Charge-transfer-activated SERS detection of methylene blue using an ultrastable, reliable, and highly sensitive semiconductor Fe 3 O 4 @C@TiO 2 nano-platform

- approaching those of noble-metal substrates and significantly higher than most semiconductor-based counterparts. The system further enables accurate MB detection in tap water, yielding recovery values of 93-106%. These results highlight the strong potential of semiconductor heterostructures for stable and practical SERS sensing platforms.