Recycling of iron from vanadium titanium magnetite tailings and its application in an asymmetric supercapacitor

Vanadium titanomagnetite tailings (VTMT) contain many beneficial elements and have a high comprehensive utilization value. In this report, a new strategy for iron recycling from VTMT is provided. Using VTMT as a metal source and carboxyl-containing organic compounds as ligands, iron was recycled in the form of Fe2O3 through a three-step method (alkali fusion, selective coordination reaction, and derivation of Fe-based metal-organic frameworks (Fe-MOFs)). The capacitive performance and the effect of the ligand species on the capacitive performance of Fe2O3 are discussed. Using VTMT-derived Fe2O3 as a negative electrode and NiCo-(oxy)sulfide (NiCo(O)S) as a positive electrode, the constructed NiCo(O)S//Fe2O3 asymmetric supercapacitor (ASC) exhibited better capacitive performance (151.5 F g(-1) at a current density of 1 A g(-1)) compared to the previously reported ASCs, in which the iron-based electrode materials were prepared using pure iron salt as a metal source. More importantly, the constructed NiCo(O)S//Fe2O3 ASC can be used as an energy storage device for LED lamps. From mining waste to energy storage devices, this work proposed a bright way for the reutilization of VTMT for high-value-added energy applications.