Ti–O coupled graphene edges induced high electrochemical activity of the carbon film

In this work, we investigated the electrochemical activity induced by the Ti–O coupled graphene edges on the graphene structured carbon (GSC) film. The Ti-O-GSC film was prepared by the electron cyclotron resonance (ECR) plasma sputtering system under low energy electron irradiation with O and Ti atoms doped in one step. According to the nanostructure characterization, the graphene edges and groups with O and Ti were formed on the surface of film. In the Fe(CN)₆^4−/3− and Fe^3+/2+ redox systems, the redox peak separation was reduced to 69.6 m V and 611.5 m V, respectively, and the charge-transfer resistance decreased from 507.50 Ω·cm² to 15.88 Ω·cm², due to the doping of O and Ti. In the sensing of the DNA bases, the Ti-O-GSC film reduced the oxidation potentials to 138 mV and 755.2 mV for adenine and guanine, and realized the simultaneous detection of adenine and guanine with detection limits of 1.09 μM and 0.76 μM. The mechanism could be that the simultaneous presence of Ti and O atoms at the graphene edge facilitates numerous active sites, improving the electrochemical activity of the Ti-O-GSC film. These results indicate that the Ti-O-GSC films are promising electrode materials to construct sensitive electrochemical biosensors.