One-pot fabrication of Ni/Co-MOFs/GNS nanohybrid as electrode material with high performance

Metal–organic frameworks (MOFs) are supposed to be promising electrode materials for supercapacitors for the excellent porosity, variable pore size, and structural variety. Bi-metal MOFs have higher electrochemical performances compared to the corresponding single-metal MOFs as various metal ions could provide an increased number of electron transfer paths and active sites. Nevertheless, inferior stability and unsatisfactory electroconductivity of bi-metal MOFs greatly restrict further applications. In this work, using graphite nanosheets (GNS) as supports, Ni/Co-MOFs were loaded on the GNS by in situ growth to fabricate Ni/Co-MOFs/GNS nanohybrids via a one-pot solvothermal method. GNS as carbon materials have good electroconductivity and stability. Ni/Co-MOFs loaded on the GNS by in situ growth could avoid Ni/Co-MOFs aggregation and improve the dispersity, increasing the specific surface area and exposing more redox active sites, resulting in improvement of the electrochemical performances. The electrochemical performances of Ni/Co-MOFs/GNS were optimized by altering the molar ratio of Co(NO₃)₂·6H₂O to Ni(NO₃)₂·6H₂O and the condition of the reaction. According to the research findings, the Ni/Co-MOFs/GNS nanohybrid had a higher specific capacity which was 1080.0 C g⁻¹ at 1 A g⁻¹. Active carbon (AC) serving as the negative electrode and Ni/Co-MOFs/GNS as the positive electrode, Ni/Co-MOFs/GNS//AC asymmetric supercapacitor (ASC) was assembled. The energy density of Ni/Co-MOFs/GNS//AC ASC was 28.7 Wh kg⁻¹ and the power density was 849.9 W kg⁻¹.