Nanoclay‐Modulated Interfacial Chemical Bond and Internal Electric Field at the Co₃O₄/TiO₂ p‐n Junction for Efficient Charge Separation

Abstract To achieve a high separation efficiency of photogenerated carriers in semiconductors, constructing high‐quality heterogeneous interfaces as charge flow highways is critical and challenging. This study successfully demonstrates an interfacial chemical bond and internal electric field (IEF) simultaneously modulated 0D/0D/1D‐Co₃O₄/TiO₂/sepiolite composite catalyst by exploiting sepiolite surface‐interfacial interactions to adjust the Co²⁺/Co³⁺ ratio at the Co₃O₄/TiO₂ heterointerface. In situ irradiation X‐ray photoelectron spectroscopy and density functional theory (DFT) calculations reveal that the interfacial Co²⁺OTi bond (compared to the Co³⁺OTi bond) plays a major role as an atomic‐level charge transport channel at the p‐n junction. Co²⁺/Co³⁺ ratio increase also enhances the IEF intensity. Therefore, the enhanced IEF cooperates with the interfacial Co²⁺OTi bond to enhance the photoelectron separation and migration efficiency. A coupled photocatalysis‐peroxymonosulfate activation system is used to evaluate the catalytic activity of Co₃O₄/TiO₂/sepiolite. Furthermore, this work demonstrates how efficiently separated photoelectrons facilitate the synergy between photocatalysis and peroxymonosulfate activation to achieve deep pollutant degradation and reduce its ecotoxicity. This study presents a new strategy for constructing high‐quality heterogeneous interfaces by consciously modulating interfacial chemical bonds and IEF, and the strategy is expected to extend to this class of spinel‐structured semiconductors.