Hydrothermal synthesis of a CoIn 2 S 4 /g-C 3 N 4 heterojunctional photocatalyst with enhanced photocatalytic H 2 evolution activity under visible light illumination

Abstract CoIn 2 S 4 , a black semiconducting material, possesses an outstanding visible light response and is employed to modify g-C 3 N 4 . A series of CoIn 2 S 4 /g-C 3 N 4 heterojunctional photocatalysts are synthesized via a hydrothermal method, whereby cubic CoIn 2 S 4 nanosheets are in situ immobilized on the surfaces of porous g-C 3 N 4 nanosheets. Compared with the pristine g-C 3 N 4 and CoIn 2 S 4 , under visible light ( λ > 420 nm) irradiation, the CoIn 2 S 4 /g-C 3 N 4 composite samples show markedly enhanced photocatalytic activity in hydrogen evolution. Among all of the samples, the 30% CoIn 2 S 4 /g-C 3 N 4 sample shows the maximum H 2 evolution rates, 5.2 and 23.9 times higher than those of g-C 3 N 4 and CoIn 2 S 4 , respectively. The efficient photocatalytic activity of CoIn 2 S 4 /g-C 3 N 4 composite photocatalysts is attributed to the formation of an intimate heterostructure, which not only significantly facilitates charge migration, but also enhances visible light absorption. Moreover, a plausible photocatalytic mechanism for the composite photocatalyst has been elucidated. This research provides a novel hint for fabricating visible-light-responsive heterojunction photocatalysts with high performance for energy production.