Step-scheme NiO/BiOI heterojunction photocatalyst for rhodamine photodegradation

Herein, a step-scheme heterostructure photocatalyst formed by macroporous NiO foams and BiOI microspheres is successfully fabricated. The as-obtained NiO/BiOI heterostructure can be employed as an effective photocatalyst under solar light for the RhB degradation, and the optimum rate constant of 57.2 × 10−3 min−1 is achieved with an optimal mass ratio of NiO to BiOI (10%) in the composite, which is 1.7 and 8.0 times as high as that of singular BiOI and NiO, respectively. The increased light utilization of the macroporous/microspheric hierarchical system and the formation of high quality heterojunction interface between NiO and BiOI are responsible for the improvement in photocatalytic activity. In addition, the underlying step-scheme heterojunction mechanism for efficient charge transportation and separation is also proposed. Our present work demonstrates that the step-scheme heterojunction is a feasible way to obtain high efficiently photocatalysts and might inspire some new strategies in the area of photocatalysis.