Microstructure Engineered Bulk Nanoporous Copper With Tunable Plasmonic Properties for Surface-Enhanced Raman Spectroscopy

This study presents a kinetically guided approach for fabricating robust, bulk nanoporous copper (NPC) with tunable plasmonic properties. A free-corrosion dealloying process was used to produce uniform, three-dimensional bicontinuous structures by systematically varying the initial Ti–Cu alloy composition and HF etchant concentration. We demonstrate that the precursor's phase constitution—single-phase TiCu versus dual-phase TiCu + TiCu₂—combined with the HF concentration governs, dealloying kinetics and final pore architecture. Electrochemical Tafel analysis confirms that the dual-phase precursor exhibits accelerated dissolution kinetics, enabling precise pore size tuning from ∼50 to ∼200 nm. An optimal macroscopically crack-free, interpenetrating ligament-channel network with ∼150 nm pores is achieved under specific kinetic conditions. When employed as substrates for surface-enhanced Raman spectroscopy (SERS), these NPC exhibit plasmonic properties intrinsically linked to microstructure. Maximum SERS enhancement for Rhodamine 6G occurs at ∼150 nm pore size, reflecting an optimal balance between electromagnetic field enhancement and plasmonic damping associated with residual titanium. This work provides a comprehensive investigation of kinetic effects during Ti–Cu dealloying and demonstrates how controlled processing–microstructure relationships can be utilized to engineer macroscopically crack-free bulk nanoporous copper for SERS applications.