Correlation of crystal structures, electronic structures, and photocatalytic properties in a series of Ag-based oxides:: AgAlO2, AgCrO2, and Ag2CrO4

Three Ag-based oxides, AgAlO2, AgCrO2, and Ag2CrO4, were prepared by the cation exchange method. Powder X-ray diffraction analysis showed that AgAlO2 and Ag2CrO4 crystallized in orthorhombic structures and AgCrO2 crystallized in a hexagonal structure. The band gaps of AgAlO2, AgCrO2, and Ag2CrO4 were estimated to be 2.95, 1.68, and 1.75 eV, respectively. The photooxidation of Methyl Orange and gaseous benzene were performed to test the activities of the three materials. In the two kinds of reactions, the activity orders were both Ag2CrO4 > AgAlO2 > AgCrO2, and it was found that the novel photocatalyst, Ag2CrO4, showed activity in the visible region up to 570 nm. The correlation among crystal structures, electronic structures, and photocatalytic properties in the three Ag-based oxides is discussed in detail.