Fluorine-doped β-Ni(OH)2-Ti3C2 MXene composite: a bifunctional electrode

Abstract

Developing a multifunctional material with high capacity, vigorous electrocatalytic activity for both the OER and HER, and long-term stability is a significant challenge for electrochemical applications. In this work, a fluorine-doped beta-nickel hydroxide composite with varying Ti3C2 concentrations has been synthesized. The F-doped Ni(OH)2-Ti3C2_3% (NT-3@NF) electrode exhibits superior electrocatalytic performance compared to other composite electrodes, with overpotentials of 53 mV for the HER and 263 mV for the OER at a current density of 10 mA cm-2 in a 1 M KOH alkaline electrolyte medium. The fluorine-doped beta-Ni(OH)2 composite with Ti3C2 Mxene (beta-Ni(OH)2-Ti3C2_3%), referred to as the NT-3 electrode, achieves a practical specific capacity of 242.16 mAh g-1 at a current density of 1 A g-1, which is 83% of the electrode's theoretical specific capacity. A hybrid capacitor with a gel electrolyte, fabricated for both bare and composite electrodes, was configured as AC & Vert;PVA-KOH & Vert;NT-0 and AC & Vert;PVA-KOH & Vert;NT-3, delivering specific energies of 37.21 and 62.13 Wh kg-1, respectively. The long-term cycle stability of the fabricated supercapacitors has been evaluated over approximately 20 000 cycles at a current density of 1 A g-1. The AC & Vert;PVA-KOH & Vert;NT-3 supercapacitor exhibits 71.2% capacitance retention and a coulombic efficiency of 99.62%. A class of 11 V hybrid capacitor prototypes was also fabricated, and their practical viability has been analyzed to ensure high energy density. Thus, the synthesized multifunctional beta-Ni(OH)2 and F-doped beta-Ni(OH)2-Ti3C2 composite electrode can be a promising candidate for a highly efficient electrode for energy conversion and storage applications.