Electrocatalytic technology is one of several methods currently used to achieve water splitting. It mainly relies on rare metal (e.g. platinum, ruthenium) oxide catalysts, limiting large-scale applications owing to their cost/scarcity. The need for new materials with higher performance is the framework where HEPHOTO project takes place. This project is part of the joint laboratory between the Luxembourg Institute of Science and Technology (LIST) and 3D-Oxides. It will be set up at the Material Research and Technology (MRT) department. The development of cation doped NaTaO3 by Chemical Beam Vapour Deposition (CBVD) will contribute to answering to this requirement. The challenge is to provide a photocatalyst with tuneable properties and reduced bandgap which could be efficient under the whole solar spectrum. The success of the project would help to widen the use of hydrogen as a source of clean energy.