Multicarbazole-Based D-π-A Dyes Sensitized Hydrogen Evolution under Visible Light Irradiation.

Donor-π bridge-acceptor (D-π-A) organic dyes, well studied in dye-sensitized solar cells (DSSCs), are found to possess great potential in light-inducing hydrogen evolution due to their distinguished light-harvesting ability and suitable electron energy level. In this work, multicarbazole-based organic dyes (2C, 3C, 4C) were used as photosensitizers of Pt/TiO for photocatalytic hydrogen evolution (PHE) from water under visible light irradiation. 3C-Pt/TiO shows the best photocatalytic activity among the three dye-sensitized photocatalysts, with a hydrogen evolution rate of 24.7 μmol h and a turnover number of 247 h. The activity of 3C-Pt/TiO declines significantly after 3 h irradiation. The deactivation was caused by the partial degradation of the electron acceptor, cyanoacrylate moiety, during the photocatalytic process, which was evidenced by UV-vis, Fourier transform infrared spectra (FT-IR), NMR, and mass spectra. This work is expected to contribute toward the understanding of stability issues of organic dyes and the development of more efficient and steady dyes for hydrogen evolution from water splitting.