高稳定的电催化剂复合碳载体强化设计、制备与构效关系研究

One of the main reasons leading to the poor stability of electrocatalysts and short lifetime of polymer exchange membrane fuel cells (PEMFC) is the low chemical and electrochemical resistance of the catalyst support， which hampers the commercialization of PEMFCs. This project aims at fabrication methods with high novelty for highly stable composite supports through addition of oxides such as TiO2 into traditionally used carbon black, followed by doping of transitional metals to enhance their inherent electron conductivity. These tailor-designed composite supports are cost-effective and can be fabricated by a facile method. Nano-sized CaO will be added before heat-treatment to produce porosity. The doped titanium oxides with optimized sizes would situate in the voids between carbon particulates and effectively prevent carbon agglomerations. The metal-support and electronic effects of the modified titanium oxides promote the effective adsorption of oxophilic groups for the Pt electrocatalysts as catalysts promoters. Furthermore, the doped or modified titanium oxides are highly corrosion resistant towards chemicals and electrochemical cycling, thus preventing the electrocatalysts from dissolution or detachment from the composite supports and leading to enhanced life time of PEMFCs. The enhanced catalyst performance and the composite support will be investigated to study their inherent correlations in order to reveal the mechanism. This project will hopefully provide useful theoretical knowledge for designing of electrocatalysts with enhanced stability and performance.

电催化剂载体的电化学\化学腐蚀能力差、稳定性低，造成质子交换膜燃料电池催化剂失效、电池寿命短，达不到商业化要求。本项目创新性的设计并提出一种具有高稳定性复合载体的制备方法，即在传统炭黑中添加廉价的氧化钛等氧化物，然后高温过渡金属掺杂提高导电性，制备成复合碳载体，经济、实用的解决困扰燃料电池稳定性这一科学难题。本项目所制备的复合载体具有成本低廉、制备工艺简单等显著优点。在制备过程中，创新性的添加氧化钙造孔，防止热处理时烧结。合适粒径的掺杂氧化钛将优先占据炭-炭颗粒之间的空隙，有效防止自我团聚；通过“载体-金属”界面和电子效应，促进铂表面含氧基团的吸附，起助催化作用；掺杂或改性氧化钛极强的耐化学\电化学腐蚀能力有效防止铂的熟化长大，从而大幅度提高电极寿命。本项目通过对复合载体与电催化剂之间的性能构效关系研究，揭示复合载体稳定电催化剂的内在机理，进而为设计高性能、高稳定的电催化剂提供理论依据。

背景：质子交换膜燃料电池目前在中国已经进入商业化阶段，然而限制其大规模布局的关键原因之一在于燃料电池电催化剂为卡脖子的关键技术。目前，商业化的电堆几乎全部采用进口的电催化剂，因此研发能够替代国际上商业催化剂的国产电催化剂和实现其商业化具有非常重要的意义。.主要研究内容：本项目在燃料电池铂碳催化剂和铂合金催化剂以及高稳定性碳载体方面展开研究。铂碳催化剂方面，开发了简单实用的室温乙二醇还原法，铂合金催化剂方面，开发了铂钯核壳结构催化剂、铂钌合金催化剂；碳载体方面，开发了以化学镀为基础的制备纳米碳纤维的工业制备方法。这些催化剂的制备方法和碳载体的制备方法为开发具有实用性的商业催化剂奠定了良好的基础。.重要结果: 铂碳催化剂和铂钌合金催化剂方面发表论文13篇，更重要的是已经在铂碳催化剂方面成功孵化高科技企业一家，实现量产并有公斤级销售。.关键数据及其科学意义：批量化铂碳电催剂的粒径远远小于商业催化剂，平均2nm，电化学活性面积大于80m2/g。