Graphene-Based TiO2 Nanocomposite for Photocatalytic Degradation of Dyes in Aqueous Solution under Solar-Like Radiation

Abstract

This study presents a novel method for the development of TiO2/reduced graphene oxide (rGO) nanocomposites for photocatalytic degradation of dyes in an aqueous solution. The synergistic integration of rGO and TiO2, through the formation of Ti–O–C bonds, offers an interesting opportunity to design photocatalyst nanocomposite materials with the maximum absorption shift to the visible region of the spectra, where photodegradation can be activated not only with UV but also with the visible part of natural solar irradiation. TiO2@rGO nanocomposites with different content of rGO have been self-assembled by the hydrothermal method followed by calcination treatment. The morphological and structural analysis of the synthesized photocatalysts was performed by FTIR, XRD, XPS, UV-Vis DRS, SEM/EDX, and Raman spectroscopy. The effectiveness of the synthesized nanocomposites as photocatalysts was examined through the photodegradation of methylene blue (MB) and rhodamine B (RhB) dye under artificial solar-like radiation. The influence of rGO concentration (5 and 15 wt.%) on TiO2 performance for photodegradation of the different dyes was monitored by UV-Vis spectroscopy. The obtained results showed that the synthesized TiO2@rGO nanocomposites significantly increased the decomposition of RhB and MB compared to the synthesized TiO2 photocatalyst. Furthermore, TiO2@rGO nanocomposite with high contents of rGO (15 wt.%) presented an improved performance in photodegradation of MB (98.1%) and RhB (99.8%) after 120 min of exposition to solar-like radiation. These results could be mainly attributed to the decrease of the bandgap of synthesized TiO2@rGO nanocomposites with the increased contents of rGO. Energy gap (Eg) values of nanocomposites are 2.71 eV and 3.03 eV, when pure TiO2 particles have 3.15 eV. These results show the potential of graphene-based TiO2 nanocomposite to be explored as a highly efficient solar light-driven photocatalyst for water purification.

Enhanced Photocatalytic Activity of Hybrid rGO@TiO2/CN Nanocomposite for Organic Pollutant Degradation under Solar Light Irradiation

“…The obtained binding energy values correspond with Ti 4+ in the TiO2 chemical environments. The peak was determined at 456.7 eV, which can be attributed to the Ti-N bond due to the solid adhesion of TiO2 on the g-C3N4 surface [18,30]. Based on this, Figure 5C shows the O 1s spectrum.…”

“…The high-re spectrum of Ti 2p is shown in Figure 5B. The Ti 2p spectrum contains two sy peaks centered at 465.0 eV and 459.3 eV, which correspond to the Ti 2p1/2 and Ti 2 obtained binding energy values correspond with Ti 4+ in the TiO2 chemical enviro The peak was determined at 456.7 eV, which can be attributed to the Ti-N bond d solid adhesion of TiO2 on the g-C3N4 surface [18,30]. Based on this, Figure 5C sho The surface chemical composition and oxidation state of the as-prepared rGO@TiO 2 /CN hybrid material were determined by XPS analysis, as shown in Figure 5.…”

“…In the catalytic process, a graphene-based material, more commonly (rGO), serves as an electron sink, which in addition also decreases the recombination rates of the semiconductor [16,17]. The rGO/TiO 2 nanocomposites can easily be prepared by the sol-gel and hydrothermal method, with simultaneous TiO 2 growth and GO reduction to rGO [18,19].…”

Citrus sinensis and Musa acuminata Peel Waste Extract Mediated Synthesis of TiO2/rGO Nanocomposites for Photocatalytic Degradation of Methylene Blue under Visible Light Irradiation

“…In both of the peel waste extract mediated synthesized TiO 2 NPs using different volume ratios, the particle size was found to be increased with an increase in the amount of the peel waste extracts, which is in agreement with the calculated average crystalline size from the XRD analysis. Furthermore, homogenized and small particle size TiO 2 NPs was obtained while using peel extract of Citrus sinensis due to its richness in biomolecules [ 32 – 34 ].…”

“…The differences in the photocatalytic performance of those various compositions of TiO 2 /rGO NCs obtained in the presence of peel waste extracts of Citrus sinensis and Musa acuminata could be attributed to the amount of rGO to TiO 2 composition ratio, in addition to the differences in the morphological structure [ 34 ].…”