Revealing the Synergism of Active and Durable PtAu/TiO2 Catalysts in Aqueous Oxidation of Diethylene Glycol to para-Dioxanone

Abstract

As a key monomer for future surgical polymers, para-dioxanone (PDO) has been widely used in clinical and medical applications. However, environmentally beneficial synthesis of PDO remains a grand challenge in this area, as conventional routes demand toxic additives and harsh reaction temperatures. In this work, we report facile aqueous phase synthesis of PDO via oxidation of diethylene glycol (DEG) over active and durable PtAu/TiO₂ catalysts. Detailed surface characterization studies have revealed that electronic coupling in the PtAu alloy and metal–support interface facilitates activation of the O–H bond and formation of 1,4-dioxan-2-ol as the key intermediate toward PDO, rather than unwanted ring-opening reactions (O–C–O bond cleavage). The proposed PtAu/TiO₂ catalysts exhibit a record high activity (TOF: 2,129 h^–1) and PDO yield of 48% in aqueous medium. A combinatory study of morphological characterization and kinetic modeling further demonstrated that the lattice mismatch between Pt and Au crystals has induced the formulation of twinned phases with additional active sites for conversion of DEG to PDO. Surface characterization further revealed the intrinsically active sites with remarkable durability in aqueous medium.