Two‐Dimensional‐on‐Three‐Dimensional Metal‐Organic Frameworks for Photocatalytic H2 Production

A MOF-on-MOF heterostructure is attractive in material science because of its potential combined effects in catalysis. However, precisely controlling the growth pattern at the metal-organic framework (MOF) nucleation stage to manipulate the metallic composition and structure dimensionality remain a challenge. Herein, we introduce a polyvinylpyrrolidone-assist kinetic-control strategy to achieve the "anti-epitaxial growth" pattern of a foreign MOF nucleus on the (111) facets of UiO-66-NH2 octahedron seeds, and construct diverse two-dimensional-on-three-dimensional (2D-on-3D) MOF heterostructures (2D-on-3D Cu, Zn, Cd, Co, and Ni). Notably, the 2D-on-3D Cu exhibits a unique "dimensionality-hybrid" effect in photocatalysis which led to a significant photoactivity enhancement over those of the traditional "dimensionality-identical" 2D, 3D and 3D-on-3D MOF structures.