SnS2 nanosheets coupled with 2D ultrathin MoS2 nanolayers as face-to-face 2D/2D heterojunction photocatalysts with excellent photocatalytic and photoelectrochemical activities

In this work, ultrathin 2D SnS2 nanosheets were coupled with 2D MoS2 nanolayers as face-to-face 2D/2D heterojunction photocatalysts. Compared with pristine SnS2, this face-to-face 2D/2D SnS2/MoS2 heterojunction exhibited obvious improvement in photocatalytic and photoelectrochemical performance. The highest heterojunction composite activity was nearly two times and 12 times than that of pristine SnS2 in photocatalytic activity and photoelectrochemical performance, respectively. The good performance was ascribed to the face-to-face 2D/2D heterojunction structure and suitable energy band matching. In this face-to-face 2D/2D heterojunction structure, the migration distance between the photoinduced carriers' separation site to the heterojunction interface was very short, but the contact surface was large. Furthermore, the conduction band position of MoS2 was more positive than that of SnS2. Therefore, the photoinduced electrons at the conduction band of SnS2 could flow into the conduction band of MoS2. The transmission between the SnS2/MoS2 heterojunction prolonged the carriers' life and improved the carriers' separation efficiency. In this way, photoinduced carriers produced in SnS2 and MoS2 could flow across the heterojunction quickly, which increased the carriers' separation efficiency. This work successfully developed a new structure to improve the heterojunction property for photocatalytic applications. (C) 2018 Elsevier B.V. All rights reserved.