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.

Transition Metal Selenides for Electrocatalytic Hydrogen Evolution Reaction

“…The inner yolk was pure Co 0.85 Se phase and the outer shell was the mixture of Co 0.85 Se and Ni 0.85 Se phases. Due to the synergistic combination of Co 0.85 Se and Ni 0.85 Se and the unique yolk−shell structure with more exposed active sites, the Y−S Ni−Co−Se/CFP possessed a large C dl of 8.00 mF cm −2 and a favorable charge‐transfer resistance of 85.5 Ω at −0.20 V, which resulted in a lower overpotential of 250 mV at 10 mA cm −2 and the smaller slope of 72 mV dec −1 when compared to the ZIF‐67@LDH/CFP, Co 3 O 4 @NiCo 2 O 4 /CFP, and Y−S Co 0.85 Se/CFP in 1.0 M KOH . In a similar way, Kang et al.…”

Multishelled Transition Metal‐Based Microspheres: Synthesis and Applications for Batteries and Supercapacitors

“…The shell thickness of Ni–Co selenide is ≈60 nm and is comprised of small nanoparticles (20–30 nm) with a d ‐spacing of 0.27 nm. Other yolk–shelled Ni–Co–Se structures have been prepared with a similar strategy …”

Octahedral Cu2O@Co(OH)2 Nanocages with Hierarchical Flake‐Like Walls and Yolk‐Shell Structures for Enhanced Electrocatalytic Activity

“…Benefited from these collective effects, the activity and stability of yolk‐shell materials can be largely enhanced. Notably, the cage‐like nanostructures, a kind of complex hollow architectures, possess many superior chemical and physical properties over common spherical hollow structure . The synthesis of yolk‐shell nanocages therefore would be of great significance to improve the electrocatalytic activity for electrocatalysis.…”

“…Notably, the cage-like nanostructures, a kind of complex hollow architectures, possess many superior chemical and physical properties over common spherical hollow structure. [25][26][27] The synthesis of yolk-shell nanocages therefore would be of great significance to improve the electrocatalytic activity for electrocatalysis. Unfortunately, the development of these yolk-shell nanocages is still insufficient, especially in facile and novel strategy for fabricating the highly efficient electrocatalysts with such unique and welldefined structures, although some yolk-shell nanocages have been synthesized.…”