Exploring heterometallic architectures and uncoordinated nitrogen sites in zeolitic imidazole–tetrazole frameworks provides an unconventional route to enhancing electrocatalytic activity. Herein, we report a mechanochemical alloying approach that simultaneously induces metal–metal (Co–Zn) and ligand–ligand (imidazole–tetrazole) mixing to yield an amorphous solid solution, aZn0.5Co0.5ZI0.5T0.5F-8, from pristine ZnZTF-8 and CoZIF-8 under solvent-free conditions in an inert atmosphere (Ar). Subsequent methanol vapor exposure at 25 °C transforms this disordered phase into a crystalline analogue, cZn0.5Co0.5ZI0.5T0.5F-8. X-ray adsorption spectroscopy (EXAFS and XANES), inductively coupled plasma mass spectroscopy, high-angle annular dark-field scanning transmission electron microscopy, and field emission scanning electron microscopy analyses confirm the coexistence of metal and ligand solid solution and defect-rich uncoordinated nitrogen sites in the amorphous phase. Owing to its higher density of active sites and degree of heterogeneity, aZn0.5Co0.5ZI0.5T0.5F-8 exhibits superior oxygen evolution reaction (OER) performance, featuring an overpotential of 338 mV and a Tafel slope of 94.8 mV dec–1 over parent frameworks. Furthermore, the origin of enhanced OER performance is validated using the computational hydrogen electrode approach in which the OER intermediates (*OH, *O, and *OOH) were evaluated on the optimized secondary building units of Zn0.5Co0.5ZI0.5T0.5F-8, as well as ZnZTF-8 and CoZIF-8. This work establishes mechanically induced simultaneous metal and ligand solid solution in MOFs as a sustainable and versatile strategy for engineering noncrystalline frameworks with exceptional electrocatalytic efficiency.
Sarfudeen et al. (Sat,) studied this question.