SECM study of hydrogen photogeneration in a 1,2-dichloroethane | water biphasic system with decamethylruthenocene electron donor regeneration

This paper reports light driven hydrogen evolution reaction (HER) at 1,2-dichloroethane | water (DCE | W) interface using photoexcited decamethylruthenocene (DMRc) as electron donor. DMRc is in situ regenerated by electroreduction of its oxidized form (DMRc+) formed during HER as a by-product. This enables continuous HER using small amount of DMRc. Proton transfer from the acidic aqueous phase to the DCE phase is ensured by negative chemical polarization of the liquid | liquid interface. The reduction of protons in DCE occurs only after excitation of DMRc by light. Voltammetry performed with the organic droplet-modified glassy carbon electrode immersed in the aqueous electrolyte solution of various anions, indicated that oxidation of DMRc is followed by an anion insertion from water into the organic phase. We demonstrate that DMRc can be electrochemically regenerated at the microelectrode positioned close to the interface between two immiscible electrolyte solutions (ITIES) by the scanning electrochemical microscopy. Regeneration of the electron donor allows further development of biphasic system towards continuous hydrogen generation platform.