Tunable Organic Photocatalysts for Visible-Light-Driven Hydrogen Evolution

Abstract

Photocatalytic hydrogen production from water offers an abundant, clean fuel source, but it is challenging to produce photocatalysts that use the solar spectrum effectively. Many hydrogen-evolving photocatalysts are active in the ultraviolet range, but ultraviolet light accounts for only 3% of the energy available in the solar spectrum at ground level. Solid-state crystalline photocatalysts have light absorption profiles that are a discrete function of their crystalline phase and that are not always tunable. Here, we prepare a series of amorphous, microporous organic polymers with exquisite synthetic control over the optical gap in the range 1.94-2.95 eV. Specific monomer compositions give polymers that are robust and effective photocatalysts for the evolution of hydrogen from water in the presence of a sacrificial electron donor, without the apparent need for an added metal cocatalyst. Remarkably, unlike other organic systems, the best performing polymer is only photoactive under visible rather than ultraviolet irradiation.

Modelling materials for solar fuel synthesis by artificial photosynthesis; predicting the optical, electronic and redox properties of photocatalysts

“…Vertical potentials, based on approach I or II, are routinely reported in the literature [33,[89][90][91][92][93][94][95][96][97][98][99]. See the work of Stevanovic et al [89] for a nice illustration for the case of GW vertical potentials for the surfaces of typical crystalline photocatalysts, which also clearly illustrates that potentials are surface rather than bulk properties (see figure 3).…”

Dendritic Tip-on Polytriazine-Based Carbon Nitride Photocatalyst with High Hydrogen Evolution Activity

“…[1][2][3][4][5][6][7][8][9][10][11][12] Polymeric carbon nitride (CN), initially reported by Berzelius and Liebig in 1834, has been found to be a stable organic photocatalyst for the photoredox splitting of water (half-reactions with suitable sacrificial reagents). 13,14 The basic sub-unit would be either triazine or heptazine or even both interconnected through NH-bridges, resulting from the polycondensation of precursors such as dicyandiamide, cyanuric acid, melamine, and urea, with continuous elimination of NH 3 .…”

An Electron‐Poor C64 Nanographene by Palladium‐Catalyzed Cascade C−C Bond Formation: One‐Pot Synthesis and Single‐Crystal Structure Analysis

“…To increase the driving force for the intramolecular ring‐closure reaction, we changed our strategy and introduced an additional halogen atom next to the reaction center for Suzuki–Miyaura cross‐coupling, anticipating a subsequent facile dehydrohalogenation reaction similar to literature‐known procedures for pyrenes and other polyarenes 18. Accordingly, we repeated our initial Suzuki–Miyaura cross‐coupling reaction, but this time using tetraboronated pyrene 5 19 and dibrominated naphthalimide 6 20 as the coupling components (Scheme 1, bottom). To our surprise, under the standard reaction conditions as applied before, we observed the direct formation of the fully conjugated compound 1 by C−C cross‐coupling (highlighted in red), intramolecular dehydrohalogenation (highlighted in orange), and, more intriguingly, additional C−C bond formation between adjacent naphthalimide moieties formally by oxidative dehydrogenation (highlighted in green).…”