High-Entropy Metal Interstitials Activate TiO₂ for Robust Catalytic Oxidation

Substitution metal doping strategies are crucial for developing catalysts capable of activating O₂, but the leaching of metal dopants has greatly hindered their potential for extensive oxidation reactions under mild conditions. Here, the study develops an entropy-increase strategy to synthesize high-entropy metal (Mg, Ca, Mn, Fe, and Co) interstitial functionalized anatase TiO₂ (HE-TiO₂) nanosheets, demonstrating remarkable degradation efficiency across a wide pH range and exceptional stability in a flow-by electro-catalytic reactor. Relative to that of pristine TiO₂, the intense lattice distortion on the (001) plane, an average lattice expansion of 2% on the (100) plane, and decrease of second shell peak of X-ray absorption spectra serve as compelling evidence for the formation of metal interstitials in HE-TiO₂. Theoretical analysis and in situ synchrotron radiation Fourier transform infrared studies reveal that the electron of metal interstitials can populate the subgap states within the host TiO₂, enabling a moderate adsorption band for robust and efficient O₂ activation. This study introduces a universal strategy for synthesizing a novel class of high-entropy materials with integrated metal interstitials in metal oxides, promising to enhance the stability and efficiency of O₂ activation catalysts and broaden their potential applications.