Preparation of Zirconium-Based\nMOF-Derived Phosphide\non GO/MXene Double Substrates for High-Performance Asymmetric Supercapacitors

At present, it is very necessary to select and prepare\nsuitable\npositive and negative electrode materials to fabricate high-performance\nasymmetric supercapacitors. Metal–organic frameworks (MOFs)\nhave garnered significant attention in the energy storage field due\nto their high conductivity. As a branch, the zirconium organic framework\n(UIO-66) is a promising porous material due to its large specific\nsurface area and abundant Zr centers. Graphene oxide (GO) and MXene\nare very suitable as substrate materials for conducting an MOF due\nto their abundant active sites and adjustable interlayer distance.\nThe GO/MXene@NiZrP prepared through an in situ composite of GO and\nMxene with the hydrothermal method and calcining method showed excellent\nelectrochemical performance. Compared with the precursor UIO-66, the\nspecific capacitance of the final product GO/MXene@NiZrP increases\nmore than ten times, mainly because of its special layered porous\nstructure, and GO/MXene@NiZrP has a larger specific surface area,\npore volume, and surface defects caused by unstable Zr<sup>4+</sup> than those of UIO-66. Using GO/MXene@NiZrP as the positive electrode\nand biochar (BC) as the negative electrode, an asymmetric supercapacitor,\nBC//GO/MXene@NiZrP, is assembled. After 10,000 cycles at a current\ndensity of 10 A g<sup>–1</sup>, the capacitance retention remains\nat 83.3%, showing excellent cycle stability.