Photocatalytic and Electrochemical properties of green synthesized Mn-doped ZnO/rGO nanoparticles

Mn-doped ZnO/reduced graphene oxide (rGO) nanoparticles are prepared by green synthesis method. The incorporation of Mn and rGO in the ZnO nanoparticles on the photocatalytic and electrochemical properties is examined. The XRD pattern reveals the Wurtzite geometry of the prepared material. The micro-structural properties, such as crystallite size, dislocation density, strain and lattice constants, are evaluated. Both Debye-Scherrer's formula and Williamson-Hall equation are employed to examine the crystallite size of the prepared material. The bond length of Mn-doped ZnO/CQD is higher than undoped ZnO. The chemical composition and morphology are also reported. The Mn-doped ZnO as well as Mn-doped ZnO/rGO has a lower band gap as compared with the band gap of undoped ZnO. The solar-light-driven photocatalytic activity of the prepared nanoparticles is reported. The undoped ZnO shows 38.68 % degradation at (Formula presented) min, but the same is ∼80 % when Mn and rGO are incorporated. The prepared Mn-doped ZnO/CQD nanoparticles as the electrode material in the supercapacitor show the specific capacitance of 603 F/g at 0.5 A/g and 354 F/g at 5 mV/s. At higher scan rates, the capacitive contribution corresponding to ZnO is 72 %, whereas the incorporation of Mn and CQD enhances the capacitive contribution. The number of active sites on the surface of the electrodes are examined.