Preparation of solid-state Z-scheme Bi 2 MoO 6 /MO (M Cu, Co 3/4 , 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 Bi2MoO6/MO (M = Cu, Co3/4, 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 Bi2MoO6 hierarchical microspheres, and they close contact with distinct heterojunction interfaces. X-ray photoelectron spectra (XPS) suggest that the electron transfer occurs between the Bi2MoO6 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 Bi2MoO6 and MO are defined, and directions of the interfacial IEFs are determined. The IEFs play key roles for the formation of the Z-scheme Bi2MoO6/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.