Photocatalysts Based on Cobalt-Chelating Conjugated Polymers for Hydrogen Evolution from Water

Abstract

Developing photocatalytic systems for water splitting to generate oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this work, we report the first example of heterogeneous photocatalysts for hydrogen evolution based on in-chain cobalt-chelating conjugated polymers. Two conjugated polymers chelated with earth-abundant cobalt ions were synthesized and found to evolve hydrogen photocatalytically from water. These polymers are designed to combine functions of the conjugated backbone as a light-harvesting antenna and electron-transfer conduit with the in-chain bipyridyl-chelated transition metal centers as catalytic active sites. In addition, these polymers are soluble in organic solvents, enabling effective interactions with the substrates as well as detailed characterization. We also found a polymer-dependent optimal cobalt chelating concentration at which the highest photocatalytic hydrogen production (PHP) activity can be achieved.

Current understanding and challenges of solar-driven hydrogen generation using polymeric photocatalysts

“…Another photocatalytically active linear co-polymer (B-BT-1,4) 78 featured alternating electron-donor-acceptor units in the form of phenyl and 2,1,3-benzothiadiazole units. Cobalt-chelating PPDI-bpy (perylenediimide-bipyridine) and PPDT-bpy (benzo [1,2-b:4,5b]dithiophene-bipyridine) co-polymers were developed, combining a light-harvesting polymeric backbone with molecular catalytic active sites (bpy-metal complex) 79 .…”

Narrow‐Bandgap Chalcogenoviologens for Electrochromism and Visible‐Light‐Driven Hydrogen Evolution

“…This may lead to capture of more photon flux from the solar spectrum to further improve hydrogen evolution efficiency in 5 b . Thus, the subtle electron properties, the faster formation of radical species and electron‐transfer rates led to higher AQY and increased hydrogen generation of Se‐BnV 2+ ( 5 b ) than Te‐BnV 2+ ( 5 c ). The hydrogen generation of 5 b exhibited decent cycle stability due to the simplified catalytic process (Figure S27).…”

Trends and challenges for microporous polymers

“…Indeed, several linear or planarized, thus noncrosslinked and non-porous conjugated polymers have been recently shown to exhibit comparable or even better photocatalytic activities than their microporous network counterparts. 151,156,157 It is thus slightly surprising that so far no single paper on gas phase photocatalysis, e.g. CO 2 reduction has appeared as CMPs seem to be ideal candidates for such reactions.…”