Direct Z-scheme ZnIn2S4 spheres and CeO2 nanorods decorated on reduced-graphene-oxide heterojunction photocatalysts for hydrogen evolution and photocatalytic degradation

Nanocomposite photocatalysts can potentially produce clean hydrogen (H-2) and degrade organic pollutants such as tetracycline (TC). We present hydrothermally synthesized ternary composites of ZnIn2S4-CeO2 implanted into reduced graphene oxide (rGO) layers that outperform typical, expensive catalysts used in the hydrogen evolution reaction (HER). The structural morphology of the composite along with its H2 photocatalytic production and TC degradation ability are evaluated. The results reveal that the ZnIn2S4/rGO/CeO2 heterojunctions demonstrate higher photocatalytic activity for H2 generation and TC degradation than their bare and binary counterparts. The higher efficiency of the ZnIn2S4 -rGO-CeO2 composite is attributable to the synergetic effect of rGO as an electron (e(-))-transfer bridge, as evidenced by the photocurrent density and photoluminescence results. The ZnIn2S4/rGO/CeO2 ternary catalyst absorbs a wide range of wavelengths, diffuses and separates the photoinduced charge carriers quickly and efficiently, and slowly recombines e(-) and h(+). The generated ternary composite material is then used to demonstrate plausible photocatalytic HER and degradation processes.