Département de chimie moléculaire

Visible light-driven water splitting performed within a photoelectrochemical cell (PEC) is one of the most investigated processes to produce hydrogen in a sustainable manner. Developing a photoanode for the water oxidation reaction (oxygen evolving reaction{,} OER) is considered more challenging than designing a photocathode for the water reduction reaction (hydrogen evolving reaction{,} HER) because the OER requires a higher overpotential and displays a higher activation barrier. Since the work of Fujishima and Honda in 1972{,} intense research has been devoted to the development of photoelectrodes solely based on inorganic semiconductor materials. Nevertheless{,} the large majority of photoanodes using inorganic semiconductors weakly absorb in the visible spectrum and present poor long-term stability. An alternative design{,} more recently explored{,} is to decouple the light absorption and the catalytic function by adsorbing a molecular photosensitizer on an n-type semiconducting electrode (generally TiO2){,} to promote visible light absorption{,} and an oxygen-evolving catalyst to promote the OER. Herein{,} we provide a comprehensive review of such hybrid photoanodes that associate with a molecular photosensitizer and an oxygen-evolving catalyst based on metal oxide nanoparticles. For these hybrid photoanodes{,} tris(bipyridine) ruthenium complexes and organic dyes such as perylenes{,} free-base porphyrins{,} polyheptazine and π-conjugated naphthalene benzimidazole polymers have been employed as molecular photosensitizers in combination with IrOx or CoOx OER catalysts. The preparation of these photoanodes{,} the evaluation of their photocatalytic performance for the OER{,} and the key factors that govern their efficiency and stability are highlighted.