Rational design of bimetallic metal - organic framework composites and their derived sulfides with superior electrochemical performance to remarkably boost oxygen evolution and supercapacitors

Developing highly efficient and stable multi-functional metal-organic framework electrochemical materials is of prime importance for renewable energy technologies and electrocatalytic applications. Herein, a novel series of bimetallic metal-organic framework (MOF) hybrid materials were successfully designedly fabricated through an in-situ growth and MOF-on-MOF strategies, namely as NiFeMOF/NF, NiCoMOF/NF, FeMOF/NiMOF/NF, and CoMOF/NiMOF/NF. Benefiting from the synergistic effect of bimetallic centers, conductive substrate and unique fabrication, they exhibit remarking electrochemical performance. Among them, FeMOF/NiMOF/NF composite with ultrathin nanosheets displays the best electrochecatalytic performance with ultralow overpotentials of 293 mV at 50 mA cm(-2) and 359 mV at 100 mA cm(-2) for oxygen evolution reaction (OER), and remarking electrochemical stability with high current density of 100 mA cm(-2) after testing for 24 h, that 88% of initial current density can be remained. Based on these fabricated bimetallic MOF hybrid materials as precursors, the corresponding MOF-derived nano sulfides were obtained with massive exposure of active sites. As an excellent supercapacitor electrode, NiCoS/NF-1 converted from CoMOF/NiMOF/NF shows admirable specific capacitance of 2815.4 F g(-1) at 1 mA cm(-2) and a remarkable rate capability of 82%.