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

Abstract

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.