Nano-flower like NiO modified BiOBr composites with direct Z-scheme: Improved visible light degradation activity for dyes

Facing environmental pollution, the development of semiconductor photocatalysts with efficient electron-hole pairs separation is necessary for better performance optimization and utilization. Here, a direct Z-scheme BiOBr–NiO-x% (x ​= ​5, 10, 20, 30) photocatalysts with outstanding photocatalytic activity for dye degradation were prepared via the hydrothermal process. The XRD, XPS, FESEM, HRTEM and UV–vis DRS were used to characterize the components, phase structure, morphology and optical properties of the prepared samples. The prepared nano-flower like BiOBr–NiO-x% (x ​= ​5, 10, 20, 30) composites had an extensive visible light absorption range and more vigorous absorption intensity than pure BiOBr. All the prepared composites exhibited better photocatalytic activity for rhodamine (RhB) degradation than that of pure BiOBr, with BiOBr/NiO-20% showing the best photocatalytic efficiency. The photocatalytic efficiency had reached 98% within 50 ​min for the BiOBr/NiO-20% composite. Due to the tight interfacial contact and matching band positions between BiOBr and NiO, a direct Z-scheme BiOBr/NiO heterojunction was built, which accelerated the visible light absorption, superior separation of photoinduced electron-hole pairs in space and improved the oxidation and reduction capacity of the catalysts, further leading to the excellent photocatalytic activity for degradation of RhB.