Enhanced Visible-Light Response of Ultrathin Er-Doped MoS2 Nanosheets through a Wet-Chemical Method

Doping is one of the important technologies for modifying the properties of two-dimensional (2D) transition metal dichalcogenides (TMDs). Herein, ultrathin Er-doped MoS2 nanosheets with an enhanced visible-light response have been synthesized by a wet-chemical method. The few-layer characteristic of the MoS2:Er nanosheets is beneficial from the H2S generated during the preparation process. Near-infrared emission at ∼1530 nm from MoS2:Er nanosheets has been observed under 980 nm laser excitation, which corresponds to the energy transition from 4I13/2 to 4I15/2 of Er3+. Meanwhile, the enhanced visible-light response of MoS2:Er has been demonstrated by the photocatalytic performance (removing rhodamine B) and photocurrent response compared with undoped MoS2. Based on the experiments and density functional theory calculation, the enhanced visible-light response is attributed to the improved separation capability of photogenerated electron–hole pairs of the ultrathin MoS2:Er nanosheets. Er-doping induces an increase of S vacancies and the energy transfer between Er3+ ions and the host. The work demonstrates a developed universal and recyclable synthesis strategy for various metal-doped MoS2 nanosheets and their applications in the fields of photocatalysis and photodetection.