Ag2O/TiO2 Nanocomposite Heterostructure as a Dual Functional Semiconducting Substrate for SERS/SEIRAS Application

Surface enhanced Raman spectroscopy (SERS) and surface enhanced infrared absorption spectroscopy (SEIRAS) are complementary and powerful techniques for molecular characterization and detection. However, studies on substrates that can enhance both Raman and IR singles are extremely scanty. Here we reported a hybrid semiconductor material (Ag2O/TiO2) coupled with a portable solid support served as a dual functional platform for both SERS and SEIRAS applications. A facile two-step deposition method was used to synthesize Ag2O/TiO2 nanocomposite on a flexible polymeric membrane without bringing any external chemical capping agent and background signal. The presence of Ag2O was proposed to enrich the photogenerated electrons onto TiO2 surface and facilitate the photon-induced charge transfer (PICT) between TiO2 and adsorbate. The heterostructure of Ag2O/TiO2 could bring additional enhancement. The enhancement factor from such hybrid semiconducting substrate was at least one or two orders of magnitude over traditional semiconducting materials and comparable to noble metals. Additionally, this substrate enabled the ultra-trace detection regardless of the more Raman- or IR-active molecules and displayed distinct quantitative capacities for SERS and SEIRAS. High reproducibility of the SERS/SEIRAS spectra further confirmed the reliability and reproducibility of our substrates.