Borides and sulfide quantum dots co-enhanced the electrochemical property of metal organic framework/Ni3S2 composites for high-performance supercapacitors

Abstract

Metal organic frameworks (MOFs) as supercapacitor electrode materials still faces low electronic conductivity and poor structural stability. Herein, metal sulfides@NiCo-MOF composites were first synthesized via one-pot solvothermal method and then controllably boronized by using NaBH₄ to modulate its morphology and electronic structure. The morphology of metal sulfides@NiCo-MOFs is transformed from the original columnar structure into ultrathin nanoflakes after boronization, and B also optimizes the number of oxygen vacancies. Benefiting from the formation of Co-B-Ni bonds and abundant active sites, the as-prepared borides and sulfides quantum dots@NiCo-MOF/Ni₃S₂-2 (BSQD@MOF/S-2) composites exhibit high specific capacitance of 4230.7F g⁻¹ at 1 A g⁻¹. Additionally, the fabricated ASC device achieves an energy density of 69.2 Wh kg⁻¹ at 410.6 W kg⁻¹. The density functional theory (DFT) calculations show that boron forms p-d hybrid orbitals with transition metals after filling oxygen vacancies, which can improve the electronic conductivity and favorite the adsorption capacitance. This paper proposes a mild method to optimize the morphology and electronic structure of MOFs-based materials for high-performance supercapacitors.