Tri‐<i>s</i>‐triazine‐Based Crystalline Carbon Nitride Nanosheets for an Improved Hydrogen Evolution

Ou, Honghui; Lin, Lihua; Zheng, Yun; Yang, Pengju; Fang, Yuanxing; Wang, Xinchen

doi:10.1002/adma.201700008

Cited by 591 publications

(309 citation statements)

References 49 publications

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“…8b presents that CTF-1-100W shows much weaker charge recombination than the reference material g-C 3 N 4 , indicating a much better charge separation on CTF-1-100W than bulk g-C 3 N 4 under irradiation. 9,52,63 This is consistent with the highest photocatalytic activity in both water oxidation and proton reduction. Thus, a higher degree of polymer crystallisation shows less charge recombination, consistent with the higher photocatalytic activity.…”

supporting

confidence: 68%

“…0.34 nm calculated from the TEM contrast intensity profile and the Fast Fourier Transforms (FFT), which is consistent with the [001] peak shown in the PXRD patterns. 52 The ability of the CTF-1 samples to evolve oxygen from water, as the focus of the study, was investigated using silver ions (from AgNO 3 ) as a sacrificial electron acceptor, which is widely used in this half reaction to fairly assess catalysts' activity. Fig.…”

Section: Resultsmentioning

confidence: 99%

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

Xie

Shevlin

Ruan

et al. 2018

Energy Environ. Sci.

251

188

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aWater oxidation is a rate-determining step in solar driven H 2 fuel synthesis and is technically challenging to promote. Despite decades of effort, only a few inorganic catalysts are effective and even fewer are effective under visible light. Recently, attention has been paid to synthetic semiconducting polymers, mainly on graphitic C 3 N 4 , with encouraging hydrogen evolution performance but lower activity for water oxidation. Here, a highly ordered covalent triazine-based framework, CTF-1 (C 8 N 2 H 4 ), is synthesised by a very mild microwave-assisted polymerisation approach. It demonstrates extremely high activity for oxygen evolution under visible light irradiation, leading to an apparent quantum efficiency (AQE) of nearly 4% at 420 nm. Furthermore, the polymer can also efficiently evolve H 2 from water. A high AQE of 6% at 420 nm for H 2 production has also been achieved. The polymer holds great potential for overall water splitting. This exceptional performance is attributed to its well-defined and ordered structure, low carbonisation, and superior band positions. Broader contextSplitting water by sunlight is an attractive renewable approach to generate clean hydrogen for producing chemicals or powering vehicles. This ultra-pure hydrogen also avoids the dreaded catalyst poisoning, which occurs even with very low levels of CO residuals from fossil-fuel generated hydrogen. The key challenge to sustain continued hydrogen generation from this artificial photosynthesis process is to speed up the water oxidation reaction, which is hard to proceed due to multiple electron transfer steps. Oxidation catalysts based on polymeric semiconductors are particularly promising for this purpose because of their abundance leading to low cost, tunable band structure to match the solar spectrum and variable degree of conjugation to impact on the p-p* excitation for efficient electron transfer. With a moderate microwave assisted strategy, we are able to control the degree of conjugation and minimise the undesirable structural carbonisation of a new type of polymeric photocatalyst-covalent triazine-based framework. The optimised catalyst shows advantageous band positions, to capture a wide spectrum of visible light and enhance the charge separation efficiency, leading to very high water oxidation and hydrogen evolution capabilities. The overall discovery paves the way for the development of efficient and continuous clean hydrogen production from the renewable visible-light water splitting process.

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supporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

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

Xie

Shevlin

Ruan

et al. 2018

Energy Environ. Sci.

251

188

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“…[37][38][39] Among them, graphitic carbon nitride (g-C 3 N 4 ), as the most stable allotrope of carbon nitrides under ambient conditions, has a unique structure comprised of a 2D sheet of tri-s-triazine connected via tertiary amines. [40][41][42][43][44] However, with a relatively large band gap (≈2.7 eV) and the existence of contact resistance between the nanosheets, g-C 3 N 4 exhibits a poor electrical conductivity and low photocatalytic activity owing to the rapid recombination of photogenerated electron-hole pairs. In particular, g-C 3 N 4 , with a moderate band gap and indirect-semiconductor nature, has become a promising metal-free catalyst for water splitting and the degradation of pollutants due to the advantages of low cost and high specific surface area (2500 m 2 g −1 for the monolayer) and has been applied in organic solar cells.…”

Section: Introductionmentioning

confidence: 99%

Hybrids of Fullerenes and 2D Nanomaterials

2018

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Fullerene has a definite 0D closed‐cage molecular structure composed of merely sp2‐hybridized carbon atoms, enabling it to serve as an important building block that is useful for constructing supramolecular assemblies and micro/nanofunctional materials. Conversely, graphene has a 2D layered structure, possessing an exceptionally large specific surface area and high carrier mobility. Likewise, other emerging graphene‐analogous 2D nanomaterials, such as graphitic carbon nitride (g‐C3N4), transition‐metal dichalcogenides (TMDs), hexagonal boron nitride (h‐BN), and black phosphorus (BP), show unique electronic, physical, and chemical properties, which, however, exist only in the form of a monolayer and are typically anisotropic, limiting their applications. Upon hybridization with fullerenes, noncovalently or covalently, the physical/chemical properties of 2D nanomaterials can be tailored and, in most cases, improved, significantly extending their functionalities and applications. Here, an exhaustive review of all types of hybrids of fullerenes and 2D nanomaterials, such as graphene, g‐C3N4, TMDs, h‐BN, and BP, including their preparations, structures, properties, and applications, is presented. Finally, the prospects of fullerene‐2D nanomaterial hybrids, especially the opportunity of creating unknown functional materials by means of hybridization, are envisioned.

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“…[38] TheXRD pattern of the nanosheets was similar to that of the bulk material. [38] TheXRD pattern of the nanosheets was similar to that of the bulk material.…”

Section: Heptazine-based Ccnsmentioning

confidence: 64%

Crystalline Carbon Nitride Semiconductors for Photocatalytic Water Splitting

2019

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Conjugated carbon nitride (CN) is an emerging and promising semiconductor photocatalyst for water photolysis owing to its unique properties. However, the traditional thermally induced polymerization of N‐containing precursors typically produces melon‐based CN solids with amorphous or semi‐crystalline structures with only moderate photocatalytic performance. Many strategies have been developed to prepare crystalline CNs (CCNs), such as high‐temperature and high‐pressure routes, ionothermal synthesis, and microwave‐assisted synthesis. In this Minireview, we summarize the progress that has been made in the synthesis of CCNs and their application in photocatalytic water splitting reactions. Three kinds of CCNs are mainly discussed according to their polymeric subunits. Challenges associated with CCNs and their future development are also included.

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Tri‐s‐triazine‐Based Crystalline Carbon Nitride Nanosheets for an Improved Hydrogen Evolution

Cited by 591 publications

References 49 publications

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

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

Hybrids of Fullerenes and 2D Nanomaterials

Crystalline Carbon Nitride Semiconductors for Photocatalytic Water Splitting

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