Soft-Templated Sol–Gel Synthesis of Mesoporous Perovskite-Type Multicomponent Metal Oxide (Bi _0.2 Na _0.2 K _0.2 La _0.2 Sr _0.2 )TiO ₃ and Its Enhanced Photocatalytic Activity

The high calcination temperature required for the crystallization of multicomponent metal oxides is a challenge because this treatment significantly reduces their specific surface area while increasing the crystallite size, thereby limiting their photocatalytic performances. In this study, we have addressed this issue for a multicomponent perovskite photocatalyst, (Bi_0.2Na_0.2K_0.2La_0.2Sr_0.2)-TiO₃ (BNKLST), by employing a soft-templating sol-gel method using Pluronic F-127. The synthesis process was optimized by adjusting the solution's pH to ensure uniform micelle self-assembly and by determining the optimum calcination temperature for the pore formation. This approach enabled the successful low-temperature synthesis of BNKLST, which retained a high specific surface area of 50.4 m² g^-1 at 400 °C. The resulting catalyst exhibited excellent photocatalytic activity, degrading methylene blue under UV irradiation (250-450 nm) at a rate more than six times faster than that obtained using commercial SrTiO₃. These findings demonstrate that enhancing the specific surface area of multicomponent metal oxides through a soft-templating approach is an effective strategy in photocatalyst design.