Interfacial tautomerization-modulated S-scheme MOF/COF heterojunctions for enhanced photocatalytic H2O2 production

Abstract

The construction of efficient photocatalyst systems for photocatalytic H₂O₂ production has attracted extensive research interest. However, controlled improvement of interfacial charge transfer and activation energy barriers in heterostructures remains a challenge. Here, we present a facile strategy for constructing tautomerization-induced interfaces, enabling the development of zirconium–organic frameworks (UiO-66)@triformylphloroglucinol-based covalent organic frameworks (Tp-COF) S-scheme heterojunctions with tunable interfacial keto-amine moieties. Specifically, Tp units were first anchored onto the amino site of UiO-66 and then grown into Tp-COF with interfacial imine linkage, generating tautomerization between the enol-imine and keto-amine moieties. Using in situ X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations and femtosecond transient absorption spectroscopy (fs-TA), the enhanced interfacial charge transfer and lower activation energy barrier for O₂ reduction induced by moderate keto-amine moieties in the pre-designed S-scheme heterojunction were validated. The heterostructures showed improved efficiency in photocatalytic H₂O₂ production under an air atmosphere, with a yield of 54.3 times larger than that of pristine Tp-COF or UiO-66. This performance surpasses that of state-of-the-art photocatalysts and maintains its high efficacy without significant loss even after four consecutive cycles.