Phosphate poisoning of Pt electrocatalysts is one of the major barriers that constrains the performance of phosphric acid-doped polybenzimidazole (PA/PBI) membrane fuel cells. Herein, we developed new atomically dispersed bimetallic FeCu coordinated with nitrogen-doped carbon nanotubes (FeCu/N-CNTs) as Pt-free fuel cell oxygen reduction reaction (ORR) electrocatalysts. The cell with FeCu/N-CNTs cathodes delivers a peak power density of 302 mWcm^-2 at 230℃, similar to that using Pt/C electrocatalysts (1 mg_Pt cm^-2) but with a much better stability. In contrast to phosphate poisoning of Pt/C, FeCu/N-CNTs show PA enhanced activities. DFT calcualtions indicate that phosphate promotion effect results from the stronger binding of phosphate on Cu sites, which decreases the activation energy barrier for the cleavage of the O₂ double bond and provides local protons to facilitate the proton-coupled electron transfer ORR. The results also show that FeCu/N-CNTs have a much better activity for ORR as comapre to Fe single atom catalysts coordinated with nitrogen-doped carbon nanotubes, Fe/N-CNTs. This study demonstrates the promising potential of bimetallic FeCu/N-CNTs as true Pt-free, highly active and durable cathodes of PA/PBI based high temperature polymer electrolyte fuel cells.

Pt电催化剂的磷酸盐中毒是限制磷酸掺杂的聚苯并咪唑（PA / PBI）膜燃料电池性能的主要障碍之一。在这里，我们开发了新型的原子分散双金属FeCu与氮掺杂碳纳米管（FeCu / N-CNTs）配合使用，作为无Pt燃料电池氧还原反应（ORR）电催化剂。具有FeCu / N-CNTs阴极的电池在230℃时可提供302 mWcm ^-2的峰值功率密度，类似于使用Pt / C电催化剂（1 mg _Pt  cm ^-2），但稳定性更好。与Pt / C的磷酸盐中毒相反，FeCu / N-CNTs显示出PA增强的活性。DFT计算表明，磷酸盐促进作用是由于磷酸盐在Cu位点上的较强结合而产生的，这降低了O ₂双键裂解的活化能垒，并提供了局部质子以促进质子耦合电子转移ORR。结果还表明，与与掺氮碳纳米管Fe / N-CNT配位的Fe单原子催化剂相比，FeCu / N-CNTs对ORR具有更好的活性。这项研究证明了双金属FeCu / N-CNT作为基于PA / PBI的高温聚合物电解质燃料电池的真正无铂，高活性和耐用阴极的潜力。