Functionality and design of Co-MOFs: unique opportunities in electrocatalysts for oxygen reduction reaction

Zeolitic imidazolate framework (ZIF)-derived electrocatalysts have emerged as efficient, environmentally innocuous, low-cost, non-noble-metal alternatives to precious group metals for the oxygen reduction reaction (ORR) and utilization in clean and sustainable energy systems such as metal-air batteries and fuel cells. Recently, there has been tremendous interest in ZIF-based materials due to the large N content and M-N bonds in the parent ZIF backbone and derived nanostructures, which are responsible for their high ORR catalytic activity. This review summarizes the origin of the activity of ZIF-based materials and their recent progress and focuses specifically on advancements in ZIF-67-based materials for efficient ORR electrocatalysis. Furthermore, this review also outlines the recent strategies for designing more efficient catalysts based on ZIF-67, such as doping with heteroatoms, alloying with various metallic species, and compositing with carbonaceous nanostructures, and discusses their underlying mechanisms. Finally, insight into the remaining challenges and directions for future perspectives and research is provided.