Developing a full cycled silicon cathode-zinc electrolyte based solar cell using copper recovery electrodes

This work presents an effective and low cost method to develop a fully cycled photo electrochemical solar cell by incorporating a copper auxiliary electrode. The continued function of the previously demonstrated photo-electrochemical solar cells consisting of silicon and zinc electrodes, relies on the existence of a zinc source. Therefore, consumption of the zinc anode and transfer of metallic zinc to the silicon electrode surface is the most critical factor limiting the lifetime of such cells [1]. This work demonstrates how this limitation could be bypassed by recovering the zinc particles falling off the silicon electrode on the bottom of the reaction container. The zinc particles initially deposited on the silicon photocathode as a result of photo electrochemical reduction, eventually flake off the surface due to their porosity and poor adhesion to the surface. In this work, a pathway has been introduced using a copper auxiliary electrode to recycle and reengage the recovered zinc particles accumulated on the bottom of the cell in the redox cycle. The experiment results confirm the viability of the proposed approach. Recycling of 30% of the consumed zinc has been confirmed by the generated electric current after 350 hours of cell operation. This fully cycled photocell, along with the previously presented long term stability of the p-type silicon photocathode could fulfill the 10,000 hour lifetime requirement established by the United State Department of Energy without any fortifying surface modification.