Electromagnetic and Charge Transfer Enhancement Synergistically Boost the SERS Activity of Urchin-like Tungsten Oxide Nanostructures

Semiconductors are regarded as promising alternatives to traditional noble metals for constructing surface-enhanced Raman scattering (SERS) substrates. Nevertheless, their sensitivity is insufficient for widespread practical applications. In this work, urchin-like tungsten oxide (WO3) nanostructures with different oxygen-vacancy contents are fabricated by tuning the solvothermal reaction temperature. Oxygen-vacancy-rich WO3 nanostructures display a broad localized surface plasmon resonance band, whose resonance maximum is centered at ~585 nm. Owing to the synergistic coupling of electromagnetic enhancement and interfacial charge transfer enhancement, the as-synthesized urchin-like WO3 nanostructures exhibit outstanding SERS sensing capability toward Rhodamine 6G molecules. The lowest detectable concentration of 1 × 10−7 M and a remarkable enhancement factor of 5.1 × 105 are achieved. The relative standard deviations below 6.5% are obtained, indicating outstanding signal uniformity of the WO3 SERS substrates. In addition, these urchin-like WO3 nanostructures can serve as SERS substrates for the detection of prohibited fishery drugs. This work offers a feasible strategy for fabricating high-performance semiconductor-based SERS platforms, and the plasmonic urchin-like WO3 nanostructures show great prospects for practical chemical sensing applications.