Formation of porphyrin adlayer on glassy carbon electrode surface from ionic liquid media

• 5,10,15,20-Tetra(4-pyridyl)porphyrin concentrations influence the adlayer formation kinetics. • The overlap of the capacitance curves after 3 days suggests that the electrode surface becomes uniformly covered by porphyrin molecules. • The system reaches a stationary/stable state much faster than the neat EMImBF 4 system. The interface between the glassy carbon (GC) electrode and an electrolyte (mixture of ionic liquid (IL) 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4 ) and 5,10,15,20-Tetra(4-pyridyl)porphyrin (TPyP)) was electrochemically characterised by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. TPyP concentrations affect adlayer formation kinetics; however, the overlap of series capacitance curves after 3 days suggests that the electrode surface becomes covered with porphyrin molecules, regardless of the initial concentration. Further analysis reveals that the system reaches a stationary/stable state much faster than in the neat EMImBF 4 system, for which equilibrium has been reported to require up to 14 days.