Improving Carbon Nitride Photocatalysis by Supramolecular Preorganization of Monomers

Shalom, Menny; Inal, Sahika; Fettkenhauer, Christian; Neher, Dieter; Antonietti, Markus

doi:10.1021/ja402521s

Cited by 834 publications

(598 citation statements)

References 26 publications

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“…22 In photocatalysis, particularly when using CN photocatalysts, morphology and surface area, in relation to the effective charge separation, are important parameters. [23][24][25][26][27][28][29][30] Density functional theory (DFT) is a useful and powerful technique to obtain the relevant photophysical and optoelectronic parameters of a given photocatalyst. 31,32 In addition to structure determination, DFT calculations can lead to the simulation of several semiconductor properties such as the bandgap, the dielectric constants and band positions, with good accuracy thanks to recently developed functionals such as HSE06.…”

Section: Introductionmentioning

confidence: 99%

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

Bhunia¹,

Melissen

Parida³

et al. 2015

Chem. Mater.

144

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Developing stable, ubiquitous and efficient water-splitting photocatalyst material that has extensive absorption in the visible-light range is desired for a sustainable solar energy-conversion device. We herein report a triazine-based carbon nitride (CN) material with different C/N ratios achieved by varying the monomer composition ratio between melamine (Mel) and 2,4,6-triaminopyrimidine (TAP). The CN material with a different C/N ratio was obtained through a two-step synthesis protocol: starting with the solution state dispersion of the monomers via hydrogen-bonding supramolecular aggregate, followed by a salt-melt high temperature polycondensation. This protocol ensures the production of a highly crystalline polytriazine imide (PTI) structure consisting of a copolymerized Mel-TAP network. The observed bandgap narrowing with an increasing TAP/Mel ratio is well simulated by density functional theory (DFT) calculations, revealing a negative shift in the valence band upon substitution of N with CH in the aromatic rings. Increasing the TAP amount could not maintain the crystalline PTI structure, consistent with DFT calculation showing the repulsion associated with additional C-H introduced in the aromatic rings. Due to the high exciton binding energy calculated by DFT for the obtained CN, the cocatalyst must be close to any portion of the material to assist the separation of excited charge carriers for an improved photocatalytic performance. The photocatalytic activity was improved by providing a dendritic tipon-like shape grown on a porous fibrous silica KCC-1 spheres, and highly dispersed Pt nanoparticles (<5 nm) were photodeposited to introduce heterojunction. As a result, the Pt/CN/KCC-1 photocatalyst exhibited an apparent quantum efficiency (AQE) as high as 22.1 ± 3% at 400 nm and the silica was also beneficial for improving photocatalytic stability. The results obtained by time-resolved transient absorption spectroscopy measurements were consistent with the improved photocatalytic activity with the slowest carrier recombination for the optimized CN photocatalyst.

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Section: Introductionmentioning

confidence: 99%

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

Bhunia¹,

Melissen

Parida³

et al. 2015

Chem. Mater.

144

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“…CN obtained by supramolecular aggregation followed by ionic melt polycondensation was shown to capture photons beyond 650 nm, while a photochemical synthesis of carbon nitride extends the absorption edge to 735 nm 51, 55, 56. Recently, we have reported carbon nitride nanosheets with redshifted photon absorption edge with high AQE (16%) 33.…”

Section: Selective Techniques For Tuning Intrinsic Properties Of Cnmentioning

confidence: 99%

Tuning the Intrinsic Properties of Carbon Nitride for High Quantum Yield Photocatalytic Hydrogen Production

2018

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The low quantum yield of photocatalytic hydrogen production in carbon nitride (CN) has been improved upon via the modulation of both the extrinsic and intrinsic properties of the material. Although the modification of extrinsic properties has been widely investigated in the past, recently there has been growing interest in the alteration of intrinsic properties. Refining the intrinsic properties of CN provides flexibility in controlling the charge transport and selectivity in photoredox reactions, and therefore makes available a pathway toward superior photocatalytic performance. An analysis of recent progress in tuning the intrinsic photophysical properties of CN facilitates an assessment of the goals, achievements, and gaps. This article is intended to serve this purpose. Therefore, selected techniques and mechanisms of the tuning of intrinsic properties of CN are critically discussed here. This article concludes with a recommendation of the issues that need to be considered for the further enhancement in the quantum efficiency of CN photocatalysts.

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“…Thus, molecular doping proved itself as very efficient technique for efficient H 2 production. Tri-s-triazine-based g-C 3 N 4 is commonly prepared from the thermal polymerization of carbon and nitrogen containing organic and inorganic materials such as melamine, cyanamide, urea, thiourea, ammonium thiocyanate and guanidine sulphate [33][34][35][36][37][38][39][40][41]. These materials are known as efficient photocatalysts for splitting of water.…”

Section: Carbon Nitride-based Polymersmentioning

confidence: 99%

Visible Light–Driven Hydrogen Production by Carbon based Polymeric Materials

Pati¹,

In²,

Tian³

2018

Visible-Light Photocatalysis of Carbon-Based Materials

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Converting solar energy into storable solar fuels such as H 2 from earth abundant sourcewater-is a nice approach to find the solution of energy crisis and environmental protection. There are two half reactions; first, water oxidation into oxygen and proton and followed by proton reduction led to H 2 evolution from water. After two decades of continuous attempts, there have been several efficient water oxidation photocatalysts introduced, whereas the proton reduction photocatalyst were relatively less explored. Major portion of reported photocatalysts for proton reduction are mainly derived from either noble metals or precious metals. Carbon-based organic photocatalysts have become attractive recently. These organic materials have several advantages like light weight, cheap, well-defined structure-property relationship and the most attractive one is better batch to batch reproducibility. Here, the reported organic photocatalysts and their performance are summarized which in fact help others to get an idea about ongoing progress in this area of research and to understand the basic designing principle for efficient photocatalysts for fuel production.

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Improving Carbon Nitride Photocatalysis by Supramolecular Preorganization of Monomers

Cited by 834 publications

References 26 publications

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

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

Tuning the Intrinsic Properties of Carbon Nitride for High Quantum Yield Photocatalytic Hydrogen Production

Visible Light–Driven Hydrogen Production by Carbon based Polymeric Materials

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