Enhancing Charge Separation and Photocatalytic Activity of Cubic SrTiO₃ with Perovskite-Type Materials MTaO₃ (M=Na, K) for Environmental Remediation: A First-Principles Study

Due to increasingly global environmental and energy crises, visible light semiconductor photocatalyst with a tunable bandgap and optical properties have received attention. This study aid in the design of bifunctional MTaO₃/SrTiO₃(010) (M=Na, K) heterostructure photocatalyst material for environmental remediation. In this study, the stability, electronic and optical properties of coupled MTaO₃ and SrTiO₃ are systematically studied using the hybrid HSE06 method. The MTaO₃/SrTiO₃(010) heterostructure show high photocatalytic activity under visible light irradiation with good stability and reduced bandgap compared to the bulk SrTiO₃. The heterostructures formed a type-II band alignment to accelerates the interfacial charge transfer process and the photocatalytic activity. By comparing the relative ratio of effective mass, we could conclude that MTaO₃/SrTiO₃(010) heterostructure has not only superior mobility of charge carriers but also higher separation of photoinduced electrons and holes. The band alignment results showed that the MTaO₃/SrTiO₃(010) heterostructure are highly efficient for pollutants degradation and energy conversion. Significantly, the origin of the enhanced photocatalytic activity is observed from the O 2p state of SrTiO₃ to the Ta 5d state of MTaO₃. In summary, this study shows a key role of SrTiO₃ as an electron donor to enhance the optical properties and stability of MTaO₃/SrTiO₃(010) heterostructure.