非共价修饰石墨烯负载的高稳定Pt电催化剂的制备与性能研究

Fuel cells are expected to be a main source of clean energy in the future, due to their advantages of high power density and environmental-friendly emissions. However, the poor durability of Pt electrocatalysts has greatly restricted the broad-based application of the fuel cells. Taking the advantage of superior electrochemical stability of the graphene materials, the current project plans to prepare polymer-modified graphene materials with varied surface structures and chemical properties by using the noncovalent method of functionalization, which is important for preserving the intrinsic structure of the graphene. By loading Pt or Pt-based alloy nanoparticles onto the as-prepared polymer-modified graphene, Pt/graphene nanocomposite catalysts (denoted as Pt/GR-P) would then be obtained. We intend to investigate the effect of the types of polymers used in the nonconvalent functionalization on the structure/properties of active component Pt as well as the interactions between Pt and polymer-modified graphene, in a hope to develop efficient synthetic approaches to prepare durable Pt-based electrocatalysts with polymer-modified graphene as support. Furthermore, the electrocatalytic performance of Pt/GR-P for anodic oxidation of hydrogen/methanol and cathodic oxygen reduction would also be investigated, aiming to establish the fundamental correlationships between the catalytic behavior and composition/structure of the electrocatalysts. The current proposal has the potential to develop some novel nanostructures and catalytic systems as highly durable electrocatalysts for fuel cells, which would be of significance in promoting the broad-based applications of fuel cells.

燃料电池因比能量密度高、环境友好等特点被视为未来主要的清洁能源。目前，燃料电池采用的Pt电催化剂较差的稳定性是限制其大规模应用的主要因素之一。本项目拟从具有高电化学稳定性的石墨烯材料入手，首先采用不同聚合物分子对石墨烯表面进行非共价修饰，在不破坏石墨烯本征结构情况下，合成具有不同表面结构和性质的高稳定石墨烯材料；然后以上述石墨烯作为载体制备碳负载型Pt基电催化剂，考察不同非共价修饰分子对活性组分Pt的结构和性质以及Pt与石墨烯之间Pt-C相互作用的影响规律，探索具有高电化学稳定性的非共价修饰石墨烯负载Pt电催化剂的制备方法；此外，通过考察其对氢气，甲醇等小分子氧化反应及氧气还原反应的电催化性能，尝试建立催化剂组成、结构和性能之间的构性关系。本项研究不但有望发现几种具有优越电化学稳定性的燃料电池电极催化剂的新体系与新结构，而且对促进燃料电池的大规模应用具有重要意义。

以苯胺(ANI)及聚苯胺(PANI)对还原氧化石墨烯(RGO)进行非共价修饰，并以其为载体负载Pt制备了Pt/ANI-RGO和Pt/PANI-RGO催化剂。结果显示，ANI及PANI对RGO进行修饰能明显减小Pt纳米颗粒的尺寸和分布范围；ANI及PANI的引入，提高了催化剂Pt的电化学活性面积，所制备的Pt/ANI-RGO和Pt/PANI-RGO催化剂对甲醇氧化的催化活性(125.6 A·g-1和86.4 A·g-1)要高于Pt/RGO催化剂(77.3 A·g-1)，但ANI及PANI对RGO的修饰对RGO负载的Pt电催化剂的催化稳定性造成下降。. 采用聚乙烯吡咯烷酮(PVP)非共价修饰的RGO为载体，以其负载Pt得到Pt/PVP-RGO催化剂。结果显示，Pt/PVP-RGO催化剂表面的Pt颗粒分布均匀、尺寸较小；相对于Pt/RGO催化剂而言，PVP的加入，对Pt/PVP-RGO催化剂甲醇氧化活性无显著改善；但Pt/PVP-RGO催化剂的稳定性(下降51 %)明显高于Pt/RGO催化剂(下降62 %)，PVP的存在对催化剂稳定性的提高有一定的积极作用。.利用甲基紫精(MV)非共价功能化RGO，并以其负载Pt制备了Pt/MV-RGO纳米催化剂。结果表明，Pt/MV-RGO催化剂表面的Pt颗粒分布状况和尺寸大小有明显改善；Pt/MV-RGO催化剂的电化学活性面积为24.7 m2·g-1，是Pt/RGO的3倍；同时，Pt/MV-RGO催化剂催化甲醇氧化的电流密度为221.4 A∙g−1，是Pt/RGO的2.6倍；在氧还原反应中Pt/MV-RGO催化剂亦有着较高的催化活性，Pt/MV-RGO催化剂的稳定性也较好。. 采用高温热解聚苯胺修饰的氧化石墨烯(PANI-GO)，通过改变氧化石墨烯与苯胺(GO/ANI)的质量比，制备了一系列氮掺杂还原氧化石墨烯碳材料(N-RGO)，以其负载Pt合成了Pt/N-RGO纳米结构电催化剂。采用透射电镜(TEM)、X射线衍射谱(XRD)、拉曼光谱(Raman)及X射线光电子能谱(XPS)等技术对Pt/N-RGO的形貌及结构进行表征。用循环伏安和计时电流等电化学技术研究了Pt/N-RGO电极催化剂对CO溶出反应和甲醇电氧化反应的催化性能。发现GO/ANI质量比为1:1.3时所制备Pt/N-RGO(1:1.3)催化剂显示出最好的抗CO