An Integrated Device for the Solar-Driven Electrochemical Conversion of CO2 to CO

The conversion of carbon dioxide into value-added products using sunlight, also called artificial photosynthesis, represents a remarkable and sustainable approach to store solar energy, transforming it into chemical energy. There are mainly two strategies to carry out this process: the photocatalytic reduction of carbon dioxide (CO2) or the photovoltaic-powered electrochemical reduction of CO2. Herein, we focus on the latter route, i.e., the development of a device coupling a solar cell to an electrochemical reactor for CO2 reduction. Different literature works demonstrated the possibility to achieve such a coupling, but no evidence of a real integration between the two systems has been given up to now. In this work, we present an integrated device constituted by a dye-sensitized solar module (based on a mesoporous titanium dioxide photoanode) and an electrochemical cell (based on a coppertin cathode). The integration of the two systems is accomplished through a common platinum-based electrode, which acts either as a cathode for the photovoltaic module and as an anode for the electrochemical reactor. The integrated system was characterized by a stable current of 3.6 mA under continuous solar irradiation, enabling the production of 80 mmol of carbon monoxide per day, with a solar-to-fuel efficiency equal to 0.97%.