的MOR/ORR催化活性，以及更好的稳定性。该项目的研究可为设计DMFC催化剂载体提供研究基础和理论依据。此外，一步法制备的氮掺杂介孔碳球材料可以拓展应用于其他新能源领域。