Synergistic enhancement of photocatalytic H2O2 production via promoting O2 adsorption and sequential energy/electron transfer process in anthraquinone-engineering of fluorinated metal–organic framework

Solar-driven photocatalytic H 2 O 2 production presents a sustainable alternative to the industrial anthraquinone process. An in situ anthraquinone (AQ) functionalized metal–organic framework (UiO-66-F 4 ) with fluorinated linkers enables efficient concurrent synthesis of H 2 O 2 and value-added benzaldehyde (BzH) in a two-phase system. The AQ-modified F-MOF achieves exceptional H 2 O 2 production rates of 118.1mmol g -1 h −1 under visible light and 328.2mmol g -1 h −1 under simulated sunlight, along with high BzH selectivity (∼95%). Fluorinated linkers and AQ act synergistically to enhance the built-in electric field, promote charge separation, and facilitate oxygen adsorption and activation. RDE and RRDE studies verify a highly selective two-electron oxygen reduction pathway (94% H 2 O 2 selectivity) and reveal a non-traditional mechanism involving energy transfer to form electrophilic 1 O 2 , which is subsequently reduced to •O 2 – by electron and protonated to H 2 O 2 . Both experimental and theoretical results demonstrate that the 1 O 2 mediated pathway proceeds with a lower free energy barrier compared to the molecular oxygen route. Meanwhile, the incorporation of AQ reduces the oxygen adsorption energy and provides additional adsorption sites, further enhancing photocatalytic H 2 O 2 production. EPR spectroscopy corroborates the interconversion between 1 O 2 and •O 2 – during the reaction. This work offers mechanistic insight into the coexistence and interconversion of reactive oxygen species, while demonstrating spontaneous separation and collection of both H 2 O 2 and high-value oxidation products in a two-phase system.