Electronic modulation of Mo=O sites in Anderson POMs: A molecular platform for rational catalyst design in oxidation desulfurization

Electronic structure modulation of active sites plays a critical role in oxidation catalysis reactions but remains insufficiently explored in polyoxometalate (POM) systems. Here, we employ Anderson-type polyoxomolybdates (XMo 6 , X  = Fe, Co, Ni) as molecular platforms to elucidate how central transition metals regulate the electronic properties and catalytic behavior of Mo=O sites. Through atomic-precision synthesis and heterogenization on ionic liquid-modified h -BN, a series of MMo 6 -C 4 /BN were constructed and enabled precise structure–activity correlation in oxidative desulfurization (ODS). Among them, NiMo 6 -C 4 /BN exhibits the best performance, achieving 100 % DBT removal within 50 min at 60 °C. DFT calculations reveal that the electron-withdrawing Ni center optimally modulates the Mo d-band center, resulting in the most favorable reaction energetics, which fundamentally explains the superior activity. Furthermore, Radical trapping and electron paramagnetic resonance (EPR) measurements identified • OH and • O 2 − as the key reactive species involved in the oxidation process. The catalyst also demonstrated strong practical potential by achieving a 69 % desulfurization rate in real diesel. This work establishes a general strategy for electronic tuning in POM catalysts and provides molecular-level insights into active site engineering for advanced oxidative catalysis.