Photocatalytic hydrogen evolution through fully conjugated poly(azomethine) networks

Schwab, Matthias Georg; Hamburger, Manuel; Feng, Xinliang; Shu, Jie; Spiess, Hans Wolfgang; Wang, Xinchen; Antonietti, Markus; Müllen, Kläus

doi:10.1039/c0cc04057f

Cited by 247 publications

(171 citation statements)

References 21 publications

(62 reference statements)

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“…The most well-known of these photocatalysts are the inorganic solids [1][2][3]6], mostly oxides but also sulfides and selenides, the former including titanium dioxide [13][14][15], the quintessential photocatalyst. Perhaps less well-known, a range of supramolecular systems [16,17] and even organic polymers [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] have also been reported to act as photocatalysts. In this mini-review we will discuss computational work on modelling such photocatalysts in terms of the relevant material properties and processes, as well as what we believe to be key aspects to consider when performing such calculations.…”

Section: Which States That Photocatalysis Is the 'Change In The Rate mentioning

confidence: 99%

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

Guiglion

Berardo

Butchosa

et al. 2016

J. Phys.: Condens. Matter

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In this mini-review, we discuss what insight computational modelling can provide into the working of photocatalysts for solar fuel synthesis and how calculations can be used to screen for new promising materials for photocatalytic water splitting and carbon dioxide reduction. We will extensively discuss the different relevant (material) properties and the computational approaches (DFT, TD-DFT, GW/BSE) available to model them. We illustrate this with examples from the literature, focussing on polymeric and nanoparticle photocatalysts. We finish with a perspective on the outstanding conceptual and computational challenges.

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Section: Which States That Photocatalysis Is the 'Change In The Rate mentioning

confidence: 99%

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

Guiglion

Berardo

Butchosa

et al. 2016

J. Phys.: Condens. Matter

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“…Recently, nitrogencontaining poly(azomethine) networks and covalent triazinebased frameworks (CTFs) were shown to have photocatalytic activity with the addition of platinum cocatalysts. [18,19] We have shown that a series of conjugated microporous polymers (CMPs) could facilitate hydrogen evolution from water in the presence of a sacrificial electron donor, without any additional heavy metal cocatalyst. [20,21] Other CMPs have since been studied for photocatalysis [22,23] and recent studies have demonstrated that linear conjugated polymers can have high photocatalytic activities.…”

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confidence: 99%

A Solution‐Processable Polymer Photocatalyst for Hydrogen Evolution from Water

Woods

Sprick

Smith

et al. 2017

Advanced Energy Materials

147

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exhibit photocatalytic hydrogen evolution in 2009, [12] and many advances have been made since then. [13,14] After the potential of g-C 3 N 4 was first observed, while focusing on the hydrogen evolution half-reaction, interest has begun to shift to achieving overall water splitting using these materials. [15,16] However, the exact structure of most g-C 3 N 4 materials is unknown and the synthesis usually involves high temperature processing, which offers limited scope for fine-tuning structure and properties. Also, while g-C 3 N 4 can be produced from inexpensive starting materials, the synthetic yield of the material is typically low. [15,17] Of special relevance here, graphitic carbon nitrides are insoluble solids: as for many inorganic catalysts, this can present challenges in terms of processing.Rather few organic photocatalysts have been studied for hydrogen evolution other than g-C 3 N 4 . Recently, nitrogencontaining poly(azomethine) networks and covalent triazinebased frameworks (CTFs) were shown to have photocatalytic activity with the addition of platinum cocatalysts. [18,19] We have shown that a series of conjugated microporous polymers (CMPs) could facilitate hydrogen evolution from water in the presence of a sacrificial electron donor, without any additional heavy metal cocatalyst. [20,21] Other CMPs have since been studied for photocatalysis [22,23] and recent studies have demonstrated that linear conjugated polymers can have high photocatalytic activities. [24,25] However, as with g-C 3 N 4 , none of these organic materials are soluble in common organic solvents. This insolu bility makes it more challenging to process these materials into functional composites. Moreover, photocatalysts are typically kept in suspension by stirring to prevent sedimentation, which results in loss of photocatalytic activity. [26] The loss of activity of insoluble catalysts can be prevented with the use of support substrates, [27] however, using solution processability allows the use of simpler supports and easier development of photoelectrodes.Soluble oligo(phenylene)s have been previously reported as photocatalysts, however, they displayed low activity, were only active under UV light, required a Ru cocatalyst and were only poorly soluble in organic solvents limiting processability. [28] More recently soluble metal-chelating polymers have been prepared although the photocatalytic activity of these polymers also appear to be very low with apparent quantum yields (AQY) below 3 × 10 −4 %. [29] The solubility of some alkylated conjugated polymers has also facilitated the preparation of polymer nanoparticles (PDots). [30,31] The preparation of these PDots enabled significant enhancements in rate over the pristine polymer although scalability and long-term stability of this approach has yet to be shown. Direct photocatalytic water splitting is an attractive strategy for clean energy production, but multicomponent nanostructured systems that mimic natural photosynthesis can be difficult to fabricate because of the insolubil...

