Oxygen vacancies of NiMoO4 nanoneedles on Ni foam for high-performance asymmetric supercapacitors

Abstract

Although bimetallic oxide electrodes have excellent physical and chemical properties, as well as a high theoretical capacity, their low energy density and poor cycling stability restrict their application in supercapacitors (SCs). This study demonstrates an effective method for enhancing the conductivity and capacitance performance of NiMoO₄ by inducing oxygen vacancies. The electrochemical performance of Ov-NiMoO₄ nanoneedles soaked in NaBH₄ solution was significantly superior to that of untreated NiMoO₄ electrodes, exhibiting excellent electrochemical properties. Moreover, the density functional theory (DFT) calculations further indicate that the material possesses a higher electron transmission rate. An asymmetric supercapacitor (ASC) based on NiMoO₄ was prepared, using Ov-NiMoO₄@Ni foam (NF) as the positive electrode and activated carbon as the negative electrode. These findings could further expand the applications of transition metal-based materials and provide an effective approach for the study of ASCs.