EFFECT OF GRAPHENE OXIDE LOADING ON THE CATALYTIC ACTIVITY OF TiO2/MGO IN PHOTOCATALYTIC OZONATION OF RR195 DYE

Abstract

A series of TiO2/graphene oxide (TMGx) nanocomposites were synthesized via the hydrothermal method.
The X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses confirm the reduction of
graphene oxide (MGO) to reduced graphene oxide (rGO) in the presence of TiO2. Enhanced MGO loading
increases the material's surface area and mitigates the aggregation of TiO2 nanotubes on the MGO surface.
The X-ray Photoelectron Spectroscopy (XPS) method, complemented by UV-Vis spectra, reveals the
formation of Ti-O-C bonds, which function as electron transport pathways from TiO2 to MGO, thereby
reducing electron/hole recombination and extending light absorption into the visible spectrum, narrowing
the bandgap (Ebg) relative to TiO2 nanotubes. The TMG5 catalyst demonstrated the highest degradation
efficiency for RR195 dye among the catalysts studied. Within 20 minutes of reaction, TMG5 achieved
complete removal of RR195 dye, with TOC mineralization reaching 75% after 60 minutes of catalytic ozone
oxidation synergistic photocatalysis (COP). However, further increasing MGO content slightly decreased
the catalytic activity of RR195 (with TOC reaching 70% after 60 minutes), attributed to the shielding effect
of MGO which covers TiO2 active sites and obstructs light penetration.