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Photocatalytic water oxidation by layered Co/h-BCN hybrids

et al. 2015

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The search for new materials has progressed from metal-based photocatalysts to elemental semiconductors (C, Si, P, S, B) [11][12][13][14][15] and recently to metal-free binary materials and polymers, such as carbon nitride [16], boron carbide [17] and conjugated semiconductors [18][19][20]. These researches indicate that photon absorbing materials can be constituted by using lightweight elements such as carbon, nitrogen, and boron, opening up new opportunities for the selection of innovative and intriguing materials for artificial photosynthesis. It is of particular interest that some of these elements themselves (graphene [21], silicone [22]) or their combinations (h-BN, g-C 3 N 4 ) [23] can form layered structures with reduced thickness comparable to charge-diffusion distance, and thus if a semiconducting electronic structure was imparted in these materials, the fast separation of light-induced charge carrier would significantly benefit surface photoredox process that relied on the excitation and separation of electron-hole pairs and their subsequent participation in surface chemical reactions [24][25][26]. An interesting case of such a layered material is ternary h-BCN with tuneable ba nd gap energies between graphene (zero bandgap) and h-BN (bandgap = 5.6 eV) [27], which have the same atomic structure and share many similar properties. The hybridized phases of the two two-dimensional (2D) materials by atomic mixture of B, N, and C with broad composition ranges to create various layered semiconducting structures would produce new material functions complementary to graphene and h-BN, enabling a wide variety of electronic structures, applications and properties [28][29][30]. Such an emerging family of chemically inert and mechanically strong 2D materials practically allows the bandgap-engineered applications in heterogeneous photocatalysis by creating a medium-gap ternary semiconductor, in which the band gap, redox energy levels, p/n-type properties and surface acid-base chemistry can in principle be modulated by rational design and synthesis [31,32].A hexagonal boron carbon nitride (h-BCN) semiconductor was applied to intercalate cobalt ions to catalyze oxygen evolution reaction (OER) with light illumination, without using noble metals. The h-BCN with high specific surface area showed a strong chemical affinity towards metal ions due to the "lop-sided" densities characteristic of ionic B-N bonding, enabling the creation of metal/h-BCN hybrid layered structures with unique properties. As exemplified here by Co/h-BCN for water oxidation catalysis, after intercalating cobalt ions in the h-BCN host, the photocatalytic activity of the resultant layered hybrid is optimized due to their synergic catalysis that promotes charge separation and lowers reaction barriers. This finding promises a new nobel-metal-free nanocompsite using cost-acceptable and earth-abundant sust ances for photocatalytic OER, and enables the facile design of duel catalytic cascades by merging transition metal catalysis with h-BCN (photo)catalys...

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Photocatalytic hydrogen evolution through fully conjugated poly(azomethine) networks

Cited by 247 publications

References 21 publications

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

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

A Solution‐Processable Polymer Photocatalyst for Hydrogen Evolution from Water

Photocatalytic water oxidation by layered Co/h-BCN hybrids

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