Large-area photoelectrochemical water splitting using a multi-photoelectrode approach

Abstract

In the field of photoelectrochemical hydrogen generation, constructing an efficient and stable upscaled device remains a major challenge. One of the main limitations to achieve this goal is the difficulty in preparing efficient large-area nanostructured photoelectrodes. This work reports a segmented support for holding up to eight photoelectrodes connected in parallel, with an active area of 3.2 cm(2) each, and tested in the CooIPEC cell. CFD results show that the use of internal separators between electrodes is needed to avoid parasitic ionic paths and additional overpotential losses. Inside the cell, an optimized electrolyte flow path is guaranteed through the internal separators; each internal plate is strategically perforated to assure flow circulation, preventing the accumulation of evolved gases. J-V measurements performed in 2- and 3-electrode configurations show that when eight hematite photoelectrodes are operated in parallel neither the photocurrent density nor the photovoltage are affected; without the internal separators a current loss of ca. 15% is observed. This work also demonstrates that the negative effect of an underperforming photoelectrode in the overall performance of the cell decreases exponentially with the number of photoelectrodes connected in parallel.