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, much better than commercial RuO and the control samples. Moreover, the optimal sample has the lowest Tafel slope of 54.3 mV dec, 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 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.