Plasma synthesized molybdenum derived nano-fiber films: The influence of surface composition on their SERS effect

Owing to the direct activation of reactant species, plasma has been playing an important role in surface engineering in recently years, especially for production of nano-materials. Herein, molybdenum derived nano-fiber films have been synthesized via thermal plasma method under the irradiation of dense helium plasma. Surface composition of the nano-fiber films can be controlled by following plasma treatment or chemical reaction to produce molybdenum nitrides or molybdenum oxides while the nanofiber structure is retained. When applied as substrates for the Raman detection of Rhodamine 6G molecule (R6G), the Mo nano-fiber film with amorphous MoOx layer on surface showed strong SERS effect, by pushing the detection limit of R6G from 10−4 M to 10−7 M, while those with MoO3 and Mo2N surface compositions only displayed very weak or none SERS effect. These results indicated that the surface composition of the nano-fiber molybdenum films rather than surface structure plays an important role regarding to their SERS performance.