For the purpose of redesigning a PEM fuel cell with ultralow Pt loading, this review comprehensively summarizes and comments on recent important findings on ultrathin catalyst layer structures. We introduce recent advances in electrocatalyst research and development (R&D), highlighting the urgency of ultralow Pt loading in the total design of PEM fuel cells. Following that, the reason for a thinner and more ordered electrode structure is presented for the next generation of PEM fuel cells. We then review recent progress in methods for preparing Pt nanoparticles on high-aspect-ratio supports, extended surface area of nanowires (confined agglomerates and nanowires) and ordered arrays. Regarding the ordered arrays, we expatiate on proton conductor arrays and electron conductor arrays, including carbon nanotube-assisted arrays, TiO₂ nanotube-assisted arrays, Co-OH-CO₃ nanowire-assisted arrays, and pigment red 149-assisted arrays. Challenges related to proton transport and transfer, electron conduction and mass transport are then discussed to supply further research direction.

中文翻译：

---

优化用于PEM燃料电池的纳米复合催化剂层的结构设计，以提高质量比功率密度。

为了重新设计具有超低Pt负载的PEM燃料电池，本综述全面总结和评论了有关超薄催化剂层结构的最新重要发现。我们介绍了电催化剂研究与开发（R＆D）的最新进展，突出了PEM燃料电池总体设计中超低Pt负载的紧迫性。随后，提出了用于下一代PEM燃料电池的更薄，更有序的电极结构的原因。然后，我们回顾了在高纵横比载体上制备Pt纳米颗粒的方法，纳米线（受限团聚物和纳米线）的扩展表面积以及有序阵列的最新进展。关于有序阵列，我们详细介绍了质子导体阵列和电子导体阵列，包括碳纳米管辅助阵列TiO_2个纳米管辅助阵列，Co-OH-CO ₃纳米线辅助阵列和颜料红149辅助阵列。然后讨论了与质子传输和转移，电子传导和质量传输有关的挑战，以提供进一步的研究方向。