Conjugated Polymers: Catalysts for Photocatalytic Hydrogen Evolution

Abstract

Conjugated polymers, comprising fully π-conjugated systems, present a new generation of heterogeneous photocatalysts for solar-energy utilization. They have three key features, namely robustness, nontoxicity, and visible-light activity, for photocatalytic processes, thus making them appealing candidates for scale-up. Presented in this Minireview, is a brief summary on the recent development of various promising polymer photocatalysts for hydrogen evolution from aqueous solutions, including linear polymers, planarized polymers, triazine/heptazine polymers, and other related organic conjugated semiconductors, with a particular focus on the rational manipulation in the composition, architectures, and optical and electronic properties that are relevant to photophysical and photochemical properties. Some future trends and prospects for organic conjugated photocatalysts in artificial photosynthesis, by water splitting, are also envisaged.

Efficient visible light-driven water oxidation and proton reduction by an ordered covalent triazine-based framework

“…To the best of our knowledge, the photocatalytic activity of CTF-1-100W shows much superior quantum efficiency for water oxidation to any reported carbon based or carbon-nitride based polymer photocatalyst, according to the recently published reviews. 21,56 As shown in Table S1 (ESI †), the new polymer photocatalyst synthesised by our approach almost presents both the highest H 2 and O 2 evolution rates under visible light irradiation, 22,45,[57][58][59][60][61][62] which is attributed to the well-controlled crystallisation by tuning the microwave power and the avoidance of carbonisation.…”

Trends and challenges for microporous polymers

“…79 First, the research on metal-free photocatalysts for water splitting has gained momentum with the discovery in 2009 that polymeric carbon nitride can act as a photocatalyst for hydrogen and oxygen generation from water. 135 In the following years more than one thousand papers have appeared on the usage of polymeric carbon nitride for photocatalytic applications.…”

“…77,78 Furthermore, conjugated microporous polymers have come into focus of catalysis research, especially for photocatalysis. 79 This point will also be discussed in more detail later. Excellent and comprehensive reviews on the use of microporous polymers for catalytic applications were recently published by Rose 40 and Zhang and Ying.…”

Electron donor-free photoredox catalysis via an electron transfer cascade by cooperative organic photocatalysts

“…Organic semiconductor (OS)-containing photocatalysts have emerged as a promising alternative to traditional metalcontaining photocatalysts due to their highly tunable electronical properties via flexible structural design. Recent research activities have demonstrated a vast number of structural design methods of small molecular 8,10,[16][17][18][19][20] or macromolecular [21][22][23][24][25][26][27][28][29][30] OS systems as efficient photocatalysts for visible light-promoted photoredox reactions. Nevertheless, most developed OS photocatalysts, similar to traditional transition metal complexes, [31][32][33][34][35][36][37][38] are single photocatalytic systems.…”