Influence of Meso-Substitution of the Porphyrin Ring on Enhanced Hydrogen Evolution in a Photochemical System

This study establishes the relationships between the structure of a series of meso-substituted tin(IV) porphyrins and their efficiency as photosensitizers for hydrogen generation in the Sn(IV)P/Pt–TiO2 nanocomposite system. The electrochemical properties of a series of SnPs, the catalytic performance of Pt nanomodifications, and the morphology of the Pt/TiO2 nanocomposites were characterized by electrochemical and electron microscopy methods. The dependence of photocatalytic performance on the structure for a series of Sn(IV) meso-substituted phenyl porphyrins was studied, and possible mechanisms are discussed employing the results of the electrochemical studies. It was found that the time course and type of the photochemically reduced species of Sn(IV)Ps, which are essential intermediates, are important factors and depend on the electronegativity of the metal center, the character of meso-substituents of the porphyrin ring, and pH and are correlated with the redox potential sequence of the respective Sn(...