Morphological modulation of Co-based Zeolitic imidazolate framework for oxygen evolution reaction

Abstract

The development of efficient, cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for advancing sustainable energy. In this study, we investigated the influence of the solvent type on the morphological evolution and electrocatalytic performance of cobalt-based ZIF-67 metal-organic frameworks (MOFs). Particularly, we demonstrated the significant effect of solvent-mediated morphological control on the OER performance using methanol (MeOH), N, N-dimethylformamide (DMF), and deionized (DI) water. The ZIF-L(W), synthesized in DI water, exhibited a unique 2D leaf-like structure, and achieved remarkably low overpotentials of 360, 398, and 460 mV at current densities of 50, 100, and 200 mA cm⁻², respectively. This performance significantly surpasses those of the polyhedral ZIF-67(D) and ZIF-67(M) structures synthesized in DMF and MeOH, respectively. The superior OER activity of ZIF-L(W) was attributed to its larger pore size, enhanced electron transfer properties, and the formation of unsaturated coordination sites. These results present a scalable, low-temperature route for designing high-performance MOF-based electrocatalysts with potential applications in sustainable energy systems.