Chemically Reduced Graphene Oxide Thin Films: Characterization and Application for Photocatalytic Degradation of Azo Dyes under Natural Sunlight

Abstract

This study investigates the synthesis, characterization, and application of chemically reduced graphene oxide (rGO) thin films fabricated from a graphene oxide (GO) nanocolloidal solution using varied dosages of hydrazine hydrate (HH) as the reducing agent. Using a spray deposition technique, we obtain rGO thin films with distinct properties regarding their electrical conductivity, optical absorption, and surface morphology. X-ray diffraction and Raman spectroscopy confirm that increased HH levels lead to greater reduction, while a significant drop in sheet resistance accompanies the decrease in the oxygen-to-carbon ratio in rGO. The progressive reduction of GO slightly shifts the apparent optical transition energy and leads to a broader optical absorption. Interestingly, we observe a transition from a uniform GO structure to a porous, sponge-like morphology as the rGO is subjected to larger reduction levels. We then evaluated the photocatalytic performance of the rGO thin films under natural sunlight. The presence of rGO thin films enhances the degradation of methylene blue and methyl orange dyes by 82 and 75%, respectively, with the highest level of photocatalytic activity observed, with the sample corresponding to the highest reduction level. Furthermore, we show that the photocatalytic material retains performance over three reuse cycles, suggesting the potential for extended use. Our study underscores the potential of rGO thin films as practical, efficient, stable solar-light-driven photocatalysts, demonstrating their potential for solar-driven water treatment.