Toward Tandem Solar Cells for Water Splitting Using Polymer Electrolytes

Tandem photoelectrochemical cells, formed by two photoelectrodes with complementary light absorption, have been proposed to be a viable approach for obtaining clean hydrogen. This requires the development of new designs that allow for upscaling, which would be favored by the use of transparent polymer electrolyte membranes (PEMs) instead of conventional liquid electrolytes. This article focuses on the photoelectrochemical performance of a water-splitting tandem cell based on a phosphorus-modified α-Fe₂O₃ photoanode and on an iron-modified CuO photocathode, with the employment of an alkaline PEM. Such a photoelectrochemical cell works even in the absence of bias, although significant effort should be directed to the optimization of the photoelectrode/PEM interface. In addition, the results reveal that the employment of polymer electrolytes increases the stability of the device, especially in the case of the photocathode.