Structural control and element doping are two popular strategies to produce semiconductors with surface enhanced Raman spectroscopy (SERS) properties. For TiO

2

based SERS substrates

maintaining a good crystallinity is critical to achieve excellent Raman scattering. At elevated temperatures (600 ℃)

the phase transition from anatase to rutile TiO

2

could result in a poor SERS performance. In this work

we report the successful synthesis of TiO

2

nanowhiskers with excellent SERS properties. The enhancement factor

an index of SERS performance

is 4.96×10

6

for methylene blue molecule detecting

with a detection sensitivity around 10

-7

mol·L

-1

. Characterizations

such as XRD

Raman

TEM

UV-vis and Zeta potential measurement

have been performed to decrypt structural and chemical characteristics of the newly synthesized TiO

2

nanowhiskers. The photo absorption onset of MB adsorbed TiO

2

nanowhiskers was similar to that of bare TiO

2

nanowhiskers. In addition

no new band was observed from the UV-vis of MB modified TiO

2

nanowhiskers. Both results suggest that the high enhancement factor

cannot be explained by the charge-transfer mechanism. With the support of

ab initio

density functional theory calculations

we reveal that interfacial potassium is critical to maintain thermal stability of the anatase phase up to 900 ℃. In addition

the deposition of potassium results in a negatively charged TiO

2

nanowhisker surface

which favors specific adsorption of methylene blue molecules and significantly improves SERS performance

via

the electrostatic adsorption effect.