2.5. Material Characterization

Surface morphologies of the SnO₂-rGO hybrid composite and rGO sample were examined using variable pressure field emission scanning electron microscopy (FESEM: SUPRA 55VP, Carl Zeiss AG, Oberkochen, Baden-Württemberg, Germany) with energy dispersive spectroscopy (EDX). The morphological analysis was further analyzed by high-resolution transmission electron microscopy (HRTEM: Tecnai G2 F20, FEI, Hillsboro, OR, USA). The Raman spectra of the samples were obtained using a Raman spectrometer (Jobin-Yvon LabRAM, HR800, Horiba, Kyoto, Kansai, Japan, 514 nm). The XPS measurements were recorded on an X-ray Photoelectron Spectrometer (K-Alpha, Thermo Scientific, Waltham, MA, USA, 400 µm) using an Al X-ray radiation excitation source.