Evaluation of the Scaffolding Effect of Pt Nanowires Supported on Reduced Graphene Oxide in PEMFC Electrodes

The stacking and overlapping effect of two-dimensional (2D) graphene nanosheets in the catalyst coating layer is a big challenge for their practical application in proton exchange membrane fuel cells (PEMFCs). These effects hinder the effective transfer of reactant gases to reach the active catalytic sites on catalysts supported on the graphene surface and the removal of the produced water, finally leading to large mass transfer resistances in practical electrodes and poor power performance. In this work, we evaluate the catalytic power performance of aligned Pt nanowires grown on reduced graphene oxide (rGO) (PtNW/rGO) as cathodes in 16-cm2 single PEMFCs. The results are compared to Pt nanoparticles deposited on rGO (Pt/rGO) and commercial Pt/C nanoparticle catalysts. It is found that the scaffolding effect from the aligned Pt nanowire structure reduces the mass transfer resistance in rGO-based catalyst electrodes, and a nearly double power performance is achieved as compared with the Pt/rGO electrodes. However, although a higher mass activity was observed for PtNW/rGO in membrane electrode assembly (MEA) measurement, the power performance obtained at a large current density region is still lower than the Pt/C in PEMFCs because of the stacking effect of rGO.

二维（2D）石墨烯纳米片在催化剂涂层中的堆叠和重叠效应是其在质子交换膜燃料电池（PEMFCs）实际应用中的一大挑战。这些效应阻碍了反应气体有效传输以到达石墨烯表面负载的催化剂上的活性催化位点，以及生成水的排出，最终导致实际电极中较大的传质阻力和较差的功率性能。在这项工作中，我们评估了在还原氧化石墨烯（rGO）上生长的定向铂纳米线（PtNW/rGO）作为16平方厘米单电池质子交换膜燃料电池阴极的催化功率性能。将结果与沉积在rGO上的铂纳米粒子（Pt/rGO）以及商业Pt/C纳米粒子催化剂进行了比较。研究发现，定向铂纳米线结构的支架效应降低了基于rGO的催化剂电极中的传质阻力，与Pt/rGO电极相比，功率性能几乎提高了一倍。然而，尽管在膜电极组件（MEA）测量中观察到PtNW/rGO具有更高的质量活性，但由于rGO的堆叠效应，在大电流密度区域获得的功率性能仍然低于质子交换膜燃料电池中的Pt/C。