The scope of this work is the finding of important information on copper (I) oxide and its use in the development of Cu-Sn-based photo-electrochemical catalysts for the valorization of carbon dioxide. Initially, the activities are focused on a bibliographic research on the most active crystalline phase of Cu2O for the photoelectrochemical CO2 reduction and its synthesis. From literature, it appears that the rhombic dodecahedral Cu2O is the most photoactive form, while the cubic is the least photoactive. Subsequently, the attention was turned to the synthesis, characterization and testing of Cu2O-SnO2 catalysts prepared by two synthesis methods: co-precipitation and precipitation-impregnation two-steps strategy.