Au纳米异构体内核对Pt单层外壳的结构调控以及电催化性能的影响

As a cathode catalyst for proton exchange membrane fuel cell, Au@Pt/C can significantly reduce the amount of Pt and improve the stability of Pt, however, the oxygen reduction catalytic activity of Au@Pt/C can not meet the demand of commercial application. Pt with the different crystal faces has the different catalytic activity. If the Pt shell has more high activity index crystal face, the oxygen reduction catalytic activity of Au@Pt/C catalyst can be improved. 2D epitaxial growth of Pt on the Au surface with high activity index crystal face to form Pt monolayer Au@Pt/C catalyst is required, but it is difficult to achieve this goal using current existing methods. In this project, we propose a new method to prepare Pt monolayer Au@Pt/C catalyst by using spontaneous reduction deposition method. It can be ensure that the Pt shell has the same crystal face as the Au core and the morphology of Au@Pt can be controlled by 2D epitaxial growth of Pt monolayer on the surface of Au heteronanostructures (spherical nanoparticle, nanocube, nanorod, nanooctahedral) with the different crystal faces. Electrochemically test the catalytic activity for oxygen reduction and long-duration stability of the as-prepared catalysts, and then discuss the relationship between the catalyst structure and electrochemical properties through combining with theoretical calculation. So as to improve the Pt catalytic activity by controlling the morphology and promote the development of the proton exchange membrane fuel cell.

碳载Pt包Au核壳结构纳米颗粒（Au@Pt/C）作为质子交换膜燃料电池阴极催化剂，虽然可以大幅度降低Pt用量和提高Pt稳定性，但其氧还原反应催化活性还有待提高。不同Pt晶面具有不同催化活性，让Pt单层外壳具有较多的高活性晶面，可以改善Au@Pt/C催化剂的氧还原反应催化性能。但目前现有方法难以让Pt在具有较多高活性晶面的Au表面实现2D外延性生长，形成Pt单层Au@Pt/C催化剂。本项目拟利用自发还原沉积法提出一种制备Pt单层Au@Pt/C催化剂的新方法，通过Pt在具有不同晶面的Au纳米异构体（球形纳米颗粒、纳米立方体、纳米棒、纳米八面体）表面2d外延性生长，保证Pt壳具有与Au核相同的晶面，实现Au@Pt/C的形貌控制；研究其电催化性能与稳定性，结合理论计算探讨Au@Pt/C结构对其高催化活性的影响。期望通过形貌来调控Au@Pt/C催化活性，推动燃料电池发展。

碳载Pt包Au（Pt@Au/C）核壳结构纳米颗粒的氧还原反应催化活性尚未满足商业化需求，Pt外壳的形貌控制可以进一步提高催化剂催化活性。本项目通过对不同Pt层厚度与多种Au晶面所形成的合金进行密度泛函理论计算热力学和化学性质，从理论上预测Au表面的Pt有利于催化剂的稳定性与氧还原催化活性，各种Au晶面上对Pt层覆盖度的需求不同。不需要添加还原剂，通过正二价Pt离子的自发沉积我们制备了多种Pt@Au/C纳米异构体（纳米球、空心球、纳米立方体、纳米棒、纳米八面体），通过研究Pt@Au/C纳米异构体的形貌、体相结构、表面结构、晶面间距及电子状态，表明Pt的自发沉积可以使Pt@Au维持与Au内核相同的形貌，外层Pt壳具有与Au内核相同的晶面，实现了Pt@Au/C的形貌控制。我们研究了Pt@Au/C异构体作为氧还原催化剂的稳定性和催化活性，并探讨催化剂结构的改变对催化性能与稳定性的影响。其中Pt@Au/C纳米棒表面Pt分散均匀，含有较多的高活性（110）晶面，使得Pt@Au/C纳米棒催化剂具有高的氧还原催化活性，Pt质量活性比商业Pt/C提高了近10倍，并且具有优秀的稳定性，具有商业化应用前景。