Hierarchical MOF-derived Selenide/Ti3C2Tx hybrids for high-performance supercapacitors

The slow kinetics and poor structural stability prevent 2D transition metal selenides from wide application in supercapacitors. However, as a representative of new two-dimensional materials, Ti 3 C 2 T X (MXene) has excellent transport properties and rich surface functional groups, which can well make up for the shortcomings of metal selenides. The optimized morphology engineering from a combination of MXene and 2D bimetallic selenide will bring the performance of supercapacitor electrode material to a new level. In this paper, MXene/Mn 0.8 Ni 0.2 Se composites are creatively prepared by ultrasonic stirring and solvothermal synthesis. The hierarchically layered composite electrode material composed of MXene nanosheets and selenide nanosheets is successfully synthesized and its electrochemical performance as electrode material for supercapacitors is studied. The results show water not only promotes the deprotonation of triethylamine to participate in coordination but also causes triethylamine to generate OH − , which makes it easier to form layered products and restrict the growth of NiMn-Metal Organic Framework (MOF) into a three-dimensional structure. Subsequently, during the selenization process, a small amount of water and disodium ethylenediaminetetraacetic acid are added to further promote the stability of the 2D/2D structure. The wavy hierarchically layered structure can shorten the diffusion path of metal ions and enhance electronic conductivity. As a supercapacitor material, under the current density of 1 A g −1 , the specific capacitance of MXene/Mn 0.8 Ni 0.2 Se is 1126 F g −1 . This capacity is higher than most selenide capacities reported to date. In addition, the energy density of the asymmetric supercapacitor constructed with activated carbon as cathode and Mn 0.8 Ni 0.2 Se as anode can reach 46.18 Wh kg −1 when the power density is 750 W kg −1 . The outstanding specific capacitance and high energy density endow it with great potential for practical application.