Hydrothermal synthesis of a CoIn2S4/g-C3N4 heterojunctional photocatalyst with enhanced photocatalytic H2 evolution activity under visible light illumination

CoIn2S4, a black semiconducting material, possesses an outstanding visible light response and is employed to modify g-C3N4. A series of CoIn2S4/g-C3N4 heterojunctional photocatalysts are synthesized via a hydrothermal method, whereby cubic CoIn2S4 nanosheets are in situ immobilized on the surfaces of porous g-C3N4 nanosheets. Compared with the pristine g-C3N4 and CoIn2S4, under visible light (λ > 420 nm) irradiation, the CoIn2S4/g-C3N4 composite samples show markedly enhanced photocatalytic activity in hydrogen evolution. Among all of the samples, the 30% CoIn2S4/g-C3N4 sample shows the maximum H2 evolution rates, 5.2 and 23.9 times higher than those of g-C3N4 and CoIn2S4, respectively. The efficient photocatalytic activity of CoIn2S4/g-C3N4 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.