Breaking Linear Scaling Relations for Regioselective Phenol Hydroxylation via SiC-Supported Dual-Atom Catalysts

The electrochemical hydroxylation of phenol offers a sustainable route to valueadded dihydroxybenzene isomers, yet rational catalyst design remains limited by 2 poor regioselectivity and structural instability. This study investigates silicon carbide (SiC) monoliths as exceptionally robust supports for dual-atom catalysts, utilizing density functional theory and operando ab initio molecular dynamics (AIMD) to screen 45 bimetallic combinations. Mechanistic analysis reveals that phenol undergoes site-specific activation directly at the Si-lattice, dictating regioselectivity toward catechol (ortho-pathway) or hydroquinone (para-pathway). Crystal Orbital Hamilton Population analyses and energetic span modeling demonstrate that macroscopic turnover is strictly governed by dynamic orbital overlap and precise d-band alignment. The TiFe configuration optimally minimizes the energetic span for ortho-hydroxylation, while TiMn provide the most competitive pathways for para-hydroxylation. Two-dimensional microkinetic mapping confirms that optimizing surface binding thermodynamics and bimetallic electronics successfully circumvents traditional linear scaling relations. Furthermore, operando AIMD simulations at 298 K validate these models, confirming that aromatic 𝜋-electron disruption constitutes the kinetic bottleneck (0.70 eV) and highlighting the critical role of interfacial potassium cations in electrostatically shielding polarized radical transition states.