Polyoxothiometalate-Derivatized Silicon Photocathodes for Sunlight-Driven Hydrogen Evolution Reaction

Dong Fu (1) , Bruno Fabre (1) , Gabriel Loget (2) , Cristelle Mériadec (2) , Soraya Ababou-Girard (2) , Emmanuel Cadot (3) , Nathalie Leclerc-Laronze (3) , Jérôme Marrot (3) , Quentin de Ponfilly (3)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 IPR - Institut de Physique de Rennes
3 ILV - Institut Lavoisier de Versailles

Silicon photocathodes coated with drop-casted {Mo3S4}-based polyoxothiometalate assemblies are demonstrated to be effective for sunlight-driven hydrogen evolution reaction (HER) in acid conditions. These photocathodes are catalytically more efficient than that coated with the parent thiomolybdate incorporating an organic ligand, as supported by a higher onset potential and a lower overvoltage at 10 mA cm(-2). At pH 7.3, the trend is inversed and the beneficial effect of the polyoxometalate for the HER is not observed. Moreover, the polyoxothiometalate-modified photocathode is found to be also more stable under acid conditions and can be operated at the light-limited catalytic current for more than 40 h. Furthermore, X-ray photoelectron spectroscopy and atomic force microscopy measurements indicate that the cathodic polarization of both photocathodes leads to the release of a large amount of the deposited material into the electrolyte solution concomitantly with the formation of mixed valence species {Mo(IV)(3-x)Mo(III)(x)O4-nSn}((4-x)+) resulting from the replacement of S2- sulfido ligands in the cluster by oxo O2- groups; these combined effects are shown to be beneficial for the photoelectrocatalysis.

Domaines: Physique [physics]

Dong Fu, Bruno Fabre, Gabriel Loget, Cristelle Mériadec, Soraya Ababou-Girard, et al.. Polyoxothiometalate-Derivatized Silicon Photocathodes for Sunlight-Driven Hydrogen Evolution Reaction. ACS Omega, 2018, 3 (10), pp.13837-13849. ⟨10.1021/acsomega.8b01734⟩. ⟨hal-01935236⟩