Time‐Resolved Spectroscopy and High‐Efficiency Light‐Driven Hydrogen Evolution of a {Mo3S4}‐Containing Polyoxometalate‐Based System

• Published in: Chemistry : a European journal Vol. 27; no. 68; pp. 17094 - 17103
• Main Authors: Smortsova, Yevheniia, Falaise, Clément, Fatima, Anam, Ha‐Thi, Minh‐Huong, Méallet‐Renault, Rachel, Steenkeste, Karine, Al‐Bacha, Serge, Chaib, Tesnim, Assaud, Loïc, Lepeltier, Marc, Haouas, Mohamed, Leclerc, Nathalie, Pino, Thomas, Cadot, Emmanuel
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 06-12-2021; Wiley-VCH Verlag
• Subjects: Catalysts; Chemical Sciences; Chemistry; Cores; Electron transfer; Hydrogen evolution reactions; hydrogen-evolution reaction; Oxidants; Oxidizing agents; photocatalysis; polyoxometalates; Polyoxometallates; Protecting groups; Spectroscopy; thiomolybdates; Triethanolamine; thiomolybdate; HER; spectroscopy; photocalysis; polyoxometalate
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202102693

Polyoxothiometalate ions (ThioPOM) are active hydrogen‐evolution reaction (HER) catalysts based on modular assembly built from electrophilic clusters {MoSx} and vacant polyoxotungstates. Herein, the dumbbell‐like anion [{(PW11O39)Mo3S4(H2O)3(OH)}2]8− exhibits very high light‐driven HER activity, while the active cores {Mo3S4} do not contain any exposed disulfido ligands, which were suspected to be the origin of the HER activity. Moreover, in the catalyst architecture, the two central {Mo3S4} cores are sandwiched by two {PW11O39}7− subunits that act as oxidant‐resistant protecting groups and behave as electron‐collecting units. A detailed photophysical study was carried out confirming the reductive quenching mechanism of the photosensitizer [Ir(ppy)2(dtbbpy)]+ by the sacrificial donor triethanolamine (TEOA) and highlighting the very high rate constant of the electron transfer from the reduced photosensitizer to the ThioPOM catalyst. Such results provide new insights into the field of molecular catalytic systems able to promote high HER activity.
The synergistic effect between a {Mo3S4} catalytic unit and a POM electron‐collecting unit gives rise to highly efficient light‐driven HER photocatalysis. Such behavior is directly correlated to the very high rate constant for electron transfer from the reduced photosensitizer to the ThioPOM catalyst. Furthermore, the high stability of the catalytic system should be related to the protected {Mo3S4} cores within the dumbbell‐like arrangement.