Polyoxometalate Directional Etching for Fabricating Defect Hollow Metal–Organic Framework with Hierarchical Structure
Wenxiong Shi, Heng‐Rui Fan, Wen‐Rui Liu, Yixuan Qi, Maxwell Cui, Tong‐Bu Lu, Zhiming Zhang
Abstract
Abstract Encapsulating guests in metal–organic frameworks (MOFs) can widely expand their functionality, but usually reduces porosity, hindering reactant and product diffusion. Herein, a simple and rapid room temperature directional etching technique is developed to engineer MOFs with tailored hierarchical structures. With H 3 PMo 12 O 40 (PMo 12 ) as an etchant, classical cubic morphology of WNi@Z8, a ZIF‐8 MOF encapsulating SiW 11 NiO 39 (WNi), can be transformed into various defect‐engineered hollow structures, and a comprehensive phase diagram is established by systematically adjusting etching parameters. Mechanistic studies reveal that PMo 12 infiltrates ZIF‐8 preferentially through {111} facet, followed by controlled etching along {110} and {100} facets, enabling precise spatial control over cavity formation. The etched WNi@Z8 achieves an exceptional H 2 evolution rate of 12,667 µmol g −1 h −1 , nearly threefold enhancement over the non‐etched counterpart due to the enhanced exposure of encapsulated WNi clusters in the hollow structure. This work provides a generalizable strategy for engineering guest@MOFs to achieve high‐efficiency catalysis.