Electrochemistry and photoelectrochemistry of sodium 9,10-anthraquinone-2,6-disulfonate in aqueous media: Application to rechargeable solar cells and to the synthesis of hydrogen peroxide

Abstract

A single redox couple, sodium, 9,10-anthraquinone-2,6-disulfonate/sodium 9,10-anthrahydroquinone-2,6-disulfonate (AQ/AQH 2) is used to illustrate various aspects of photoelectrochemical cells: regenerative photocells with p-type Si and p-type WSe 2 photocathodes and synthetic photocells. In each case, the whole cell reaction is described. Furthermore, the data establish that p-type Si and p-type WSe 2 are suitable to sustain the uphill generation of AQH 2. They also establish that the negative photopotentials produced by illumination of n-WSe 2/I −, I 3/ − and n-MoS 2/I −, I 3/ − systems are sufficient to reduce efficiently AQ into AQH 2 at a dark vitreous carbon (C) cathode. An evaluation of various rechargeable solar cells based on the preceding layer-type materials and I −/I 3/ − and AQ/AQH 2 redox couples is presented. The efficiencies of conversion of 632.8 nm light, are in the range of 2% for p-type Si electrode and 10% for layer-type materials, in agreement with literature results. AQ has also been shown to drive the overall process: 2HI+O 2→H 2O 2+I 2 The reduction of O 2 into H 2O 2 could then be photoelectrochemically effected very close to its thermodynamic potential.