Ultrahigh capacitive performance of three-dimensional electrode nanomaterials based on α-MnO2 nanocrystallines induced by doping Au through Å-scale channels

Abstract

Poor electrical conductivity of metal oxides is the primary challenge that limits their energy storage capacity. Intercalating metal atoms into the crystal lattices of metal oxides are expected to change the electronic structure of metal oxides, and thus improve the conductivity as well as electrochemical performance of the metal oxides. Herein, we demonstrate the doping of α-MnO2 nanocrystallines by Au through Å-scale channels via cyclic voltammetry at different scan rates on the basis of first-principle calculation. Experiments elucidate that the doped Au atoms in α-MnO2 lattice and distributed Au nanoparticles in α-MnO2 nanothin layers can greatly enhance the conductivity and electrochemical performance of MnO2. Hence, the designed carbon cloth electrodes modified with ZnO-nanorods/Au-doped-α-MnO2 (ZNs/ADM) nanocomposites exhibit excellent electrochemical performances. Moreover, an asymmetric supercapacitor based on ZNs/ADM (positive) and reduced-graphene-oxide-CNTs (negative) hybrid materials demonstrates cycled reversibly in a wide potential window and exhibits high energy density (101Wh/kg), power density (33.6kW/kg), and reasonable cycling performance. This work opens the possibility to develop new types of metal-doped metal-oxides that can meet the needs of specific applications, ranging from energy-storage devices to biosensors.