Highly Reactive Facet Modulation of Ti-Based MOFs by Selective Anchoring of Au Metal for Photocatalytic H2O2 Production

Crystal facet engineering in metal–organic frameworks (MOFs) offers a promising strategy to enhance the photocatalytic performance. However, there is ongoing debate about which facet is most effective for enhancing the charge transfer and catalytic efficiency. Here, we demonstrate the transformation of the less reactive {111} facet of MIL-125-NH₂ into a highly reactive {111} facet (from TM(111) to AuTM(111)) via simple Au incorporation. On the {001} facet, Au anchors around Ti-oxo clusters, while on the {111} facet, strong Au–NH₂ group interactions enable rapid electron transfer, suppressing electron–hole recombination and enhancing catalytic activity by 5-fold. AuTM(111) facilitates a direct two-electron oxygen reduction reaction (2e-ORR) for hydrogen peroxide (H₂O₂) production with singlet oxygen (¹O₂) as the key intermediate. Moreover, hydrophobically modified AuTM(111) was applied in a benzyl alcohol (BA)/water dual-phase system, achieving 2160 μmol g^–1 h^–1 of H₂O₂ production rate under λ > 420 nm irradiation, with suppressed H₂O₂ decomposition and enhanced yield via extra BA oxidation by ¹O₂. These findings demonstrate a practical strategy for transforming less reactive facets into highly reactive facets via simple metal modification, offering crucial insights and advancing the application of MOF-based photocatalysts.