Cyclic Voltammetry Measurements of the Photoelectrogenic Reactions of Thylakoid Membranes

In this paper, the technique of cyclic voltammetry has been used in a photoelectrochemical cell in order to follow the redox species formed in solution by the photo‐induced electron transfer between the thylakoids and various acceptors and donors. The photoelectrochemical behavior of artificial electron acceptors (such as 2,5‐dichlorobenzoquinone and methylviologen) and donors (such as sym‐diphenylcarbazide and durohydroquinone) specific for either Photosystem I or Photosystem II has been investigated. The influence of inhibiting agents (such as 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea and Tris) on the cell photoresponse has also been characterized, together with the capability of donors to restore the photocurrent. Evidence for H2O2 formation by way of a Mehler‐type reaction has been provided and an electrochemical model of its coupled photochemical and electrochemical reactions in solution is reported.