TIO2-TI SEMICONDUCTOR SEPTUM BASED ELECTROCHEMICAL PHOTOVOLTAIC CELL

Described arc the fabrication and structural and photoclectrochemical characterization of a semiconductor-septum based photoclectrochemical (SC-SEP, PEC) solar cell, with a TiO2-Ti septum electrode connecting the illuminated and dark compartments, containing different redox electrolytes. The output power characteristics (V(oc) and I(sc)) of the SC-SEP PEC cell having various redox couples such as Sn4+/Sn2+, Cu2+/Cu+, Cu2+/Cu, Fe(CN)63-/Fe(CN)64-, Cu+/Cu, I-/I2, Fe3+/Fe2+, Ag+, Ag/Pt, Pd2+/Pd, and Pt2+/Pt in the dark compartment have been studied. When rodox couples of higher E(redox) potential are added into the dark compartment, keeping ingredients of the illuminated compartment unchanged, there is an increase in the photovoltage of the SC-SEP PEC cell. For example, a conventional Pt, 1 M NaOH parallel-to TiO2-Ti PEC cell yields V(oc) and I(sc) of 0.7 V and 5 mA cm-2, whereas Pt, 1 M NaOH parallel-to TiO2-Ti parallel-to 0.1 M AgNO3, Pt SC-SEP cell yields reproducible V(oc) and I(sc) values of 1.2 V and 15 mA cm-2. When an external bias of +0.2 V vs SCE is applied to this SC-SEP cell, the V(oc) and I(sc) values of this cell have been found to increase to 1.9 V and 9 mA cm-2 . The short-circuit photocurrent characteristics of this SC-SEP cell monitored for a long time revealed that the cell is quite stable. The structural and compositional analysis of septum electrode carried out through X-ray diffractometry, scanning electron microscopy, and EDAX confirmed that the TiO2-Ti electrode shows a negligible change in its gross and surface structure with no discernible change in its elemental composition, even after prolonged operation.