Carbon-catalyzed dye-sensitization for solar hydrogen production

The catalytic effects of four different carbon materials (graphite, multi-walled carbon nanotubes, carbon fibers, and activated carbon) on dye-sensitized solar hydrogen production were investigated under a simulated solar light (AM 1.5G, 100 mW/cm(2)). Eosin-Y (EY) and triethanolamine (TEOA) were employed as a sensitizer and electron donor, respectively. All the tested carbon materials enhanced the sensitized H-2 production, while multi-walled carbon nanotubes (CNT) exhibited the highest catalytic activity with 9- and 4-fold enhanced H-2 production and photocurrent generation, respectively. This suggests that CNT is highly effective in catalyzing charge injection and thus sensitized H-2 production. With Pt loading onto the carbon materials, the H-2 production was further improved by a maximum of 10 times. With the bare carbon materials, EY underwent simultaneous spectral shifts and decreases in absorbance presumably due to stepwise de-bromination and cleavage of chromophoric groups. With CNT/Pt, however, only the former was observed despite far higher H-2 production. This indicates that the regeneration of EY is significantly enhanced with CNT/Pt. A detailed comparison of carbon materials and the sensitized mechanism was discussed. (C) 2013 Elsevier B.V. All rights reserved.