A Unique RGO Aerogel/TiO2/MoS2 Composite Photocatalyst with a 3D Sandwich Network for the Removal of Organic Dyes by the Cooperative Action of Adsorption and Photocatalysis

Abstract A unique composite with a three dimensional (3D) sandwich network structure consisting of reduced graphene oxide aerogel/titanium dioxide/molybdenum disulfide (abbreviated as RGO aerogel/TiO2/MoS2) was developed for the removal of organic dyes from solution cooperatively by adsorption and photocatalytic degradation mechanisms. The composite was successfully synthesized by stepwise hierarchical assembly integration, including sol-gel and physical vapor deposition (PVD) methods. The resulting multicomponent composite material featured a high specific surface area (255.441 m2/g) absorption capacity manifested by the myriad negatively charged carboxylate function groups on the surface of the composite. The composite material demonstrated ideal optical and photocatalytic properties, including a large absorbance in the visible light region and a fast transfer of photogenerated electron-hole pairs, resulting in a superb photodegradation performance. The RGO aerogel/TiO2/MoS2 also exhibited a high cationic dyes removal efficiency through the cooperative adsorption and photocatalytic degradation mechanisms. Moreover, electron paramagnetic resonance (EPR) analysis and reactive oxygen species scavenging experiments confirmed that superoxide radicals (O2•−), holes (h+), and hydroxyl radicals (•OH) were involved in photocatalytic degradation of the organic dyes.