Introduction of a Fe₃O₄ Core Enhances the Photocatalytic Activity of MIL‐100(Fe) with Tunable Shell Thickness in the Presence of H₂O₂

Metal–organic frameworks (MOFs) are a new class of porous crystallized materials, which have attracted great interest for sustainable energy and environmental remediation. The functionalization of MOF‐based catalysts has been investigated to improve their photocatalytic ability. Here, we present a way of enhancing a magnetic MOF‐based photocatalyst composed of MIL‐100(Fe) and Fe 3 O 4 . The photocatalytic performance of the MOFs was significantly enhanced by the simultaneous introduction of a Fe 3 O 4 core and H 2 O 2 , as the photoinduced holes and electrons of the MOF were relayed to the core F 3 O 4 and reacted with H 2 O 2 , respectively. The optimal thickness of the MOF shell is ≈50 nm for core–shell Fe 3 O 4 @MIL‐100 microspheres to achieve the highest photocatalytic ability. Moreover, core–shell Fe 3 O 4 @MIL‐100(Fe) can be easily recycled without significant loss of photocatalytic ability after being used several times.