Unveiling the role of lattice oxygen in promoting direct electrochemical propylene oxidation to propylene glycol

Propylene glycol (PG) demands sustainable electrochemical synthesis to overcome the environmental and economic drawbacks of thermochemical processes. The activation of reactive oxygen species (ROS) represents a critical determinant in optimizing the electrocatalytic oxidation of propylene (Pr) to PG. Here, we propose a lattice oxygen involving mechanism (LOM) to enhance *OH generation and Pr activation, achieving direct conversion of Pr to PG using Mn 3 O 4 nanoparticle-loaded Pd metallene (Mn 3 O 4 /Pdene). Mn 3 O 4 /Pdene achieves 86.5 % PG selectivity and 55.4 % Faradaic efficiency at 1.15 V via LOM pathway with stable performance over 80 h. In situ ATR-SEIRAS, 18 O isotope labeling experiments, and in situ differential electrochemical mass spectrometry (DEMS) validate the LOM pathway: Lattice-O activates Pr through C-O-C bond formation, while *OH from lattice-O attacks tertiary carbons to generate *PrOH, with water-derived *OH replenishing lattice-O for PG synthesis. DFT reveals that the LOM pathway facilitates H 2 O dissociation and C C bonds polarization, lowering the rate-determining step energy barrier. This work highlights the role of lattice oxygen in the electrocatalytic propylene oxidation and unveils a novel LOM pathway of propylene oxidation.