调整双金属纳米晶体的晶相为改善其电催化性能提供了另一种途径。
该文中，研究人员提出了一种简便的一锅合成方法，用于通过控制Pd–Bi纳米晶体的晶体结构来提高碱性介质中氧还原反应（ORR）的催化活性和稳定性。在相同的条件下，只需改变钯前驱体的类型，就可以分别精确地合成具有相同尺寸和形貌的单斜结构Pd5Bi2和传统面心立方结构（fcc）Pd3Bi纳米晶体。有趣的是，碳支撑的单斜Pd5Bi2纳米晶体在碱性介质中表现出优异的ORR活性，其质量活性（MA）高达2.05 a/mgPd。经过10000次ORR耐久性试验后，单斜结构的Pd5Bi2/C纳米催化剂仍然保持1.52 a/mgPd的MA，分别是fcc Pd3Bi/C对应物、商用Pd/C和Pt/C电催化剂的3.6倍、16.9倍和21.7倍。
此外，耐久性试验后单斜Pd5Bi2/C纳米晶体的结构表征表明，其原始尺寸、形貌、成分和晶相保持良好，大大减轻了双组分的浸出。
该项工作为合成具有亚稳相的多金属催化剂提供了新的见解，并证明了相依赖的催化性能。
附：英文原文
Title: Improvement of Oxygen Reduction Performance in Alkaline Media by Tuning Phase Structure of Pd–Bi Nanocatalysts
Author: Ming Zhou, Jiangna Guo, Bo Zhao, Can Li, Lihua Zhang, Jiye Fang
Issue&Volume: September 14, 2021
Abstract: Tuning the crystal phase of bimetallic nanocrystals offers an alternative avenue to improving their electrocatalytic performance. Herein, we present a facile and one-pot synthesis approach that is used to enhance the catalytic activity and stability toward oxygen reduction reaction (ORR) in alkaline media via control of the crystal structure of Pd–Bi nanocrystals. By merely altering the types of Pd precursors under the same conditions, the monoclinic structured Pd5Bi2 and conventional face-centered cubic (fcc) structured Pd3Bi nanocrystals with comparable size and morphology can be precisely synthesized, respectively. Interestingly, the carbon-supported monoclinic Pd5Bi2 nanocrystals exhibit superior ORR activity in alkaline media, delivering a mass activity (MA) as high as 2.05 A/mgPd. After 10,000 cycles of ORR durability test, the monoclinic structured Pd5Bi2/C nanocatalysts still remain a MA of 1.52 A/mgPd, which is 3.6 times, 16.9 times, and 21.7 times as high as those of the fcc Pd3Bi/C counterpart, commercial Pd/C, and Pt/C electrocatalysts, respectively. Moreover, structural characterizations of the monoclinic Pd5Bi2/C nanocrystals after the durability test demonstrate the excellent retention of the original size, morphology, composition, and crystal phase, greatly alleviating the leaching of the Bi component. This work provides new insight for the synthesis of multimetallic catalysts with a metastable phase and demonstrates phase-dependent catalytic performance.
DOI: 10.1021/jacs.1c08644
Source: https://pubs.acs.org/doi/10.1021/jacs.1c08644
