Formation of Yolk-Shelled Nickel-Cobalt Selenide Dodecahedral Nanocages from Metal-Organic Frameworks for Efficient Hydrogen and Oxygen Evolution

The development of cost-effective electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER) in alkaline media is crucial in renewable energy conversion technologies. Metal-organic frameworks (MOFs) can act as precursors to the design and construct of varied nanostructured materials which may be difficult to produce in other ways. Herein, we put forward a serial ion-exchange reaction and selenation strategy to prepare novel yolk-shelled Ni-Co-Se dodecahedral nanocages on carbon fiber paper (Y-S Ni-Co-Se/CFP). ZIF-67@LDH/CFP was first synthesized by a simple ion-exchange reaction, followed by a hydrothermal selenation process to form Y-S Ni-Co-Se/CFP. Moreover, the composition of the as-prepared yolk shelled Ni-Co-Se nanocages was a mixture of Co0.85Se and Ni0.85Se (Co/Ni atomic ratio of about 2.42). Due to their structural and compositional merits, the as-prepared Y-S Ni-Co-Se/CFP exhibited remarkable electrocatalytic activity and long-term stability (over 80% current retention for at least 18 h) for both HER and OER For HER, it required an overpotential of 250 mV to attain a current density of 10 mA cm(-2), which was 162 mV less than that of the Y-S Co0.85Se/CFP counterpart. The catalyst also efficiently catalyzed OER with a current density of 10 mA cm(-2) at an overpotential of 300 mV, which was lower than those of other reported Co-based catalysts.