Ultra-low Ru doped MOF-derived hollow nanorods for efficient oxygen evolution reaction

Abstract

Metal–organic frameworks (MOFs) which consist of metal ions and organic ligands, have been considered as promising precursors for designing efficient electrocatalysts. Herein, we report ultra-low ruthenium (Ru) doped defective CoFe-MOF (Ru@CoFe/D-MOF) hollow nanorods by the NaBH₄ reduction strategy at room temperature for efficient oxygen evolution reaction (OER). The partial reduction process endowed the catalysts with rich oxygen vacancies (O_v) and low coordinated CoFe nanoparticles (CoFe NPs), which have advantages in exposing abundant active sites. In addition, benefiting from the defective features and heterostructure surfaces, an ultra-low amount of Ru could be stabilized on the surface of CoFe/D-MOFs to further enhance their catalytic activity. Consequently, the well-designed Ru@CoFe/D-MOFs demonstrated excellent OER performance with a low overpotential (η = 265 mV at 10 mA cm⁻²), good overall water splitting activity (1.56 V at 10 mA cm⁻²) and long-term stability for more than 40 hours in alkaline solution. The mechanistic analysis validated that the ultra-low amount of Ru was able to optimize the electronic configuration of CoFe/D-MOFs and tailor the adsorption between the OER intermediates and the heterostructure surface, thus leading to enhanced OER performance.