Formation of carnation-like ZIF-9 nanostructure to achieve superior electrocatalytic oxygen evolution

Rational design and controllable synthesis of metal-organic frameworks nanosheets is critical for electrochemical catalysis. Herein, a carnation-like ZIF-9 nanostructure made of nanosheets is grown on nickel foam (ZIF-9/NF) by a simple one-step solvothermal method, the morphology evolution and the electrocatalytic oxygen evolution properties have been investigated by controlling the solvothermal time. The binder-free ZIF-9-d/NF (60 h, solvothermal time is 60 h) electrode delivers efficient electrocatalytic oxygen evolution reaction activity with low overpotentials of 312 and 337 mV at 50 and 100 mA cm^-2, respectively. Furthermore, ZIF-9-d/NF (60 h) exhibits excellent stability without obvious attenuation for at least 30 h at 200 mA cm^-2. The excellent performances can be attributed to the combination of the highly exposed active sites in the ZIF-9-d nanosheets, as well as the effective electron conduction and mass transfer. This work provides much possibilities for ZIF-9 nanosheets as binder-free electrode for electrocatalyst.