基于过渡金属与氮化碳非贵金属多孔催化剂的设计合成、电子结构调控及电催化性能研究

Two of the greatest stumbling blocks hindering broad applications of Direct Methanol Fuel Cells (DMFCs) are the high cost and weak durability of the precious metal catalysts. It is highly desirable but challenging to develop non-precious hybrid catalysts as precious metal alternatives for DMFCs system featuring excellent performance, low cost and long life. The objective of this project is to explore a high-performance transition metal/carbon nitride hybrid catalyst. The catalytic performance of carbon nitride catalysts will be investigated from two key aspects: (1) Preparation of porous carbon nitride materials with large surface area and incorporation of conductive materials to improve electron transfer of carbon nitride; (2) Non-metallic elements such as F, B, P, S, et al. are doped into special sites of the carbon nitride framework, so as to tune the electronic structure of carbon nitride with uniquely promoted catalytic activity. A combination of theoretical molecular simulation and experimental tests will be also applied to optimize the molecular design with controllable doping contents and sites. In addition, the hybrid catalysts base on carbon nitride and transition metals/their derives with a precise control over a wide range of physical/chemical properties including dispersibility, particle size, morphology and composition, as well as their influences on the overall catalytic performance, will be systematically investigated. Based on these research results, a series of carbon nitride/transition metals based hybrid catalysts will be explored. Moreover, the fundamental scientific problems, such as interface structures effect, the mechanism of synergetic effect between transition metals and carbon nitride and the related control factors will be revealed.

贵金属基催化剂的成本与可靠性问题是阻碍直接甲醇燃料电池(DMFC)商品化进程的两大技术瓶颈，开发廉价、高活性、长寿命的催化剂对DMFC的发展具有重要的意义。本课题旨在研究一种基于过渡金属化合物与氮化碳材料的非贵金属高效催化剂。从内外两个方面入手研究氮化碳的催化活性、稳定性与导电性：(1)调控氮化碳材料的微观形貌(比表面积与多孔性)以及引入导电材料优化电子传输特性; (2)采用非金属元素掺杂调控氮化碳材料的电子结构，并结合计算机模拟，优化元素掺杂浓度与掺杂位. 并对杂化催化剂的分散性，颗粒大小，形貌与组成等物理/化学性质进行精确调控，探讨其对催化性能的影响。并开发基于过渡金属与氮化碳的复合催化剂，阐明复合材料界面结构对催化活性的影响，以及过渡金属与氮化碳之间相关增效作用机制与控制因数等一系列基础科学问题

过渡金属/碳基复合材料是一类重要的电化学储能材料，在燃料电池，锂/钠电池中展现出了非常重要的应用，目前研究的主要方向集中在探索新的合成路线以及有效的复合方式。本项目旨在合成一种廉价、高活性的基于过渡金属与碳材料的复合电极材料。通过探索碳材料的微观形貌(比表面积与多孔性控制)以及电子传输特性，过渡金属的分散性以及接触界面，并对其催化活性进行深入研究。基于此，在本项目的资助下，申请人主要研究了MOF材料衍生的碳复合电极材料。通过原位限域热解路线获得了氮掺杂碳管包埋钴纳米颗粒电催化剂。少量钴的引入，有效调节了碳管的电子结构，导致更多的催化活性位生成，从而导致提高了碳的电催化活性，所得电极材料的催化活性接近于商业化铂电极。并且，在MOF研究的基础上进行延伸，发展了一种普适性并且廉价的三维碳复合电极制备技术，通过反向利用金属有机前躯体，利用离子交换路线在氧化锌表面包覆一层金属有机框架结构(MOF)。并以此为碳源，原位热解制备出了三维ZnO/ZnO quantum dots/C核壳电极材料(Adv. Mater., 2015, 27, 2400-2405)，以及类固溶体Sn/碳纤维复合电极材料(Nano Energy 2014, 9, 61-70)。该方法有效提高了氧化物与碳材料的复合水平，对电极材料电化学活性的发挥具有重大的指导意义。