Dynamic Electronic Modulation of MOF-808 via Vacancy-Driven Ligand-to-Metal Charge Transfer for Self-amplifying Photocatalysis

The mechanistic insight into the relationship between pollutant adsorption and the corresponding photocatalytic response remains a critical yet elusive facet of heterogeneous catalysis. Here, we unravel the multiplicity of adsorption pathways governing norfloxacin (NOR) uptake on oxygen- and organic-vacancy-engineered MOF-808 (MOF-808-OVs) and demonstrate that these interfacial interactions actively reconfigure the framework’s electronic landscape through a vacancy-driven ligand-to-metal charge transfer (v-LMCT) process. While Lewis acid–base pairing and electrostatic forces at the Zr–O clusters constitute the primary binding determinants, π–π stacking and hydrophobic contacts serve as auxiliary contributions. Crucially, combined partial density of states (PDOS) analysis reveals that the resultant MOF-808–pollutant adduct enables a v-LMCT pathway, wherein electron injection from NOR into the O 2p orbitals of the Zr–O nodes not only reinforces adsorbate retention but also primes a rapid electron shuttling cascade from the inorganic clusters to dissolved O2 in aqueous media. This synergistic charge-transfer regime substantially amplifies reactive oxygen species generation, boosting •OH and 1O2 production by factors of 2.2 and 6.0, respectively, relative to pristine MOF-808 in the absence of NOR. Thus, these findings establish a mechanistic paradigm wherein adsorption serves as an electronic tuning lever, engendering a self-amplifying photocatalytic cycle. This work provides a foundational strategy for the rational design of next-generation photocatalysts predicated on adsorption-driven electronic modulation.