1D/2D CdS/WS2 heterojunction photocatalyst: First-principles insights for hydrogen production

1D/2D CdS/WS2 heterojunctions have been considered to be efficient photocatalysts for visible-light driven hydrolysis; however, the catalytic mechanisms underpinning this behavior remain unclear. Here, a 1D/2D CdS/ WS2 heterojunction, with mechanical and thermodynamic stability, was designed and studied by first-principles calculations. The calculated results demonstrate that the CdS/WS2 heterojunction exhibits a typical type-II band arrangement. Through the synergistic effect of band offset together with a built-in electric field, photogenerated electrons and holes will each unidirectionally migrate to the conduction band of WS2 and the valence band of CdS, respectively, thereby improving the utilization efficiency for solar energy. This is also indicated by the excellent visible light absorption of the CdS/WS2 heterojunction. Excitingly, the oxidation and reduction potentials of the CdS/WS2 heterojunction not only satisfy the requirements for water splitting, but further have very balanced oxidation and reduction reactions, which guarantees that the redox process can occur more efficiently. The above findings provide theoretical guidance for the design and understanding of efficient heterojunction photocatalysts based on 1D CdS nanostructures.