Novel organically linked ZnII hydrogenselenite coordination polymers: synthesis, characterization, and efficient TiO2 photosensitization for enhanced photocatalytic hydrogen production

Abstract

This study focused on the solvothermal synthesis, characterization, and photocatalytic activities of two novel coordination polymers, namely [Zn(μ-HSeO₃)₂(bipy)]_n (1) and [Zn(μ-HSeO₃)₂(phen)]_n (2). These compounds represent the first organically linked Zn^II hydrogenselenite coordination polymers. The synthesis of compounds 1 and 2 involved the addition of 2,2′-bipyridine and 1,10-phenanthroline, respectively, to SeO₂ and ZnO in methanol as the solvent. The novel hydrogenselenite compounds were thoroughly characterized using spectroscopic and crystallographic methods. The photocatalytic solids (TiO₂-1A and TiO₂-2A) were prepared by immobilizing compounds 1–2 onto TiO₂ through the sol–gel approach. These photocatalysts were then evaluated for hydrogen evolution via water splitting using a 300 W Hg/Xe lamp as the irradiation source. Among the newly synthesized photocatalytic materials, TiO₂-1A demonstrated auspicious photocatalytic performance for hydrogen gas production. Its catalytic activity overcame the observed for the pure solid support TiO₂ and Degussa P25 (commercial titania), making compound 1 a particularly attractive TiO₂ photosensitizer. Additionally, TiO₂-1A exhibited superior photocatalytic activity compared to TiO₂-2A. The latter performed better than freshly prepared TiO₂, approaching that of Degussa P25. These findings highlight the potential of compound 1 as an effective photosensitizer for TiO₂-based photocatalysis, making it a promising candidate for applications in clean energy generation, specifically in hydrogen production by water splitting.