Synthesis of cuprous oxide/silver (Cu(2)O/Ag) hybrid as surface-enhanced Raman scattering probe for trace determination of methyl orange

Recently, there have been publications on preparing hybrid materials between noble metal and semiconductor for applications in surface-enhanced Raman scattering (SERS) substrates to detect some toxic organic dyes. However, the use of cuprous oxide/silver (Cu(2)O/Ag) to measure the trace amounts of methyl orange (MO) has not been reported. Therefore, in this study, the trace level of MO in water solvent was determined using a SERS substrate based on Cu(2)O microcubes combined with silver nanoparticles (Ag NPs). Herein, a series of Cu(2)O/Agx ([Formula: see text] 1–5) hybrids with various Ag amounts was synthesized via a solvothermal method followed by a reduction process, and their SERS performance was studied in detail. X-ray diffraction (XRD) and scanning electron microscopy results confirmed that 10 nm Ag NPs were well dispersed on 200–500 nm Cu(2)O microcubes to form Cu(2)O/Ag heterojunctions. Using the as-prepared Cu(2)O and Cu(2)O/Agx as MO probe, the Cu(2)O/Ag5 nanocomposite showed the highest SERS activity of all samples with the limit of detection as low to 1 nM and the enhancement factor as high as 4 × 10(8). The logarithm of the SERS peak intensity at 1389 cm(−1) increased linearly with the logarithm of the concentration of MO in the range from 1 nM to 0.1 mM.