Water Oxidation by Ru-Polyoxometalate Catalysts: Overpotential Dependency on the Number and Charge of the Metal Centers

Inorganics

Simone Piccinin¹  Stefano Fabris²  Greta Ricarda Patzke² 

[1] CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, c/o SISSA, Via Bonomea 265, Trieste 34136, Italy; E-Mail

关键词: water oxidation;    DFT;    polyoxometalates;    electrochemistry;   

DOI  :  10.3390/inorganics3030374

来源: mdpi

【 摘 要 】

Water oxidation is efficiently catalyzed by several Ru-based polyoxometalate (POM) molecular catalysts differing in the number, local atomistic environment and oxidation state of the Ru sites. We employ density functional theory calculations to rationalize the dependency of the reaction overpotential on the main structural and electronic molecular properties. In particular, we compare the thermodynamics of the water oxidation cycle for single-site Ru-POM and multiple-site Ru-POM complexes. For the Ru-POM case, we also investigate the reaction free energy as a function of the Ru oxidation state. We find that the overpotential of these molecular catalysts is primarily determined by the oxidation state of the metal center and is minimum for Ru(IV). In solution, the number of active sites is shown to play a minor role on the reaction energetics. The results are rationalized and discussed in terms of the local structure around the active sites and of the electrostatic screening due to the molecular structure or the solvent.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.