Geng Xin, Vega-Paredes Miquel, Lu Xiaolong, Chakraborty Poulami, Li Yue, Scheu Christina, Wang Zhenyu, Gault Baptiste
Max Planck Institute for Sustainable Materials, Max-Planck-Straße 1, 40237, Düsseldorf, Germany.
Division of Advanced Materials, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China.
Adv Mater. 2024 Nov;36(44):e2404839. doi: 10.1002/adma.202404839. Epub 2024 Sep 17.
The oxygen reduction reaction (ORR) is a critical process that limits the efficiency of fuel cells and metal-air batteries due to its slow kinetics, even when catalyzed by platinum (Pt). To reduce Pt usage, enhancing both the specific activity and electrochemically active surface area (ECSA) of Pt catalysts is essential. Here, ultrafine, grain boundary (GB)-rich Pt nanoparticle assemblies are proposed as efficient ORR catalysts. These nanowires offer a large ECSA and a high density of concave GB sites, which improve specific activity. Atoms at these GB sites exhibit increased coordination and lattice distortion, leading to a favorable reduction in oxygen binding energy and enhanced ORR performance. Furthermore, boron segregation stabilizes these GBs, preserving active sites during catalysis. The resulting boron-stabilized Pt nanoassemblies demonstrate ORR specific and mass activities of 9.18 mA cm and 6.40 A mg (at 0.9 V vs. RHE), surpassing commercial Pt/C catalysts by over 35-fold, with minimal degradation after 60 000 potential cycles. This approach offers a versatile platform for optimizing the catalytic performance of a wide range of nanoparticle systems.
氧还原反应（ORR）是一个关键过程，由于其动力学缓慢，即使由铂（Pt）催化，也会限制燃料电池和金属空气电池的效率。为了减少Pt的用量，提高Pt催化剂的比活性和电化学活性表面积（ECSA）至关重要。在此，提出了富含晶界（GB）的超细Pt纳米颗粒组装体作为高效的ORR催化剂。这些纳米线具有较大的ECSA和高密度的凹面GB位点，可提高比活性。这些GB位点的原子表现出增加的配位和晶格畸变，导致氧结合能有利降低并增强了ORR性能。此外，硼偏析使这些GB稳定，在催化过程中保留活性位点。所得的硼稳定的Pt纳米组装体在0.9 V（相对于可逆氢电极，RHE）下表现出9.18 mA cm和6.40 A mg的ORR比活性和质量活性，比商业Pt/C催化剂高出35倍以上，在60000次电位循环后降解最小。这种方法为优化各种纳米颗粒系统的催化性能提供了一个通用平台。
