Electrohydrodynamic redox printing vs. physical vapour deposition: a comparative study of nanoporous Ag morphology and SERS performance.

The increasing demand for miniaturised, high-performance sensing platforms necessitates materials that can be deposited with high spatial precision. Surface-enhanced Raman spectroscopy (SERS) has emerged as a powerful analytical technique, offering significant signal amplification. Nanoporous (np) metals, particularly np Ag, are promising candidates for SERS substrates due to their high surface area and tunable nanostructure. In this study, we compare np Ag fabricated via electrohydrodynamic redox printing (EHD-RP), an additive manufacturing technique with high spatial resolution, to conventionally produced counterparts using physical vapour deposition (PVD). EHD-RP-derived np Ag exhibits comparable SERS performance to PVD samples. Structural analysis reveals that the density of sub-25 nm pores and the degree of structural disorder strongly contribute to enhancement factors. Additionally, EHD-RP-derived np Ag demonstrates excellent stability under varying illumination conditions and effectively catalyses the plasmon-driven dimerisation of 4-nitrobenzenethiol. These results underscore the potential of EHD-RP for fabricating functional nanostructured materials for integrated sensing applications.