Defects and band gap shrinkage in ZnO/rGO composite nano-pebbles prepared by solid–state reaction

Abstract

In the present investigation, ZnO/rGO nanocomposites were prepared using conventional solid-state reaction method. Raman, XRD, FTIR, UV–Vis, PL and FESEM characterization tools were used to analyze the synthesized materials. Raman analysis reveals the formation of rGO with prominent D and G-band peaks. XRD patterns confirm the crystalline and hexagonal wurtzite structure with P63mc space group of all the samples. Rietveld refinement demonstrates the size variation (33 nm–56 nm) and strain profile. FESEM micrographs of ZnO/rGO composites have established the formation of densely packed hexagonal nano-pebbles. UV–Vis and room temperature PL measurements indicate that the optical properties of ZnO and ZnO/rGO nanocomposites are affected by the rGO concentration. It also confirms a band gap shrinkage during nanocomposite preparation compared to the pure ZnO structure. Urbach energy is found to increase with increase in rGO content and the strength of electron-phonon interaction enhances. It also affects the PL emission in the UV region. FTIR spectra confirm the presence of different functional groups. Present investigation shows that ZnO/rGO materials are potential candidates for design and development of sensors for detecting gases.