3D-Printing of Hierarchical Porous Copper-Based Metal–Organic-Framework Structures for Efficient Fixed-Bed Catalysts

Metallic structures with hierarchical open pores that span several orders of magnitude are ideal candidates for various catalyst applications. However, porous metal materials prepared using alloy/dealloy methods still struggle to achieve continuous pore distribution across a broad size range. Herein, we report a printable copper (Cu)/iron (Fe) composite ink that produces a hierarchical porous Cu material with pores spanning over 4 orders of magnitude. The manufacturing process involves four steps: 3D-printing, annealing, dealloying, and reannealing. Because of the unique annealing process, the resulting hierarchical pore surface becomes coated with a layer of Cu-Fe alloy. This feature imparts remarkable catalytic ability and versatile functionality within fixed bed reactors for 4-nitrophenol (4-NP) reduction and Friedländer cyclization. Specifically, for 4-NP reduction, the porous Cu catalyst demonstrates an excellent reaction rate constant (