Electrical Tuning of MoO_x/Ag Hybrids and Investigation of their Surface‐Enhanced Raman Scattering Performance

Surface‐enhanced Raman scattering (SERS) technology is a cutting‐edge analytical tool for molecule detection. Attractive SERS performance has been achieved on noble metal nanostructures; however these substrates usually suffer from difficulties of direct adjusting of the physical structures to achieve tunable SERS performance. Studies on semiconductor oxides have revealed that attractive SERS performance can be obtained on them, but strategies of engineering material properties for SERS performance improvement still pose a challenge. Here, an electrically programmable SERS substrate is prepared by depositing hydrothermally synthesized MoO_x/Ag hybrids within electrodes as the SERS active region. In the experiment, an electrical field is applied on the electrodes to regulate Ag⁺ ion migration and redeposition in the MoO_x solid electrolyte. Through adjusting the leakage current level, the size of the Ag nanoparticles in the MoO_x/Ag hybrids is electrically controlled. The SERS performance of the substrate is evaluated using rhodamine 6G as the Raman reporter. The results evidence that Raman enhancement factors of 1.13 × 10⁵, 4.75 × 10⁵, and 1.04 × 10⁶ can be obtained by programming the leakage current level to 10⁻⁷, 10⁻⁵, and 10⁻³ A, respectively. A maximum detection limit of 10⁻⁸ m is achieved on the 10⁻³ A substrate.