Chemisorbed oxygen or surface oxides steer the selectivity in Pd electrocatalytic propene oxidation observed by <i>operando</i> Pd L-edge X-ray absorption spectroscopy

Koroidov, Sergey; Winiwarter, Anna; Díaz‐Morales, Oscar; Görlin, Mikaela; Stenlid, Joakim Halldin; Wang, Hsin‐Yi; Börner, Mia; Goodwin, Christopher M.; Soldemo, Markus; Pettersson, Lars; Hansson, Tony; Chorkendorff, Ib; Nilsson, Anders

doi:10.1039/d0cy02134b

Cited by 7 publications

(12 citation statements)

References 28 publications

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“…16 The results showed that the metallic Pd surface has been covered by chemisorbed O/OH species below 1.1 V, and the deprotonated allyl carbon of propene was proposed to react with O (ad) or OH (ad) species and consequently to generate acrolein and acrylic acid in this potential window. 16 Above 1.1 V, the short-range structure of ultrathin surface oxide resembles bulk PdO. At this potential window, propene glycol is formed simultaneously, indicating that the oxidation of the vinyl group may require an oxide surface.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, the activity and selectivity of propene oxidation electrocatalysts cannot meet the application requirements of the electrolyzers yet. So far, a variety of catalyst materials, such as Pt, ,− Pd, ,,, Ag, Au, , and PdAu, have been explored for this reaction. The adsorbates of propene electrooxidation on Pt electrodes include C3, C2, and/or C1 oxygen-containing species, which favor overoxidation to CO 2 due to the high reactivity of Pt.…”

Section: Introductionmentioning

confidence: 99%

“…Au surfaces have a weak interaction with propene and mainly generate partially oxidized products, such as acetone. The noble-metal Pd has been regarded as the most promising electrocatalyst for propene oxidation because it can produce various valuable products including propene oxide, propene glycol, acrylic acid, and so on. ,,, Chorkendorff’s group have systematically investigated propene electrooxidation on Pd electrodes and proposed that the adsorbed organic species formed in situ determine the selectivity of allylic oxidation. Furthermore, Seger et al have succeeded in the synthesis of a PdAu alloy to enhance the activity and selectivity of allyl oxidation.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the fact that the configurations of propene intermediate adsorbates may be changed at the electrochemical interface should be taken into consideration since the surface state and environment are greatly altered with applied potential at the electrochemical interface. In situ X-ray adsorption spectroscopy has been adopted to reveal the evolution of the chemical state of Pd during propene oxidation . The results showed that the metallic Pd surface has been covered by chemisorbed O/OH species below 1.1 V, and the deprotonated allyl carbon of propene was proposed to react with O (ad) or OH (ad) species and consequently to generate acrolein and acrylic acid in this potential window .…”

Section: Introductionmentioning

confidence: 99%

“…In situ X-ray adsorption spectroscopy has been adopted to reveal the evolution of the chemical state of Pd during propene oxidation . The results showed that the metallic Pd surface has been covered by chemisorbed O/OH species below 1.1 V, and the deprotonated allyl carbon of propene was proposed to react with O (ad) or OH (ad) species and consequently to generate acrolein and acrylic acid in this potential window . Above 1.1 V, the short-range structure of ultrathin surface oxide resembles bulk PdO.…”

Section: Introductionmentioning

confidence: 99%

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Reaction Mechanism and Selectivity Tuning of Propene Oxidation at the Electrochemical Interface

et al. 2022

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Electrochemical conversion of propene is a promising technique for manufacturing commodity chemicals by using renewable electricity. To achieve this goal, we still need to develop high-performance electrocatalysts for propene electrooxidation, which highly relies on understanding the reaction mechanism at the molecular level. Although the propene oxidation mechanism has been well investigated at the solid/gas interface under thermocatalytic conditions, it still remains elusive at the solid/liquid interface under an electrochemical environment. Here, we report the mechanistic studies of propene electrooxidation on PdO/C and Pd/C catalysts, considering that the Pd-based catalyst is one of the most promising electrocatalytic systems. By electrochemical in situ attenuated total reflection Fourier transform infrared spectroscopy, a distinct reaction pathway was observed compared with conventional thermocatalysis, emphasizing that propene can be dehydrogenated at a potential higher than 0.80 V, and strongly adsorb via μ-CCHCH3 and μ3-η2-CCHCH3 configuration on PdO and Pd, respectively. The μ-CCHCH3 is via bridge bonds on adjacent Pd and O atoms on PdO, and it can be further oxidized by directly taking surface oxygen from PdO, verified by the H2 18O isotope-edited experiment. A high surface oxygen content on PdO/C results in a 3 times higher turnover frequency than that on Pd/C for converting propene into propene glycol. This finding highlights the different reaction pathways under an electrochemical environment, which sheds light on designing next-generation electrocatalysts for propene electrooxidation.

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Section: ■ Introductionmentioning

confidence: 99%