I made working electrode of bare TiO2 film, carbon quantum dots (CQD) coated TiO2 film, N3 dye loaded TiO2 film, and CQD+N3 dye coated TiO2 film. FTO glass (7 ohm/sq) was used as substrate. Pt coated FTO was used as counter electrode, and Ag/AgCl was used as reference electrode. Cyclic voltammetry test was done using Acetonitrile solution containing 0.01 M of iodolyte Z-50 elecytolyte. The individual curves are attached in the origin file. How can I estimate the Onset Redox potential of the following curve, so that I can calculate the HOMO and LUMO level of the individual sample? I really appreciate your kind suggestions.