CdIn2S4‐xSex Solid‐Solution Nanocrystal Photocatalyst: One‐Step Hydrothermal Synthesis, Controllable Band Structure, and Improved H2‐Evolution Activity

Abstract Metal sulfide solid‐solutions have served as one of the most promising photocatalysts due to continuously adjustable bandgap structure and light‐absorption performance. Herein, a novel quaternary CdIn 2 S 4‐ x Se x solid‐solution nanocrystal photocatalyst is prepared by one‐step hydrothermal synthesis, including the initial production of CdIn 2 S 4‐ x (SeO 3 ) x and its in situ reduction of SeO 3 2− to produce Se 2− by N 2 H 4 . It is found that the bandgap structure of CdIn 2 S 4‐ x Se x nanocrystals can be adjusted from 2.42 to 1.87 eV by varying the molar ratio of Se/S. Compared with pure CdIn 2 S 4 , the CdIn 2 S 4‐ x Se x solid‐solution photocatalyst clearly represents excellent photocatalytic hydrogen production performance, while the CdIn 2 S 4‐ x Se x ( x = 0.4) solid‐solution nanocrystal exhibits the optimal hydrogen‐production efficiency of 314.24 µmol h −1 , which is 3.3 times superior to that of CdIn 2 S 4 (94.83 µmol h −1 ). It is found that the introduction of Se increases the charge density of S 2− to form electron‐enriched S (2+δ )− , which can promote the effective adsorption of H + for the following interfacial hydrogen‐evolution reaction. Meanwhile, the CdIn 2 S 4‐ x Se x solid‐solution nanocrystals have a higher conduction band and stronger visible‐light absorption ability, which is also essential for accelerating photocatalytic hydrogen‐production efficiency. This study may offer possibilities for developing high‐performance photocatalysts.