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 ultratrace 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.