Study on deactivation and reaction mechanism of Co thiolate complexes in photocatalytic hydrogen production system

Abstract

Hydrogen is an environment-friendly source with high efficiency, which is also an important alternative to traditional energy sources. In this paper, noble-metal-free photocatalyst Co thiolate complexes Co(bpy)(pyS)2 (M1) and Co(phen)(pyS)2 (M2) were synthesized and used in photocatalytic decomposition of water to generate hydrogen. The deactivation and reaction mechanism of Co thiolate complexes in photocatalytic hydrogen generation system were studied. The results of photocatalytic hydrogen generation with regeneration of system by re-addition of catalyst and fluorescein exhibited that the main reasons for the deactivation of system were probably the deactivation of catalyst and small part of decomposition of photosensitizer. The results of UV-vis spectra of the system after irradiation revealed that the electron transfer mode between fluorescein, catalyst, and triethylamine was favorable for the stability and life of fluorescein. Furthermore, the electron transfer rates from fluorescein to M1 and M2 were 2.1 × 1012M−1 S−1 and 1.5 × 1012M−1 S−1. This investigation may lay the theories foundation for further research on hydrogen evolution of noble-metal-free catalysts and also may provide a novel approach for building a feasible and more environmental-friendly photocatalytic hydrogen production system.