Metal‐Oxo Electronic Tuning via In Situ CO Decoration for Promoting Methane Conversion to Oxygenates over Single‐Atom Catalysts

In situ CO decoration can significantly tune the electronic state of metal-oxo center in single-atom catalysts for promoting oxygenates production. CO activated Pd₁-ZSM-5 displays the highest turnover frequency of 207 h⁻¹ and ~100 % oxygenates selectivity with H₂O₂ as oxidant at 25 °C.

Abstract

Direct methane conversion (DMC) to oxygenates at low temperature is of great value but remains challenging due to the high energy barrier for C−H bond activation. Here, we report that in situ decoration of Pd₁-ZSM-5 single atom catalyst (SAC) by CO molecules significantly promoted the DMC reaction, giving the highest turnover frequency of 207 h⁻¹ ever reported at room temperature and ~100 % oxygenates selectivity with H₂O₂ as oxidant. Combined characterizations and DFT calculations illustrate that the C-atom of CO prefers to coordinate with Pd₁, which donates electrons to the Pd₁−O active center (L−Pd₁−O, L=CO) generated by H₂O₂ oxidation. The correspondingly improved electron density over Pd−O pair renders a favorable heterolytic dissociation of C−H bond with low energy barrier of 0.48 eV. Applying CO decoration strategy to M₁-ZSM-5 (M=Pd, Rh, Ru, Fe) enables improvement of oxygenates productivity by 3.2–11.3 times, highlighting the generalizability of this method in tuning metal-oxo electronic structure of SACs for efficient DMC process.

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