Silver-modified MoS2 nanosheets as a high-efficiency visible-light photocatalyst for water splitting

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One of the major challenges that the human beings are facing is the shortage of the fossil fuels. Hydrogen is considered as the most attractive renewable energy because of its abundant high energy density. Semiconductor photocatalytic technology for water decomposition is a promising method for converting sunlight into hydrogen energy, which has attracted considerable attention. Compared with bulk materials, two-dimensional (2D) materials exhibit remarkable photocatalytic properties. In this work, the pristine high-quality hexagonal molybdenum disulfide (MoS2) nanosheets and Ag-doped MoS2 nanosheets were synthesized by hydrothermal method, and the thickness of nanosheets was ranged from 0.9 to 1.1 nm. In addition, the absorption spectra of Ag-doped MoS2 nanosheets increased with the increase of Ag content. What's more, the photocatalytic properties of Ag-doped MoS2 nanosheets were tested, and the results show that Ag-doped MoS2 nanosheets have good stability, high hydrogen production efficiency and strong photocatalytic activity. It is worth mentioning that the photocatalytic hydrogen production rate of Ag-doped MoS2 nanosheets can reach 2695 μmol h−1 g−1. Meanwhile, density functional theory was used to calculate the optical properties, electronic structure of pristine and Ag-doped monolayer MoS2. These calculated results indicate that the absorption intensity of Ag-doped MoS2 in the ultraviolet–visible and visible light region increases significantly, and the conduction band of Ag-doped monolayer MoS2 is downshift compared with pristine MoS2. Therefore, Ag-doped MoS2 can optimize the band structure and promote the absorption of visible light, thereby improving the photocatalytic activity.