Crystal Facet‐Dependent Photocatalytic Hydrogen Evolution From Ultra‐Stable Cu‐Zr/Hf Heterobimetallic Metal–Organic Frameworks

Abstract Solar‐driven water splitting for hydrogen production over metal–organic frameworks (MOFs) is particularly attractive yet remains a challenge. Here, we report a series of ultra‐stable heterobimetallic MOFs (M‐BCA‐M', M = Cu + , M′ = Zr 4+ or Hf 4+ ) for photocatalytic hydrogen production, in which, the Cu(I) species act as the active center, whereas Zr(IV)/Hf(IV) plays an essential role in stabilizing the framework. Uniform MOF crystals with distinct morphologies were obtained, showing a rare crystal facet‐dependent photocatalytic behavior. The octahedral MOF crystals denoted as Cu‐BCA‐Hf‐O with the exposure of only {101} and {011} facets exhibit a record‐high hydrogen production rate (49825.71 µmol g −1 h −1 ) among pristine MOF photocatalysts. The exceptional performance of Cu‐BCA‐Hf‐O can be primarily attributed to its superior photogenerated carrier transfer ability and abundant active sites exposed on the crystal surface. This study provides molecular‐level insights into the coordination regulation and morphology control of MOFs for highly efficient photocatalysis, highlighting the promising future of pristine MOF photocatalysts.