Preparation of Single-Crystalline AgInS Octahedrons with Exposed {111} Facets and Its Visible-Light-Responsive Photocatalytic H Production Activity.

Although AgInS as one kind of ternary chalcogenides has been extensively investigated due to its band-edge positions meeting the thermodynamic requirement for water photosplitting, very little attention has been focused on the crystallinity and facet effects of AgInS on its photocatalytic activity. Herein, a facile hydrothermal route was developed to fabricate regular single-crystalline AgInS octahedrons with only {111} facets exposed. Also, the effects of the hydrothermal reaction conditions on the composition, crystal phase, crystallinity, and morphology of the obtained AgInS products (hereafter denoted as AIS-x, where x represents the pH value of the reaction solution) were investigated, and it was found that the accurately released S ions from the thermal decomposition of thioacetamide (TAA) is the central factor for the nucleation and growth of the AgInS octahedrons. The experimental results indicate that the resultant regular AgInS octahedrons (AIS-10.6) exhibit the best photocatalytic activity for H production among those AgInS products, and the higher crystallinity and fewer defects of the AgInS octahedrons compared to the other AgInS products can retard the photogenerated charge recombination, while those indium atoms with higher density in the exposed {111} facets might be beneficial for the photocatalytic H production reaction by acting as active sites to promote the charge separation and transfer processes. The results presented here provide new insights into the significance of crystallinity and exposed facets in the visible-light-responsive activity of AgInS, thus paving new ways into the design and synthesis of high-performance, cost-effective AgInS photocatalysts for H production.