Preparation of solid-state Z-scheme Bi2MoO6/MO (MCu, Co3/4, or Ni) heterojunctions with internal electric field-improved performance in photocatalysis

Up to now, studies on solid-state Z-scheme two-component heterojunctions have hardly referred to roles of interfacial internal electric fields (IEFs). Herein, solid-state Z-scheme Bi 2 MoO 6 /MO (M   =   Cu, Co 3/4 , or Ni) heterojunction photocatalysts were simply synthesized, for the first time, with enhanced photocatalytic performance toward organic degradation. Electron microscopy images reveal that the MO homogeneously distributes on surfaces of the Bi 2 MoO 6 hierarchical microspheres, and they close contact with distinct heterojunction interfaces. X-ray photoelectron spectra (XPS) suggest that the electron transfer occurs between the Bi 2 MoO 6 and MO after they contact, resulting in formation of IEFs at their interfaces. Based on band gap values and valance-band XPS and ultraviolet photoelectron spectra, energy band levels of the Bi 2 MoO 6 and MO are defined, and directions of the interfacial IEFs are determined. The IEFs play key roles for the formation of the Z-scheme Bi 2 MoO 6 /MO heterojunctions and for the photoactivity enhancement. This work provides a better insight into the formation mechanism of solid-state two-component Z-scheme heterojunctions and a significant experimental guidance for studying other similar systems.