Eco-friendly sonochemical reduction of graphene oxide in water using TiO2 photocatalyst activated by sonoluminescence

Abstract

Reduced graphene oxide (rGO) is a representative commercialized graphene-related material that can be mass-produced. However, the conventional thermal and chemical reduction methods require high temperatures and toxic reducing agents and consume energy and cause environmental pollution. Therefore, alternative eco-friendly methods that are less energy-intensive are required for their mass production. Herein, we propose a facile and eco-friendly reduction method that enables the mass production of rGO. Specifically, a custom-built focused ultrasound circulation system was used to reduce graphene oxide in a suspension without using toxic reagents. The sonicated rGO was reduced to a significant extent, and its carbon-to-oxygen atomic ratio (87.79%) and electrical conductance (9.15 μS) were comparable to those of commercially available rGO. Raman spectroscopic analysis revealed that sonicated rGO gave a lower D-to-G band intensity ratio than commercial rGO reduced by heat treatment. This method can contribute to the active utilization of rGO in next-generation industrial products with lower environmental and energy impacts.