Enhanced singlet oxygen generation by hybrid Mn-doped nanocomposites for selective photo-oxidation of benzylic alcohols

Transition-metal ions doped nanocrystals (NCs), specifically Mn-doped NCs, hold great potential in the field of photocatalysis, especially, to improve photocatalytic performance for singlet oxygen (¹O₂) generation. Here, we report the design of a novel Mn-doped NC-based nanocomposites, specifically, silica-coated Mn-doped CdS/ZnS NCs decorated with Pt NCs (denoted as Mn-NCs@SiO₂-Pt), which enhance photocatalytic ¹O₂ generation. Owing to the long-lived Mn excited state (on the order of ms), the energy-transfer between Mn-NCs and molecular oxygen is facilitated with the assistance of the Pt NCs adhered to the Mn-NC@SiO₂ surface. Therefore, the Mn-NCs@SiO₂-Pt composites, integrate the advantages of Mn-doped NCs, a protective silica layer, and Pt NCs to exhibit excellent catalytic activity and selectivity for the selective oxidation of primary benzylic alcohols to aldehydes through an ¹O₂ engaged oxidation process under visible-light irradiation. This work paves the way for enhancing catalytic performance via facilitated energy transfer relaxation by utilizing the long-lived excited-state of Mn²⁺ dopant ions in nanocomposites.