Singlet Oxygen From Lattice Oxygen-Adsorbate Hybridization Drives Highly Selective Electrooxidation of Methallyl...

Selective oxidation of methallyl alcohol (MAO) to methacrolein (MAC) is crucial yet challenged by C═C cleavage and overoxidation in both thermochemical and radical-mediated routes. Herein, we report a Mn-doped NiMoO₄ catalyst anchored on partially oxidized copper-foam (M-NMO/Cu₂₊₁O/CF) achieves unprecedented 100% selectivity and Faradaic efficiency for MAO to MAC at a record production rate of 1776 µmol cm^-2 h^-1 (420 C,1.0 M K₂CO₃, 1.62 V vs. RHE). The catalyst synergizes lattice-oxygen mechanism (LOM) with adsorbate-evolution mechanism (AEM) to generate singlet oxygen (¹O₂). This electrophilic ¹O₂ dominates the selective oxidation of Cα-OH in MAO, preserving its C═C bond via preferential α-hydrogen abstraction. Isotope labeling (H₂ ¹⁸O) and operando Fourier-transform infrared spectroscopy (FT-IR) reveal that ¹O₂ is generated primarily from lattice-oxygen through critical peroxide-like M-O-O intermediates, with a secondary contribution from adsorbed water. Density functional theory (DFT) reveals Mn-induced asymmetric d-band engineering concurrently lowers the LOM barrier and raises the AEM barrier at Ni centers, establishing a Ni-governed, LOM-dominant dual-pathway for ¹O₂ generation. The catalyst further enables general furfuryl and benzyl alcohol oxidation, and scale-up in a flow electrolyzer achieves 90% MAO conversion. This work establishes an asymmetric electronic modulation strategy for in situ generation of singlet oxygen via peroxide-like intermediates, enabling highly selective electrooxidation of alcohols.