In space missions, in which materials can be scarce, CO2 appears as a valuable resource to yield chemicals and fuels. This technological approach is of particular interest in future missions to Mars, where CO2 is 95 % of the atmosphere composition. The aim of the idea is to make signs of progress for a photoelectrochemical (PEC) system, related to reactor design, process control, and developing innovative photoelectrodes with high-efficiency catalytic materials processed by magnetron sputtering, an industrial-scalable technology. The catalyst is a fundamental component of a PEC cell because is responsible for the selectivity and catalytic activity of the photoelectrodes and being decisive for efficiency. Also, the synthetic method is a crucial point because it affects the properties and structure of the catalyst, and magnetron sputtering allows the manufacturing nanostructures with accurate morphology, size, and composition maximizing the catalytic activity and the efficiency of the systems. Catalysts for the photoelectrodes, using semiconductors with nanostructured, plasmonic metals like Cu, Au, or Pt as a co-catalyst will be developed. Furthermore, it would be interesting to couple sewage treatment to the production of value-added materials from CO2, which would compensate for any lack of cell efficiency and it might allow saving room as a single device can deal with two tasks. A compact prototype two-chamber cell will be manufactured with two different compartments for the two reactions separated by a proton exchange membrane. The project goal is to provide an improved PEC system for CO2 reduction and connect it with sewage treatment. In this sense, the oxidation in a PEC cell of the organic content (including pathogens) of the sewage would allow detoxify the water and make it also reusable for other purposes. The subtracted electrons from this process would reduce CO2 in the cathode producing fuels by direct conversion using solar light as energy source.
