# Skeletal High‐Strength Nanoporous Copper and Metamaterials: The Hakka Tulou Design Heritage

## TL;DR

Inspired by ancient Hakka Tulou architecture, a new type of strong nanoporous copper is created, offering high strength and surface area for advanced applications.

## Contribution

A novel skeletal nanoporous copper design inspired by Hakka Tulou architecture achieves exceptional mechanical strength and multifunctionality.

## Key findings

- Skeletal nanoporous copper achieves a yield strength of 200.4 ± 15.2 MPa, surpassing conventional nanoporous metals.
- Lattice metamaterials made from skeletal nanoporous copper exceed Gibson-Ashby strength model predictions by 800%.
- The material offers a specific surface area of 27.6 ± 1.2 m2 g−1, enhancing its multifunctional potential.

## Abstract

Nanoporous metals (NPMs) are pivotal for next‐generation technologies, yet their inherent mechanical fragility has long hindered practical implementation. Drawing inspiration from the ingenious architecture of the ancient Hakka Tulou walls, a novel class of nanoporous copper (NPCu) materials—skeletal NPCu—is developed to overcome this limitation. To achieve this, we leverage the principles of solidification and dealloying in alloy design to engineer a unique two‐phase precursor alloy microstructure. This microstructure comprises a strong, ductile, non‐dealloyable skeletal phase (minor phase) and a readily dealloyable principal phase. Upon dealloying, the precursor transforms into skeletal NPCu, achieving exceptional yield strength (200.4 ± 15.2 MPa)—significantly surpassing that of conventional NPMs. Extending this design concept, we fabricate skeletal NPCu lattice metamaterials that surpass the Gibson‐Ashby strength model predictions by 800%, while offering an outstanding specific surface area (27.6 ± 1.2 m2 g−1) that enhances multifunctionality. By marrying ancient architectural wisdom with modern materials science, this innovation unlocks the vast potential of advanced NPMs for applications spanning energy, aerospace, and beyond.

Inspired by the Hakka Tulou walls, skeletal nanoporous copper is fabricated via a two‐phase MnCu precursor and controlled dealloying. This strategy achieves high strength (200 MPa) and large specific surface area (27.6 m2/g), and extends to lattice metamaterials with hierarchical porosity, offering new design pathways for multifunctional metal architectures.