TiO2 nanosheets with exposed {001} facets co-modified by AgxAu1-x NPs and 3D ZnIn2S4 microsphere for enhanced visible light absorption and photocatalytic H2 production

A novel AgxAu1-x/ZnIn2S4/TiO2 photocatalyst with high photoactivity under visible light illumination is designed in this work, in which ZnIn2S4 displays a 3D flower-like microsphere structure, while TiO2 nanosheets with highly active {001} facets (TiO2 NS) are tightly embedded in the interspaces of ZnIn2S4 microspheres, and AgxAu1-x nanoparticles (NPs) are loaded on its surface, respectively. The exquisite design of AgxAu1-x/ZnIn2S4/TiO2 makes it possess remarkable superiority in photocatalysis. Firstly, by the dual modification of ZnIn2S4 and AgxAu1-x, the AgxAu1-x/ZnIn2S4/TiO2 displays a strong absorption in visible light region, and their absorption region can be modulated by changing the ratio of Ag and Au in AgxAu1-x nanoparticles due to the plasmon coupling effect of Ag and Au. Secondly, the high separation and transfer efficiency of photogenerated carriers is achieved in AgxAu1-x/ZnIn2S4/TiO2 by utilizing TiO2 as the electron transfer intermediary of ZnIn2S4 and AgxAu1-x. All of these make AgxAu1-x/ZnIn2S4/TiO2 exhibit an evident enhancement in the photocatalytic activity of H-2 production. Significantly, the hydrogen production amount and rate of Ag0.2Au0.8/ZnIn2S4/TiO2 with 60 wt% ZIS after 10 h are 9862 mu mol/g and 986.2 mu mol/g/h, which is around 2098 times of pristine TiO2. The apparent quantum yield of Ag0.2Au0.8/ZnIn2S4/TiO2 after 10 h is about 1.47%. Moreover, the cycling test reveals that AgxAu1-x/ZnIn2S4/TiO2 shows the high stability in photocatalytic water spitting. Based on the characterization and photocatalytic results, the proposed photocatalytic mechanism is proposed.