posted on 2020-03-10, 16:04authored byTalha Al-Zoubi, Yu Zhou, Xi Yin, Blanka Janicek, Chengjun Sun, Charles E. Schulz, Xiaohui Zhang, Andrew A. Gewirth, Pinshane Huang, Piotr Zelenay, Hong Yang
Non-platinum group
metal (non-PGM) electrocatalysts for the oxygen
reduction reaction (ORR) are generally composed of iron, nitrogen,
and carbon synthesized through high-temperature pyrolysis. Among the
various types of precursors, metal–organic frameworks (MOFs),
zeolitic imidazolate framework (ZIF)-8 in particular, have often been
used in the synthesis. The pyrolysis of ZIF-8 precursor relies on
the use of Zn as a sacrificial metal (SM), and the optimal processing
temperatures often exceed 1000 °C to generate active non-PGM
catalysts. The high pyrolysis temperature tends to result in heterogeneous
active moieties ranging from Fe single atoms to nanoparticles. In
this study, we present the synthesis of non-PGM catalysts using Cd
as the sacrificial metal instead of Zn. By using Cd, we were able
to generate active non-PGM electrocatalysts from the MOF precursors
at a low pyrolysis temperature of 750 °C, which helps preserve
the single atomic iron active sites.