Photocatalytic degradation of antibiotic drug and dye pollutants under visible-light irradiation by reduced graphene oxide decorated MoO3/TiO2 nanocomposite

Abstract

This study explored the effect of reduced graphene oxide (RGO) amount (1, 3, and 5 wt%) loading on the MoO3/TiO2 nanocomposite (Gr1/MoO3/TiO2 NCs, Gr3/MoO3/TiO2 NCs, and Gr5/MoO3/TiO2 NCs) for their photocatalytic activity against the Tetracycline (TC) antibiotic drug and Rhodamine B (RhB) dye under visible light illumination and compared it with the MoO3/TiO2 nanocomposite. Crystallite sizes of MoO3/TiO2 NCs, Gr1/MoO3/TiO2 NCs, Gr3/MoO3/TiO2 NCs, and Gr5/MoO3/TiO2 NCs are 17.69 nm, 16.24 nm, 12.64 nm, and 11.74 nm, respectively, with energy band gaps of 2.72 eV, 2.59 eV, 2.49 eV, and 2.38 eV correspondingly. The photocatalytic performance of the nanocomposites was revealed to be highly affected by the weight ratio of RGO on MoO3–TiO2. The results showed that about 98% of RhB and 94% of TC drug were photodegraded under visible light irradiation during the 60 min and 80 min respectively. RhB and TC drug photocatalysis degradation showed pseudo-first-order reaction kinetics, with order rate constants of 0.06435 min−1 and 0.0351 min−1, respectively. By electrostatic interactions, the stacked MoO3 being bound to the surface of TiO2 nanoparticles and concurrently anchored onto graphene nanosheets through π–π stacking. In addition, the inclusion of reduced graphene oxide nanosheets was shown to enhance photocatalytic activity. The mechanism was also portrayed: the synergetic (interfacial) interaction of the graphene sheets and the MoO3/TiO2 was responsible for the excellent photo-degradation impact of the RhB dye and the TC drug pollutants through the Gr/MoO3/TiO2. Furthermore, the MoO3/TiO2 has been used as a migration vehicle for the visible light carrier, while a high surface area and the number of active sites of the reduced graphene sheet enhanced the photocatalytic activity.