Roles of Bi, M and VO4 tetrahedron in photocatalytic properties of novel Bi0.5M0.5VO4 (M = La, Eu, Sm and Y) solid solutions for overall water splitting

Novel Bi0.5M0.5VO4 (BMV; M = La, Eu, Sm and Y) solid solutions were prepared and studied in this paper. All the samples were proved to produce H-2 and O-2 simultaneously from pure water under the irradiation of UV light. M-O bond lengths were proved to increase with M cations by refining cell parameters and atomic positions. Besides, band gaps, energy gaps and photocatalytic activities of BMV also changed with M cations. Both of M-O and V-O bond lengths were suggested to account for this phenomenon. Inactive A(0.5)Y(0.5)VO(4) (A = La, Ce) for water splitting proved incorporation of Bi rather than distortion of VO4 tetrahedron was a critical factor for improving efficiency of overall water splitting by facilitating the generation of electron and hole with lighter effective masses. Replacement of Bi by M cations not only gave indirect effect on band structure but also raised position of conduction band minimum to meet requirement Of H-2 production. (C) 2011 Elsevier Inc. All rights reserved.