Facile synthesis of hybridized Co/Fe-ZIF under solvent-free conditions for efficient oxidation evolution reaction electrocatalysis

Developing non-noble catalyst synthesis under green conditions with efficient electrochemical reactions is a challenging task in green energy technologies. To meet this challenge, the synthesis of hybridized non-noble cobalt and iron in the zeolitic-imidazole framework (Co/Fe-ZIF) through a solid-state thermal (SST) method is developed. In the obtained Co/Fe-ZIF structure, iron atoms are uniformly dispersed and randomly hybridized with primary cobalt atoms and imidazole linker, similar to the structure of ZIF-67. The hybridized Co/Fe-ZIF shows potential as an electrocatalyst for oxidation evolution reaction (OER). The optimal iron-incorporating catalyst, Co/Fe_0.2-ZIF, demonstrates remarkable performance with a minimized overpotential of 285 mV at the current density (j) of 10 mA·cm⁻² in 1 M KOH. The synergistic effect of iron and cobalt ions on the catalyst provides active sites that bind to intermediate (OOH*) more strongly and facilitate high electron charge transfer, enhancing efficient electrocatalyst. Furthermore, the synergistic Co/Fe_0.2-ZIF catalyst demonstrates excellent durable reaction time compared to non-iron catalyst (ZIF-67) and conventional catalyst (RuO₂).