Combining Dithienosilole-Based Organic Dyes with a Brookite/Platinum Photocatalyst toward Enhanced Visible-Light-Driven Hydrogen Production

Abstract

Dye-sensitized photocatalytic hydrogen generation is emerging as a promising process to produce fuels using a clean and abundant energy source such as sunlight. In the first part of this work, three organic dyes featuring a dithieno[3,2-b:2′,3′-d]silole heterocyclic unit (OB1−OB3), bearing different substituents on various parts of the molecular scaffold, were synthesized, characterized, and used as sensitizers for the commercially available benchmark TiO 2 (P25), first in dye-sensitized solar cells and then for the photocatalyzed production of hydrogen with triethanolamine as a sacrificial electron donor. In the second part of the study, aiming to improve the efficiency of the photocatalytic system, P25 was replaced with the less investigated brookite TiO 2 polymorph. The photocatalyst obtained upon sensitization with the best performing dye, OB2, still in the presence of Pt as co-catalyst, displayed an enhanced performance in hydrogen production compared to that based on P25 at a lower dye loading. Extended time experiments confirmed that the catalyst was still significantly active after 1 week under continuous illumination, providing a maximum TON of 4201. The higher efficiency of the brookite-based catalytic system and its prolonged stability are especially significant in the perspective of the practical application of the dye-sensitized photocatalytic H 2 production technology.

Photocatalytic H2 Production from Water by Metal‐free Dye‐sensitized TiO2 Semiconductors: The Role and Development Process of Organic Sensitizers

“…40-42). [44] OB1 has a bare TPA donor and two methyl groups substituted on the Si atom of the dithienosilole unit, while for OB2 the two methyl groups of OB1 are replaced by two n-octyl groups, and OB3 differs from OB2 due to two extra n-hexyloxy groups modified on the 4',4'' positions of TPA donor.…”

“…Imren Hatay Patir's group reported two D-π-A organic dyes MZ-235 and MZ-341 ( Figure 16 and Table 1, No. [43][44], with TPA and its derivative with two hexyloxy groups as donor, Figure 15. A) Structures of dyes OB1-3, B) H 2 production plots of OB1-3@P25, C) H 2 production plots of OB2@P25 and OB2@Brookite, and D) prolonged H 2 production plot of OB2@Brookite.…”

“…[41], a similar but novel dithienosilole (DTS) group was introduced as π‐spacer and three organic dyes featuring a dithieno[3,2‐b:2’,3’‐d]silole heterocyclic unit, OB1–OB3, were synthesized and used to sensitize the less investigated brookite TiO 2 polymorph, while the commercial P25−TiO 2 was used as a reference (Figure 15 and Table 1, No. 40–42) [44] . OB1 has a bare TPA donor and two methyl groups substituted on the Si atom of the dithienosilole unit, while for OB2 the two methyl groups of OB1 are replaced by two n‐octyl groups, and OB3 differs from OB2 due to two extra n‐hexyloxy groups modified on the 4’,4’’ positions of TPA donor.…”

Photocatalysts for H2 Generation from Starburst Triphenylamine/Carbazole Donor‐Based Metal‐Free Dyes and Porous Anatase TiO2 Cube

“…However, most of the reported organic dyes for DSPs suffered from instability, and the corresponding stability studies have rarely been performed for more than 20 h in H 2 evolution experiments. Until now the longest test was performed by Bettucci et al., and the related catalyst remained stable after 170 h . It is known that D –π–A dyes follow an oxidative quenching mechanism, and thus their durability in DSP reactions mainly depends on the stability of dye cations .…”

Arylene Ethynylene-Functionalized Bithiazole-Based Zinc Polymers for Ultraefficient Photocatalytic Activity

“…It also offers to tune the optical properties of the PAE-based ligand, including the catalytic and optical properties of the coordinated metal complexes. 18,19…”