Linker Engineering of Sandwich‐Structured Metal–Organic Framework Composites for Optimized Photocatalytic H2 Production

Abstract While the microenvironment around catalytic sites is recognized to be crucial in thermocatalysis, its roles in photocatalysis remain subtle. In this work, a series of sandwich‐structured metal–organic framework (MOF) composites, UiO‐66‐NH 2 @Pt@UiO‐66‐X (X means functional groups), is rationally constructed for visible‐light photocatalytic H 2 production. By varying the ─X groups of the UiO‐66‐X shell, the microenvironment of the Pt sites and photosensitive UiO‐66‐NH 2 core can be simultaneously modulated. Significantly, the MOF composites with identical light absorption and Pt loading present distinctly different photocatalytic H 2 production rates, following the ─X group sequence of ─H > ─Br > ─NA (naphthalene) > ─OCH 3 > ─Cl > ─NO 2 . UiO‐66‐NH 2 @Pt@UiO‐66‐H demonstrates H 2 production rate up to 2708.2 µmol g −1 h −1 , ≈222 times that of UiO‐66‐NH 2 @Pt@UiO‐66‐NO 2 . Mechanism investigations suggest that the variation of the ─X group can balance the charge separation of the UiO‐66‐NH 2 core and the proton reduction ability of Pt, leading to an optimal activity of UiO‐66‐NH 2 @Pt@UiO‐66‐H at the equilibrium point.