Prussian blue analog nanocubes tuning synthesis of coral-like Ni3S2@MIL-53(NiFeCo) core-shell nanowires array and boosting oxygen evolution reaction

Abstract

Developing highly-efficient and robust electrocatalysts for oxygen evolution reaction (OER) is crucial to relieve energy crisis. Herein, a facile two-step method involving Prussian blue nanocubes as template is introduced to synthesize coral-like Ni3S2@MIL-53(NiFeCo) core-shell nanowires array as an excellent OER electrocatalyst. The metal sulfides as a core in the core-shell structure could effectively adjust the morphology of the metal-organic frameworks (MOFs) in the shell layer forming ultrathin 2D MOFs nanosheets. The synthesized Ni3S2@MIL-53(NiFeCo)/NF nanowires exhibit excellent activity, which needs overpotential of only 236 mV to drive high current density of 50 mA cm−2 in 1.0 M KOH. This excellent catalytic performance can be attributed to the following aspects: 1) The synergy between the metal sulfides and the MOF contributes substantially to the OER performance. 2) The compact three-dimensional nano-array structure increases the electrochemically active surface area of Ni3S2@MIL-53(NiFeCo)/NF nanowires, which promotes electrolyte permeation and gas overflow. 3) The tight integration of the vertically aligned nanowires structure with the conductive substrate ensures rapid electron transport and ultra-high structural stability of the electrode material. We anticipate that our research will extend the strategy for assembling advanced materials as an effective electrocatalyst for OER.