双壳层核壳结构催化剂的可控制备及电催化氧还原机理

Proton exchange membrane fuel cells (PEMFCs) have attracted growing interests for their high efficiency and environmental benignity, but their commercialization is hindered by high cost and poor stability of catalysts. In this project, the catalysts with double-core-shell nanostructures will be prepared according to the phase segregation effect, which employ the nitrides as core, Pt and Pd as shell, and also with controllable nanostructures. Here, the nitrides of W, Mo and V that are alloyed with Fe, Co and Ni, which could promote the stability and activity for oxygen reduction. The on-line and off-line methods, such as ETEM and RRDE are used to investigate the corresponding physio-chemical properties and the catalytic performance for oxygen reduction reaction. Meanwhile, the DFT method is employed to design the double-core-shell catalysts, which is helpful for us to understand the mechanisms of the catalytic effects, and the methods to control the nanostructures of the core-shell catalysts. The results could be meaningful for us to develop nanostructure catalysts that with high performance for oxygen reduction, which could reduce the costs of catalysts and promote the commercialization of fuel cells, meanwhile, the prepared catalysts could also be used in other fields.

质子交换膜燃料电池(PEMFCs)具有能量转换效率高和环境友好等优点而备受关注。但是，目前广泛应用的Pt基催化剂并不能满足PEMFCs阴极催化剂高效、稳定及廉价的使用要求。本项目根据金属表面偏析的原理，利用过渡金属氮化物的稳定性及过渡层金属原子对表层金属原子的电子和化学修饰作用，开发以钨钼钒和铁钴镍等二元过渡金属氮化物为核，铂和钯为壳，且壳层结构可调的双壳层核壳结构氧还原催化剂。结合原位化学和现场电化学等物性表征手段及分子计算模拟的结果分析催化剂中各组元的催化特性，揭示催化剂的构-效关系，阐明相关的催化机理，以期掌握核壳催化剂的结构调控方法，开发出高效稳定且廉价的质子交换膜燃料电池催化材料。本项目成果可望为降低燃料电池成本和解决燃料电池产业化的瓶颈问题提供科学依据。拟开发的新型催化剂可用于电解水、金属-空气电池、电化学传感器等领域，具有广阔的应用前景。

质子交换膜燃料电池(PEMFCs)具有能量转换效率高和环境友好等优点而备受关注。但是，目前广泛应用的Pt基催化剂并不能满足PEMFCs阴极催化剂高效、稳定及廉价的使用要求。本项目根据偏析的原理，通过改变反应气氛和热处理温度制备了高性能双壳层核壳氧还原催化剂，实现过渡金属氮化物和过渡金属合金对Pt壳层氧还原活性的调控。通过改变Pt合金组分和形貌，载体等方式调控催化剂的电子结构，可控合成了系列目标催化剂。结合球差电镜等先进表征手段，揭示了双壳层催化剂结构组成调控机制和催化剂活性位点的形成机制，系统地研究了氧还原过程中催化剂的表面组成、形貌、化学结构和电子结构等对催化剂表面的吸附和催化性能的影响及规律，并结合理论计算，掌握了氧气分子在催化剂活性位点上的反应机制和反应路径，进一步获得催化剂结构、活性位点与电催化反应机理之间的关系。该项目的研究成果对于推动以氢氧燃料电池为代表的新能源技术的发展具有重要意义。