Flower-like MOF-74 nanocomposites directed by selenylation towards high-efficient oxygen evolution

Sluggish kinetics of the oxygen evolution reaction during the water splitting requires high-performance electrocatalysts with low cost and good stability. Metal-organic frameworks (MOFs) have attracted much attention as electrocatalysts owing to their unique properties. To improve their electrocatalytic activity and stability, we report a selenylation method to modulate the morphology and interfaces by forming flower-like MOF-selenide nanocomposites. The optimal sample exhibits high activity with an overpotential of 260 mV at 10 mA cm-2, much better than commercial RuO2 and the control samples. Moreover, the optimal sample has the lowest Tafel slope of 54.3 mV dec-1, indicating the fast reaction kinetics, which can be attributed to the lower charge-transfer resistance and high intrinsic activity. Chronoamperometry shows that the optimal sample can maintain the current density for 60 h at 10 mA cm-2 after the initial surface reconstruction, demonstrating good stability. This study provides a new perspective on the development of highly efficient electrocatalysts based on polymetallic MOFs.