TY - JOUR A1 - Yun, Tae Gyu A1 - Chen, Boqiang A1 - Wells, Sarah A1 - Lim, Younghwan A1 - Kim, Jun Seop A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Waegele, Matthias M. A1 - Risch, Marcel A1 - Grimaud, Alexis ED - de Oliveira Guilherme Buzanich, Ana T1 - Extrinsic and Intrinsic Factors Governing the Electrochemical Oxidation of Propylene in Aqueous Solutions N2 - The electrochemical synthesis of commoditychemicals such as epoxides and glycols offers a sustainablealternative to conventional methods that involve hazardouschemicals. Efforts to improve the yield and selectivity of propyleneoxidation using Pd-based catalysts have been shown to be highlysensitive to applied potential, pH, and electrochemical cell design.Record efficiencies and yields were obtained by substitution ofPdO by 4d or 5d transition metals, including Pt, with thus far littlerationale regarding the origin for the improvement. Throughelectrochemical analysis, scanning transmission electron micros-copy, X-ray absorption spectroscopy, and surface-enhanced infraredabsorption spectroscopy, we investigated the mechanism ofpropylene oxidation on Pd-based catalysts. We demonstrate thatadsorbates forming on PdO, where Pd adopts a square-planar coordination [PdO4], differ from that forming on the surface ofoxidized metallic Pd catalysts with an oxo intermediate mediating propylene oxidation on PdO. We further show that Pt substitutionin PdO does not modify this oxo intermediate. Varying pH, we found that the onset for propylene oxidation is pH independent,indicating a potential-determining step where the proton is not involved in and similar reaction pathway in acidic and near-neutralconditions. Finally, our work undoubtedly demonstrates that high Faradaic efficiency toward propylene glycol and propylene oxideformation, such as those previously reported in the literature, can be achieved by means of electrode engineering and mastery ofmass transport and local pH. Notably, we achieved ≈100% faradaic efficiency for propylene glycol at 1.7 V vs RHE in acidic mediausing a Pt-substituted PdO catalyst loaded onto a gas diffusion electrode. KW - XAS KW - Electrochemistry KW - Popylene oxidation KW - 4d metals PY - 2025 DO - https://doi.org/10.1021/jacs.5c02585 SN - 0002-7863 VL - 147 IS - 14 SP - 12318 EP - 12330 PB - American Chemical Society (ACS) AN - OPUS4-63112 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -