Toward quantification of active site density and size-dependent ORR activity of ZIF-derived carbons in alkaline electrolyte

ZIF-derived carbons (ZDCs) represent a novel category of non-precious metal catalysts (NPMCs) for the oxygen reduction reaction (ORR). Nevertheless, establishing the correlation between their structure and performance is challenging due to their diverse structural properties and ill-defined active site moieties. Here we investigate the effect of ZIF-67 derived carbon's particle size and corresponding distribution of assorted nitrogen functionalities on the ORR. Our findings reveal a substantial increase in ORR activity with decreasing ZDC particle size, while the exact influence of nitrogen functionalities remains uncertain. Most importantly, the present work unveils a correlation between the ORR activity and the site density (SD) of Co-Nx within the ZDC materials, which can be attributed to the concurrently increasing SD and accessibility of Co-Nx on the ZDC particles with small sizes. The present work provides novel insights into the optimization of ZDCs as high-performance NPMCs for ORR in alkaline electrolytes.

Automated summary

ZIF-derived carbons are a new type of non-precious metal catalyst for the oxygen reduction reaction. The smaller the ZDC particle size, the higher the ORR activity, but the exact influence of nitrogen functionalities is still uncertain. This study also reveals a correlation between the ORR activity and the site density of Co-Nx within the ZDC materials.