Amorphous-Phase Tailoring of TiO₂-ZrO₂ Interfacial Linkages Regulates Radical Pathways for Highly Selective...

Amorphous oxides offer unique short-range order and coordination flexibility, yet their capacity to orchestrate interfacial radical chemistry and suppress over-oxidation during photocatalytic methane to liquid conversion remains a critical frontier. Herein, we strategically construct TiO₂-ZrO₂ architectures where the ZrO₂ phase is precisely tuned from amorphous (TiO₂-ZrO₂-A) to crystalline (TiO₂-ZrO₂-A800) to elucidate the governance of structural disorder over aerobic CH₄ functionalization. Multimodal characterizations-including x-ray absorption near-edge structure (XANES)/extended x-ray absorption fine structure (EXAFS), AC-HRTEM, transient electron paramagnetic resonance (EPR), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT), reveal that the amorphous ZrO₂ phase enriches surface oxygen vacancies relative to its crystalline counterpart and establishes robust Ti-O-Zr interfacial linkages. This configuration enhances charge separation and supports higher effective steady-state hole availability for efficient C-H bond activation while effectively tempering the flux of water-derived reactive oxygen species. At room temperature TiO₂-ZrO₂-A achieves an exceptional liquid oxygenate selectivity of up to 98.2%, remarkably outperforming its crystalline analogue by resisting deep oxidation to CO₂. Kinetic analyses reveal the rapid formation of *CH₃ and *CH₃O intermediates, consistent with faster intermediate turnover and reduced overoxidation on the amorphous interface, consistent with DFT-calculated barriers that favor methane activation over non-selective reactive oxygen species (ROS) generation. These findings identify amorphous-phase engineering as a kinetic valve for tuning pathways and selectivity in photocatalytic C-H transformations.