Effect of surface Ag metallization on the photocatalytic properties of BaTiO3: Surface plasmon effect and variation in the Schottky barrier height

Surface Ag metallized BaTiO3 samples were prepared by varying Ag concentration in the range of 0.2% to 0.8% by photoreduction method and the performance of these catalysts were tested for the degradation of Rhodamine B dye under the illumination of UV/solar light. The values of lattice parameter, cell volume and lattice strain has increased with increase in the Ag concentration, while the crystallite size decreased with increase in the deposited Ag concentration. The surface plasmon absorption bands of Ag deposited BTO samples showed a red-shift and the absorption bands broadened with increase in the Ag content. The presence of surface metallic silver in the Ag-0 state was confirmed by the XPS analysis. The enhanced activity of Ag deposited photocatalyst under UV light is majorly due to the formation of Schottky barrier, creation of metal induced gap states, polarization effects, reduced crystallite size and increased surface area of the photocatalyst. Under solar light it is due to synergistic effects between Surface Plasmon Resonance (SPR) effect and formation of Schottky barriers. The photocurrent measurements substantiates the effective charge transfer migrations. The energy states/term symbols of the metallic Ag under the illumination of UV light is S-2(1/2) and it is P-2(1/2) under the illumination of solar light.