A systematical study on photocatalytic properties of agmo₂ (m ) al, ga, in): Effects of chemical compositions, crystal structures, and electronic structures

Four Ag-based semiconductor oxides with visible-light absorption, α-AgGaO₂, α-AgInO₂, β-AgAlO₂, and β-AgGaO₂, were prepared to investigate the influences of chemical composition and the crystal structure on the electronic structures and photocatalytic properties of AgMO₂ (M ) Al, Ga, In). The catalytic efficiencies of these oxides were characterized by testing the photooxidation of gaseous 2-propanol to acetone under visible-light irradiation. The ranking of the activity was α-AgGaO₂ > β-AgAlO₂ > β-AgGaO₂ > α-AgInO₂. The electronic structures of these compounds were investigated in terms of density functional theory. These experimental and computational studies of these materials reveal the following: (1) regarding chemical compositions, the conduction bands constructed through hybridization of the Ag 5_s5_p states with Ga 4_s4_p states and Al 3_s3_p states are necessary for promotion of photocatalytic activities under visible light for α-phase and β-phase, respectively, and (2) regarding crystal structures, the Ag 4d states in the absence of crystal-field splitting in the α-phase are favorable for a well-dispersed valence band that is responsible for higher photocatalytic activity.