Pulsed Current Electrodeposition of Ag Nanoparticles on Bamboo-like TiO ₂ Nanotubes for Surface-Enhanced Raman Scattering Substrates

In this work, we investigate the performance of surface-enhanced Raman scattering (SERS) substrates based on bamboo-like TiO₂ nanotubes (BTNTs) functionalized with silver nanoparticles (AgNPs) through pulsed-current electrodeposition (50 ms ON/250 ms OFF). The BTNT arrays, fabricated via alternating-voltage anodization, exhibit segmented morphologies that enhance nanoparticle anchoring and promote the dense generation of electromagnetic hotspots. Systematic optimization of deposition parameters revealed that 400 deposition cycles at a current density of 5 mA/cm² yielded the most favorable combination of nanoparticle distribution, structural morphology, and SERS activity. Under these conditions, the substrates achieved an analytical enhancement factor (AEF) of 1 × 10⁶ and enabled the experimental detection of methylene blue down to 1 × 10^-8 M (theoretical LoD 1 × 10^-9 M). This study demonstrates a cost-effective, scalable, and tunable fabrication strategy for highly active SERS platforms, offering significant potential for practical sensing applications.