The textbook "Cu-based oxide photocathodes for photoelectrochemical water splitting" by Adriana Paracchino offers a comprehensive analysis of the development of cost-effective and environmentally friendly solutions for hydrogen production through photoelectrochemical water splitting. It explains how chemical energy can be stored in the form of hydrogen and converted into electrical energy. The process of photoelectrochemical water splitting utilizes solar-absorbing semiconductor materials to generate the necessary photovoltage that splits water into hydrogen and oxygen. The dissertation focuses on the use of cost-effective copper oxide semiconductors with p-type conductivity, which are ideally suited for application as photocathodes. By using atomic deposition of water-stable oxide layers on copper oxide, a record efficiency has been achieved, highlighting the significance of this research for the future hydrogen economy.