Structural Analysis of Selenium Coordination Compounds and Mesoporous TiO2-Based Photocatalysts for Hydrogen Generation

This study reports the synthesis of ten coordination compounds (1–10) derived from the ligand bis((3-aminopyridin-2-yl)selanyl)methane (L) and different metal centers (Co^II, Cu^I, Cu^II, Zn^II, and Ag^I). Single crystals of the complexes were obtained via slow diffusion from overlaid solutions of ligand L and the corresponding metal. Their crystalline structures were determined by single-crystal X-ray diffraction (SCXRD) and further characterized using spectroscopic, spectrometric, and voltammetric techniques. Complexes 1–5, 7, and 10 were evaluated as cocatalysts of mesoporous titanium dioxide (m-TiO₂) for photocatalytic hydrogen production via water photolysis under solar light simulation, using triethanolamine (TEOA) as the sacrificial agent. The results showed that complexes 4, 5, 7, and 10 enhanced m-TiO₂ photocatalytic activity, achieving hydrogen evolution rates at least four times higher than standard m-TiO₂ and P25. Among these, the photocatalyst m-TiO₂-7 (7 = [Cu₂(μ-SO₄)₂L₂]) exhibited the highest hydrogen production, reaching approximately 7800 μmol/g over a 6-h experiment–nearly 26 times greater than pure m-TiO₂ (300 μmol/g). These findings highlight the potential of organoselenium metal complexes for the development of novel photocatalytic materials based on nonprecious metals.