Synthesis of nanosized MnO₂ decorated SWCNTs and their photocatalytic improved activity as well as enhanced electrode performance

In this report, manganese dioxide (MnO2) nanoparticles were grown directly over single walled carbon nanotubes (SWCNTs) in order to produce SWCNTs/MnO2 nanocomposite. SWCNTs were firstly synthesized by plasma enhanced chemical vapour deposition (PECVD) technique and then loaded with MnO2 nanoparticles through a hydrothermal process. FESEM, HRTEM, Raman, BET, XPS, FTIR, UV-Vis, photoluminescence, and EIS techniques were employed for characterizing as-prepared nanocomposite. The morphology and size of the MnO2 nanoparticles were assessed through FESEM and HRTEM, demonstrating excellent growth of SWCNTs and further decoration with MnO2 nanoparticles. The size/diameter distribution of SWCNTs was evaluated by Raman spectroscopy. Cyclic voltammetry and Galvanostatic charge-discharge measurements demonstrated that the SWCNTs/MnO2 nanocomposite has superior electrochemical performance as compared to MnO2 nanoparticles alone. The photocatalytic activity of the samples was investigated through the degradation of methylene blue and methylene orange dyes in an aqueous solution under visible light irradiation. The results exhibited that SWCNTs/MnO2 nanocomposite displayed relatively high visible-light driven photocatalytic performance compared to MnO2 nanoparticles, which could be attributed to the enhancement in light absorption in the visible region and reduction in electron-hole pair recombination. The superior photocatalytic activity of the prepared nanocomposite revealed their potential applications in wastewater treatment.