Submicron Size C@TiO ₂ with Multiple Resonance Effects for Surface-Enhanced Raman Spectroscopy and Photocatalysis

Semiconductor materials are biocompatible and stable and have excellent controllable properties; nevertheless, their low sensitivity and enhancement factor limit their application and development in the field of surface-enhanced Raman scattering (SERS). Herein and for the first time, noble-metal-free submicrometer C@TiO 2 was developed as a bifunctional photocatalyst and SERS-enhanced material. Equally, by optimizing the thickness of the C@TiO 2 shell to regulate the electric field strength, the degradation rates of R6G and antibiotic CIP under simulated sunlight irradiation reached 97% and 93% within 14 and 40 min, respectively, which were much higher than those previously reported. Additionally, the C@TiO 2 demonstrated outstanding SERS sensitivity with an EF of 1.13 × 10 5 . Both experiments and theoretical simulations show that the submicrometer hollow-shell C@TiO 2 has multiple resonance effects, i.e., Mie resonance and CT resonance. The efficient SERS and photocatalytic activity of C@TiO 2 are mainly attributed to the strong light trapping ability of the hollow shells as well as the Mie-resonance-induced electric field, providing an additional driving force that reduces the recombination of photogenerated carriers. The electric field strength around C@TiO 2 is directly proportional to its photocatalytic activity, making it feasible to predict catalytic performance by analyzing the spectral information on molecules. As a bifunctional material, the hollow-shell C@TiO 2 not only provides favorable evidence for the study of the SERS synergistic enhancement mechanism but also brings new ideas for the development of photocatalysts.