Fabrication of sulfuretted NiFe-layered double hydroxides/nitrogen self-doped g-C3N4 Z-scheme heterojunction for hexavalent chromium reduction under visible light irradiation

High poisonous Cr(Ⅵ) metal ions have seriously threatened the ecology and human health safety. Designing the special structure of photocatalysts is an available strategy to enhance its photocatalytic performances for above-mentioned heavy metals treatment. The eye-catching Z-scheme heterojunction could improve its photocatalytic activities since it can improve the separation efficiency of photo-induced carriers and provide the strong redox capacities. In this study, the novel sulfuretted NiFe-layered double hydroxides/nitrogen self-doped g-C3N4 (NFS/NCN) Z-scheme heterojunction was designed and applied for photoreduction of Cr(Ⅵ). The results indicated that NFS/NCN-2 exhibited the good photoreduction performance (90.52%), which was notably higher than those of the NFS (73.88%) and NCN (57.50%). Besides, NFS/NCN-2 also possessed good cycle stability. The Z-scheme NFS/NCN-2 heterojunction played an important role in increasing the visible light absorption capacities and accelerating the photo-induced carriers’ separation and transmitting. This research will provide new insights to design and prepare novel Z-scheme heterojunction photocatalysts for photoreduction of Cr(Ⅵ).