A noble-metal-free photocatalytic hydrogen production system based on cobalt(iii) complex and eosin Y-sensitized TiO2

Abstract

Although dye-sensitized TiO₂ for photocatalytic H₂ production have been investigated for more than 20 years, research on using low-cost transition metal complexes as catalysts for proton reduction on TiO₂ is still relatively rare. In this paper, three cobalt complexes (CoL1–CoL3) were prepared and used as hydrogen evolution catalysts, and a noble-metal-free H₂-evolving system was fabricated by using an organic dye, eosin Y (EY), as photosensitizer and triethylamine (TEA) as sacrificial agent. Under visible light irradiation, a turnover number of 90 (based on CoL2) was obtained for 2 wt% CoL2/TiO₂ within 6 h in aqueous solution under the optimal conditions of 4 μmol EY, 5% TEA (v/v) and pH 11. In addition, much higher hydrogen production efficiency and stability were achieved for the heterogeneous system, in comparison with the homogeneous one.