Facile synthesis of Zn0.5Cd0.5S nanosheets with tunable S vacancies for highly efficient photocatalytic hydrogen evolution

Abstract

In order to effectively improve the separation efficiency of photogenerated charge carriers and thus the photocatalytic activity, in this work, porous Zn_0.5Cd_0.5S nanosheets with a controlled amount of S vacancies were prepared by a multistep chemical transformation strategy using the inorganic–organic hybrid ZnS-ethylenediamine (denoted as ZnS(en)_0.5) as a hard template. The amount of S vacancies and the morphology of the Zn_0.5Cd_0.5S nanostructures were tailored by adjusting the hydrolysis time. Furthermore, we report the observation of S vacancies in porous Zn_0.5Cd_0.5S nanosheets at the atomic level using spherical aberration-corrected (Cs-aberrated) transmission electron microscopy (Cs-corrected-TEM). The results revealed that Zn_0.5Cd_0.5S nanosheets with S vacancies absorb more visible light and generate more electron–hole carriers due to their porous nanosheet structure. At the same time, sulfur vacancies are introduced into the Zn_0.5Cd_0.5S nanosheets to capture the electrons generated by the light and further extend the lifetime of the carriers. As expected, the photocatalytic activity of Zn_0.5Cd_0.5S nanosheets prepared by 4 h hydrolysis is 20.5 times higher than that of Zn_0.5Cd_0.5S(en)_x intermediates. Moreover, Zn_0.5Cd_0.5S-4h showed excellent cycling stability. This work provides a new strategy for the optimization of Zn_0.5Cd_0.5S photocatalysts to improve photocatalytic hydrogen evolution.