Cd<sub>1–<i>x</i></sub>Zn<sub><i>x</i></sub>S Nanorod Solid Solutions with Sulfur Vacancies as Effective Electron Traps for Highly Efficient Photocatalytic Hydrogen Evolution
Jingyi Zhang, Shuai Yuan, Jun Lin
Abstract
In this work, Cd1–xZnxS nanorod solid solutions with the features of sulfur (S) vacancies and a single phase (x ≤ 0.2) or two phases (x ≥ 0.3) have been successfully prepared using a facile hydrothermal process. Without any assistance of noble metals as a cocatalyst, all prepared solid solutions present in either a single phase or two phases exhibit remarkably higher photocatalytic H2 evolution than pure single-phase CdS in Na2S/Na2SO3 aqueous solution. The effects of the incorporation of Zn2+ into the CdS lattice on the phase structure and constitutions, optical properties, electronic band structure, Fermi levels, and S vacancies’ ability to trap electrons were investigated in detail. It was revealed that the formation of the Cd1–xZnxS solid solution upgrades the Fermi level closer to the energy level of S vacancies. As a result, the S vacancies near the Fermi level become an effective electron trap center to inhibit the recombination of photogenerated electron–hole pairs, resulting in the enhanced photocatalytic H2 evolution. This study might open up a new avenue for the understanding and design of CdS-based solid solutions with efficient photocatalytic H2 evolution from water splitting.