Low temperature synthesis and SERS application of silver molybdenum oxides

AgxMoyOz (Ag/α-MoO3, Ag/h-MoO3, Ag/β-MoO3, Ag2Mo2O7, and Ag2MoO4) nanomaterials are synthesized at relatively low temperature (80 °C) and with a short hydrothermal treatment time (3 h) using glucose (Glc) as a catalyst. Contrary to previous studies, it is possible to synthesize one of the AgxMoyOz binaries at 80 °C by altering the pH of the reaction media in the presence of glucose. In addition, further experiments indicate that Ag/h-MoO3, Ag2Mo2O7 and Ag/β-MoO3 can be converted to Ag/α-MoO3 which can also be synthesized from a reaction involving ammonium heptamolybdate tetrahydrate and AgNO3 at room temperature using cysteamine in both methods. Characterization with UV-Vis, XRD and Raman spectroscopy reveals high purity of as-synthesized product. These synthesized products are finally used to fabricate SERS substrates by coating a silicon wafer with a mixture of silver nanoparticles (Ag NPs) and AgxMoyOz (Si@Ag/AgxMoyOz). The results show a good sensitivity and stability. In addition, it is also found that the SERS activity of Si@Ag/AgxMoyOz is higher than that of Si@Ag.