Engineered Au@CuO Nanoparticles for Wide-Range Quantitation of Sulfur Ions by Surface-Enhanced Raman Spectroscopy
Haoming Bao, Kenta Motobayashi, Katsuyoshi Ikeda
Abstract
Efficient detection of sulfide ions (S2–), especially in a wide quantitative range, is of significance but faces challenges. This work strategizes and fabricates Au@CuO nanoparticles for quantitative surface-enhanced Raman spectroscopy (SERS) detection of the S2– ions based on the S2– concentration-dependent ion–solid interactions. We have achieved fast and quantitative S2– detection in a wide range from 5 ppb to 64,000 ppm (saturation concentration of the S2– source). We also demonstrated that the optimal CuO shell thickness for the detection is about 7 nm and that the detection can be further improved by prolonging the soaking duration. Moreover, this detection method has also shown the merits of reusable substrates (especially for low S2– concentrations) and good anti-interference ability to many common anions (Cl–, NO3–, OH–, HCOO–, CO32–, and SO42–). Finally, the high feasibility of this detection in actual water (tap water and pond water) has also been demonstrated. This work provides efficient S2– detection with great potential in practical use and also inspires the design of quantifiable SERS substrates for detecting more small inorganic molecules and ions.