@article {13569, title = {Nanographene oxide-TiO2\ photonic films as plasmon-free substrates for surface-enhanced Raman scattering}, journal = {Nanoscale}, volume = {11}, year = {2019}, pages = {21542-21553}, abstract = {The development of nanostructured semiconductors with tailored morphology and electronic properties for surface-enhanced Raman scattering (SERS) has been attracting significant attention as a promising alternative to conventional coinage metal SERS substrates. In this work, functionalized TiO2\ photonic crystals by graphene oxide nanocolloids (nanoGO) are demonstrated as highly sensitive, recyclable, plasmon-free SERS substrates that combine slow-photon amplification effects with the high adsorption capacity and surface reactivity of GO nanosheets. Comparative evaluation of photonic band gap engineered nanoGO{\textendash}TiO2\ inverse opal films was performed on methylene blue SERS detection under different laser excitations in combination with rigorous theoretical simulations of the photonic band structure. A very low detection limit of 6 {\texttimes} 10-7\ M and an enhancement factor of 5 {\texttimes} 104\ along with excellent self-cleaning performance and reusability could be achieved by the interplay of slow-photon effects assisted by interfacial charge transfer between the analyte and the nanoGO{\textendash}TiO2\ semiconducting substrate. Slow-photon management in combination with judicious engineering of chemical enhancement in photonic nanostructures is accordingly proposed as an advanced approach for the design of efficient dielectric SERS substrates.}, author = {D. Papadakis and Diamantopoulou, A. and P.A. Pantazopoulos and D. Palles and E. Sakellis and N. Boukos and N. Stefanou and V. Likodinos} }