A novel MnO2/MXene composite prepared by electrostatic self-assembly and its use as an electrode for enhanced supercapacitive performance

Abstract

MXene is a new 2D transition metal carbide possessing metallic conductivity and hydrophilic surfaces. It has drawn widespread attention as a potential material for electrode use. However, the applications of MXene are limited by its property of low electrical capacity. In this paper, a novel MnO₂/MXene composite is prepared by electrostatic self-assembly. Firstly, delaminated MnO₂ nanosheets are obtained through the intercalation delamination of multilayered H-MnO₂ in a cationic Gemini surfactant (Gem) solution, leading to a positively charged surface. Then, the positive MnO₂ nanosheets are assembled on negative MXene nanosheets through electrostatic self-assembly to form a MnO₂/MXene composite. The characterization results show that the MnO₂ nanosheets are intimately assembled on the MXene nanosheets. As an electrode material, the MnO₂/MXene composite displays a specific capacitance of 340 F g⁻¹ at 1 A g⁻¹, which is three times the performance of an MXene electrode. In addition, the MnO₂/MXene electrode shows a high retention rate (90.3% retention at 10 A g⁻¹) and good cycling life (87.6% of the initial specific capacitance is retained after 2000 cycles at 4 A g⁻¹). The properties of the proposed composite are attributed to the excellent conductivity of MXene and the high specific capacitance of MnO₂.