New Avenues to MOF-Derived Cobalt Chalgogenides for Efficient Electrocatalysis

Abstract

Metal–organic frameworks (MOFs) are a class of porous hybrid solids consisting of metal-containing nodes coordinated with multitopic organic linkers. Recently there has been tremendous interest in the exploration of MOFs and their derivatives for electrocatalysis, however slow charge-transport kinetics often limit the performance. Therefore, making suitable carbon composites would greatly improve their electronic conductivity and subsequently the electrocatalytic activity. Herein, we have developed two different routes using cobalt imidazolate frameworks (ZIF-67) to design cobalt selenide (CoSe) hybridized with nitrogen doped carbon. The solid-state strategy involves direct conversion of ZIF-67 into CoSe nanoparticles with an average size of ~20 nm encapsulated within N-doped graphitic carbon shells with an average size of 300 nm. Interestingly, this method can easily be extended to similarly synthesize CoTe encapsulated N-doped graphitic carbon cages by simply changing the precursor. The other method involved the self-templated conversion of ZIF-67 into Co nanoparticles encapsulated N-doped carbon polyhedral and their subsequent transformation into vertically aligned CoSe grafted N-doped carbon sheets via a hydrothermal selenization method. Both, these class of materials so synthesized were found to exhibit excellent electrocatalytic activity towards HER and OER in alkaline medium. It is believed that the methods being developed here may be extended to other transition metal chalcogenides for various applications.