Facile construction of a sulfur vacancy defect-decorated CoS x @In 2 S 3 core/shell heterojunction for efficient visible-light-driven photocatalytic hydrogen evolution.

Photoinduced electron-separation and -transport processes are two independent crucial factors for determining the efficiency of photocatalytic hydrogen production. Herein, a sulfur vacancy defect-decorated CoS x @In 2 S 3 (CoS x @V S -In 2 S 3 ) core/shell heterojunction photocatalyst was synthesized via an in situ sulfidation method followed by a liquid-phase corrosion process. Photocatalytic hydrogen evolution experiments showed that the CoS x @V S -In 2 S 3 nanohybrids delivered an attractive photocatalytic activity of 4.136 mmol h -1 g -1 under visible-light irradiation, which was 8.23 times higher than that of the pristine In 2 S 3 samples. As expected, V S could enhance the charge-separation efficiency of In 2 S 3 through rearranging the electrons of the In 2 S 3 basal plane, in addition to improving the electron-transfer efficiency, as visually verified by transient absorption spectroscopy. Mechanism studies based on density functional theory calculations confirmed that the In atoms adjacent to V S played a key role in the translation, rotation, and transformation of electrons for water reduction. This scalable strategy focused on defect engineering paves a new avenue for the design and assembly of 2D core/shell heterostructures for efficient and robust water-splitting photocatalysts.