Hierarchical Nanoporous Copper Fabricated by One-Step Dealloying Toward Ultrasensitive Surface-Enhanced Raman Sensing

Geometry-tunable substrates with abundant plasmon resonant structure are ideal to proffer high surface-enhanced Raman scattering (SERS) activity for trace sensing including pollutants and toxics, whereas great challenge remains in creating high-density “hotspots” in these structures for further improving Raman signals and detection sensitivity. Herein, one-step dealloying strategy is proposed to fabricate free-standing copper membranes with hierarchical porous architecture where a high density of inherent “hotspots” is built in the vicinity of secondary pores in 3D ligaments. The hierarchical nanoporous copper shows excellent SERS activity with an average enhancement factor of 6.4 × 10⁹, originating from strong electromagnetic coupling effects induced by its highly dense “hotspots” and highly accessible surface. Moreover, the proposed one-step dealloying strategy of dual-phase binary alloys propounds an inexpensive yet effective route to construct ultrasensitive SERS substrate for trace detection and molecular diagnosis.