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@TiO2 was developed as a bifunctional photocatalyst and SERS-enhanced material. Equally, by optimizing the thickness of the C@TiO2 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@TiO2 demonstrated outstanding SERS sensitivity with an EF of 1.13 × 105. Both experiments and theoretical simulations show that the submicrometer hollow-shell C@TiO2 has multiple resonance effects, i.e., Mie resonance and CT resonance. The efficient SERS and photocatalytic activity of C@TiO2 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@TiO2 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@TiO2 not only provides favorable evidence for the study of the SERS synergistic enhancement mechanism but also brings new ideas for the development of photocatalysts.
Zhu et al. (Wed,) studied this question.