Control of Electrons’ Spin Eliminates Hydrogen Peroxide Formation During Water Splitting

The production of hydrogen through water splitting in a photoelectrochemical cell suffers from an overpotential that limits the efficiencies.In addition, hydrogen-peroxide formation is identified as a competing process affecting the oxidative stability of photoelectrodes.We impose spin-selectivity by coating the anode with chiral organic semiconductors from helically aggregated dyes as sensitizers; Znporphyrins and triarylamines.Hydrogen peroxide formation is dramatically suppressed, while the overall current through the cell, correlating with the water splitting process, is enhanced.Evidence for a strong spin-selection in the chiral semiconductors is presented by magnetic conducting (mc-)AFM measurements, in which chiral and achiral Zn-porphyrins are compared.These findings contribute to our understanding of the underlying mechanism of spin selectivity in multiple electron-transfer reactions and pave the way toward better chiral dye-sensitized photoelectrochemical cells.