Surface-enhanced Raman scattering of CoTiO₃@Ag nanofibers for high-performance sensing applications

Surface-enhanced Raman scattering (SERS) has proven to be a powerful fingerprinting technique for the ultra-sensitive detection of a variety of biological and chemical analytes. Hence, the development of facile, low-cost, and reliable SERS-active substrates is essential for practical applications. In this study, electrospun CoTiO₃@Ag nanofibers annealed at different temperatures were developed and explored for SERS detection using R6G as a probe. The results showed that with increasing annealing temperature, more Ag nanoparticles grew on the surface of the CoTiO₃ nanofibers, leading to a maximum SERS effect achieved at 700 °C. The substrate showed good reusability during repeated SERS detection of R6G and RhB without appreciable loss of activity. High sensitivity over a range of R6G concentrations (10^-9–10^-3 M) and good uniformity (RSD = 12.3%) were also observed for the prepared substrate. Moreover, when the individual nanofibers were assembled into helically bundled CoTiO₃@Ag nanofibers, the SERS effect was increased by a factor of 9.27. This further enhancement was attributed to the interparticle plasmonic couplings and consequently increased number of hot spots, as demonstrated by FEM simulations of bundled CoTiO₃@Ag nanofibers with different spacings. These findings demonstrate that elegant manipulation of the nanofibers can effectively boost the resulting SERS performance.