Zeng Wei-Jie, Wang Chang, Yin Peng, Tong Lei, Yan Qiang-Qiang, Chen Ming-Xi, Xu Shi-Long, Liang Hai-Wei
Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Inorg Chem. 2023 Apr 3;62(13):5262-5269. doi: 10.1021/acs.inorgchem.3c00331. Epub 2023 Mar 22.
Porous carbon-supported atomically ordered intermetallic compounds (IMCs) are promising electrocatalysts in boosting oxygen reduction reaction (ORR) for fuel cell applications. However, the formation mechanism of IMC structures under high temperatures is poorly understood, which hampers the synthesis of highly ordered IMC catalysts with promoted ORR performance. Here, we employ high-temperature X-ray diffraction and energy-dispersive spectroscopic elemental mapping techniques to study the formation process of IMCs, by taking PtCo for example, in an industry-relevant impregnation synthesis. We find that high-temperature annealing is crucial in promoting the formation of alloy particles with a stoichiometric Co/Pt ratio, which in turn is the precondition for transforming the disordered alloys to ordered intermetallic structures at a relatively low temperature. Based on the findings, we accordingly synthesize highly ordered L1-type PtCo catalysts with a remarkable ORR performance in fuel cells.
多孔碳负载的原子有序金属间化合物（IMCs）是用于燃料电池应用中促进氧还原反应（ORR）的有前景的电催化剂。然而，高温下IMC结构的形成机制尚不清楚，这阻碍了具有促进的ORR性能的高度有序IMC催化剂的合成。在此，我们采用高温X射线衍射和能量色散光谱元素映射技术，以工业相关的浸渍合成法为例，研究以PtCo为例的IMCs的形成过程。我们发现高温退火对于促进具有化学计量比Co/Pt的合金颗粒的形成至关重要，而这反过来又是在相对较低温度下将无序合金转变为有序金属间结构的前提条件。基于这些发现，我们相应地合成了在燃料电池中具有卓越ORR性能的高度有序的L1型PtCo催化剂。
