The production of solar fuels, and first of all hydrogen, is an identified objective of the ecological transition. Photoelectrochemical processes offer a solution to produce green hydrogen from water and solar energy in a decentralized way, but their performance and cost still limit the exploitation of these systems on a large scale.

In collaboration with researchers at the Hanoi University of Science and Technology (Vietnam), IRIG researchers have developed an artificial sheet based on a photovoltaic core (triple junction silicon cell) by developing a photochemical process for the one-step deposition from a single precursor of the two catalysts that perform the release of hydrogen and the oxidation of water on each side of the artificial leaf. When immersed in a neutral salty medium, the monolithic device converts solar energy into hydrogen with a yield of 2%.

The optimization of these performances now requires a better understanding of the phenomena limiting the conversion steps and the measurement of The optimization of these performances now requires a better understanding of the phenomena limiting the conversion steps and, namely, the determination of the catalysis metrics on each side of the artificial leaf. The researchers at IRIG have thus instrumented the cell in a way that allows the independent measurement of the electrochemical potential of each of the catalysts, the current flowing through the cell and to quantify hydrogen production. Such an operando characterization highlighted the impact of the defects of the protective layers of the triple junction core cell and allowed to propose ways for the optimization of the device.